Induction and regulation of highly branched penetration structure of Colletotrichum acutatum

• Main Authors: Mei-Ya Chen, 陳美雅
• Other Authors: Miin-Huey Lee
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/h69p6v

碩士 === 國立中興大學 === 植物病理學系所 === 100 === Chili pepper (Capsicum spp.) anthracnose caused by Colletotrichum acutatum results in severe losses in yield and fruit quality in Taiwan. Our previous study has shown that C. acutatum penetrates the cuticle layer of chili pepper fruits by forming a highly branched penetration structure (HBPS) which was not previously characterized in any Colletotrichum-plant interactions. The purpose of the study is to investigate the induction and regulation of HBPS formation. Cuticle layer PC1, PC2, PC3 and PC4 from pepper fruit were isolated (Capsicum annuum, GroupZest) C. acuttaum strain Coll-153 forms high proportion of HBPS in PC1 and PC2, but hardly forms HBPS in PC3 and PC4. Overall C. acutatum forms the highest frequency of HBPS in PC2. Therefore, PC2 was used to study factors involved in HBPS induction and regulation. The results show that HBPS formation can be regulated by light and osmotic stress. Light has highly significant impact on HBPS formation, the longer exposure time the lower proportion of HBPS formation. The formation of HBPS doesn’t seem to be regulated by stress caused by temperature and fungicides. Oxidative stress, when treated at early stage, was able to inhibit HBPS formation, but the inhibition was not found when treated at late stage. Pharmacological effectors of signal transduction pathways were used to study the regulation of HBPS formation. HBPS formation was found to be inhibited by the stimulators of cAMP dependent protein kinase A and by the inhibitors of phospholipase C and MAP kinase. The imbalance of cellular calcium level also seems to have a role on HBPS formation. However, HBPS was not inhibited by calcium ionophore A23187, calcium channel blocker nicardipine hydrochloride and calcium/calmodulin kinase II inhibitor. Light, neomycin sulfate and cAMP did not inhibit HBPS formation in chili pepper fruits when treated on 18 h post-inoculated fruits. However, certain amounts of neomycin sulfate could reduce disease of chili pepper fruits caused by C. acutatum Coll-153.