甘蔗花叶病毒四川分离物的鉴定和遗传变异分析

Identification and Genetic Variability of the Isolates of Sugarcane Mosaic Virus from Sichuan Province, China

玉米和甘蔗是西南地区两种重要的禾本科农作物,而病毒病的常年发生严重威胁着玉米和甘蔗的生产.从四川攀枝花田间采集表现花叶、褪绿、斑驳或矮化等病毒病症状的玉米样品54份和甘蔗样品42份,用小RNA深度测序结合反转录聚合酶链式反应进行病毒检测,以明确引起该地区玉米和甘蔗病毒病的病原.结果显示:从玉米病株上检测到甘蔗花叶病毒(sugarcane mosaic virus,SCMV)、玉米黄花叶病毒(maize yellow mosaic virus,MaYMV)和留尼旺玉米线条病毒(maize streak Reunion virus,MSRV),3种病毒的检出率分别为66.7%,59.3%和3.7%;从甘蔗病样中检测到SCMV(52.4%)、甘蔗瓜德罗普杆状病毒A(sugarcane bacilliform Guadeloupe A virus,SCBGAV)(76.2%)和高粱花叶病毒(sorghum mosaic virus,SrMV)(28.6%).鉴于SCMV在玉米和甘蔗田间样品中的高检出率,利用其外壳蛋白基因对SCMV四川分离物的遗传变异进行综合分析.系统发育分析表明:120个SCMV中国分离物被分为5组,且其进化分组表现出宿主和地理起源的相关性,来源于玉米的SCMV四川分离物主要被聚入C组,而来源于甘蔗的SCMV四川分离物被聚入E组.核苷酸多样性分析表明:来源于玉米和甘蔗的SCMV四川分离物群体间变异度较高.FST测试表明:四川和云南两地SCMV群体间存在频繁基因流,且群体统计分析结果显示SCMV四川和云南分离物群体存在潜在的扩张趋势.该研究是对四川玉米和甘蔗上病毒病原的综合鉴定,也是对SCMV四川分离物遗传变异情况的首次报道,为SCMV病毒病的防控提供了重要参考依据.

Maize(Zea mays) and sugarcane(Saccharum officinarum) are both important and widely grown gramineous crops in Southwest China, whereas some viral diseases pose serious threats to their production and quality. In this study, small RNA deep sequencing and reverse-transcription polymerase chain reaction(RT-PCR) were performed to identify the pathogens of viral disease with 54 maize and 42 sugarcane samples collected from Panzhihua City of Sichuan Province. Sugarcane mosaic virus(SCMV), maize yellow mosaic virus(MaYMV) and maize streak Reunion virus(MSRV) were found in 66.7%, 59.3% and 3.7% of the maize samples, respectively. For sugarcane plants, sugarcane bacilliform Guadeloupe A virus(SCBGAV), SCMV and sorghum mosaic virus(SrMV) were detected in 76.2%, 52.4% and 28.6% of the samples, respectively. The genetic variability of the China SCMV isolates, with high positive rate in the fields, was comprehensively characterized based on the coat protein gene. Phylogenetic analysis clustered CP genes of all 120 available SCMV isolates from China(including 11 newly obtained Sichuan isolates) into five groups in relation to the hosts and geographical origins. The Sichuan SCMV isolates were clustered in group C and E. The Ftest revealed that frequent gene flow existed between the Sichuan and Yunnan SCMV isolates populations, and the population demographical analyses suggested a trend of inter-transmission of SCMV populations(SC/YN-group C and SC/YN-group E) between these two provinces and the expansion of SCMV subpopulations in these two groups(SC/YN-group C and SC/YN-group E). This is the first report to identify virus pathogens and genetic variation of SCMV isolates from maize and sugarcane in Sichuan Province.