The Co-infection Ratio And Sequence Variation Analysis Of ToCV And TYLCV Of Tomato In China

Tomato chlorosis virus(ToCV)and Tomato yellow leaf curl virus(TYLCV)are both transmitted by whityfly(Bemisia tabaci),have been severely epidemic in most regions of Solenaceae crops accompanied with dispersing of its transmission vector--whitefly.The yield loss would be res ulted by co-infection of ToCV and TYLCV compared with individual infection.So it is urgently to understand the distribution,co-infection ratio and virus molec ular evolution of ToCV and TYLCV,to scientifically decipher the adaptation evolution of To C V and TYLCV.The 625 of tomato samples with suspected symptoms infected by ToCV and(or)TYLCV were sampled in Shandong,Neimenggu,Gansu,Hebei,Shanxi,Shanghai,Anhui,Jiangsu,Henan,Guizhou,Yunan,Guangxi and H ainan provinces from2017-2019.The 28.48% of tomato samples were verified ToCV positive by specific RT-PCR.Amid the highest ToCV infection ratio was upto 91.36% in Guagnxi province.The nucleotide sequences of CP gene of ToCV isolates shared over 99% identity in China,however shared only 96.25% identity with ToCV isolate of Turkey.The phylogenetic analysis hinted certain molecular evolution appeared between ToCV isolates without region-dependent.The 27 of full genomic sequences of ToCV isolates were finished and compared.The nucleotide sequence identity of genomic RNA1 and RNA2 shared over 99% and98% in 27 sequenced ToCV isolates.The nucleotide substitution/subversion and neutrality analysis shown the certain genetic evo lution,which higher than RNA1 appeared in genomic RNA2 with region-dependent.The TYLCV positive ratio was 74.88% for sampled 625 of tomato saples in 13 provinces in China,amid highest upto 100% in Jiangsu and lowest of 18.75% in Shanxi.The average co-infection ration of ToCV/TYLCV was 20.00%,the highest co-infection ratio of 46.67% was in Henan province,and lowest of 5.06% in Yunnan province.The genomic sequences of TYLCV isolates was sequenced,and shared 99.32%nucleotide identity,no genetic evolution detected.