| Wheat stripe rust is one of the most serious diseases threatening the safe production of wheat in China.The pathogen Puccinia striiformis f.sp.tritici(Pst)is transmitted remotely by air currents.To explore the rule of wheat stripe rust is popular in Sichuan winter breeding area and wheat stripe rust was urediniospores are spread in the wheat canopy influence factors,this article through to the Sichuan of wheat stripe rust,sampling investigation,analysis of genetic diversity and population genetic structure,high altitude wind field analysis,meteorological and field data fitting and indoor simulation spore spread,The study on the epidemic and spore diffusion of wheat stripe rust in Sichuan province provided a theoretical reference for understanding the epidemic and spread of wheat stripe rust and exploring the mechanism of plant morphology to avoid the disease.The results are as follows:1.Genetic diversity and population genetic structure analysis of wheat stripe rust in Sichuan province SSR markers showed that the genetic diversity of stripe rust was higher in the northern Sichuan Basin(Guangyuan,Nanchong,Mianyang and Deyang)than in the southern Sichuan Basin(Ziyang,Neijiang and Chongqing).The results of cluster analysis showed that the genetic distance between northern Sichuan Basin,southern Sichuan Basin and Chongqing area was far.The genetic structure of wheat stripe rust in Guangyuan,Nanchong,Mianyang and Deyang tended to be diversified.The single samples from Deyang and Guangyuan were consistent,while the single samples from Mianyang and Nanchong showed more gene sources.At the Nei genetic distance level of 0.07,the northern Sichuan Basin,southern Sichuan Basin and Chongqing region could be divided into two genetic populations of stripe rust.2.Study on the epidemic and spread rule of wheat stripe rust in Sichuan(1)Air flow analysis based on upper air wind field data showed that the wind direction of upper air flow at700 h Pa(about 3000 m above sea level)and above the main wheat field in Sichuan province was mainly southwest air flow,which could provide favorable transport air for wheat stripe rust to spread from winter breeding area to Shaanxi and Gansu.At 700 h Pa-950 h Pa,the wind direction is variable;At 950 h Pa(about 700 m above sea level),the upper air flow is mostly northeast,which is roughly the same as the path of wheat stripe rust spreading from north to south along the river in Sichuan Basin.(2)The field study of stripe rust of Zitong wheat from 2016 to 2020 showed that the spring epidemic period of Zitong wheat stripe rust could be divided into initial period(early January to early March),outbreak period(mid-March to early April)and decline period(mid-April and later).In the initial stage,air temperature 10 days before the onset and precipitation 10 to 20 days before the onset were significantly positively correlated with the incidence area of wheat stripe rust.During the outbreak period,there was no significant correlation between meteorological factors and the area of wheat stripe rust.There was a significant negative correlation between temperature and rainfall and the incidence area of stripe rust in the declining period.Logistic curve was used to fit the relationship between the incidence area and time of Zitong wheat stripe rust,and the fitting effect was good.(3)Combined with genetic diversity analysis and upper-air wind field analysis of wheat stripe rust in different areas of Sichuan Basin,the results showed that: There may be multiple transmission routes of exotic bacteria in different time periods in Sichuan Basin,including from north to south in northwest sichuan and Longnan oversummer region,from Guangyuan to southwest Sichuan in Hanzhong Of Shaanxi province,and from Hubei,Guizhou and Yunnan provinces to Chongqing and southeast Sichuan in late epidemic period.3.Influencing factors of urediniospores transmission of wheat stripe rust in the canopyThe results of laboratory simulation and field experiment showed that the gravity sedimentation velocity range of single urediniospore of wheat stripe rust was 1.491±0.055 cm/s.The wind speed was different under different canopy height and planting density.The morphology and quantity of the barrier could lead to significant difference in the number of intercepted spores.The horizontal propagation of spores in canopy was greatly affected by wheat barrier.Conclusion: The sources of wheat stripe rust in Sichuan Basin are diverse,and there are two populations of stripe rust in the north and south of Sichuan Basin.It is better to divide the time to study the prevalence of wheat stripe rust.The gravity deposition of urediniospores of wheat stripe rust had little effect on the horizontal propagation distance of spores in the canopy.Host leaf morphology and plant density can regulate leaf surface colonization and spore diffusion.The results are discussed in Sichuan wheat stripe rust was population genetic structure,wheat stripe rust epidemic regularity and wheat stripe rust was urediniospores in the canopy factors,could be used to understand the popularity of wheat stripe rust and explore morphological to provide theoretical reference for preventing disease mechanism,is of great significance for comprehensive prevention and control of wheat stripe rust. |
