Dynamic of Puccinia striiformis f. sp. tritici Urediniospore in Longnan, a Critical Oversummering Region of China.

Abstract

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici Erikss (Pst), is a devastating disease resulting in yield reduction. Because the temperature limits the overwintering and oversummering of Pst, and it cannot complete the whole year cycle in most areas of China. Longnan located in the southeast of Gansu province is one of the annual cycle areas of Pst, which can supply urediniospores in autumn to eastern wheat-growing areas in China. In this study, a TaqMan real-time quantitative PCR (TaqMan-qPCR) detection system for Pst urediniospores was established, and the detection limit was a single urediniospore. The dynamics of Pst urediniospores in Longnan were monitored by spore trapping and TaqMan-qPCR for 3 years. Meanwhile, the meteorological conditions including air temperature, relative humidity and precipitation were recorded. Results showed that Pst urediniospores can be captured from March to December, and two peaks of urediniospore number appeared in May and June, respectively. The number of urediniospore is closely related to temperature and precipitation from March to June. In addition, we found that the number of Pst urediniospore had the peak value when the average air temperature was 10~21℃ and the relative humidity was 60%~85% from May to June. The exponential model could describe the variation of Pst urediniospore number based on average temperature and precipitation from March to June. It is worth mentioning that the exponential model based on average temperature 7 days before spore capture has a great advantage in predicting the urediniospore density in the air. This study laid a foundation for establishment of a prediction model for wheat stripe rust based on the number of urediniospores and meteorological factors.