Analysis Of Genetic Structure Of Wheat Stripe Rust Populations In Five Provinces Of Chin

Wheat stripe rust is an important wheat disease caused by Puccinia striiformis f.sp.tritici,which seriously threatens national food security.In recent years,the disease incidence of wheat stripe rust has increased significantly,and once the disease is rampant,it can become more and more severe and uncontrolled.Furthermore,based on the characteristic that wheat stripe rust can be spread over long distances at high altitude by summer spores,wheat stripe rust can rapidly migrate,spread and infest new hosts under suitable conditions,resulting in directed changes in population genetic structure through natural screening of the pathogen by different new hosts.The molecular genetic structure of wheat streak rust in five provinces,was investigated to reveal the relationship between the fungal sources of wheat streak rust transmission in five provinces,by exploring the molecular genetic structure among the four major ecological zones and among seven different populations in the remaining four provinces where the fungal sources are more closely related,except for the southwest large group.In this study,409 wheat stripe rusts from 5 provinces in Henan,Shandong,Gansu,Hubei and Yunnan in 2021 were studied using Simple Sequence Repeat(SSR)molecular marker technology,combined with field disease incidence and analysis of overhead airflow trajectories,and the following results were obtained:(1).A total of 300 genotypes were monitored in a total of 399 wheat stripe rust samples from the five provinces used for the available analyses,which were relatively rich in genotypes and showed a high overall genetic diversity.(2).The results of chain disequilibrium analysis showed that the wheat stripe rust populations in five provinces showed chain disequilibrium,among which the wheat stripe rust populations collected in Gansu showed chain equilibrium and were presumed to be sexual populations;the wheat stripe rust populations in Hubei,Henan,Shandong and Yunnan showed chain disequilibrium.(3).The results of genetic variability showed that intra-group variation was 66%higher than inter-group variation of 19%,and thus intra-group variation was the main source of genetic variation in Puccinia striiformis f.sp.tritici.It can be seen that the Puccinia striiformis f.sp.tritici populations in the five provinces showed large differences in genetic structure and can be divided into three large groups according to the four ecological regions: the northwest group represented by Gansu and the middle and lower reaches of the Yangtze River represented by Hubei as a large group,the Huang Huai groups represented by Henan and Shandong as a large group,and the southwest group represented by Yunnan as a large group.(4)The results of genetic correlation analysis showed that there was some gene exchange among the seven populations divided by urban geographic location in the remaining four provinces except for the large southwestern cluster.According to the meaning of the range of values of Gene flow(Nm)and genetic differentiation coefficient(F-statistics,Fst),it is clear that there are some affinity differences in the exchange of bacterial sources among the seven wheat stripe rust populations in the four provinces.The northern Hubei population was closely related to the southern Hubei population,the Gansu population,the southern Henan population,and the northern Henan population to the southwestern Shandong population and the northeastern Shandong population.However,the exchange relationship between the two subpopulations in Henan Province was less frequent.Combined with the genetic variability analysis and the analysis of overhead airflow trajectory,it can be inferred that the gene flow in Hubei roughly flows from the north to the south,and the fungal source of the southern Hubei population may come from the northern Hubei population and the southern Henan population.The northern population of Henan may come from the northwest and spread to the southwest of Shandong,and then spread from west to east to northeast Shandong,showing an overall route from northwest to central to east.In summary,the findings of this study can provide a theoretical basis for future inve stigations into the causes of wheat stripe rust,the rational allocation of wheat stripe rustresistant varieties and the integrated prevention and control technology management sys tem for it,and it is of practical importance to find out the relationship between the sourc es of wheat stripe rust transmission in different wheat regions for disease prediction and effective control.