Biological characters of Bipolaris spp. causing brown spot on rice and water bamboo

• Main Authors: Shu-Mei Chen, 陳淑媚
• Other Authors: 鍾文鑫
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/96844191977618555806

碩士 === 國立中興大學 === 植物病理學系所 === 102 === Bipolaris oryzae and B. zizaniae are the pathogens to cause brown spot on rice (Oryza sativa) and water bamboo (Zizania latifolia). Previous studies indicated that B. oryzae could be distinguished from B. zizaniae based on the hilum structure of conidia basal part. Several researchers suggested that B. zinaniae should be a synonym of B. oryzae due to similar morphology, pathogenicity and cross fertility test. However, previous studies showed the number limitation of observed isolates and the relationship between the two pathogens were still obscure. For carrying out the relationship of Bipolaris spp. causing brown spot on water bamboo and rice, the symptom was investigated in field and morphology, cross fertility, pathogenicity and molecular characters of Bipolaris spp. were be analyzed. Field investigation revealed that Bipolaris sp. could cause typical spot and long lesion on water bamboo. The conidia morphology indicated that 112 and 47 Bipolaris sp. isolates from rice and water bamboo, respectively, showed similar morphology and rectangular hilum was the major type. The conidial length, width and number of distoseptate could not diversify all isolates from rice or water bamboo based on principal component analysis. The MAT-2 gene amplification showed that 28.6 % from rice and 31.9 % from water bamboo were MAT-2 isolates. The cross fertility test confirmed that light could improve sexual reproduction. Certain isolates from rice or water bamboo mated successfully each isolate and produce ascospores. However, the result of cross fertility test did not company with the result of mating type identification completely. The virulence test demonstrated that the isolates from rice and water bamboo could infect both detached leaves of rice and water bamboo, resulting in typical brown spot, leaf blight or long lesion. Molecular phylogenetic analyses showed that Bipolaris isolates from rice and water bamboo formed a molecular group based on ITS (internal transcribed spacer) region. The other side, the analysis of GPDH (glycerol-3-phosphate dehydrogenase) sequence showed that isolates from rice could be separated into two molecular groups and one group isolates formed the same molecular group with isolates from water bamboo. ITS sequence combined with GPDH sequence showed similar result with GPDH sequence. Thus, the molecular diversity of isolates from rice is higher than the isolates from water bamboo. This study reveals that the Bipolaris spp. causing brown spot on rice or water bamboo have similar biological characters according to the morphology of conidia, affinity test, pathogenicity test and molecular analysis,.