Identification of a novel phylogenetic lineage of Alternaria alternata causing citrus brown spot in China.
Alternaria alternata sensu lato, casual agent of citrus brown spot, first identified in Yunnan province in 2010 and subsequently found in Zhejiang, Hunan, Guangdong provinces, Chongqing municipality andGuangxi autonomous region in China. During 2010-2012, 86 isolates were collected from diseased citrus, of which 85 % isolates were pathogenic to Ponkan tangerine. Phylogenetic analyses of Chinese and worldwide isolates using partial sequences of an endopolygalacturonase gene (endoPG) and combined dataset ofendoPG and two anonymous loci (OPA1-3, OPA2-1) found that Chinese isolates fell into two of three previously described clades. One clade ('clade 3') contained isolates from Turkey and Israel, and the other clade ('clade 1') contained isolates from Florida, USA. None of the isolates from China fell into the last previously described clade ('clade 2'). However, 24 isolates from Hunan, Guangdong and Guangxi fell into a fourth clade ('clade 4') not previously reported to be associated with citrus brown spot. This clade included multilocus haplotypes known to infect Japanese pear and strawberry. The observation that Chinese brown spot isolates fell into only two of three known worldwide lineages suggests that this fungus may not have co-evolved with its host in China but elsewhere in Southeast Asia and introduced to China.
Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
Feng
F
Huang
Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
Yushi
Y
Fu
Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
Danni
D
Nie
Department of Plant Pathology, University of Georgia, Athens, GA 30602, USA.
Jane E
JE
Stewart
Department of Plant Pathology, Washington State University, Pullman 99164, USA.
Tobin L
TL
Peever
Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China. Electronic address: hyli@zju.edu.cn.
Hongye
H
Li
D000528:Alternaria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D002681:China; D002957:Citrus / Q000382:microbiology*; D005656:Fungal Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D011096:Polygalacturonase / Q000235:genetics
D005656:Fungal Proteins; D011096:Polygalacturonase
Alternaria alternata; Anonymous genomic loci; Citrus brown spot; Endopolygalacturonase gene; Phylogenetic analysis