Functional Analysis Of Transcription Factor TaMYB73 Of Wheat Cultivar Xiaoyan 6 And The Construction Of Puccinia Striiformis F.sp.tritici CYR34 On Molecular Marker System

Wheat stripe rust,caused by Puccinia striiformis f.sp.tritici(Pst),is a fungal disease that can cause significant yield loss in epidemic years.Breeding resistant cultivars is the most economical,safe and effective method to control wheat stripe rust.However,resistant cultivars often "lose" their resistance due to the rapid variation of Pst.Therefore,planting non-racespecific and durable resistant cultivars is an important approach to control wheat stripe rust.XY6 is a typical disease-resistant wheat cultivar which maintained high-temperature resistance to stripe rust in the field since its release in 1975.In this study,we selected Pst race CYR32 and CYR34 to test the resistance of XY6 to stripe rust,and investigated the functions of the transcription factor TaMYB73 in the process of high-temperature resistance of XY6.Additionally,we developed the race-specific marker of stripe rust CYR34,which can be used in identifying CYR34 in fields.The following are the main findings of the study:1.Transcription factor TaMYB73 plays a positive regulatory role in high-temperature resistance to Pst in wheat.The open reading frame of TaMYB73 is 765 bp,which encodes 254 amino acids.TaMYB73 was highly expressed in wheat roots and leaves,and the expression of TaMYB73 reached a peak at 24 h after dual induction by Pst and high temperature,which was about 7.97 times compared to the control group;The TaMYB73-silenced plants produced more pustules and longer linear uredinia than the non-silenced plants,and silencing TaMYB73 reduced the resistance to Pst.The expression of the gene was significantly up-regulated after0.5 h treatment with SA,Me JA and ET,and the up-regulation was up to 15.82-fold under SA treatment.After silencing TaMYB73,the expression levels of SA signaling pathway defenserelated genes TaPR1 and TaPR2 were significantly decreased.The interaction protein TaPR4 of TaMYB73 was screened by yeast two-hybrid,which may enhance wheat resistance by degrading chitin in fungal cell walls.2.The molecular marker system of Pst race CYR34 was constructed.Chinese Yellow Rust 34(CYR34)is currently the physiological race with the broadest virulent spectrum and the highest virulence of Pst.In this study,a specific primer among 300 random RAPD primers was screened to differentiate the CYR34 of Pst from other races using RAPD-SCAR molecular marker technique.The specific band was purified from the agarose,cloned into p MD18-T vector,and sequenced to obtain the specific fragment sequence(Gen Bank accession:OL907303).Specific primers S2008F34/S2008R34 was designed based on the sequence,which could amplify a 417 bp specific band from both the genome DNA of CYR34 and the total DNA of wheat leaves inoculated with CYR34.The molecular marker system of Pst CYR34 was constructed,including the specific primers S2008F34(5’-CACAGCCGAAGCATGGTAGG-3’)and S2008R34(5’-TCCACAGCCGATGTTGACG-3’),and the PCR reaction system(94℃ for 5 min;94℃ for 30 sec,60℃ for 30 sec,72℃ for 40 sec,30 cycles;72℃ for 7 min).The system was applied to detect the epidemic frequency of CYR34 in Weinan,Xianyang,and Baoji in Shaanxi Province in 2021.The results showed that the epidemic frequency of CYR34 were 8.6%,6.0%,and 10.8%,respectively.