Evidence and Consequence of a Highly Adapted Clonal Haplotype within the Australian Ascochyta rabiei Population

Frontiers in Plant Science

Sukhjiwan Kaur¹  Kristy Hobson²  Kevin Moore²  Prabhakaran Sambasivam³  Yasir Mehmood³  Jeremy Brownlie³  Rebecca Ford³  Audrey E. Leo⁴  Celeste C. Linde⁵  Jenny Davidson⁶ 

[1] Agriculture Victoria, AgriBio, The Centre for AgriBioscience, BundooraVIC, Australia;Department of Primary Industries, Tamworth Agricultural Institute, TamworthNSW, Australia;Environmental Futures Research Institute, School of Natural Sciences, Griffith University, NathanQLD, Australia;New South Wales Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga WaggaNSW, Australia;Research School of Biology, Australian National University, CanberraACT, Australia;South Australian Research and Development Institute, UrrbraeSA, Australia;

关键词: chickpea;    Ascochyta rabiei;    resistance sources;    SSR genotype;    haplotype and highly aggressive;   

DOI  :  10.3389/fpls.2017.01029

来源: DOAJ

【 摘 要 】

The Australian Ascochyta rabiei (Pass.) Labr. (syn. Phoma rabiei) population has low genotypic diversity with only one mating type detected to date, potentially precluding substantial evolution through recombination. However, a large diversity in aggressiveness exists. In an effort to better understand the risk from selective adaptation to currently used resistance sources and chemical control strategies, the population was examined in detail. For this, a total of 598 isolates were quasi-hierarchically sampled between 2013 and 2015 across all major Australian chickpea growing regions and commonly grown host genotypes. Although a large number of haplotypes were identified (66) through short sequence repeat (SSR) genotyping, overall low gene diversity (Hexp = 0.066) and genotypic diversity (D = 0.57) was detected. Almost 70% of the isolates assessed were of a single dominant haplotype (ARH01). Disease screening on a differential host set, including three commonly deployed resistance sources, revealed distinct aggressiveness among the isolates, with 17% of all isolates identified as highly aggressive. Almost 75% of these were of the ARH01 haplotype. A similar pattern was observed at the host level, with 46% of all isolates collected from the commonly grown host genotype Genesis090 (classified as “resistant” during the term of collection) identified as highly aggressive. Of these, 63% belonged to the ARH01 haplotype. In conclusion, the ARH01 haplotype represents a significant risk to the Australian chickpea industry, being not only widely adapted to the diverse agro-geographical environments of the Australian chickpea growing regions, but also containing a disproportionately large number of aggressive isolates, indicating fitness to survive and replicate on the best resistance sources in the Australian germplasm.

【 授权许可】

Unknown