Investigation of UV-B sensitivity of Puccinia striiformis f.sp.tritici isolates from Gansu and Qinghai provinces,China
Gansu and Qinghai provinces,located in high altitude of the northwest of China with high-intensity ultraviolet(UV)radiation,are important oversummering and high-frequency virulence-variation areas for Puccinia striiformis f.sp.tritici(Pst)in China.To explore the effects of UV radiation on the survival and viru-lence variation of Pst,the UV-B sensitivity of 21 Pst isolates collected from some regions of Gansu and Qinghai provinces was investigated based on relative germination rates of the urediospores and the LT50(lethal time 50％,i.e.,radiation time required to obtain a lethal rate of 50％for the Pst urediospores under certain UV-B radiation intensity)values for all the Pst isolates.The results showed that the relative germination rates of urediospores of Pst isolates from Gansu and Qinghai were extremely negatively correlated with the time length of UV-B radiation under each of the three UV-B radiation intensities(150,200,and 250 μw·cm-2)(P＜0.000 1).The comparison results of relative germination rates and LT50 values among all the isolates under the three UV-B intensities demonstrated that there were differences in sensitivity to UV-B radiation among all the Pst isolates and that the difference in sensitivity to UV-B radiation among the Pst isolates from Qinghai Province was higher than that among the Pst isolates from Gansu Province.In this study,a theoretical basis was provided for further studying virulence variation of Pst,and for monitoring,resistance breeding,and management of wheat stripe rust caused by Pst.
wheat stripe rustrelative germination ratelethal time 50％sensitivity to UV-B radiation
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