Genetic and cytological characterization of the rice blast fungus, Pyricularia oryzae
1985
Leung, H. | Williams, P.H.
Pyricularia oryzae parasitizes on a variety of gramineous hosts and causes the rice blast disease worldwide. Although a high degree of pathogenic variation has been reported in the fungus, little is known about the nature of this variability. Genetic and cytological studies were done to facilitate further investigation of pathogenic variation. Polymorphism in 12 enzymes was examined among 350 isolates from 12 rice growing regions. All isolates were monomorphic at 16 of the 18 enzyme putative loci. In contrast, a sample of isolates from several gramineous host displayed more allelic diversity. Through matings among isolates from rice, finger millet, and weeping lovegrass, monogenic control of six enzyme variants was demonstrated. Ascospores derived from rice isolates were either nonpathogenic or only partially pathogenic on rice. A light microscopic survey of nuclear number in living hyphal cells from geographic isolate showed that 91.1% of cells were uninucleate. Six chromosomes were observed at the pachytene, diakinesis, and metaphase stages of ascospores mitosis. Chromosome movement at meiotic and mitotic anaphase was asynchronous, which might account for the variable chromosome numbers previously reported
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