Distribution and molecular characterization of citrus chlorotic dwarf-associated virus in China

Abstract

In 2009, a new citrus viral disease caused by Citrus chlorotic dwarf-associated virus (CCDaV) was discovered in China. To more effectively monitor the presence of CCDaV, a survey was conducted in 175 citrus orchards from 11 major citrus growing provinces in China from May 2014 to August 2016. 4 out of a total of 2, 432 citrus samples tested positive for CCDaV, demonstrating there were still sporadic CCDaV cases occurred in China, and the virus was restricted to a few orchards. In this study, the complete genome sequences of four CCDaV isolates from Eureka lemon were sequenced and characterized. Comparisons of the whole genome sequences of these four CCDaV isolates as well as two isolates previously reported from around the world revealed that sequence identity ranged from 98.1% to 99.8%, indicating that there is a very low level of sequence heterogeneity among CCDaV isolates of different geographic origins. To our knowledge, this is the first extensive survey conducted in China for CCDaV incidence.