Genetic diversity and population differentiation of Sclerotinia sclerotiorum collected from canola in China and in U.S.A.

Abstract

Sclerotinia sclerotiorum is an important pathogen of canola and many other crops worldwide. Genetic diversity and population differentiation of S. sclerotiorum collected from canola fields in Anhui Province, China (30 isolates) and in North Dakota, U.S.A. (29 isolates) were investigated in terms of genetic variation in 8 simple sequence repeat (SSR) marker loci, mycelial compatibility groups (MCGs) and three phenotypic traits: sensitivity to fungicides benomyl, iprodione and fluzinam, oxalic acid production, and pathogenicity. Significant genetic differences were observed; there were no shared SSR haplotypes and no shared MCGs between the two populations. Population differentiation was significant (p = 0.000) indicating lack of gene flow between the two populations. There were also significant differences between the two populations in oxalic acid production and in fungicide sensitivity. The Chinese population displayed high levels of insensitivity (faster growth rate) to benomyl and fluzinam and higher levels of oxalic acid production per unit dry weight of mycelium than did the U.S. population. However, there was no significant difference in pathogenicity between the two populations as measured by colonization of detached canola leaves. Data Vol. 101, No. 6 (Supplement), 2011 S11 suggest that despite geographic and genetic isolation the two populations of S. sclerotiorum were equally adapted to colonizing canola plants, and pathogenicity is under different selection pressure than the other genetic and phenotypic traits.