Studies On The Function Of TaDeg7 In Triticum Aestivum L.

Photoinhibition leads to decrease photosynthetic efficiency,limit plant growth and reduce productivity,especially when combined with other abiotic stresses.The combination of photooxidative stress and photoinhibition in wheat can significantly reduce the rate of photosynthesis,which is an important physiological factor affecting agricultural productivity.Studies in Arabidopsis thaliana showed that Deg7protease participated in the repair of damaged PS? by degrading D1,D2,CP47 and CP43 proteins in photoinduced damage,and thus relieved photoinhibition.So far,Deg7 protease in wheat has not been reported.In previous studies,transcriptome analysis has found that TaDeg7 gene,which is highly homologous to Deg7 protease gene in Arabidopsis thaliana,differentially expressed in newly bread wheat variety Xiaoyan 101 and its parents Liangxing 99 and Xiaoyan 41.Taking TaDeg7 gene as the research object,this experiment used the barley-stripe mosaic virus(BSMV)mediated gene silencing(VIGS)system to preliminarily study.The main results are as follows:1.The expression pattern of TaDeg7 gene was analyzed by RT-PCR.The results showed that TaDeg7 gene was expressed in all tissues of wheat,with the highest expression in leaf and the lowest expression in cob.In different leaf positions,the expression levels were also different.The expression levels of flag leaf,top second leaf and top third leaf were similar,while the expression levels of top fourth leaf and top fifth leaf were significantly decreased.After the flowering of wheat,TaDeg7 gene showed a trend of first rising and then declining,and the expression reached the highest level on the tenth day after the flowering,and then gradually decreased.2.The cDNA of Xiaoyan 101 was isolated into the fragment of TaDeg7 gene(160 bp),which was connected to the BSMV vector,and transcribed into viral RNA in vitro.The seedlings of Xiaoyan 101 were successfully infected.Following the infection of plant disease spot of the target genes of BSMV plant gene expression verification,RT-PCR(Reverse transcription PCR)results showed that the TaDeg7 gene expression in BSMV plants,compared with its controll plant(BSMV:g00),islow,revealing TaDeg7 silence genes have been successful.3.Determination of BSMV:TaDeg7 plant photosynthetic rate,compared with controls,the photosynthetic rate(A),stomatal conductance(g_s),intercellular CO2 concentration(C_i),transpiration rate(E)are dropped significantly,MV was carried out on the in vitro leaf light and strong light PS? maximum photochemical efficiency Fv/Fm significantly lower than control,showed TaDeg7 involved in photosynthesis in wheat and light regulation of oxidative stress resistance.4.Fluorescence kinetics of plant leaves of BSMV:TaDeg7 was determined.It was found that the silencing of TaDeg7 gene resulted in the decline of PS? comprehensive index of photosynthetic performance,maximum photochemical efficiency and electron transfer rate,and significantly increased energy dissipation.The results indicated that TaDeg7 gene played an important role in maintaining PS? activity.5.Under intense light culture,BSMV:TaDeg7 accumulated more malondialdehyde (MDA),and the activity of various antioxidant enzymes decreased significantly.It indicated that the silencing of TaDeg7 gene led to the intensification of intracellular oxidative stress.6.The silencing of TaDeg7 gene resulted in the accumulation of D1 protein,which was consistent with the studies in Arabidopsis thaliana.However,the TaPsbA expression of D1 gene increased under weak light and decreased under high light compared with the control.Meanwhile,CB2 protein and Rubisco protein are also accumulated.The activity of Rubisco enzyme was significantly increased under low light and significantly decreased under high light,while its expression level was significantly lower than that of the control under both culture conditions.