| Summary: | 碩士 === 國立臺灣大學 === 植物病理學研究所 === 90 === The initial infection events, e.g. spore germination, appressorium formation, penetration and esterase production of B. elliptica and B. cinerea on the leaves of lily cv. ‘Star Gazer’ were compared. The germination rates of both species were more than 90% on lily leaves 12 hr post inoculation. B. elliptica produced more appressoria than B. cinerea did. The successful penetration rate of B. elliptica on lily leaves was about 55%; however, B. cinerea was not able to penetrate the cuticular layers of lily leaves. On the other hand, B. elliptica and B. cinerea cultured in Czapek's medium containing cutin as sole carbon source produced different esterases. The esterases recovered from the inoculation fluids of B. elliptica and B. cinerea on lily leaves were different from that in in vitro culture. Thus, the discrepancy of the infection by B. elliptica and B. cinerea is possibly due to the differences in the appressorium formation rate and the esterase production.
Further examination of the inoculation fluids of both Botrytis spp. by SDS- PAGE revealed four individual proteins with relative molecular weight of 49, 33, 27 and 16 kDa in the recovered inoculation fluids of B. elliptica on lily leaves. Theses protein bands did not appear in the inoculation fluids of B. elliptica on lily flowers and B. cinerea on lily leaves and flowers. The N-terminal sequence of the 33 kDa protein showed high similarity with that of b-1,3-glucanases from various plants and named LPGul1 (lily pathogen-induced glucanase 1). The glucanase activity of LPGlu1 was verified by an in-gel activity staining. The full length cDNA of LPGlu1 gene was cloned by performing RT-PCR and RACE method. The sequence analysis showed that full length cDNA of LPGlu1 is 1,125 bp long, the predicted open reading frame (1,011 bp) encoding a 35 kDa protein (337 amino acid residues) with a calculated isoelectric point of 4.0. The deduced amino acid sequence of LPGlu1 showed 59.8% to 61.2% identity to the b-1,3-glucanases of several monocot species including maize, barley, and wheat. Southern blot analysis indicated that LPGlu1 was a single copy gene in the genome of lily. Observation under fluorescence microscope showed the interactions between Botrytis and the leaf cells of lily around the infection sites and revealed the appearance of necrotic cells in lily leaves. The involvement of LPGlu1 in the mini-necrosis formation during Botrytis attack is discussed.
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