Molecular and biological characterization of a novel citrus tristeza virus isolate that causes severe symptoms in Citrus junos cv. Ziyangxiangcheng

The complete genomic sequence of a novel citrus tristeza virus (CTV) isolate, CT91-A1, from Orah tangor grafted on Citrus junos cv. Ziyangxiangcheng rootstock in China was determined by transcriptome sequencing. Sequence alignments showed that isolate CT91-A1 shared 83.3 to 95.5% nucleotide sequence identity with extant CTV genotypes at the whole-genome level, with the highest similarity to the S1 genotype. Phylogenetic analysis revealed that CT91-A1 clustered in a unique subclade with the S1 genotype. Isolate CT91-A1 induced severe stem pitting in Mexican lime and C. junos cv. Ziyangxiangcheng and moderate stem pitting in Guanximiyou pummelo and Duncan grapefruit. It was successfully transmitted by Aphis citricidus, and it can potentially cause significant damage to the citrus industry in China.