苹果茎沟病毒柑橘碎叶株系的分布与序列分析

Distribution and molecular characterization of citrus tatter leaf virus in China

为明确苹果茎沟病毒(apple stem grooving virus,ASGV)柑橘碎叶株系(citrus tatter leaf virus,CTLV)在中国柑橘产区的发生分布及其分子特性,于2017—2021年对我国12个柑橘主产区开展系统调查,并采用多重比对以及系统发育分析法对CTLV的全序列进行分析。结果表明,从12个柑橘主产区采集的2012份疑似样品中检测出413份感CTLV阳性样品。除陕西省外,其余11个柑橘主产区样品中均检测出CTLV,并且柚类样品中CTLV的检出率最高,达到32.31%。对分离获得的22株CTLV毒株和已知的7株CTLV以及5株ASGV毒株进行全序列分析,发现所有34株毒株的核苷酸序列相似性为78.6%~99.8%,且CTLV序列的保守性较高。此外,与其他4株ASGV毒株相比,本研究中22株CTLV毒株与ASGV-MK毒株(GenBank登录号为MZ127820.1)具有更近的亲缘关系。推测CTLV中国毒株间的亲缘关系可能与其采样地和寄主品种有关。

To better understand the distribution and molecular characteristics of citrus tatter leaf virus(CTLV)in China,a field survey was conducted from 2017 to 2021,and a total of 2012 citrus samples were collected from 12 Chinese major citrus-growing provinces.Among these,413 citrus samples were tested positive for CTLV,and this virus was present in all of the Chinese major citrus-growing provinces,except Shaanxi Province.In surveyed citrus genotypes,the most frequently infected genotype was pummelo,with an infection rate of 32.31%.CTLV is a strain of apple stem grooving virus(ASGV,Capillovirus).In this study,the complete genome sequences of 22 CTLV isolates from different provinces and hosts were sequenced.Comparisons of the whole-genome sequences of these 22 CTLV isolates as well as seven CTLV and five ASGV isolates previously reported from around the world revealed that the sequence identity ranged from 78.6%to 99.8%,indicating that there was a very low level of sequence heterogeneity among CTLV isolates of different geographic origins and hosts.Phylogenetic analyses of these 34 genomic sequences suggest that ASGV-MK(GenBank accession no.:MZ127820.1)has a closer relationship with CTLV than other four ASGV isolates.These results indicate that the evolutionary relationships of Chinese CTLV isolates may be associated with geographic origin and host species.