# Molecular Genotyping by 20K Gene Arrays (Genobait) to Unravel the Genetic Structure and Genetic Diversity of the Puccinia striiformis f. sp. tritici Population in the Eastern Xizang Autonomous Region

## TL;DR

This study uses gene arrays to analyze the genetic diversity and structure of wheat stripe rust in the eastern Xizang region of China.

## Contribution

The study provides new insights into the genetic diversity and population structure of Puccinia striiformis f. sp. tritici in a high-altitude region.

## Key findings

- Low genotypic diversity was observed in the Basu region, while the highest diversity was found in Mangkang.
- Mangkang's population showed admixed groups due to sexual recombination between two ancestor groups.
- Gene flow occurred between Zuogong and Basu, but not between Mangkang and these regions.

## Abstract

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), poses a significant threat to wheat production in China. Previous epidemic studies have demonstrated the potential of high genetic diversity in the southwest regions of China. Among this epidemic region, the eastern Xizang (Tibet) region holds particular significance, as both wheat and barley crops are susceptible to Pst. However, limited information exists regarding the level of population genetic diversity, reproduction model, and migration patterns of the rust in eastern Xizang. The present study seeks to address this gap by analyzing 146 Pst isolates collected from the Basu, Zuogong, and Mangkang regions, genotyping by the 20K target Gene Array (Genobait). Our results showed relatively low genotypic diversity in the Basu region, while the highest genetic diversity was observed in the Mangkang area. Structural analysis revealed the abundance of admixed groups in Mangkang, which exhibited this population occurred due to sexual recombination between two different ancestor groups. Gene flow was observed between Zuogong and Basu populations, but it almost did not occur between Mangkang and Zuogong/Basu populations. This region is the world’s highest-altitude epidemic area, thus facilitating the evolution of the rust and possessing the potential to transmit newly evolved Pst races to lower wheat-growing regions. Implementing disease management strategies in this area is of potential importance to prevent the transmission of Pst races to other parts of Xizang, even neighboring regions possibly. This study facilitates our understanding of epidemiological and population genetic knowledge and the evolution of Pst in Xizang.