Pathotypes and Genetic Diversity of Chinese Collections of Elsinoë fawcettii Causing Citrus Scab

Two scab diseases are currently recognized on citrus: citrus scab, caused by Elsinoë fawcettii, and sweet orange scab, caused by E. australis. Although these pathogens are economically important, there is no molecular data on these species in China. Here we use internal transcribed spacer sequence data to report on host-specificity and genetic relationships among 46 isolates collected from the main citrus varieties grown across China. All strains isolated were E. fawcettii. Based on pathogenicity testing on 9 different citrus species, isolates were divided into 11 pathotypes (SM, FBHR, SJCR, SPOJCR, SR, SOJG, SPOJC, SRGC, Lemon and two unnamed pathotypes). SM is a new pathotype, and two isolates did not fit into any of the known pathotypes of E. fawcettii. Inter-simple sequence repeat (ISSR-PCR) assays separated the E. fawcettii isolates into 10 subgroups; the groupings basically corresponded to the pathogenicity test.