Studies On The Correlation Among Germination And Content Of3’-5’-cyclic Adenosine Monophosphate (cAMP)and Melanin Of Different Color Chlamydospores In Ustiloginoidea Virens

Rice false smut, caused by Ustilaginoidea virens, is one of the important fungal diseases in the panicles of rice. The disease is not only influence greatly on the rice grain yield, but the pathogen ustiloxins also cause poisoning to human and animals. Chlamydospores are the important primary infection sourses of the disease. Therefore, the correlation between germination rate and the content of3′-5’-cyclic adenosine monophosphate (cAMP) and melanin from the dormant (black or green-black) and non-dormant (yellow) chlamydospore was studied in the paper. The main research results are followed:Optimum extraction cAMP conditions based on ultrasonic-bath method using3factors at3levels were conducted by high-performance liquid chromatography (HPLC). The results showed that the optimum extracting conditions were identified as ultrasonic broken at400W and interval for2s for10min, bathing at80℃-for120min and the material ratio is1:100(V/V), as the extracting sample with yellow-green chlamydospores. Based on the above the extracting conditions, the contents of cAMP in the yellow, yellow-green and the black were12.8050±0.5332μg/mL,6.8276(μg/mL and4.1717±0.0971μg/mL, respectively.Freshly chlamydospores collected from the false smut balls during their germination, cAMP content of yellow chlamydospore with the determination method of the above cAMP appeared a slight growth during0-12h, while their cAMP content showed declining rapidly as the extension of germination time (12-48h). In all, the germination rate and the content of cAMP presented the very notably negative correlation(|r|=0.8619>ro.o1=0.834), but the correlation between germination rate and content of cAMP was not obvious. The germination rate and the content of cAMP presented the notably positive correlation by storage periodically (0,2,4,6,8,10months) of different color chlamydospores were investigated in detail (the yellow of chlamydospore:|r|=0.7851> ro.05=0.707; the black of chlamydospore:|r|=0.9579>ro.05=0.707). Freshly chlamydospores collected from the false smut balls during their germination, melanin content of the black and yellow with the alkaline extraction metho were1.5532mg/mL and0.9069mg/mL, respectively. Melanin content in black chlamydospore is significantly higher than in yellow. The germination rate and the content of melanin presented the notably positive correlation during the germination of chlamydospore in U. virens (the black chlamydospore:|r|=0.9578> ro.oi=0.834; the yellow chlamydospore:|r|=0.8549> ro.oi=0.834). The germination rate and the content of melanin presented the very notably negative correlation by storage periodically (0,2,4,6,8,10months) of different color chlamydospores were investigated in detail (the yellow chlamydospore:|r|=0.8549> r0.01=0.834; the black chlamydospore:|r|=0.9578> r0.01=0.834).By the above research showed that contents of cAMP and melanin were related to germination rate in the dormant (black or green-black) and non-dormant (yellow) chlamydospore, and had some influence on the dormancy of chlamydospores. Therefore, the study has important value for revealing dormancy mechanism of chlamydospores in U. virens.