Characteristic and evolution of HAT and HDAC genes in Gramineae genomes and their expression analysis under diverse stress in Oryza sativa

Characterisation and evolution of the PRC2 complex and its functional analysis under various stress conditions in rice

The polycomb repressive complex 2 (PRC2) is a chromatin-associated methyltransferase responsible for catalysing the trimethylation of H3K27, an inhibitory chromatin marker associated with gene silencing. This enzymatic activity is crucial for normal organismal development and the maintenance of gene expression patterns that preserve cellular identity, subsequently influencing plant growth and abiotic stress responses. Therefore, in this study, we investigated the evolutionary characteristics and functional roles of PRC2 in plants. We identified 209 PRC2 genes, including E(z), Su(z), Esc, and Nurf55 families, using 18 representative plant species and revealed that recent gene replication events have led to an expansion in the Nurf55 family, resulting in a greater number of members compared to the E(z), Su(z), and Esc families. Furthermore, protein structure and motif composition analyses highlighted the potential functional site regions within PRC2 members. In addition, we selected rice, a representative monocotyledonous plant, as the model species for food crops. Our findings revealed that SDG711, SDG718, and MSI1-5 genes were induced by abscisic acid (ABA) and/or methyl jasmonate (MeJA) hormones, suggesting that these genes play an important role in abiotic stress and disease resistance. Further experiments involving rice blast fungus treatments confirmed that the expression of SDG711 and MSI1-5 was induced by Magnaporthe oryzae strain GUY11. Multiple protein interaction assays revealed that the M. oryzae effector AvrPiz-t interacts with PRC2 core member SDG711 to increase H3K27me3 levels. Notably, inhibition of PRC2 or mutation of SDG711 enhanced rice resistance to M. oryzae. Collectively, these results provide new insights into PRC2 evolution in plants and its significant functions in rice.

Advances in understanding the roles of plant HAT and HDAC in non-histone protein acetylation and deacetylation

MAIN CONCLUSION

This review focuses on HATs and HDACs that modify non-histone proteins, summarizes functional mechanisms of non-histone acetylation as well as the roles of HATs and HDACs in rice and Arabidopsis. The growth and development of plants, as well as their responses to biotic and abiotic stresses, are governed by intricate gene and protein regulatory networks, in which epigenetic modifying enzymes play a crucial role. Histone lysine acetylation levels, modulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), are well-studied in the realm of transcriptional regulation. However, the advent of advanced proteomics has unveiled that non-histone proteins also undergo acetylation, with its underlying mechanisms now being clarified. Indeed, non-histone acetylation influences protein functionality through diverse pathways, such as modulating protein stability, adjusting enzymatic activity, steering subcellular localization, influencing interactions with other post-translational modifications, and managing protein-protein and protein-DNA interactions. This review delves into the recent insights into the functional mechanisms of non-histone acetylation in plants. We also provide a summary of the roles of HATs and HDACs in rice and Arabidopsis, and explore their potential involvement in the regulation of non-histone proteins.

Genome-wide comparative analyses highlight selection signatures underlying saline adaptation in Chilika buffalo

Chilika, a native buffalo breed of the Eastern coast of India, is mainly distributed around the Chilika brackish water lake connected with the Bay of Bengal Sea. This breed possesses a unique ability to delve deep into the salty water of the lake and stay there to feed on local vegetation of saline nature. Adaptation to salinity is a genetic phenomenon; however, the genetic basis underlying salinity tolerance is still limited in animals, specifically in livestock. The present study explores the genetic evolution that unveils the Chilika buffalo's adaptation to the harsh saline habitat, including both water and food systems. For this study, whole genome resequencing data on 18 Chilika buffalo and for comparison 10 Murrah buffalo of normal habitat were generated. For identification of selection sweeps, intrapopulation and interpopulation statistics were used. A total of 709, 309, 468, and 354 genes were detected to possess selection sweeps in Chilika buffalo using the nucleotide diversity (θπ), Tajima's D, nucleotide diversity ratio (θπ-ratio), and FST methods, respectively. Further analysis revealed a total of 23 genes including EXOC6B, VPS8, LYPD1, VPS35, CAMKMT, NCKAP5, COMMD1, myosin light chain kinase 3 (MYLK3), and B3GNT2 were found to be common by all the methods. Furthermore, functional annotation study of identified genes provided pathways such as MAPK signaling, renin secretion, endocytosis, oxytocin signaling pathway, etc. Gene network analysis enlists that hub genes provide insights into their interactions with each other. In conclusion, this study has highlighted the genetic basis underlying the local adaptive function of Chilika buffalo under saline environment.NEW & NOTEWORTHY Indian Chilika buffaloes are being maintained on extensive grazing system and have a unique ability to convert local salty vegetation into valuable human food. However, adaptability to saline habitat of Chilika buffalo has not been explored to date. Here, we identified genes and biological pathways involved, such as MAPK signaling, renin secretion, endocytosis, and oxytocin signaling pathway, underlying adaptability of Chilika buffalo to saline environment. This investigation shed light on the mechanisms underlying the buffalo's resilience in its native surroundings.

Genome-Wide Analysis of DNA Demethylases in Land Plants and Their Expression Pattern in Rice

DNA demethylation is a very important biochemical pathway regulating a group of biological processes, such as embryo development, fruit ripening, and response to stress. Despite the essential role of DNA demethylases, their evolutionary relationship and detailed biological functions in different land plants remain unclear. In this study, 48 DNA demethylases in 12 land plants were identified and classified. A phylogenetic tree was constructed to demonstrate the evolutionary relationships among these DNA demethylases, indicating how they are related across different species. Conserved domain, protein motif, and gene structure analysis showed that these 48 DNA demethylases fell into the presently identified four classes of DNA demethylases. Amino acid alignment revealed conserved catalytic sites and a previously less-studied protein region (referred to as domain A) within the DNA demethylases. An analysis showed a conserved pattern of gene duplication for DNA demethylases throughout their evolutionary history, suggesting that these genes had been maintained due to their importance. The examination of promoter cis-elements displayed potential signaling and regulating pathways of DNA demethylases. Furthermore, the expression profile was analyzed to investigate the physiological role of rice DNA demethylase in different developmental stages, in tissues, and in response to stress and various phytohormone signals. The findings offer a deeper insight into the functional regions of DNA demethylases and their evolutionary relationships, which can guide future research directions. Understanding the role of DNA demethylases can lead to improved plant stress resistance and contribute to the development of better crop and fruit varieties.

Plant responses to abiotic stress regulated by histone acetylation

In eukaryotes, histone acetylation and deacetylation play an important role in the regulation of gene expression. Histone acetylation levels are reversibly regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs). Increasing evidence highlights histone acetylation plays essential roles in the regulation of gene expression in plant response to environmental stress. In this review, we discussed the recent advance of histone acetylation in the regulation of abiotic stress responses including temperature, light, salt and drought stress. This information will contribute to our understanding of how plants adapt to environmental changes. As the mechanisms of epigenetic regulation are conserved in many plants, research in this field has potential applications in improvement of agricultural productivity.

Unveiling the mechanism of broad-spectrum blast resistance in rice: The collaborative role of transcription factor OsGRAS30 and histone deacetylase OsHDAC1

Rice blast, caused by Magnaporthe oryzae, significantly impacts grain yield, necessitating the identification of broad-spectrum resistance genes and their functional mechanisms for disease-resistant crop breeding. Here, we report that rice with knockdown OsHDAC1 gene expression displays enhanced broad-spectrum blast resistance without effects on plant height and tiller numbers compared to wild-type rice, while rice overexpressing OsHDAC1 is more susceptible to M. oryzae. We identify a novel blast resistance transcription factor, OsGRAS30, which genetically acts upstream of OsHDAC1 and interacts with OsHDAC1 to suppress its enzymatic activity. This inhibition increases the histone H3K27ac level, thereby boosting broad-spectrum blast resistance. Integrating genome-wide mapping of OsHDAC1 and H3K27ac targets with RNA sequencing analysis unveils how OsHDAC1 mediates the expression of OsSSI2, OsF3H, OsRLR1 and OsRGA5 to regulate blast resistance. Our findings reveal that the OsGRAS30-OsHDAC1 module is critical to rice blast control. Therefore, targeting either OsHDAC1 or OsGRAS30 offers a promising approach for enhancing crop blast resistance.

Mechanisms of Plant Epigenetic Regulation in Response to Plant Stress: Recent Discoveries and Implications

Plant stress is a significant challenge that affects the development, growth, and productivity of plants and causes an adverse environmental condition that disrupts normal physiological processes and hampers plant survival. Epigenetic regulation is a crucial mechanism for plants to respond and adapt to stress. Several studies have investigated the role of DNA methylation (DM), non-coding RNAs, and histone modifications in plant stress responses. However, there are various limitations or challenges in translating the research findings into practical applications. Hence, this review delves into the recent recovery, implications, and applications of epigenetic regulation in response to plant stress. To better understand plant epigenetic regulation under stress, we reviewed recent studies published in the last 5-10 years that made significant contributions, and we analyzed the novel techniques and technologies that have advanced the field, such as next-generation sequencing and genome-wide profiling of epigenetic modifications. We emphasized the breakthrough findings that have uncovered specific genes or pathways and the potential implications of understanding plant epigenetic regulation in response to stress for agriculture, crop improvement, and environmental sustainability. Finally, we concluded that plant epigenetic regulation in response to stress holds immense significance in agriculture, and understanding its mechanisms in stress tolerance can revolutionize crop breeding and genetic engineering strategies, leading to the evolution of stress-tolerant crops and ensuring sustainable food production in the face of climate change and other environmental challenges. Future research in this field will continue to unveil the intricacies of epigenetic regulation and its potential applications in crop improvement.

New insights into molecular features of the genome-wide AOX family and their responses to various stresses in common wheat (Triticum aestivum L.)

Alternative oxidase (AOX) is an important terminal oxidase involved in the alternative oxidation pathway in plants, which is closely related to various biotic and abiotic stress responses. However, a comprehensive research on AOX gene family of wheat is still lacking. In this study, the members of wheat AOX (TaAOX) family were identified, and their molecular characteristics and gene expression patterns were systematically investigated. Seventeen TaAOX genes were identified from Chinese Spring (CS) genome, which were mapped on 7 chromosomes and mainly clustered on the long arm's distal end of the second homologous groups. Phylogenetic analysis showed that TaAOX genes were classified into four subgroups (Ia, Ib, Ic, and Id), and the Ia subgroup possessed the most members. Tandem duplication and segmental duplication events were found during the evolution of TaAOX genes and they were affected by purifying selection demonstrated by Ka/Ks analysis. The exon numbers of this family gene varied greatly from 1 to 9. Except for Ta3BSAOX14, all the proteins encoded by the other 16 TaAOX genes contained the amino acid residues of the key active sites in the AOX domain (cd01053). The expression patterns of TaAOX genes in various tissues and under abiotic and biotic stresses were analyzed using public transcriptome data, furthermore, qRT-PCR analysis was performed for some selected TaAOX genes, and the results suggested that most members of this gene family play an important role in response to different stresses in common wheat. Our results provide basic information and valuable reference for further exploring the gene function of TaAOX family by using gene editing, RNAi, VIGS, and other technologies.

Genome-Wide Identification of Histone Deacetylases and Their Roles Related with Light Response in Tartary Buckwheat (Fagopyrum tataricum)

Histone deacetylases (HDACs), known as histone acetylation erasers, function crucially in plant growth and development. Although there are abundant reports focusing on HDACs of Arabidopsis and illustrating their important roles, the knowledge of HDAC genes in Tartary buckwheat (Polygonales Polygonaceae Fagopyrum tataricum (L.) Gaertn) is still scarce. In the study, a total of 14 HDAC genes were identified and divided into three main groups: Reduced Potassium Dependency-3/His-52 tone Deacetylase 1 (RPD3/HDA1), Silent Information Regulator 2 (SIR2), and the plant-53 specific HD2. Domain and motif composition analysis showed there were conserved domains and motifs in members from the same subfamilies. The 14 FtHDACs were distributed asymmetrically on 7 chromosomes, with three segmental events and one tandem duplication event identified. The prediction of the cis-element in promoters suggested that FtHDACs probably acted in numerous biological processes including plant growth, development, and response to environmental signals. Furthermore, expression analysis based on RNA-seq data displayed that all FtHDAC genes were universally and distinctly expressed in diverse tissues and fruit development stages. In addition, we found divergent alterations in FtHDACs transcript abundance in response to different light conditions according to RNA-seq and RT-qPCR data, indicating that five FtHDACs might be involved in light response. Our findings could provide fundamental information for the HDAC gene family and supply several targets for future function analysis of FtHDACs related with light response of Tartary buckwheat.

Genome-wide analysis of the CSN genes in land plants and their expression under various abiotic stress and phytohormone conditions in rice

The CONSTITUTIVE PHOTOMORPHOGENIC9 (COP9) signalosome (CSN) is a multi-functional protein complex, which is involved in plant growth and abiotic stress response. However, the evolution and function of the CSN genes in land plants are still largely unclear. Here, we have identified 124 CSN genes and constructed phylogenetic trees of these CSN proteins to elucidate their feature and evolution in twelve land plants. Analysis of gene structure, protein property and protein motif composition shows the evolutional conservation and variation of the CSN proteins in land plants. These CSN genes might evolve through whole genome duplication (WGD)/segmental duplication (SD) and tandem duplication (TD). Analysis of promoter cis-elements shows that the CSN genes are implicated in diverse biological processes and different signaling pathways. RT-qPCR indicates that the transcript abundance of the OsCSN genes is up-regulated or down-regulated in response to abiotic stress and treatment with various hormones in rice. These results provide new insights into the CSN gene evolution and its possible function in land plants.

Genome-Wide Analysis of the HDAC Gene Family and Its Functional Characterization at Low Temperatures in Tartary Buckwheat (Fagopyrum tataricum)

Histone deacetylases (HDACs), widely found in various types of eukaryotic cells, play crucial roles in biological process, including the biotic and abiotic stress responses in plants. However, no research on the HDACs of Fagopyrum tataricum has been reported. Here, 14 putative FtHDAC genes were identified and annotated in Fagopyrum tataricum. Their gene structure, motif composition, cis-acting elements, phylogenetic relationships, protein structure, alternative splicing events, subcellular localization and gene expression pattern were investigated. The gene structure showed FtHDACs were classified into three subfamilies. The promoter analysis revealed the presence of various cis-acting elements responsible for hormone, abiotic stress and developmental regulation for the specific induction of FtHDACs. Two duplication events were identified in FtHDA6-1, FtHDA6-2, and FtHDA19. The expression patterns of FtHDACs showed their correlation with the flavonoid synthesis pathway genes. In addition, alternative splicing, mRNA enrichment profiles and transgenic analysis showed the potential role of FtHDACs in cold responses. Our study characterized FtHDACs, providing a candidate gene family for agricultural breeding and crop improvement.

The histone deacetylase 1/GSK3/SHAGGY-like kinase 2/BRASSINAZOLE-RESISTANT 1 module controls lateral root formation in rice

Lateral roots (LRs) are a main component of the root system of rice (Oryza sativa) that increases root surface area, enabling efficient absorption of water and nutrients. However, the molecular mechanism regulating LR formation in rice remains largely unknown. Here, we report that histone deacetylase 1 (OsHDAC1) positively regulates LR formation in rice. Rice OsHDAC1 RNAi plants produced fewer LRs than wild-type plants, whereas plants overexpressing OsHDAC1 exhibited increased LR proliferation by promoting LR primordia formation. Brassinosteroid treatment increased the LR number, as did mutation of GSK3/SHAGGY-like kinase 2 (OsGSK2), whereas overexpression of OsGSK2 decreased the LR number. Importantly, OsHDAC1 could directly interact with and deacetylate OsGSK2, inhibiting its activity. OsGSK2 deacetylation attenuated the interaction between OsGSK2 and BRASSINAZOLE-RESISTANT 1 (OsBZR1), leading to accumulation of OsBZR1. The overexpression of OsBZR1 increased LR formation by regulating Auxin/IAA signaling genes. Taken together, the results indicate that OsHDAC1 regulates LR formation in rice by deactivating OsGSK2, thereby preventing degradation of OsBZR1, a positive regulator of LR primordia formation. Our findings suggest that OsHDAC1 is a breeding target in rice that can improve resource capture.

Comprehensive Genome-Wide Analysis of Histone Acetylation Genes in Roses and Expression Analyses in Response to Heat Stress

Roses have high economic values as garden plants and for cut-flower and cosmetics industries. The growth and development of rose plants is affected by exposure to high temperature. Histone acetylation plays an important role in plant development and responses to various stresses. It is a dynamic and reversible process mediated by histone deacetylases (HDAC) and histone acetyltransferases (HAT). However, information on HDAC and HAT genes of roses is scarce. Here, 23 HDAC genes and 10 HAT genes were identified in the Rosa chinensis ‘Old Blush’ genome. Their gene structures, conserved motifs, physicochemical properties, phylogeny, and synteny were assessed. Analyses of the expression of HDAC and HAT genes using available RNAseq data showed that these genes exhibit different expression patterns in different organs of the three analyzed rose cultivars. After heat stress, while the expression of most HDAC genes tend to be down-regulated, that of HAT genes was up-regulated when rose plants were grown at high-temperature conditions. These data suggest that rose likely respond to high-temperature exposure via modification in histone acetylation, and, thus, paves the way to more studies in order to elucidate in roses the molecular mechanisms underlying rose plants development and flowering.

HDACs Gene Family Analysis of Eight Rosaceae Genomes Reveals the Genomic Marker of Cold Stress in Prunus mume

Histone deacetylases (HDACs) play important roles in plant growth, development, and stress response. However, the pattern of how they are expressed in response to cold stress in the ornamental woody plant Prunus mume is poorly understood. Here, we identify 121 RoHDACs from eight Rosaceae plants of which 13 PmHDACs genes are from P. mume. A phylogenetic analysis suggests that the RoHDACs family is classified into three subfamilies, HDA1/RPD3, HD2, and SIR2. We identify 11 segmental duplication gene pairs of RoHDACs and find, via a sequence alignment, that the HDACs gene family, especially the plant-specific HD2 family, has experienced gene expansion and contraction at a recent genome evolution history. Each of the three HDACs subfamilies has its own conserved domains. The expression of PmHDACs in mei is found to be tissue-specific or tissue-wide. RNA-seq data and qRT-PCR experiments in cold treatments suggest that almost all PmHDACs genes-especially PmHDA1/6/14, PmHDT1, and PmSRT1/2-significantly respond to cold stress. Our analysis provides a fundamental insight into the phylogenetic relationship of the HDACs family in Rosaceae plants. Expression profiles of PmHDACs in response to cold stress could provide an important clue to improve the cold hardiness of mei.

Histone Acetylation Changes in Plant Response to Drought Stress

Drought stress causes recurrent damage to a healthy ecosystem because it has major adverse effects on the growth and productivity of plants. However, plants have developed drought avoidance and resilience for survival through many strategies, such as increasing water absorption and conduction, reducing water loss and conversing growth stages. Understanding how plants respond and regulate drought stress would be important for creating and breeding better plants to help maintain a sound ecosystem. Epigenetic marks are a group of regulators affecting drought response and resilience in plants through modification of chromatin structure to control the transcription of pertinent genes. Histone acetylation is an ubiquitous epigenetic mark. The level of histone acetylation, which is regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), determines whether the chromatin is open or closed, thereby controlling access of DNA-binding proteins for transcriptional activation. In this review, we summarize histone acetylation changes in plant response to drought stress, and review the functions of HATs and HDACs in drought response and resistance.