Population structure of Puccinia striiformis f.sp. tritici at the southern part of Pakistani Himalayan region
The Himalayan region of Pakistan has been shown to be the centre of diversity of wheat yellow rust pathogen Puccinia striiformis f.sp. tritici (Pst) with a probable role of sexual reproduction in the population temporal maintenance. However, the populations of southern part of Pakistani Himalayan region remains unexplored, where wheat yellow rust is an important disease on rainfed wheat. The current study was thus carried out to assess the disease status and population structure of Pst prevalent in the southern part of Pakistani Himalayan region, mainly the districts of Kohat, Karak, Bannu, Lakki-Marwat and DI-Khan. A high disease pressure was observed during wheat season in 2013 in the region, where the level of severity ranged from 5% to 100% depending upon the variety tested. Microsatellite genotyping of 102 isolates with 18 SSR markers revealed a high diversity ranging from 0.86 (for DI Khan) to 1.00 (for Karak). The recombination signature was lower compared to the Himalayan populations. Analyses of the population subdivision revealed no clear evidence of spatial structure, with the maximum FST value of only 0.081. The overall diversity was higher in the region as compared to European clonal population, though it was still lower than the recombinant Himalayan populations, which could be attributed to their distance from Berberis spp. plantation zone.