| Heat Shock proteins(HSPs)act as molecular chaperone under plant stress,mainly involved in nascent peptide chain folding,assembly and transmembrane transport,as well as stable protein structure,prevent protein coagulation or deformation and repair damaged protein.The HSP70 family is a kind of heat shock protein with most widespread distribution and most studied in biological body,which have close relationship with plant resistance.Further study of the HSP70 family will attribute to reveal the physiological process of plant resistance,and provide important practical guiding significance for relieving damage accompanying plant resistance.In addition,flower development as the important part of plant succession,is closely related to environment,what role HSP70 s playing still remains little understood during floral organ development.Therefore,it is crucial for us to study HSP70 proteins how to participate in the regulatory mechanism between floral organ development and environment systematically.Given that there is little about systemic analysis involved in molecular evolution of HSP70 family currently in plants.The first part in this study,based on bioinformatics methods,collected and sorted the relevant information of all HSP70 gene in model plant arabidopsis thaliana(dicots)and rice(monocots),such as gene sequences,protein structure and chromosomal location information,comparatively analyzed differential molecular evolution of HSP70 family in arabidopsis and rice;At the same time,preliminarily analysed and clarified the expression and function differentiation of HSP70 family genes in different tissue and different development stage at the transcription level.Besides,this part also focused on anther development process,carefully analysed the expression change of HSP70 family genes,speculated that HSP70 family members may play the role in the anther during different period.This research will provide important scientific basis for the comprehensive understanding the function differentiation and the function involved in plant reproductive development of HSP70 family in monocots and dicots.The normal cracking of flowers is very important to decide whether the plant can be pollination normally,and the sepals cracking is an crucial part of flower cracking.However,sepals how to respond to outside temperature change as well as the relevant mechanism of cracking is not clear in flowers at present.The second part in this study,mainly involved in the function study of HSP70-16 proteins in arabidopsis flower cracking by genetics method.We screened hsp70-16(T-DNA insertion)mutants with sepals cracking unsuccessfully from arabidopsis mutants library.Through genetic structure and promoter analysis,we can confirm that HSP70-16 gene encodes a heat shock protein induced by high temperature.In arabidopsis thaliana,the lack of HSP70-16 genes will lead to flower open abnormally,namely,owing to sepals cracking abnormally,other wrapped parts of flower organs grow twistingly,eventually had pistil pollinated incompletely or not.By different temperature(16?,23? and 27?)treatment,the results showed that the seed setting rate of hsp70-16 mutant was influenced by temperature apparently.Especially,the seed setting rate reduced by 28% and 64% at 23? and 27?,respectively.The process of flower development was further observed by semi-thin section method,the main results showed that hsp70-16 sepals cracking is abnormal,eventually gave rise to abnormal stigma pollination.Genetic complement,the separation ratio and reciprocal cross experiment,also proved that HSP70-16 belongs to a single gene and recessive mutant.Bioinformatics and qRT PCR analysis showed that The expression of the gene has broad spectrum,GUS staining confirmed the mutants specifically expressed in the sepals during floral organ development.Through the SEM,TEM,the measurement of cutin and wax metabolism and RNAseq experiment,confirmed HSP70-16 affected the expression of related wax gene,disturbed wax biosynthesis on top of the lateral sepals,which resulted in sepals abnormal cracking process.this study provide a new perspective for us to understand HSP70-16 how to sense external environment change and adjust the metabolic activities to alleviate the damage accompanying stress in plants. |
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