A novel calmodulin-interacting Domain of Unknown Function 506 protein represses root hair elongation in Arabidopsis

Comparative Transcriptome Analysis of Arabidopsis Seedlings Under Heat Stress on Whole Plants, Shoots, and Roots Reveals New HS-Regulated Genes, Organ-Specific Responses, and Shoots-Roots Communication

High temperatures can severely affect plant development and cause a notable decrease in crop yields. Currently, most studies use whole plants that are exposed to steady, high temperatures. This does not reflect the conditions encountered in natural fields, and it overlooks possible differences and coordination between the shoots and roots under heat stress (HS). Here, we analyzed the transcriptome changes in whole plants, shoots, and roots exposed separately to HS. In total, 3346 differentially expressed genes (DEGs) were obtained. Plants in which only the shoots were HS-treated showed minor transcriptional changes compared with whole plants exposed to HS. 62 genes were specifically expressed in HS treatment on shoots, and most of these genes have not been reported to function in HS. We found NAC1 may enhance plant heat tolerance. Utilizing Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses, HS-treated shoots showed enhanced gene transcription, protein folding, and MAPK signaling but decreased auxin signaling, while HS-treated roots showed an increase in oxidative stress and suppression of starch and sucrose metabolism. The binding of cis-regulatory elements by transcription factors that act downstream in reactive oxygen species (ROS), abscisic acid (ABA), and brassinosteroid (BR) signaling was significantly enriched at the putative promoters of co-expressed genes in shoots and roots under HS treatments on aboveground tissues or roots. Moreover, 194 core HS-responsive genes were identified from all HS treatments, of which 125 have not been reported to function in HS responses. Among them, we found that REV1 and MYC67 may positively regulate the response of plants to heat shock. This work uncovers many new HS-responsive genes and distinct response strategies employed by shoots and roots following HS exposure. Additionally, ROS, ABA, and BR or their downstream signaling factors may be important components for transmitting heat shock signals between shoots and roots.

ZmSIDP1, a DUF1644 gene from the halophyte Zoysia matrella, positively regulates salt tolerance in rice

As a detrimental abiotic stressor, salinity affects plant growth and yield. Domain of unknown function 1644 (DUF1644) is a large plant-specific DUF protein family that is predicted to be involved in abiotic stress responses in plants. However, the biological functions of DUF1644 genes in plants remain largely unexplored, especially in halophytes. Here, we investigated the function of the DUF1644 gene, ZmSIDP1, from the halophyte Zoysia matrella. ZmSIDP1 could enhance the salt tolerance of yeast. Furthermore, the heterologous transformation of the ZmSIDP1 gene in rice demonstrated that transgenic rice plants exhibited better growth under NaCl treatment. The Na + content was lower in ZmSIDP1 transgenic rice than in wild-type rice under salt stress. ZmSIDP1 transgenic rice showed stronger resistance to oxidative stress induced by salt stress. Further investigation indicated that ZmSIDP1 could interact with an HD-Zip transcription factor, ZmROC1. These results suggest that the ZmSIDP1 gene from the halophyte Z. matrella can positively regulate salt resistance in rice, laying a foundation for the application of salt tolerance genes from halophytes to enhance salt tolerance in rice.

The E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC 1 and transcription factors ELONGATED HYPOCOTYL 5 and ROOT HAIR DEFECTIVE6 integrate light signaling and root hair development

Light signaling plays a substantial role in regulating plant development, including the differentiation and elongation of single-celled tissue. However, the identity of the regulatory machine that affects light signaling on root hair cell (RHC) development remains unclear. Here, we investigated how darkness inhibits differentiation and elongation of RHC in Arabidopsis (Arabidopsis thaliana). We found that light promotes the growth and development of RHC. RNA-seq analysis showed that light signaling regulates the differentiation of RHC by promoting the expression of specific genes in the root epidermis associated with cell wall remodeling, jasmonic acid, auxin, and ethylene signaling pathways. Together, these genes integrate light and phytohormone signals with root hair (RH) development. Our investigation also revealed that the core light signal factor ELONGATED HYPOCOTYL 5 (HY5) directly interacts with the key RH development factor ROOT HAIR DEFECTIVE6 (RHD6), which promotes the transcription of RSL4. However, CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) repressed the RHD6 function through the COP1-HY5 complex. Our genetic studies confirm associations between RHD6, HY5, and COP1, indicating that RHD6 largely depends on HY5 for RH development. Ultimately, our work suggests a central COP1-HY5-RHD6 regulatory module that integrates light signaling and RH development with several downstream pathways, offering perspectives to decipher single-celled RH development.

Comprehensive Analysis of BrDUF506 Genes Across the Brassica rapa Genome Uncovers Potential Functions in Sexual Reproduction and Abiotic Stress Tolerance

The Domain of Unknown Function 506 (DUF506) belongs to the PD-(D/E) XK nuclease superfamily and has been reported to play critical roles in growth and development as well as responses to abiotic stresses. However, the function of DUF506 genes in Brassica rapa (B. rapa) remains unclear. In this study, a total of 18 BrDUF506 genes were identified and randomly distributed across eight chromosomes, categorized into four subfamilies. Analyzing their promoter sequences has uncovered various stress-responsive elements, such as those for drought, methyl jasmonate (MeJA), and abscisic acid (ABA). Bra000098 and Bra017099 exhibit significantly enhanced expression in response to heat and drought stress. Protein interaction predictions indicate that Bra000098 homolog, At2g38820, is interacting with ERF012 and PUB48 and is involved in abiotic stress regulation. Furthermore, gene expression profiling has identified Bra026262 with a high expression level in flowers and significantly decreased in female sterile mutants. Protein interaction prediction further revealed that its homolog, At4g32480, interacts with MYB and AGL proteins, suggesting the potential roles in female gametophyte development. The current study enhances our understanding of the functional roles of BrDUF506s, providing significant insights that are valuable in investigating sexual reproduction and abiotic stress responses in B. rapa.

The American Cherimoya Genome Reveals Insights into the Intra-Specific Divergence, the Evolution of Magnoliales, and a Putative Gene Cluster for Acetogenin Biosynthesis

Annona cherimola (cherimoya) is a species renowned for its delectable fruit and medicinal properties. In this study, we developed a chromosome-level genome assembly for the cherimoya 'Booth' cultivar from the United States. The genome assembly has a size of 794 Mb with a N50 = 97.59 Mb. The seven longest scaffolds account for 87.6% of the total genome length, which corresponds to the seven pseudo-chromosomes. A total of 45,272 protein-coding genes (≥30 aa) were predicted with 92.9% gene content completeness. No recent whole genome duplications were identified by an intra-genome collinearity analysis. Phylogenetic analysis supports that eudicots and magnoliids are more closely related to each other than to monocots. Moreover, the Magnoliales was found to be more closely related to the Laurales than the Piperales. Genome comparison revealed that the 'Booth' cultivar has 200 Mb less repeats than the Spanish cultivar 'Fino de Jete', despite their highly similar (>99%) genome sequence identity and collinearity. These two cultivars were diverged during the early Pleistocene (1.93 Mya), which suggests a different origin and domestication of the cherimoya. Terpene/terpenoid metabolism functions were found to be enriched in Magnoliales, while TNL (Toll/Interleukin-1-NBS-LRR) disease resistance gene has been lost in Magnoliales during evolution. We have also identified a gene cluster that is potentially responsible for the biosynthesis of acetogenins, a class of natural products found exclusively in Annonaceae. The cherimoya genome provides an invaluable resource for supporting characterization, conservation, and utilization of Annona genetic resources.

Calcium signaling in plant mineral nutrition: From uptake to transport

Plant mineral nutrition is essential for crop yields and human health. However, the uneven distribution of mineral elements over time and space leads to a lack or excess of available mineral elements in plants. Among the essential nutrients, calcium (Ca2+) stands out as a prominent second messenger that plays crucial roles in response to extracellular stimuli in all eukaryotes. Distinct Ca2+ signatures with unique parameters are induced by different stresses and deciphered by various Ca2+ sensors. Recent research on the participation of Ca2+ signaling in regulation of mineral elements has made great progress. In this review, we focus on the impact of Ca2+ signaling on plant mineral uptake and detoxification. Specifically, we emphasize the significance of Ca2+ signaling for regulation of plant mineral nutrition and delve into key points and novel avenues for future investigations, aiming to offer new insights into plant ion homeostasis.

Genome-wide identification of DUF506 gene family in Oryzasativa and expression profiling under abiotic stresses

The domain of unknown function 560 (DUF560), also known as the PDDEXK_6 family, is a ubiquitous plant protein that has been confirmed to play critical roles in Arabidopsis root development as well as ABA and abiotic responses. However, genome-wide identification and expression pattern analysis in rice (Oryza sativa) still need to be improved. Based on the phylogenetic relationship, 10 OsDUF506 genes were identified and classified into four subfamilies. Segmental duplication was essential to the expansion of OsDUF506s, which were subjected to purifying selective pressure. Except for OsDUF50609 and OsDUF50610, the OsDUF506s shared colinear gene pairs with five monocot species, showing that they were conserved in evolution. Furthermore, the conserved domains, gene structures, SNPs distribution, and targeting miRNAs were systematically investigated. Massive cis-regulatory elements were discovered in promoter regions, implying that OsDUF506s may be important in hormone regulation and abiotic stress response. Therefore, we analyzed plant hormone-induced transcriptome data and performed qRT-PCR on eight OsDUF506s under drought, cold, and phosphorus-deficient stresses. The results revealed that most OsDUF506s respond to ABA and JA treatment, as well as drought and cold conditions. In conclusion, our findings provided insights into the evolution and function of OsDUF506s, which could benefit crop breeding in the future.

Calcium signaling-mediated transcriptional reprogramming during abiotic stress response in plants

Calcium (Ca2+) is a second messenger in plants growth and development, as well as in stress responses. The transient elevation in cytosolic Ca2+ concentration have been reported to be involved in plants response to abiotic and biotic stresses. In plants, Ca2+-induced transcriptional changes trigger molecular mechanisms by which plants adapt and respond to environment stresses. The mechanism for transcription regulation by Ca2+ could be either rapid in which Ca2+ signals directly cause the related response through the gene transcript and protein activities, or involved amplification of Ca2+ signals by up-regulation the expression of Ca2+ responsive genes, and then increase the transmission of Ca2+ signals. Ca2+ regulates the expression of genes by directly binding to the transcription factors (TFs), or indirectly through its sensors like calmodulin, calcium-dependent protein kinases (CDPK) and calcineurin B-like protein (CBL). In recent years, significant progress has been made in understanding the role of Ca2+-mediated transcriptional regulation in different processes in plants. In this review, we have provided a comprehensive overview of Ca2+-mediated transcriptional regulation in plants in response to abiotic stresses including nutrition deficiency, temperature stresses (like heat and cold), dehydration stress, osmotic stress, hypoxic, salt stress, acid rain, and heavy metal stress.

Unraveling the Diverse Roles of Neglected Genes Containing Domains of Unknown Function (DUFs): Progress and Perspective

Domain of unknown function (DUF) is a general term for many uncharacterized domains with two distinct features: relatively conservative amino acid sequence and unknown function of the domain. In the Pfam 35.0 database, 4795 (24%) gene families belong to the DUF type, yet, their functions remain to be explored. This review summarizes the characteristics of the DUF protein families and their functions in regulating plant growth and development, generating responses to biotic and abiotic stress, and other regulatory roles in plant life. Though very limited information is available about these proteins yet, by taking advantage of emerging omics and bioinformatic tools, functional studies of DUF proteins could be utilized in future molecular studies.