Study Of Histone Variant H2A.Z And Related Chromatin Remodelers In Rice Stress Tolerance

Epigenetic modifications,including DNA methylation,histone modifications,histone variants,and nucleosome distribution,play vital roles in gene expression regulation.To cope with environmental changes,higher plants perceived complicated changes and responding system to promote its survival under different circumstances.Epigenetic modification factors are important in regulating plant stress responses.H2 A.Z,a histone H2 A variant,has its distinctive regulation mechanism and molecular function,and participates in plant development and stress response.In this study,we seek to find out the roles of H2 A.Z and its corresponding chromatin remodeling factors PIE1 and INO80 in rice abiotic stress responses.Our main results are as follows:1.Experssion profile analysis of OsH2 A.Z,Os PIE1,OsINO80,and OsARP6 showed that they are all constitutive expressed genes,and their expression are affected by salt,drought and stress hormone(ABA,SA,JA)treatments.Indicating the H2 A.Z related genes were involed in rice stress response.2.Transgenic plants of H2 A.Z(OsHTA705),H2 A.Z assembling protein OsPIE1 and OsINO80 RNAi,displayed similar phenotype such as delayed heading date(2-3 weeks later that wild type).OsPIE1 RNAi plant also showed phenotypes of plant height,spike shape,and grain size.These results suggest that OsPIE1 might be involved in seed development.3.OsPIE1 RNAi and OsHTA705 RNAi seedling showed stronger salt tolerance than wild type,while OsINO80 RNAi is more sensitive to salt stress.The germination rate of OsPIE1 RNAi and OsHTA705 RNAi is lower than that of wild type under normal conditions,but significantly increased in appropriate concentration of NaCl.4.Anti-H2 A.Z ChIP-qPCR and RT-qPCR were perfomed under NaCl treatment with 12 d wild type seedlings.Results showed that H2 A.Z was enriched in whole salt-inducible loci and depleted after salt stress treatment,which could activate corresponding loci's transcription.Under normal condition,the occupancy of H2 A.Z was significant lower in OsPIE1 RNAi compared with wild type,but much higher in OsINO80 RNAi,which caused the expression of the salt inducible gene was significant lower than the wild type;In OsINO80 RNAi,H2A.Z could not been deposited during salt treatment,which lead to much weaker inducible ability of corresponding genes under salt stress.These data indicated that the occupancy of H2 A.Z along the salt inducible genes inhibited gene transcripts under normal condition;and PIE1,INO80 play different functions in regulating H2 A.Z occupancy,of which,INO80 palyed a highlight role in regulating gene expression by influencing H2 A.Z deposition under salt stress.