Study On The Mechanism Of High Photosynthetic Efficiency In Wheat And The Identification And Expression Analysis Of TaHATs And TaHDACs Genes

Wheat is the world’s largest food crop,and the output of wheat is closely related to human survival.Photosynthesis is the physiological basis for the formation of crop yield,and high photosynthesis plays an important role in increasing wheat yield.Drought is also one of the main disasters that affect crop yields.The lack of water resources has become the main limiting factor for the high and stable yield of wheat in northern Chain.After drought stress,wheat production will be greatly reduced.Therefore,high light efficiency and high drought resistance are the guarantee for stable and high yield of wheat.In this paper,the high photosynthetic efficiency and high drought resistance wheat variety Bainong 207 and its parents Bainong 64 and Zhoumai 16 were used as experimental materials to study the relevant factors affecting wheat photosynthesis,and to determine the key factors of high photosynthetic efficiency and several candidate genes;Identified histone acetylases(HATs)and histone deacetylases(HDACs)from the whole wheat genome,and further analyzed their expression changes in Bainong 207,Bainong 64 and Zhoumai 16,and screened out possible HATs and HDACs genes that mediate the regulation of wheat drought.The research in this thesis can provide a theoretical basis for cultivating wheat varieties with high photosynthetic efficiency and strong drought resistance in production.The main experimental results are as follows: 1.The morphology and structure of leaves are closely related to photosynthesis.BN207 has thicker leaves and larger leaf area,which provides a basis for more light energy absorption;BN207 leaves have a darker color and a higher content of chlorophyll and carotenoids,which are used in energy harvesting and photoprotection of photosynthesis plays an important role;the tighter distribution of chloroplasts on the cell membrane of BN207 leaves and the tighter accumulation of thylakoids are conducive to improving photosynthesis,so that BN207 has a higher net photosynthetic rate(Pn)and maximum photochemical efficiency(Fv/ Fm).2.The higher photosynthetic efficiency in BN207 is also related to higher ribulose1,5-bisphosphate carboxylase/oxygenase(Rubisco)activity.BN207 has higher stomatal conductance(Gs)and intercellular CO2 concentration,chlorophyll is located near the cell membrane,these features promote CO2 to enter cells,promote Rubisco carboxylation reaction,increase Rubisco enzyme activity,thereby promoting carbon assimilation and the accumulation of more carbohydrates(glucose,fructose,starch),and promote wheat growth and yield formation.3.Transcriptome and gene expression analysis showed that several key genes mediate the high photosynthetic efficiency of BN207:Traes CS5D02G364100(chlorophyllase),BGI_novel_G006617(lycopene ε-cyclase),Traes CS4A02G034800 and Traes CS4A02G035100(zeaxanthin epoxy)Enzyme),Traes CS6B02G122500(light harvesting complex II chlorophyll a / b binding protein 1).These genes mainly improve the photosynthesis efficiency of BN207 by reducing chlorophyll degradation,promoting carotenoid synthesis and increasing Lhcb1 protein accumulation.4.HATs and HDACs genes mediate abiotic stress in plants.This article uses bioinformatics methods to identify Ta HATs and Ta HDACs in the wheat genome.Finally,30 HATs and 53 HDACs genes were found in wheat,and these genes were analyzed.Analysis:Phylogenetic and domain analysis showed that Ta HATs and Ta HDACs are highly similar to Arabidopsis and rice,but there are some differences.There are many stress-related cis-regulatory elements(such as ABRE,STRE,MYB,etc.)on the promoters of these genes.5.Analyzed the expression of Ta HATs and Ta HDACs in different tissues(leaf,root,ear,grain),and found that most of the genes have different expression levels in different tissues.In addition,some genes are between the A,B and D genomes different expression levels.Through the expression analysis of three different drought-resistant varieties of Bainong 207,Bainong 64 and Zhoumai 16 under drought stress,it was found that Ta HAG2,Ta HAG3 and Ta HAC2 in Ta HATs family,Ta HDA2,Ta HDA18,Ta HDT1 and Ta HDT2 in Ta HDACs family only BN207 showed a significant response to drought stress,especially Ta HAG2,Ta HAG3,Ta HAC2 and Ta HDT1 were up-regulated under drought stress,while Ta HDA2,Ta HDA18 and Ta HDT2 were down-regulated.In addition,the expression of these genes(except Ta HDA2)in BN207 under drought stress was significantly different from the levels of its parents BN64 and ZM16.It is speculated that Ta HAG2,Ta HAG3,Ta HAC2,Ta HDA18,Ta HDT1 and Ta HDT2 may regulate the drought stress of wheat.