Long-Distance Transport of Puccinia striiformis f. sp. tritici by Upper Airflow on the Yunnan–Guizhou Plateau Disrupts the Balance of Agricultural Ecology in Central China

Abstract

Long-distance dispersal of plant pathogens in the air can establish diseases in other areas and lead to an increased risk of large-scale epidemics. Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases of wheat in China. Hubei is an important overwintering region for Pst in China, and this overwintering region is a determinant of stripe rust severity in eastern China. In 2017, stripe rust disease caused a pandemic in the Hubei region and resulted in great yield losses of wheat. To explain the disease pandemic, a total of 595 single-lesion samples of stripe rust were collected in spring, including 204 in 5 provinces in 2017 and 391 in 4 provinces in 2018, and genotyped using 13 simple sequence repeat makers. The samples were classified into 12 subpopulations based on the locations and year of collection. Genetic diversity was determined for the collection and each subpopulation. Differentiation and gene flow were determined between subpopulations. STRUCTURE analyses and discriminant analysis of principal components (DAPC) were conducted, and the results were used to infer the relationships among subpopulations. Our study revealed a new route of Pst transmission from the Yunnan-Guizhou Plateau to the Hubei region. The Pst inoculum of northwestern Hubei was from Gansu in the northwest, whereas the inoculum in southern Hubei was from the Yunnan–Guizhou Plateau through the upper air. After the initial inocula infected wheat plants and multiplied in northern and southern Hubei, urediniospores produced in these regions further spread together along the middle reach of Hanshui Valley and made exchanges there. The finding of the new transmission route of Pst is important for improving integrated stripe rust disease management, which should have a profound impact on restoring the balance of agricultural ecology in China.

Analysis of genetic diversity and population structure of Puccinia striiformis f. sp. tritici infers inoculum relationships from Yunnan to the middle and lower reaches of the Yangtze River

“…According to the analysis of wind and airflow trajectory from November 2018 to February 2019, a south‐westerly wind prevailed in Yunnan during this period, and the Pst urediniospores can be taken along with the south‐westerly wind from Yunnan to southern Hubei, and then continue to spread to Zhejiang and other MLRYR. Some previous research results supported this deduction (Huang et al, 2022; Ju et al, 2022; Li et al, 2021). The sampling time of wheat stripe rust showed a gradually postponed trend from Kunming, Jingzhou to Hangzhou, implying a time delay of wheat stripe rust occurrence in the field from western to eastern regions.…”

“…Yunnan was previously considered to be an independent epidemic area of wheat stripe rust with no exchange with other geographical groups (Zeng & Luo, 2008), but recent evidence has proved that there is an exchange of Pst inoculum sources between Yunnan and Hubei and the MLRYR. The inoculum source of Pst in southern Hubei is mainly from Yunnan, and the Yunnan provided major inoculum sources to Jiangsu and Zhejiang regions (Huang et al, 2022; Ju et al, 2022). In the present study, we found that the inoculum source of Pst in Zhejiang is also mainly from Yunnan, and that the south of Hubei serves as a transfer station (or stopover) for the inoculum.…”

“…By contrast, the Yunnan-Guizhou inoculum has no impact on other wheat-growing regions of China (Chen et al, 2013). However, most recent studies have found that the Pst in Yunnan and the MLRYR are genetically closely related (Huang et al, 2022;Li et al, 2021). Making a thorough investigation of the inoculum sources of Pst in the MLRYR region will be crucial to developing a strategy for monitoring and control of wheat stripe rust nationwide.…”

Genomic analysis, trajectory tracking, and field surveys reveal sources and long-distance dispersal routes of wheat stripe rust pathogen in China

“…However, its specific inoculum centers and their related dispersal routes have not been clear. Recently, much intensive research has been performed to investigate Pst dispersal patterns in China, although it has focused on studying relationships among Pst populations in a few regions using a handful of molecular markers ( Liang et al., 2013 , 2016 , 2021 ; Wan et al., 2015 ; Wang et al., 2020 , 2022 ; Huang et al., 2021 , 2022 ; Zhan et al., 2022 ). Analyses based on a limited number of markers and sampling sites may not provide sufficient resolution to dissect the genetic diversity and structure of Pst populations ( Hubbard et al., 2015 ; Bueno-Sancho et al., 2017 ).…”

Fighting wheat rusts in China: a look back and into the future

“…As a result, this epidemiological region is almost isolated from other regions. However, recent studies revealed that the Yunnan epidemiological region and other southwestern epidemiological regions are also involved in wheat stripe rust epidemics in China (Awais et al 2022;Huang et al 2022;Ju et al 2022;Zhan et al 2022a). In addition to Yunnan region, Tibet and Xinjiang also developed to be the independent stripe rust epidemiological regions (Li and Zeng 2002;Hu et al 2017;Awais et al 2022).…”