Plant E3 Ligases and Their Role in Abiotic Stress Response

Triple Threat: How Global Fungal Rice and Wheat Pathogens Utilize Comparable Pathogenicity Mechanisms to Drive Host Colonization

Plant pathogens pose significant threats to global cereal crop production, particularly for essential crops such as rice and wheat, which are fundamental to global food security and provide nearly 40% of the global caloric intake. As the global population continues to rise, increasing agricultural production to meet food demands becomes even more critical. However, the production of these vital crops is constantly threatened by phytopathological diseases, especially those caused by fungal pathogens such as Magnaporthe oryzae, the causative agent of rice blast disease; Fusarium graminearum, responsible for Fusarium head blight in wheat; and Zymoseptoria tritici, the source of Septoria tritici blotch. All three pathogens are hemibiotrophic, initially colonizing the host through a biotrophic, symptomless lifestyle, followed by causing cell death through the necrotrophic phase. Additionally, they deploy a diverse range of effectors, including proteinaceous and non-proteinaceous molecules, to manipulate fundamental host cellular processes, evade immune responses, and promote disease progression. This review discusses recent advances in understanding the effector biology of these three pathogens, highlighting both the shared functionalities and unique molecular mechanisms they employ to regulate conserved elements of host pathways, such as directly manipulating gene transcription in host nuclei, disrupting reactive oxygen species signaling, interfering with protein stability, and undermining host structural integrity. By detailing these complex interactions, the review explores potential targets for innovative control measures and emphasizes the need for further research to develop effective strategies against these destructive pathogens in the face of evolving environmental and agricultural challenges. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

MdHMGB15-MdXERICO-MdNRP module mediates salt tolerance of apple by regulating the expression of salt stress-related genes

INTRODUCTION

Soil salinity is an important limiting factor for plant growth. As a RING-type E3 ubiquitin ligase, MdXERICO is highly responsive to salt stress and can enhance the salt tolerance of plants. However, the molecular mechanism for the response of MdXERICO to salt stress remains unclear.

OBJECTIVES

This study aims to dissect the molecular mechanisms for MdXERICO to regulate plant response to salt stress.

METHODS

Transcriptome data were compared to obtain the salt stress-induced gene MdXERICO. Transgenic apple seedlings, apple calli, Arabidopsis, and tomato material were obtained using Agrobacterium-mediated transformation assays. Semiendogenous co-immunoprecipitation analysis, yeast two-hybrid, pull-down and dual-luciferase reporter system were used to detect the protein-protein interactions. Electrophoretic mobility shift assay, yeast one-hybrids, dual luciferase and Gus staining assay were employed to verify the protein-DNA interactions.

RESULTS

The results revealed that MdXERICO interacted with MdNRP and improved salt tolerance of apple by ubiquitinating and degrading MdNRP via the 26S proteasome pathway. Moreover, the HMG box-containing transcription factor MdHMGB15 interacted with the MdXERICO promoter, thereby activating its expression and enhancing the salt tolerance of apple.

CONCLUSION

This study explores the apple's tolerance to salt stress through the MdHMGB15-MdXERICO-MdNRP module, and provides potential targets for engineering salt-tolerant varieties.

A Maize Calmodulin-like 3 Gene Positively Regulates Drought Tolerance in Maize and Arabidopsis

Drought stress is one of the important abiotic stresses that affects maize production. As an important Ca2+ sensor, calmodulin-like proteins (CMLs) play key roles in plant growth, development, and stress response, but there are a limited number of studies regarding CMLs in response to drought stress. In this study, a Calmodulin-like gene, namely ZmCML3, was isolated from maize (Zea mays L.). The coding sequence (CDS) of ZmCML3 was 474 bp and a protein of 158 aa which contains three EF-hand motifs. ZmCML3 was localized within the nucleus and plasma membrane. The expression of ZmCML3 was induced by polyethylene glycol (PEG) 6000, NaCl, methyl jasmonate (MeJA), and abscisic acid (ABA). Overexpression of ZmCML3 resulted in enhanced drought tolerance in maize through increasing proline (Pro) content and the activity of peroxide (POD) and superoxide dismutase (SOD). Meanwhile, ZmCML3 also positively regulated the expression of drought stress-responsive genes in maize under drought stress treatment. Taken together, ZmCML3 acts as a positive regulator in maize response to drought stress. These results will provide theoretical basis for breeding drought tolerance maize variety.

Wheat E3 ligase TaPRP19 is involved in drought stress tolerance in transgenic Arabidopsis

TaPRP19, a wheat U-box E3 ligase gene, was isolated and characterized for its role in drought stress tolerance. The gene encodes a 531 amino acid protein with a U-box domain at the N-terminal and a WD40 domain at the C-terminal. Subcellular localization studies using TaPRP19-GFP fusion in Nicotiana benthamiana confirmed predominant nucleus localization. In vitro ubiquitination assays demonstrated that TaPRP19 possesses E3 ligase activity. RT-qPCR analysis revealed higher expression of TaPRP19 in wheat leaves, which increased under PEG, mannitol, and ABA treatments. Transgenic Arabidopsis lines overexpressing TaPRP19 exhibited improved seed germination rates and root elongation under mannitol and ABA stress, as well as enhanced survival rates under drought conditions compared to wild-type (WT) plants. Additionally, these transgenic lines showed upregulated expression of antioxidant-related and drought-marker genes, reduced ROS accumulation, and increased activities of antioxidant enzymes, suggesting enhanced oxidative stress mitigation. These findings highlight TaPRP19 as a potential target for developing drought-tolerant crops, providing insights into its functional mechanisms and paving the way for future genetic engineering applications in wheat and other crops.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-025-01557-7.

Deciphering of Genomic Loci Associated with Alkaline Tolerance in Soybean [Glycine max (L.) Merr.] by Genome-Wide Association Study

Alkaline stress is one of the major abiotic constraints that limits plant growth and development. However, the genetic basis underlying alkaline tolerance in soybean [Glycine max (L.) Merr.] remains largely unexplored. In this study, an integrated genomic analysis approach was employed to elucidate the genetic architecture of alkaline tolerance in a diverse panel of 326 soybean cultivars. Through association mapping, we detected 28 single nucleotide polymorphisms (SNPs) significantly associated with alkaline tolerance. By examining the genomic distances around these significant SNPs, five genomic regions were characterized as stable quantitative trait loci (QTLs), which were designated as qAT1, qAT4, qAT14, qAT18, and qAT20. These QTLs are reported here for the first time in soybean. Seventeen putative candidate genes were identified within the physical intervals of these QTLs. Haplotype analysis indicated that four of these candidate genes exhibited significant allele variation associated with alkaline tolerance-related traits, and the haplotype alleles for these four genes varied in number from two to four. The findings of this study may have important implications for soybean breeding programs aimed at enhancing alkaline tolerance.

Elucidating the genetic basis of bulb-related traits in garlic (Allium sativum) through genome-wide association study

The genetic architecture of garlic bulb related traits were still not well elucidated due to its big and complex genome. In this study, genotyping-by-sequencing (GBS) in 163 garlic accessions mainly from China were conducted. All the 163 garlic accessions were divided into three subpopulations, and largely consistent with geographic origins. Genome-wide association study (GWAS) was conducted for 5 garlic bulb related traits across four environments. Totally, 26 significantly loci were identified in two or more environments and located within or near 431 genes, and explain 14.0-31.7 % of the phenotypic variances. Among these, qBW5.1 was nearly with the qBH5.1. Four loci were reported previously, whereas the remaining 22 are likely to be new. Gene ontology enrichment analysis showed that the candidate genes were significantly enriched in metabolic process, biosynthetic process and catalytic activity. Nine candidate genes encode the zinc finger domain-containing protein, serine/threonine-protein kinase, peroxygenase, auxin-induced protein, ethylene-responsive transcription and E3-Ubiquitin protein ligases were identified and validated. Additionally, a meaningful achievement is one kompetitive allele-specific PCR marker, Kasp_chr7_BW for bulb weight were successfully developed and validated in a diverse panel. These results uncover the genetic mechanism of garlic bulb related traits and provide accessions and KASP markers for further garlic molecular breeding.

Genome-Wide Identification and Expression Analysis of the Alfalfa (Medicago sativa L.) U-Box Gene Family in Response to Abiotic Stresses

E3 ubiquitin ligases known as plant U-box (PUB) proteins regulate a variety of aspects of plant growth, development, and stress response. However, the functions and characteristics of the PUB gene family in alfalfa remain unclear. This work involved a genome-wide examination of the alfalfa U-box E3 ubiquitin ligase gene. In total, 210 members were identified and divided into five categories according to their homology with the members of the U-box gene family in Arabidopsis thaliana. The phylogenetic analysis, conserved motifs, chromosomal localization, promoters, and regulatory networks of this gene were investigated. Chromosomal localization and covariance analyses indicated that the MsPUB genes expanded MsPUB gene family members through gene duplication events during evolution. MsPUB genes may be involved in the light response, phytohormone response, growth, and development of several biological activities, according to cis-acting element analysis of promoters. In addition, transcriptome analysis and expression analysis by qRT-PCR indicated that most MsPUB genes were significantly upregulated under cold stress, drought stress, and salt stress treatments. Among them, MsPUBS106 and MsPUBS185 were significantly and positively correlated with cold resistance in alfalfa. MsPUBS110, MsPUBS067, MsPUBS111 and MsPUB155 were comprehensively involved in drought stress, low temperature, and salt stress resistance. All things considered, these discoveries offer fresh perspectives on the composition, development, and roles of the PUB gene family in alfalfa. They also provide theoretical guidance for further investigations into the mechanisms regulating the development, evolution, and stress tolerance of MsPUB.

Chitosan nanoparticles (CSNPs) conferred salinity tolerance in maize by upregulating E3 ubiquitin-protein ligase, P5CS1, HKT1, NHX1, and PMP3 genes

This study explored the transcriptional behaviors of several candidate genes in response to the application of CSNPs (50 and 100 mgl-1) in maize seedlings grown under two salinity levels (NaCl of 0.07 and 0.14 gkg-1soil). Employing CSNPs at both concentrations mitigated the inhibitory role of salinity on the leaf and root fresh weights. The application of CSNPs enhanced the transcription of the E3 ubiquitin-protein ligase gene by an average of threefold, contrasted with the salinity controls. The Δ1-pyrroline-5-carboxylate synthetase (P5CS1) gene was upregulated in response to both individual and mixed treatments of CSNPs and salinity. The transcription of the high-affinity K+ transporter (HKT1) gene displayed an upward trend in response to the CSNPs and salinity treatments. The Na+/H+ exchangers (NHX1) gene exhibited a similar trend to that of the HKT1 gene. The utilization of CSNPs was accompanied by an upregulation in the plasma membrane proteolipid 3 (PMP3) gene, contrasted with the salinity controls. The phenylalanine ammonia-lyase (PAL) activity displayed an upward trend in response to the foliar application of CSNPs. The CSNPs at the 100 mgl-1 concentration were more capable of inducing the ascorbate peroxidase enzyme under both salinity conditions than the 50 mgl-1 dose. The simultaneous exposure of maize seedlings to CSNPs and salinity resulted in the drastic upregulation of the catalase activities. This study provides novel insights into the major mechanisms underlying the stress-mitigating effects of CSNPs, thereby providing a suitable platform for their application in sustainable agricultural practices.

Cullin-Conciliated Regulation of Plant Immune Responses: Implications for Sustainable Crop Protection

Cullins are crucial components of the ubiquitin-proteasome system, playing pivotal roles in the regulation of protein metabolism. This review provides insight into the wide-ranging functions of cullins, particularly focusing on their impact on plant growth, development, and environmental stress responses. By modulating cullin-mediated protein mechanisms, researchers can fine-tune hormone-signaling networks to improve various agronomic traits, including plant architecture, flowering time, fruit development, and nutrient uptake. Furthermore, the targeted manipulation of cullins that are involved in hormone-signaling pathways, e.g., cytokinin, auxin, gibberellin, abscisic acids, and ethylene, can boost crop growth and development while increasing yield and enhancing stress tolerance. Furthermore, cullins also play important roles in plant defense mechanisms through regulating the defense-associated protein metabolism, thus boosting resistance to pathogens and pests. Additionally, this review highlights the potential of integrating cullin-based strategies with advanced biological tools, such as CRISPR/Cas9-mediated genome editing, genetic engineering, marker-associated selections, gene overexpression, and gene knockout, to achieve precise modifications for crop improvement and sustainable agriculture, with the promise of creating resilient, high-yielding, and environmentally friendly crop varieties.

Deciphering the mechanism of E3 ubiquitin ligases in plant responses to abiotic and biotic stresses and perspectives on PROTACs for crop resistance

With global climate change, it is essential to find strategies to make crops more resistant to different stresses and guarantee food security worldwide. E3 ubiquitin ligases are critical regulatory elements that are gaining importance due to their role in selecting proteins for degradation in the ubiquitin-proteasome proteolysis pathway. The role of E3 Ub ligases has been demonstrated in numerous cellular processes in plants responding to biotic and abiotic stresses. E3 Ub ligases are considered a class of proteins that are difficult to control by conventional inhibitors, as they lack a standard active site with pocket, and their biological activity is mainly due to protein-protein interactions with transient conformational changes. Proteolysis-targeted chimeras (PROTACs) are a new class of heterobifunctional molecules that have emerged in recent years as relevant alternatives for incurable human diseases like cancer because they can target recalcitrant proteins for destruction. PROTACs interact with the ubiquitin-proteasome system, principally the E3 Ub ligase in the cell, and facilitate proteasome turnover of the proteins of interest. PROTAC strategies harness the essential functions of E3 Ub ligases for proteasomal degradation of proteins involved in dysfunction. This review examines critical advances in E3 Ub ligase research in plant responses to biotic and abiotic stresses. It highlights how PROTACs can be applied to target proteins involved in plant stress response to mitigate pathogenic agents and environmental adversities.

A review on ubiquitin ligases: Orchestrators of plant resilience in adversity

Ubiquitin- proteasome system (UPS) is universally present in plants and animals, mediating many cellular processes needed for growth and development. Plants constantly defend themselves against endogenous and exogenous stimuli such as hormonal signaling, biotic stresses such as viruses, fungi, nematodes, and abiotic stresses like drought, heat, and salinity by developing complex regulatory mechanisms. Ubiquitination is a regulatory mechanism involving selective elimination and stabilization of regulatory proteins through the UPS system where E3 ligases play a central role; they can bind to the targets in a substrate-specific manner, followed by poly-ubiquitylation, and subsequent protein degradation by 26 S proteasome. Increasing evidence suggests different types of E3 ligases play important roles in plant development and stress adaptation. Herein, we summarize recent advances in understanding the regulatory roles of different E3 ligases and primarily focus on protein ubiquitination in plant-environment interactions. It also highlights the diversity and complexity of these metabolic pathways that enable plant to survive under challenging conditions. This reader-friendly review provides a comprehensive overview of E3 ligases and their substrates associated with abiotic and biotic stresses that could be utilized for future crop improvement.

Gene Expression Divergence in Eugenia uniflora Highlights Adaptation across Contrasting Atlantic Forest Ecosystems

Understanding the evolution and the effect of plasticity in plant responses to environmental changes is crucial to combat global climate change. It is particularly interesting in species that survive in distinct environments, such as Eugenia uniflora, which thrives in contrasting ecosystems within the Atlantic Forest (AF). In this study, we combined transcriptome analyses of plants growing in nature (Restinga and Riparian Forest) with greenhouse experiments to unveil the DEGs within and among adaptively divergent populations of E. uniflora. We compared global gene expression among plants from two distinct ecological niches. We found many differentially expressed genes between the two populations in natural and greenhouse-cultivated environments. The changes in how genes are expressed may be related to the species' ability to adapt to specific environmental conditions. The main difference in gene expression was observed when plants from Restinga were compared with their offspring cultivated in greenhouses, suggesting that there are distinct selection pressures underlying the local environmental and ecological factors of each Restinga and Riparian Forest ecosystem. Many of these genes engage in the stress response, such as water and nutrient transport, temperature, light intensity, and gene regulation. The stress-responsive genes we found are potential genes for selection in these populations. These findings revealed the adaptive potential of E. uniflora and contributed to our understanding of the role of gene expression reprogramming in plant evolution and niche adaptation.

The F-Box Protein TaFBA1 Positively Regulates Drought Resistance and Yield Traits in Wheat

Environmental stresses, including drought stress, seriously threaten food security. Previous studies reported that wheat F-box protein, TaFBA1, responds to abiotic stresses in tobacco. Here, we generated transgenic wheat with enhanced (overexpression, OE) or suppressed (RNA interference, RNAi) expression of TaFBA1. The TaFBA1-OE seedlings showed enhanced drought tolerance, as measured by survival rate and fresh weight under severe drought stress, whereas the RNAi plants showed the opposite phenotype. Furthermore, the OE plants had stronger antioxidant capacity compared to WT and RNAi plants and maintained stomatal opening, which resulted in higher water loss under drought stress. However, stronger water absorption capacity in OE roots contributed to higher relative water contents in leaves under drought stress. Moreover, the postponed stomatal closure in OE lines helped to maintain photosynthesis machinery to produce more photoassimilate and ultimately larger seed size. Transcriptomic analyses conducted on WT and OE plants showed that genes involved in antioxidant, fatty acid and lipid metabolism and cellulose synthesis were significantly induced by drought stress in the leaves of OE lines. Together, our studies determined that the F-box protein TaFBA1 modulated drought tolerance and affected yield in wheat and the TaFBA1 gene could provide a desirable target for further breeding of wheat.

Comparative Stem Transcriptome Analysis Reveals Pathways Associated with Drought Tolerance in Maritime Pine Grafts

The maritime pine (Pinus pinaster Ait.) is a highly valuable Mediterranean conifer. However, recurrent drought events threaten its propagation and conservation. P. pinaster populations exhibit remarkable differences in drought tolerance. To explore these differences, we analyzed stem transcriptional profiles of grafts combining genotypes with contrasting drought responses under well-watered and water-stress regimes. Our analysis underscored that P. pinaster drought tolerance is mainly associated with constitutively expressed genes, which vary based on genotype provenance. However, we identified key genes encoding proteins involved in water stress response, abscisic acid signaling, and growth control including a PHD chromatin regulator, a histone deubiquitinase, the ABI5-binding protein 3, and transcription factors from Myb-related, DOF NAC and LHY families. Additionally, we identified that drought-tolerant rootstock could enhance the drought tolerance of sensitive scions by regulating the accumulation of transcripts involved in carbon mobilization, osmolyte biosynthesis, flavonoid and terpenoid metabolism, and reactive oxygen species scavenging. These included genes encoding galactinol synthase, CBL-interacting serine/threonine protein kinase 5, BEL1-like homeodomain protein, dihydroflavonol 4-reductase, and 1-deoxy-D-xylulose-5-phosphate. Our results revealed several hub genes that could help us to understand the molecular and physiological response to drought of conifers. Based on all the above, grafting with selected drought-tolerant rootstocks is a promising method for propagating elite recalcitrant conifer species, such as P. pinaster.

Pepper RING-Type E3 Ligase CaFIRF1 Negatively Regulates the Protein Stability of Pepper Stress-Associated Protein, CaSAP14, in the Dehydration Stress Response

As part of the cellular stress response in plants, the ubiquitin-proteasome system (UPS) plays a crucial role in regulating the protein stability of stress-related transcription factors. Previous study has indicated that CaSAP14 is functionally involved in enhancing pepper plant tolerance to dehydration stress by modulating the expression of downstream genes. However, the comprehensive regulatory mechanism underlying CaSAP14 remains incompletely understood. Here, we identified a RING-type E3 ligase, CaFIRF1, which interacts with and ubiquitinates CaSAP14. Pepper plants with silenced CaFIRF1 exhibited a dehydration-tolerant phenotype when subjected to dehydration stress, while overexpression of CaFIRF1 in pepper and Arabidopsis resulted in reduced dehydration tolerance. Co-silencing of CaFIRF1 and CaSAP14 in pepper increased sensitivity to dehydration, suggesting that CaFIRF1 acts upstream of CaSAP14. A cell-free degradation analysis demonstrated that silencing of CaFIRF1 led to decreased CaSAP14 protein degradation, implicating CaFIRF1 in the regulation of CaSAP14 protein via the 26S proteasomal degradation pathway. Our findings suggest a mechanism by which CaFIRF1 mediates the ubiquitin-dependent proteasomal degradation of CaSAP14, thereby influencing the response of pepper plants to dehydration stress.

Molecular and biochemical components associated with chilling tolerance in tomato: comparison of different developmental stages

The cultivated tomato, Solanum lycopersicum, is highly sensitive to cold stress (CS), resulting in significant losses during cultivation and postharvest fruit storage. Previously, we demonstrated the presence of substantial genetic variation in fruit chilling tolerance in a tomato recombinant inbred line (RIL) population derived from a cross between a chilling-sensitive tomato line and a chilling-tolerant accession of the wild species S. pimpinellifolium. Here, we investigated molecular and biochemical components associated with chilling tolerance in fruit and leaves, using contrasting groups of "chilling tolerant" and "chilling sensitive" RI lines. Transcriptomic analyses were conducted on fruit exposed to CS, and gene expressions and biochemical components were measured in fruit and leaves. The analyses revealed core responding genes specific to either the cold-tolerant or cold-sensitive RI lines, which were differentially regulated in similar fashion in both leaves and fruit within each group. These genes may be used as markers to determine tomato germplasm cold tolerance or sensitivity. This study demonstrated that tomato response to CS in different developmental stages, including seedling and postharvest fruit, might be mediated by common biological/genetic factors. Therefore, genetic selection for cold tolerance during early stages of plant development may lead to lines with greater postharvest fruit chilling tolerance.

The lowdown on breakdown: Open questions in plant proteolysis

Proteolysis, including post-translational proteolytic processing as well as protein degradation and amino acid recycling, is an essential component of the growth and development of living organisms. In this article, experts in plant proteolysis pose and discuss compelling open questions in their areas of research. Topics covered include the role of proteolysis in the cell cycle, DNA damage response, mitochondrial function, the generation of N-terminal signals (degrons) that mark many proteins for degradation (N-terminal acetylation, the Arg/N-degron pathway, and the chloroplast N-degron pathway), developmental and metabolic signaling (photomorphogenesis, abscisic acid and strigolactone signaling, sugar metabolism, and postharvest regulation), plant responses to environmental signals (endoplasmic-reticulum-associated degradation, chloroplast-associated degradation, drought tolerance, and the growth-defense trade-off), and the functional diversification of peptidases. We hope these thought-provoking discussions help to stimulate further research.

Genomic-wide analysis reveals seven in absentia genes regulating grain development in wheat (Triticum aestivum L.)

Seven in absentia proteins, which contain a conserved SINA domain, are involved in regulating various aspects of wheat (Triticum aestivum L.) growth and development, especially in response to environmental stresses. However, it is unclear whether TaSINA family members are involved in regulating grain development until now. In this study, the expression pattern, genomic polymorphism, and relationship with grain-related traits were analyzed for all TaSINA members. Most of the TaSINA genes identified showed higher expression levels in young wheat spikes or grains than other organs. The genomic polymorphism analysis revealed that at least 62 TaSINA genes had different haplotypes, where the haplotypes of five genes were significantly correlated with grain-related traits. Kompetitive allele-specific PCR markers were developed to confirm the single nucleotide polymorphisms in TaSINA101 and TaSINA109 among the five selected genes in a set of 292 wheat accessions. The TaSINA101-Hap II and TaSINA109-Hap II haplotypes had higher grain weight and width compared to TaSINA101-Hap I and TaSINA109-Hap I in at least three environments, respectively. The qRT-PCR assays revealed that TaSINA101 was highly expressed in the palea shell, seed coat, and embryo in young wheat grains. The TaSINA101 protein was unevenly distributed in the nucleus when transiently expressed in the protoplast of wheat. Three homozygous TaSINA101 transgenic lines in rice (Oryza sativa L.) showed higher grain weight and size compared to the wild type. These findings provide valuable insight into the biological function and elite haplotype of TaSINA family genes in wheat grain development at a genomic-wide level.

Rab7 GTPase-Mediated stress signaling enhances salinity tolerance in AlRabring7 tobacco transgenics by modulating physio-biochemical parameters

The RING-type E3 ligases play a significant role in stress signaling, primarily through post-translational regulation. Ubiquitination is a crucial post-translational modification that regulates the turnover and activity of proteins. The overexpression of AlRabring7, RING-HC E3 Ub ligase in tobacco provides insights into the regulation of salinity and ABA signaling in transgenic tobacco. The seed germination potential of AlRabring7 transgenics was higher than WT, with NaCl and ABA treatments. The transgenics showed improved morpho-physio-biochemical parameters in response to salinity and ABA treatments. The photosynthetic pigments, soluble sugars, reducing sugars and proline increased in transgenics in response to NaCl and ABA treatments. The decreased ROS accumulation in transgenics on NaCl and ABA treatments can be co-related to improved activity of enzymatic and non-enzymatic antioxidants. The potential of transgenics to maintain ABA levels with ABA treatment, highlights the active participation of ABA feedback loop mechanism. Interestingly, the ability of AlRabring7 transgenics to upregulate Rab7 protein, suggests its role in facilitating vacuolar transport. Furthermore, the improved potassium accumulation and reduced sodium content indicate an efficient ion regulation mechanism in transgenic plants facilitating higher stomatal opening. The expression of downstream ion transporter (NbNHX1 and NbVHA1), ABA signaling (NbABI2 and NbABI5) and vesicle trafficking (NbMON1) responsive genes were upregulated with stress. The present study, reports that AlRabring7 participates in maintaining vacuolar transport, ion balance, ROS homeostasis, stomatal regulation through activation of Rab7 protein and regulation of downstream stress-responsive during stress. This emphasizes the potential of AlRabring7 gene for improved performance and resilience in challenging environments.

Genome-Wide Identification and Functional Analysis of the Genes of the ATL Family in Maize during High-Temperature Stress in Maize

Maize is a significant food and feed product, and abiotic stress significantly impacts its growth and development. Arabidopsis Toxicosa en Levadura (ATL), a member of the RING-H2 E3 subfamily, modulates various physiological processes and stress responses in Arabidopsis. However, the role of ATL in maize remains unexplored. In this study, we systematically identified the genes encoding ATL in the maize genome. The results showed that the maize ATL family consists of 77 members, all predicted to be located in the cell membrane and cytoplasm, with a highly conserved RING domain. Tissue-specific expression analysis revealed that the expression levels of ATL family genes were significantly different in different tissues. Examination of the abiotic stress data revealed that the expression levels of ATL genes fluctuated significantly under different stress conditions. To further understand the biological functions of maize ATL family genes under high-temperature stress, we studied the high-temperature phenotypes of the maize ZmATL family gene ZmATL10 and its homologous gene AtATL27 in Arabidopsis. The results showed that overexpression of the ZmATL10 and AtATL27 genes enhanced resistance to high-temperature stress.

Single-cell transcriptome landscape elucidates the cellular and developmental responses to tomato chlorosis virus infection in tomato leaf

Plant viral diseases compromise the growth and yield of the crop globally, and they tend to be more serious under extreme temperatures and drought climate changes. Currently, regulatory dynamics during plant development and in response to virus infection at the plant cell level remain largely unknown. In this study, single-cell RNA sequencing on 23 226 individual cells from healthy and tomato chlorosis virus-infected leaves was established. The specific expression and epigenetic landscape of each cell type during the viral infection stage were depicted. Notably, the mesophyll cells showed a rapid function transition in virus-infected leaves, which is consistent with the pathological changes such as thinner leaves and decreased chloroplast lamella in virus-infected samples. Interestingly, the F-box protein SKIP2 was identified to play a pivotal role in chlorophyll maintenance during virus infection in tomato plants. Knockout of the SlSKIP2 showed a greener leaf state before and after virus infection. Moreover, we further demonstrated that SlSKIP2 was located in the cytomembrane and nucleus and directly regulated by ERF4. In conclusion, with detailed insights into the plant responses to viral infections at the cellular level, our study provides a genetic framework and gene reference in plant-virus interaction and breeding in the future research.

An insight into the roles of ubiquitin-specific proteases in plants: development and growth, morphogenesis, and stress response

Ubiquitination is a highly conserved and dynamic post-translational modification in which protein substrates are modified by ubiquitin to influence their activity, localization, or stability. Deubiquitination enzymes (DUBs) counter ubiquitin signaling by removing ubiquitin from the substrates. Ubiquitin-specific proteases (UBPs), the largest subfamily of DUBs, are conserved in plants, serving diverse functions across various cellular processes, although members within the same group often exhibit functional redundancy. Here, we briefly review recent advances in understanding the biological roles of UBPs, particularly the molecular mechanism by which UBPs regulate plant development and growth, morphogenesis, and stress response, which sheds light on the mechanistic roles of deubiquitination in plants.

PDX proteins from Arabidopsis thaliana as novel substrates of cathepsin B: implications for vitamin B6 biosynthesis regulation

Vitamin B6 is a critical molecule for metabolism, development, and stress sensitivity in plants. It is a cofactor for numerous biochemical reactions, can serve as an antioxidant, and has the potential to increase tolerance against both biotic and abiotic stressors. Due to the importance of vitamin B6, its biosynthesis is likely tightly regulated. Plants can synthesize vitamin B6 de novo via the concerted activity of Pyridoxine Biosynthesis Protein 1 (PDX1) and PDX2. Previously, PDX proteins have been identified as targets for ubiquitination, indicating they could be marked for degradation by two highly conserved pathways: the Ubiquitin Proteasome Pathway (UPP) and the autophagy pathway. Initial experiments show that PDXs are in fact degraded, but surprisingly, in a ubiquitin-independent manner. Inhibitor studies pointed toward cathepsin B, a conserved lysosomal cysteine protease, which is implicated in both programed cell death and autophagy in humans and plants. In plants, cathepsin Bs are poorly described, and no confirmed substrates have been identified. Here, we present PDX proteins from Arabidopsis thaliana as interactors and substrates of a plant Cathepsin B. These findings not only describe a novel cathepsin B substrate in plants, but also provide new insights into how plants regulate de novo biosynthesis of vitamin B6.

GhVIM28, a negative regulator identified from VIM family genes, positively responds to salt stress in cotton

The VIM (belonged to E3 ubiquitin ligase) gene family is crucial for plant growth, development, and stress responses, yet their role in salt stress remains unclear. We analyzed phylogenetic relationships, chromosomal localization, conserved motifs, gene structure, cis-acting elements, and gene expression patterns of the VIM gene family in four cotton varieties. Our findings reveal 29, 29, 17, and 14 members in Gossypium hirsutum (G.hirsutum), Gossypium barbadense (G.barbadense), Gossypium arboreum (G.arboreum), and Gossypium raimondii (G. raimondii), respectively, indicating the maturity and evolution of this gene family. motifs among GhVIMs genes were observed, along with the presence of stress-responsive, hormone-responsive, and growth-related elements in their promoter regions. Gene expression analysis showed varying patterns and tissue specificity of GhVIMs genes under abiotic stress. Silencing GhVIM28 via virus-induced gene silencing revealed its role as a salt-tolerant negative regulator. This work reveals a mechanism by which the VIM gene family in response to salt stress in cotton, identifying a potential negative regulator, GhVIM28, which could be targeted for enhancing salt tolerance in cotton. The objective of this study was to explore the evolutionary relationship of the VIM gene family and its potential function in salt stress tolerance, and provide important genetic resources for salt tolerance breeding of cotton.

A pepper RING-finger E3 ligase, CaFIRF1, negatively regulates the high-salt stress response by modulating the stability of CaFAF1

Controlling protein stability or degradation via the ubiquitin-26S proteasome system is a crucial mechanism in plant cellular responses to stress conditions. Previous studies have revealed that the pepper FANTASTIC FOUR-like gene, CaFAF1, plays a positive role in salt tolerance and that, in this process, CaFAF1 protein degradation is delayed. Here, we sought to isolate the E3 ligases potentially responsible for modulating CaFAF1 protein stability in response to salt stress. The pepper RING-type E3 ligase CaFIRF1 (Capsicum  annuum  FAF1  Interacting  RING  Finger protein  1) was found to interact with and ubiquitinate CaFAF1, leading to the degradation of CaFAF1 proteins. In response to high-salt treatments, CaFIRF1-silenced pepper plants exhibited tolerant phenotypes. In contrast, co-silencing of CaFAF1 and CaFIRF1 led to increased sensitivity to high-salt treatments, revealing that CaFIRF1 functions upstream of CaFAF1. A cell-free degradation analysis showed that high-salt treatment suppressed CaFAF1 protein degradation via the 26S proteasome pathway, in which CaFIRF1 is functionally involved. In addition, an in vivo ubiquitination assay revealed that CaFIRF1-mediated ubiquitination of CaFAF1 proteins was reduced by high-salt treatment. Taken together, these findings suggest that the degradation of CaFAF1 mediated by CaFIRF1 has a critical role in pepper plant responses to high salinity.

The F-box protein ZmFBL41 negatively regulates disease resistance to Rhizoctonia solani by degrading the abscisic acid synthase ZmNCED6 in maize

KEY MESSAGE

The maize F-box protein ZmFBL41 targets abscisic acid synthase 9-cis-epoxycarotenoid dioxygenase 6 for degradation, and this regulatory module is exploited by Rhizoctonia solani to promote infection. F-box proteins are crucial regulators of plant growth, development, and responses to abiotic and biotic stresses. Previous research identified the F-box gene ZmFBL41 as a negative regulator of maize (Zea mays) defenses against Rhizoctonia solani. However, the precise mechanisms by which F-box proteins mediate resistance to R. solani remain poorly understood. In this study, we show that ZmFBL41 interacts with an abscisic acid (ABA) synthase, 9-cis-epoxycarotenoid dioxygenase 6 (ZmNCED6), promoting its degradation via the ubiquitination pathway. We discovered that the ectopic overexpression of ZmNCED6 in rice (Oryza sativa) inhibited R. solani infection by activating stomatal closure, callose deposition, and jasmonic acid (JA) biosynthesis, indicating that ZmNCED6 enhances plant immunity against R. solani. Natural variation at ZmFBL41 across different maize haplotypes did not affect the ZmFBL41-ZmNCED6 interaction. These findings suggest that ZmFBL41 targets ZmNCED6 for degradation, leading to a decrease in ABA levels in maize, in turn, inhibiting ABA-mediated disease resistance pathways, such as stomatal closure, callose deposition, and JA biosynthesis, ultimately facilitating R. solani infection.

Long noncoding RNA TRABA suppresses β-glucosidase-encoding BGLU24 to promote salt tolerance in cotton

Salt stress severely damages the growth and yield of crops. Recently, long noncoding RNAs (lncRNAs) were demonstrated to regulate various biological processes and responses to environmental stresses. However, the regulatory mechanisms of lncRNAs in cotton (Gossypium hirsutum) response to salt stress are still poorly understood. Here, we observed that a lncRNA, trans acting of BGLU24 by lncRNA (TRABA), was highly expressed while GhBGLU24-A was weakly expressed in a salt-tolerant cotton accession (DM37) compared to a salt-sensitive accession (TM-1). Using TRABA as an effector and proGhBGLU24-A-driven GUS as a reporter, we showed that TRABA suppressed GhBGLU24-A promoter activity in double transgenic Arabidopsis (Arabidopsis thaliana), which explained why GhBGLU24-A was weakly expressed in the salt-tolerant accession compared to the salt-sensitive accession. GhBGLU24-A encodes an endoplasmic reticulum (ER)-localized β-glucosidase that responds to salt stress. Further investigation revealed that GhBGLU24-A interacted with RING-type E3 ubiquitin ligase (GhRUBL). Virus-induced gene silencing (VIGS) and transgenic Arabidopsis studies revealed that both GhBGLU24-A and GhRUBL diminish plant tolerance to salt stress and ER stress. Based on its substantial effect on ER-related degradation (ERAD)-associated gene expression, GhBGLU24-A mediates ER stress likely through the ERAD pathway. These findings provide insights into the regulatory role of the lncRNA TRABA in modulating salt and ER stresses in cotton and have potential implications for developing more resilient crops.

Maize MITOGEN-ACTIVATED PROTEIN KINASE 20 mediates high-temperature-regulated stomatal movement

High temperature induces stomatal opening; however, uncontrolled stomatal opening is dangerous for plants in response to high temperature. We identified a high-temperature sensitive (hts) mutant from the ethyl methane sulfonate (EMS)-induced maize (Zea mays) mutant library that is linked to a single base change in MITOGEN-ACTIVATED PROTEIN KINASE 20 (ZmMPK20). Our data demonstrated that hts mutants exhibit substantially increased stomatal opening and water loss rate, as well as decreased thermotolerance, compared to wild-type plants under high temperature. ZmMPK20-knockout mutants showed similar phenotypes as hts mutants. Overexpression of ZmMPK20 decreased stomatal apertures, water loss rate, and enhanced plant thermotolerance. Additional experiments showed that ZmMPK20 interacts with MAP KINASE KINASE 9 (ZmMKK9) and E3 ubiquitin ligase RPM1 INTERACTING PROTEIN 2 (ZmRIN2), a maize homolog of Arabidopsis (Arabidopsis thaliana) RIN2. ZmMPK20 prevented ZmRIN2 degradation by inhibiting ZmRIN2 self-ubiquitination. ZmMKK9 phosphorylated ZmMPK20 and enhanced the inhibitory effect of ZmMPK20 on ZmRIN2 degradation. Moreover, we employed virus-induced gene silencing (VIGS) to silence ZmMKK9 and ZmRIN2 in maize and heterologously overexpressed ZmMKK9 or ZmRIN2 in Arabidopsis. Our findings demonstrated that ZmMKK9 and ZmRIN2 play negative regulatory roles in high-temperature-induced stomatal opening. Accordingly, we propose that the ZmMKK9-ZmMPK20-ZmRIN2 cascade negatively regulates high-temperature-induced stomatal opening and balances water loss and leaf temperature, thus enhancing plant thermotolerance.

Overexpression of a C3HC4-type E3-ubiquitin ligase contributes to salinity tolerance by modulating Na+ homeostasis in rice

Soil salinity has a negative effect on crop yield. Therefore, plants have evolved many strategies to overcome decreases in yield under saline conditions. Among these, E3-ubiquitin ligase regulates salt tolerance. We characterized Oryza sativa Really Interesting New Gene (RING) Finger C3HC4-type E3 ligase (OsRFPHC-4), which plays a positive role in improving salt tolerance. The expression of OsRFPHC-4 was downregulated by high NaCl concentrations and induced by abscisic acid (ABA) treatment. GFP-fused OsRFPHC-4 was localized to the plasma membrane of rice protoplasts. OsRFPHC-4 encodes a cellular protein with a C3HC4-RING domain with E3 ligase activity. However, its variant OsRFPHC-4C161A does not possess this activity. OsRFPHC-4-overexpressing plants showed enhanced salt tolerance due to low accumulation of Na+ in both roots and leaves, low Na+ transport in the xylem sap, high accumulation of proline and soluble sugars, high activity of reactive oxygen species (ROS) scavenging enzymes, and differential regulation of Na+ /K+ transporter expression compared to wild-type (WT) and osrfphc-4 plants. In addition, OsRFPHC-4-overexpressing plants showed higher ABA sensitivity under exogenous ABA treatment than WT and osrfphc-4 plants. Overall, these results suggest that OsRFPHC-4 contributes to the improvement of salt tolerance and Na+ /K+ homeostasis via the regulation of changes in Na+ /K+ transporters.

Genome-wide analysis of the U-box E3 ubiquitin ligase family role in drought tolerance in sesame (Sesamum indicum L.)

Plant U-box (PUB) proteins belong to a class of ubiquitin ligases essential in various biological processes. Sesame (Sesamum indicum L.) is an important and worldwide cultivated oilseed crop. However few studies have been conducted to explore the role of PUBs in drought tolerance in sesame. This study identified a total of 56 members of the sesame PUB family (SiPUB) genes distributed unevenly across all 13 chromosomes. Based on phylogenetic analysis, all 56 SiPUB genes were classified into six groups with various structures and motifs. Cis-acting element analysis suggested that the SiPUB genes are involved in response to various stresses including drought. Based on RNA-seq analysis and quantitative real-time PCR, we identified nine SiPUB genes with significantly different expression profiles under drought stress. The expression patterns of six SiPUB genes in root, leaf and stem tissues corroborated the reliability of the RNA-seq datasets. These findings underscore the importance of SiPUB genes in enhancing drought tolerance in sesame plants. Our study provides novel insights into the evolutionary patterns and variations of PUB genes in sesame and lays the foundation for comprehending the functional characteristics of SiPUB genes under drought-induced stress conditions.

Ubiquitin E3 ligase AtCHYR2 functions in glucose regulation of germination and post-germinative growth in Arabidopsis thaliana

KEY MESSAGE

Cytoplasm-localized RING ubiquitin E3 ligase AtCHYR2 involved in plant glucose responses during germination and post-germinative growth. CHY ZINC FINGER AND RING PROTEIN (CHYR) containing both a CHY zinc finger and a C3H2C3-type RING domain plays important roles in plant drought tolerance and the abscisic acid (ABA) response; however, their functions in sugar signaling pathways are less studied. Here, we report a glucose (Glc) response gene AtCHYR2, a homolog of RZFP34/CHYR1, which is induced by various abiotic stresses, ABA, and sugar treatments. In vitro, we demonstrated that AtCHYR2 is a cytoplasm-localized RING ubiquitin E3 ligase. Overexpression of AtCHYR2 led to hypersensitivity to Glc and enhanced Glc-mediated inhibition of cotyledon greening and post-germinative growth. Contrastingly, AtCHYR2 loss-of-function plants were insensitive to Glc-regulated seed germination and primary root growth, suggesting that AtCHYR2 is a positively regulator of the plant glucose response. Additionally, physiological analyses showed that overexpression AtCHYR2 increased stomata aperture and photosynthesis under normal condition, and promoted accumulation of endogenous soluble sugar and starch in response to high Glc. Genome-wide RNA sequencing analysis showed that AtCHYR2 affects a major proportion of Glc-responsive genes. Particularly, sugar marker gene expression analysis suggested that AtCHYR2 enhances the Glc response via a signaling pathway dependent on glucose metabolism. Taken together, our findings show that a novel RING ubiquitin E3 ligase, AtCHYR2, plays an important role in glucose responses in Arabidopsis.

Transcriptomic and functional analyses reveal the molecular mechanisms underlying Fe-mediated tobacco resistance to potato virus Y infection

Potato virus Y (PVY) mainly infects Solanaceous crops, resulting in considerable losses in the yield and quality. Iron (Fe) is involved in various biological processes in plants, but its roles in resistance to PVY infection has not been reported. In this study, foliar application of Fe could effectively inhibit early infection of PVY, and a full-length transcriptome and Illumina RNA sequencing was performed to investigate its modes of action in PVY-infected Nicotiana tabacum. The results showed that 18,074 alternative splicing variants, 3,654 fusion transcripts, 3,086 long non-coding RNAs and 14,403 differentially expressed genes (DEGs) were identified. Specifically, Fe application down-regulated the expression levels of the DEGs related to phospholipid hydrolysis, phospholipid signal, cell wall biosynthesis, transcription factors (TFs) and photosystem I composition, while those involved with photosynthetic electron transport chain (PETC) were up-regulated at 1 day post inoculation (dpi). At 3 dpi, these DEGs related to photosystem II composition, PETC, molecular chaperones, protein degradation and some TFs were up-regulated, while those associated with light-harvesting, phospholipid hydrolysis, cell wall biosynthesis were down-regulated. At 9 dpi, Fe application had little effects on resistance to PVY infection and transcript profiles. Functional analysis of these potentially critical DEGs was thereafter performed using virus-induced gene silencing approaches and the results showed that NbCat-6A positively regulates PVY infection, while the reduced expressions of NbWRKY26, NbnsLTP, NbFAD3 and NbHSP90 significantly promote PVY infection in N. benthamiana. Our results elucidated the regulatory network of Fe-mediated resistance to PVY infection in plants, and the functional candidate genes also provide important theoretical bases to further improve host resistance against PVY infection.

Genome-wide identification and expression profiling reveal the regulatory role of U-box E3 ubiquitin ligase genes in strawberry fruit ripening and abiotic stresses resistance

The plant U-box (PUB) proteins are a type of E3 ubiquitin ligases well known for their functions in response to various stresses. They are also related to fruit development and ripening. However, PUB members possess such roles that remain unclear in strawberry. In this study, 155 PUB genes were identified in octoploid strawberry and classified into four groups. Their promoters possessed a variety of cis-acting elements, most of which are associated with abiotic stresses, followed by phytohormones response and development. Protein-protein interaction analysis suggested that FaU-box members could interact with each other as well as other proteins involved in hormone signaling and stress resistance. Transcriptome-based and RT-qPCR expression analysis revealed the potential involvement of FaU-box genes in resistance to stresses and fruit ripening. Of these, FaU-box98 and FaU-box136 were positively while FaU-box52 was negatively related to strawberry ripening. FaU-box98 comprehensively participated in resistance of ABA, cold, and salt, while FaU-box83 and FaU-box136 were broadly associated with drought and salt stresses. FaU-box18 and FaU-box52 were ABA-specific; FaU-box3 was specific to salt stress. In addition, the functional analysis of a randomly selected FaU-box (FaU-box127) showed that the transient overexpression of FaU-box127 promoted the ripening of strawberry fruit, along with significant changes in the expression levels of some ripening-related genes and the content of organic acid and soluble sugar. Overall, these findings provided comprehensive information about the FaU-box gene family and identified the potential FaU-box members participating in stress resistance and strawberry fruit ripening regulation.

The Role of Transmembrane Proteins in Plant Growth, Development, and Stress Responses

Transmembrane proteins participate in various physiological activities in plants, including signal transduction, substance transport, and energy conversion. Although more than 20% of gene products are predicted to be transmembrane proteins in the genome era, due to the complexity of transmembrane domains they are difficult to reliably identify in the predicted protein, and they may have different overall three-dimensional structures. Therefore, it is challenging to study their biological function. In this review, we describe the typical structures of transmembrane proteins and their roles in plant growth, development, and stress responses. We propose a model illustrating the roles of transmembrane proteins during plant growth and response to various stresses, which will provide important references for crop breeding.

Structural and functional analysis of stress-inducible genes and their promoters selected from young oil palm (Elaeis guineensis) under salt stress

Background

Soil salinity is a problem in more than 100 countries across all continents. It is one of the abiotic stress that threatens agriculture the most, negatively affecting crops and reducing productivity. Transcriptomics is a technology applied to characterize the transcriptome in a cell, tissue, or organism at a given time via RNA-Seq, also known as full-transcriptome shotgun sequencing. This technology allows the identification of most genes expressed at a particular stage, and different isoforms are separated and transcript expression levels measured. Once determined by this technology, the expression profile of a gene must undergo validation by another, such as quantitative real-time PCR (qRT-PCR). This study aimed to select, annotate, and validate stress-inducible genes—and their promoters—differentially expressed in the leaves of oil palm (Elaeis guineensis) plants under saline stress.

Results

The transcriptome analysis led to the selection of 14 genes that underwent structural and functional annotation, besides having their expression validated using the qRT-PCR technique. When compared, the RNA-Seq and qRT-PCR profiles of those genes resulted in some inconsistencies. The structural and functional annotation analysis of proteins coded by the selected genes showed that some of them are orthologs of genes reported as conferring resistance to salinity in other species. There were those coding for proteins related to the transport of salt into and out of cells, transcriptional regulatory activity, and opening and closing of stomata. The annotation analysis performed on the promoter sequence revealed 22 distinct types of cis-acting elements, and 14 of them are known to be involved in abiotic stress.

Conclusion

This study has helped validate the process of an accurate selection of genes responsive to salt stress with a specific and predefined expression profile and their promoter sequence. Its results also can be used in molecular-genetics-assisted breeding programs. In addition, using the identified genes is a window of opportunity for strategies trying to relieve the damages arising from the salt stress in many glycophyte crops with economic importance.

Arabidopsis thaliana E3 ligase AIRP4 is involved in GA synthesis

Arabidopsis abscisic acid ABA-Insensitive RING Proteins (AtAIRP1-4) are RING E3s that play significant roles in ABA-signaling pathways. However, it is still unclear whether they have other functions. Here, AtAIRP4 was determined to play a role in response to gibberellin A3 (GA₃) in Arabidopsis thaliana. After proAtAIRP4::GUS transgenic lines were treated with GA₃, the GUS activity decreased in hypocotyls. Increased hypocotyl elongation in response to GA₃ seen in WT was not observed in the AtAIRP4-overexpression lines, whereas AtAIRP4-overexpression lines were hypersensitive to Paclobutrazol (PAC, an inhibitor of GA biosynthesis) during the seed germination stage. Additionally, AtAIRP4-overexpressing lines showed the lowest level of primary root elongation in the presence of GA₃. The levels of endogenous GA₃ in 35S::AtAIRP4 lines were lower than those in wild-type. In addition, among the plants, the mRNA levels of the GA synthetic gene GIBBERELLIN 20-OXIDASE1 (GA20ox1) was the lowest in overexpressing line. However, the expression of the response gene DELLA RGA-LIKE3 (RGL3) was the highest in overexpressing lines after treatment with GA₃. Thus, AtAIRP4 plays a negative role in GA-mediated hypocotyl elongation and root growth, and it inhibits the synthesis of endogenous biologically active GA₃ to some extent.

The role of APC/C in cell cycle dynamics, growth and development in cereal crops

Cereal crops can be considered the basis of human civilization. Thus, it is not surprising that these crops are grown in larger quantities worldwide than any other food supply and provide more energy to humankind than any other provision. Additionally, attempts to harness biomass consumption continue to increase to meet human energy needs. The high pressures for energy will determine the demand for crop plants as resources for biofuel, heat, and electricity. Thus, the search for plant traits associated with genetic increases in yield is mandatory. In multicellular organisms, including plants, growth and development are driven by cell division. These processes require a sequence of intricated events that are carried out by various protein complexes and molecules that act punctually throughout the cycle. Temporal controlled degradation of key cell division proteins ensures a correct onset of the different cell cycle phases and exit from the cell division program. Considering the cell cycle, the Anaphase-Promoting Complex/Cyclosome (APC/C) is an important conserved multi-subunit ubiquitin ligase, marking targets for degradation by the 26S proteasome. Studies on plant APC/C subunits and activators, mainly in the model plant Arabidopsis, revealed that they play a pivotal role in several developmental processes during growth. However, little is known about the role of APC/C in cereal crops. Here, we discuss the current understanding of the APC/C controlling cereal crop development.

Current perspectives of ubiquitination and SUMOylation in abiotic stress tolerance in plants

Post-translational modification (PTM) is a critical and rapid mechanism to regulate all the major cellular processes through the modification of diverse protein substrates. Substrate-specific covalent attachment of ubiquitin and Small Ubiquitin-Like Modifier (SUMO) with the target proteins, known as ubiquitination and SUMOylation, respectively, are crucial PTMs that regulate almost every process in the cell by modulating the stability and fidelity of the proteins. Ubiquitination and SUMOylation play a very significant role to provide tolerance to the plants in adverse environmental conditions by activating/deactivating the pre-existing proteins to a great extent. We reviewed the importance of ubiquitination and SUMOylation in plants, implicating its prospects in various abiotic stress regulations. An exhaustive study of molecular mechanisms of ubiquitination and SUMOylation of plant proteins and their role will contribute to the understanding of physiology underlying mitigation of the abiotic stresses and survival in plants. It will be helpful to strategize the improvement of crops for abiotic stress tolerance.