Genome-Wide Identification of the A20/AN1 Zinc Finger Protein Family Genes in Ipomoea batatas and Its Two Relatives and Function Analysis of IbSAP16 in Salinity Tolerance

Comprehensive analysis of the stress associated protein (SAP) family and the function of PagSAP9 from Populus alba × P. glandulosa in salt stress

Poplar tree growth is frequently hindered by environmental stressors, particularly soil salinization. Enhancing salt tolerance is essential for improving their adaptability and biomass under these conditions. The Stress-Associated Protein (SAP) family, characterized by A20/AN1 zinc finger domains, plays a crucial role in plants' tolerance to abiotic stress. However, functional investigations on SAP proteins in poplar are limited. In our study, we identified 19 SAP members in poplar, distributed unevenly across ten chromosomes and classified them into two major groups based on phylogenetic relationship and structure characteristics. Notably, only three segmental duplications were found, while no tandem duplications were detected. The PagSAP9 gene from Populus alba x P. glandulosa, featured both A20 and AN1 domains, was successfully characterized and localized to both cytoplasm and nucleus. It was predominantly expressed in roots and leaves and showed significantly upregulation under salt stress. And the overexpressing PagSAP9 transgenic poplars enhanced the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), alongside reduced malondialdehyde (MDA) content. Additionally, DAB and NBT histological stainings further confirmed the positive effects of PagSAP9 gene. Collectively, these findings highlight the potential of the PagSAP9 gene to improve salt tolerance in poplar, emphasizing the broader applicability of SAP genes in plant stress resistance and providing valuable genetic resources for developing resilient plant varieties.

Physiological and transcriptional reprogramming for salinity tolerance of endangered mangrove associate Hernandia nymphaeifolia

BACKGROUND

Hernandia nymphaeifolia is a typical mangrove associate with high ecological, ornamental, and medicinal values, but in China, it has become endangered in recent years, and an urgent protection is needed. Salinity is a key factor for growth and survival of mangrove seedlings, and thus a comprehensive understanding of salt tolerance in mangroves is important for their conservation and afforestation. However, little is known regarding salt-responsive mechanisms in H. nymphaeifolia.

RESULTS

In this study, we posed gradient salt treatments on H. nymphaeifolia seedlings and investigated their physiological and transcriptional reprogramming in response to salinity stress. The results revealed that hyper-salinity stress adversely impacted on leaf growth, cell integrity and photosynthetic performance of H. nymphaeifolia seedlings than those growing in fresh water or low salt conditions, mirroring its moderate salinity tolerance as a mangrove associate. Genes involved in osmotic sensing and regulation, reactive oxygen species (ROS) scavenging and ion homeostasis were differentially expressed to alleviate the destructive effects. Furthermore, our results identified some kinase-encoding genes as hub genes in co-expression networks, which may play a key role in regulating the synergistic expression of salt-responsive genes upon stress conditions.

CONCLUSION

This research enriches our knowledge of the molecular mechanisms underlying the salinity tolerance of mangrove associates, which can theoretically assist the conservation and restoration of H. nymphaeifolia. Our findings also provide valuable genetic resources for future potential bioengineering applications in the fields of agriculture and forestry.

Activators of the 26S proteasome when protein degradation increases

In response to extra- and intracellular stimuli that constantly challenge and disturb the proteome, cells rapidly change their proteolytic capacity to maintain proteostasis. Failure of such efforts often becomes a major cause of diseases or is associated with exacerbation. Increase in protein breakdown occurs at multiple steps in the ubiquitin-proteasome system, and the regulation of ubiquitination has been extensively studied. However, the activities of the 26S proteasome are also stimulated, especially under highly catabolic conditions such as those associated with atrophying skeletal muscle, proteotoxic stress such as heat shock and arsenite, or hormonal cues such as cAMP or cGMP agonists. Among the proteins that enhance proteasomal degradation are the PKA, PKG, UBL-UBA proteins and the Zn finger AN1-type domain (ZFAND) family proteins. ZFAND proteins are of particular interest because of their inducible expression in response to various stimuli and their abilities to control protein quality by stimulating the 26S proteasome and p97/VCP. The regulatory roles of ZFAND proteins appear to be important not only for the control of protein degradation but also for other cellular processes, such as mRNA stability and signaling pathways. This review summarizes the known functions of proteasome activators and discusses their possible roles in regulating proteostasis and other cellular processes.

Comparative transcriptome analysis and functional verification revealed that GhSAP6 negatively regulates salt tolerance in upland cotton

Owing to the scarcity of cultivable land in China, the agricultural sector is primarily focused on grain and oil crops. Simultaneously, the cultivation of cotton has gradually shifted towards regions characterized by elevated soil salinity levels. Additionally, the mechanism behind cotton's ability to tolerate salt remains elusive. In this study, we identified the Z9807 genotype as highly tolerant to salt stress, exhibiting superior leaf wilting resistance, antioxidant activity, catalase activity, K+/Na+ ratio, and growth compared to the salt-sensitive ZJ0102. Comparative transcriptome analysis revealed marked differences in salt stress responses between Z9807 and ZJ0102. This study identified a considerable number of differentially expressed genes associated with salt tolerance across multiple time points. By integration of QTL and GWAS mapping data, we successfully identified 621 candidate genes associated with salt tolerance. Weighted gene correlation network analysis exhibited three co-expression modules related to salt-tolerant Z9807 samples, ultimately identifying 15 core salt-tolerant candidate genes. We also conducted in-depth research on the salt tolerance of the stress-associated protein (SAP) GhSAP6 (GhSAP6_At and GhSAP6_Dt homologs). Results revealed that these candidate genes may inhibit salt tolerance through Virus-Induced Gene Silencing (VIGS) and transgenic overexpression assays conducted in Arabidopsis thaliana. Furthermore, we used yeast two-hybrid and luciferase assay experiments to confirm the ubiquitin degradation pathway between selected interacting proteins and verified the interaction with RAD23C. This study will provide new insights into the mechanisms related to salt tolerance in upland cotton.

Genome-wide identification of SAP family genes and characterization of TaSAP6-A1 to improve Cd tolerance in Triticum aestivum L

Stress Associated Proteins (SAPs) contain A20/AN1 zinc finger domains and, have been proposed to function in various physiological processes such as cold, salinity, drought, heavy metals, damage, and flooding resistance in plants. Here, a total of 131 SAP genes were identified, including T. aestivum (60), T. urartu (10), Ae. Tauschii (16), T. dicoccoides (13), O. sativa (18), and A. thaliana (14). A phylogenetic analysis revealed that the SAPs are clustered into two subfamilies. The TaSAP genes in the collinear region comprised 34 pairs of duplicated genes formed through segmental duplication events. Overexpressing TaSAP6-A1 in wheat enhanced Cd tolerance, whereas knock-down of this gene increased Cd sensitivity. Yeast two-hybrid (Y2H) and bimolecular fluorescent complementation assays (BiFC) demonstrated interaction between TaSAP6-A1 and phenylalanine ammonia-lyase (TaPAL), the first enzyme in the phenylpropanoid pathway. This study provides a valuable reference for further investigations into the functional and molecular mechanisms of the SAP gene family.

Research progress on plant stress-associated protein (SAP) family: Master regulators to deal with environmental stresses

Every year, unfavorable environmental factors significantly affect crop productivity and threaten food security. Plants are sessile; they cannot move to escape unfavorable environmental conditions, and therefore, they activate a variety of defense pathways. Among them are processes regulated by stress-associated proteins (SAPs). SAPs have a specific zinc finger domain (A20) at the N-terminus and either AN1 or C2H2 at the C-terminus. SAP proteins are involved in many biological processes and in response to various abiotic or biotic constraints. Most SAPs play a role in conferring transgenic stress resistance and are stress-inducible. The emerging field of SAPs in abiotic or biotic stress response regulation has attracted the attention of researchers. Although SAPs interact with various proteins to perform their functions, the exact mechanisms of these interactions remain incompletely understood. This review aims to provide a comprehensive understanding of SAPs, covering their diversity, structure, expression, and subcellular localization. SAPs play a pivotal role in enabling crosstalk between abiotic and biotic stress signaling pathways, making them essential for developing stress-tolerant crops without yield penalties. Collectively, understanding the complex regulation of SAPs in stress responses can contribute to enhancing tolerance against various environmental stresses through several techniques such as transgenesis, classical breeding, or gene editing.

Genome-wide identification and evolution of the SAP gene family in sunflower (Helianthus annuus L.) and expression analysis under salt and drought stress

Stress-associated proteins (SAPs) are known to play an important role in plant responses to abiotic stresses. This study systematically identified members of the sunflower SAP gene family using sunflower genome data. The genes of the sunflower SAP gene family were analyzed using bioinformatic methods, and gene expression was assessed through fluorescence quantification (qRT-PCR) under salt and drought stress. A comprehensive analysis was also performed on the number, structure, collinearity, and phylogeny of seven Compositae species and eight other plant SAP gene families. The sunflower genome was found to have 27 SAP genes, distributed across 14 chromosomes. The evolutionary analysis revealed that the SAP family genes could be divided into three subgroups. Notably, the annuus variety exhibited amplification of the SAP gene for Group 3. Among the Compositae species, C. morifolium demonstrated the highest number of collinearity gene pairs and the closest distance on the phylogenetic tree, suggesting relative conservation in the evolutionary process. An analysis of gene structure revealed that Group 1 exhibited the most complex gene structure, while the majority of HaSAP genes in Group 2 and Group 3 lacked introns. The promoter analysis revealed the presence of cis-acting elements related to ABA, indicating their involvement in stress responses. The expression analysis indicated the potential involvement of 10 genes (HaSAP1, HaSAP3, HaSAP8, HaSAP10, HaSAP15, HaSAP16, HaSAP21, HaSAP22, HaSAP23, and HaSAP26) in sunflower salt tolerance. The expression of these 10 genes were then examined under salt and drought stress using qRT-PCR, and the tissue-specific expression patterns of these 10 genes were also analyzed. HaSAP1, HaSAP21, and HaSAP23 exhibited consistent expression patterns under both salt and drought stress, indicating these genes play a role in both salt tolerance and drought resistance in sunflower. The findings of this study highlight the significant contribution of the SAP gene family to salt tolerance and drought resistance in sunflower.

A comprehensive overview of omics-based approaches to enhance biotic and abiotic stress tolerance in sweet potato

Biotic and abiotic stresses negatively affect the yield and overall plant developmental process, thus causing substantial losses in global sweet potato production. To cope with stresses, sweet potato has evolved numerous strategies to tackle ever-changing surroundings and biological and environmental conditions. The invention of modern sequencing technology and the latest data processing and analysis instruments has paved the way to integrate biological information from different approaches and helps to understand plant system biology more precisely. The advancement in omics technologies has accumulated and provided a great source of information at all levels (genome, transcript, protein, and metabolite) under stressful conditions. These latest molecular tools facilitate us to understand better the plant's responses to stress signaling and help to process/integrate the biological information encoded within the biological system of plants. This review briefly addresses utilizing the latest omics strategies for deciphering the adaptive mechanisms for sweet potatoes' biotic and abiotic stress tolerance via functional genomics, transcriptomics, proteomics, and metabolomics. This information also provides a powerful reference to understand the complex, well-coordinated stress signaling genetic regulatory networks and better comprehend the plant phenotypic responses at the cellular/molecular level under various environmental stimuli, thus accelerating the design of stress-resilient sweet potato via the latest genetic engineering approaches.