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[Objective] The present paper aimed to study the molecular characteristics, genetic structure and evolutionary mechanism of cucurbit aphid-borne yellows virus ( CABYV), in order to clarify the epidemic pattern of the virus in the field and formulate long-term sustainable prevention and control strategies which is of great significance. [ Method] 120 melon leaves suspected to be infected with CABYV were randomly collected from Aksu city, Xinjiang. RT-PCR was used to detect the virus. MEGA 7. 0 was used to construct phylogenetic tree, DnaSP vS. 10 was used to analyze the genetic diversity among different sequences, and RDP v. 4. 31 software was used to analyze the possible recombination events of CABYV sequence. [Result] As verified by RT-PCR, 38 samples were CABYV positive, and the detection rate was 31. 67%. A new CABYV-2 was isolated, sequenced and cloned from these positive samples. The length of the genome was 5497 bp, encoding six open reading frames. Compared with 23 CABYV strains isolated from different countries in NCBI database, CABYV-2 had the highest homology with KR231942. 1 and the lowest homology with JF939812. 1. The results of evolutionary tree analysis showed that 24 isolates were divided into two branchesdue to different geographical factors, including CABYV-2 and KR231942. 1 come together and belong to branch 1. The results of genetic diversity and neutral test showed that CABYV was highly variable and population was expanding. The results of recombination analysis showed that there were two recombination events, EU636992. 1 and KR231949.1, which exacerbated the variation of CABYV. [Conclusion] CABYV was isolated from Aksu, Xinjiang and KR231942. 1 from Korea had the closest genetic relationship and the farthest genetic relationship with isolates from European countries. There were great genetic differences between branch 1 and branch 2 isolates. The recombination of cabyv among different hosts intensifies the variation of CABYV recombination and negative selection may be important reasons affecting the genetic variation of CAB YV. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to fully understand the genetic diversity and phylogenetics of Xinjiang indigenous sheep breeds, and provide theoretical basis for breeds, conservation and utilization. [Method] The squences of mitochondrial DNA (mtDNA) Cylb of 13 Xinjiang indigenous sheep breeds were amplified and sequenced. [Result] It was found that these breeds had abundant genetic diversity, except Hotan sheep. Neutral test showed that Hotan sheep had experienced population expansion. The genetic distance between Hotan sheep breeds and Qira black sheep breeds was the closest, and between Hotan sheep breeds and Bachu sheep breeds was the furthest. There were relatively far genetic distance between Bachu sheep breeds and other breeds. 13 indigenous sheep breeds were divided into 3 branches by haplotype network. After AMOVA molecular variation analysis, genetic variation between populations and within populations was 91.33% and 8.67%, respectively. There was no significant genetic differentiation among populations. [Conclusion] The results showed that there were three matrilineal origins in 13 Xinjiang indigenous sheep breeds. The genetic relationship was basically consistent with the breeding history and geographical distribution. Hotan sheep had low genetic diversity and need to strengthen the protection of germplasm resources. [ABSTRACT FROM AUTHOR]