Studies On The Mechanisms By Which Host PTB1 Promotes The Infection Of Rice Stripe Virus

Rice stripe tenuivirus(RSV)is one of the most important food crop viruses in China.Polypyrimidine-tract-binding protein(PTB)is a conserved RNA-binding protein in eukaryotes,which is involved in the regulation of m RNA splicing and stability.Our previous study found that overexpression of PTB1 in N.benthamiana significantly promoted RSV infection.In order to analyze the mechanism of PTB1 promoting RSV infection,this paper carried out the following research :(1)Susceptibility of PTB1 overexpressing plants(PTB1 OE)to other viruses : To study whether PTB1 specifically acts on RSV,PTB1 OE was inoculated with tomato yellow leaf curl virus(TYLCV),tomato leaf curl virus(To LCHs V)and potato virus X with green fluorescent protein gene(PVX-GFP).The results showed that PTB1 OE plants inoculated with TYLCV or To LCHs V had earlier onset,more severe symptoms and higher viral DNA accumulation than wild-type plants(WT).PTB1 OE plants inoculated with PVX-GFP showed stronger green fluorescence in new leaves,and the accumulation of GFP and PVX CP proteins was also higher.These results indicated that PTB1 OE plants were more susceptible to other viruses.(2)Identification and verification of PTB1 ’ regulatory gene ’ :Because the susceptibility enhancement mediated by PTB1 is not RSVspecific,PTB1 may affect the infection efficiency of RSV by regulating one or some host genes.In view of this,the transcriptomes of PTB1 OE plants and wild-type plants(WT)were compared.The results showed that248 genes were differentially expressed in PTB1 OE plants.Ten genes were selected for fluorescence quantitative PCR verification,and the results were consistent with the transcriptome.In order to verify that these genes were indeed regulated by PTB1,PTB1 or YFP(control)was transiently expressed in WT plants,and the effect of PTB on three ’PTB1regulatory genes ’ was studied by fluorescence quantitative PCR.The results showed that all three genes showed expression changes consistent with the transcriptome results.(3)The effect of PTB1 ’ regulatory gene ’ CHD3 on RSV infection :CHD3 is one of the ’PTB1 regulatory genes ’,which is significantly upregulated in PTB1 OE plants and WT plants transiently expressing PTB1.CHD3 encodes a protein with chromatin remodeling function.In order to study the effect of CHD3 on RSV infection,CHD3-VIGS was obtained by virus-induced gene silencing.After inoculation with RSV,the onset of CHD3-VIGS was delayed by 1-2 days compared with the control plants,and the symptoms were also significantly lighter.Fluorescence quantitative PCR experiments showed that the accumulation of RSV in CHD3-VIGS plants was 1.24 times lower than that in WT plants.Western blot experiments showed that the accumulation of RSV NP protein in CHD3-VIGS plants was lower than that in WT plants.In order to study whether CHD3 also affects the susceptibility of N.benthamiana to other viruses,the same experiment was carried out with To LCHs V.The results showed that the susceptibility of CHD3-VIGS to To LCHs V was also significantly reduced.In summary,the main research results of this paper have three points :(1)It was found that overexpression of PTB1 plants was also more susceptible to other viruses;(2)Some host genes regulated by PTB1 were identified;(3)CHD3 gene regulated by PTB1 can affect the infection of RSV and other viruses.These results lay a foundation for further analysis of how PTB1 promotes RSV infection,and are also important for understanding the interaction mechanism between RSV and host.