Genetic structure of Pyrenophora teres f. teres and P. teres f. maculata populations from western Canada

Citation

Akhavan, A., Turkington, T.K., Kebede, B., Xi, K., Kumar, K., Tekauz, A., Kutcher, H.R., Tucker, J.R., Strelkov, S.E. (2016). Genetic structure of Pyrenophora teres f. teres and P. teres f. maculata populations from western Canada, 146(2), 325-335. http://dx.doi.org/10.1007/s10658-016-0919-5

Plain language summary

Infection by the net and spot forms of net blotch of barley, respectively, can result in significant yield losses for barley farmers. The genetic structure of a collection of the net blotch pathogen from Alberta, Saskatchewan, and Manitoba were analyzed DNA marker analysis. Genotypic diversity was relatively high, with most of the genetic variation occurring within populations. Results suggest that the plant pathogen that causes net blotch goes through regular cycles of sexual recombination in western Canada.

Abstract

Infection by Pyrenophora teres f. teres (Ptt) or P. teres f. maculata (Ptm), the causal agents of the net and spot forms of net blotch of barley, respectively, can result in significant yield losses. The genetic structure of a collection of 128 Ptt and 92 Ptm isolates from the western Canadian provinces of Alberta (55 Ptt, 27 Ptm), Saskatchewan (58 Ptt, 46 Ptm) and Manitoba (15 Ptt, 19 Ptm) were analyzed by simple sequence repeat (SSR) marker analysis. Thirteen SSR loci were examined and found to be polymorphic within both Ptt and Ptm populations. In total, 110 distinct alleles were identified, with 19 of these shared between Ptt and Ptm, 75 specific to Ptt, and 16 specific to Ptm. Genotypic diversity was relatively high, with a clonal fraction of approximately 10 % within Ptt and Ptm populations. Significant genetic differentiation (PhiPT = 0.230, P = 0.001) was found among all populations; 77 % of genetic variation occurred within populations and 23 % between populations. Lower, but still significant genetic differentiation (PhiPT = 0.038, P = 0.001) was detected in Ptt, with 96 % of genetic variation occurring within populations. No significant genetic differentiation (PhiPT = 0.010, P = 0.177) was observed among Ptm populations. Isolates clustered in two distinct groups conforming to Ptt or Ptm, with no intermediate cluster. The high number of haplotypes observed, combined with an equal mating type ratio for both forms of the fungus, suggests that P. teres goes through regular cycles of sexual recombination in western Canada.