Genome-wide Identification And Expression Analysis Of HMT And HDML Gene Family Under Drought Stress In Wheat

Known as one of the third widely planted food crop,wheat plays important roles in coping with population growth and ensuring food security.With the frequent occurrence of drought and other natural disasters in recent years,breeding drought resistant varieties to improve wheat drought resistance is of great concern.Histone methylation,one of the critical ways of epigenetic regulation,plays important roles in plant abiotic stress responses.In this study,we screened histone methylase and histone demethylase family members in the whole wheat genome and analyzed the physicochemical property,protein structures,genetic structure,conserved motif,and phylogenetic relationships;expression analysis was carried out for those histone methylase and histone demethylase family members to explore genes involved in drought resistance.The main results are as follows:(1)A total of 175 members were identified for wheat histone methylation(Ta HMT)family.Eight genes,Ta HMT21,Ta HMT24,Ta HMT31,Ta HMT42,Ta HMT49,Ta HMT105,Ta HMT143 and Ta HMT157,were induced by drought stress.As predicted by Prot Scale and Cell-Ploc website,those 8 encoding hydrophilic proteins,and located in the nucleus.Cis-regulatory elements of analysis in promoters showed that all Ta HMT family genes contained drought stress response elements.The results of quantitative PCR(q RT-PCR)analysis showed that 8 Ta HMT genes were induced by drought stress,and their expression levels increased firstly and then decreased with the extension of stress time.The expression levels of Ta HMT21,Ta HMT24 and Ta HMT42 in hybrid were similar to the drought-resistant paternal line,but significantly differed from the maternal line,which were consistent with the drought-resistant and female-sensitive phenotypes of hybrids and male parents.It is speculated that Ta HMT21,Ta HMT24 and Ta HMT42 may be involved in the drought resistance of hybrids.(2)Forty-nine wheat histone demethylase(Ta HDML)genes were identified genome-wide.Subcellular localization prediction showed that 25 of the Ta HDML genes located in the nucleus and 24 in the chloroplast.According to the structural characteristics and evolutionary relationship of genes,Ta HDML was divided into Ta JMJ and Ta LSD families,and KDM5/JARID,KDM4/JHDM3,KDM3/JHDM2,JMJC-only and LSD subfamilies.Multi-sequence alignment showed that Ta HDML protein sequence had high similarity with rice.Collinearity analysis showed that Ta HDML genes have fragment duplication between homologous chromosomes.Ta HDML genes were conserved due to purification selection pressure.Cis-acting elements analysis showed that all Ta HDML genes contained hormone,light and stress responsive cis-acting elements.GO annotation analysis showed that Ta HDML genes involved in response to process,cellular component and process.Tissue online expression analysis revealed that Ta HDML genes were highly expressed in roots,but lowly in leaves.Ta JMJ5,Ta JMJ9 and Ta JMJ15 specifically expressed in grains,and Ta JMJ14 specifically expressed in panicle.q RT-PCR analysis showed that Ta HDML gene family were induced by drought stress.The expression patterns of Ta JMJ2,Ta JMJ3,Ta JMJ10,Ta JMJ11,Ta JMJ12,Ta JMJ30,Ta JMJ32,Ta JMJ34,Ta JMJ35 and Ta JMJ37 were similar to the paternal line,and significantly differed from the maternal line.Only Ta JMJ34 has a similar expression level to the paternal line at different developmental stages and lower than the female parent.We may speculate that this gene is involved in the drought resistance of hybrids.In conclusion,four drought stress-related genes were preliminarily identified in this study.This result will provide stress-resistant gene resources for studying the function of histone methylation and demethylase in drought resistance of hybrid wheat.