Leaf rust of wheat caused by Puccinia triticina (Pt) is one of the most common and widespread fungal diseases which has a wide incidence area, especially in the southwest and northwest of China, the middle and lower reaches of the Yangtze river, and the southern part of the Huang-huai-hai river basin. To explore the relationship between the epidemic flora of leaf rust and transmission, a total of 709 isolates from Beijing, Hebei, Henan, Shandong, Shanxi, Shaanxi, Anhui, Jiangsu, Hubei, Yunnan, Sichuan, Gansu, Qinghai, Heilongjiang, Inner Mongolia 15 provinces was genotyped using 13 simple sequence repeat (SSR) markers. The Puccinia triticina populations from the 15 provinces were obviously divided into three predominant populations including the eastern Pt populations consisting of Pt samples from eight eastern provinces of Beijing, Hebei, Shandong, Anhui, Henan, Shanxi, Shaanxi and Heilongjiang; the four western Pt populations from Gansu, Sichuan, Qinghai and Inner Mongolia provinces; and the bridge Pt populations including Pt samples from Jiangsu, Hubei and Yunnan provinces which were communicated with the other two populations as a “bridge”. And the pathogen source transmission of eastern Pt populations was more frequent than western Pt populations. The linkage disequilibrium test indicated that the whole Pt population was linkage disequilibrium. Beijing, Hebei, Shaanxi, Jiangsu, Henan and Heilongjiang provinces were showed obviously linkage equilibrium phenomena while the five provinces of Qinghai, Hubei, Anhui, Shandong and Inner Mongolia were supported clonal mode of reproductions. In addition, provinces of Shanxi, Yunnan, Gansu, and Sichuan showed weak linkage disequilibrium phenomena. We systematically revealed the genotypic diversities, population differentiation and reproduction of P. triticina in 15 wheat producing areas in China.

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases of wheat in China. Due to the pandemic in 2017~2018, a total of 709 single-lesion samples, including 285 collected in 7 provinces in 2017 and 424 collected in 4 provinces in 2018, were isolated to explore the underlying causes. The population structure was analyzed by using 13 simple sequence repeat (SSR) makers. 306 multi-locus genotypes (MLGs) were detected and the genetic diversity was different among populations. Regardless of the year difference, 11 populations were clustered into two group: Gansu, Sichuan and Shaanxi belong to one group, while Yunnan, Guizhou, Hubei, and Anhui belong to another group. Genetic identity and shared genotypes along with the minimum spanning network (MSN) showed the Pst population from Sichuan play an intermediate role of genetic communication between Yunnan-Guizhou and Gansu. Since Berberis spp. has been identified as the alternate host of Pst, our results also provided a molecular evidence of potential sexual reproduction in Gansu population. In addition, the closer relationship between Yunnan-Guizhou and Hubei-Anhui was demonstrated. It was showed the role of Pst population in Yunnan-Guizhou might was underestimated in epidemiology. Previously, it was believed that the inoculum was limited locally. Our study provided strong evidence that the Pst inoculum source of Yunnan-Guizhou dispersed to Hubei areas by the upper airflow, and migrated to Anhui finally detriment Huang-huai regions.