title: Developmentally regulated sesquiterpene production confers resistance to Colletotrichum gloeosporioides in ripe pepper fruits.
abstract: Sesquiterpenoid capsidiol, exhibiting antifungal activity against pathogenic fungus, is accumulated in infected ripe pepper fruits. In this study, we found a negative relation between the capsidiol level and lesion size in fruits infected with Colletotrichum gloeosporioides, depending on the stage of ripening. To understand the developmental regulation of capsidiol biosynthesis, fungal-induced gene expressions in the isoprenoid biosynthetic pathways were examined in unripe and ripe pepper fruits. The sterol biosynthetic pathway was almost shut down in healthy ripe fruits, showing very low expression of hydroxymethyl glutaryl CoA reductase (HMGR) and squalene synthase (SS) genes. In contrast, genes in the carotenoid pathway were highly expressed in ripe fruits. In the sesquiterpene pathway, 5-epi-aristolochene synthase (EAS), belonging to a sesquiterpene cyclase (STC) family, was significantly induced in the ripe fruits upon fungal infection. Immunoblot and enzyme activity analyses showed that the STCs were induced both in the infected unripe and ripe fruits, while capsidiol was synthesized discriminatively in the ripe fruits, implying diverse enzymatic specificity of multiple STCs. Thereby, to divert sterol biosynthesis into sesquiterpene production, infected fruits were pretreated with an SS inhibitor, zaragozic acid (ZA), resulting in increased levels of capsidiol by more than 2-fold in the ripe fruits, with concurrent reduction of phytosterols. Taken together, the present results suggest that the enhanced expression and activity of EAS in the ripe fruits play an important role in capsidiol production, contributing to the incompatibility between the anthracnose fungus and the ripe pepper fruits.
authors.affiliation: Department of Biotechnology, Chonnam National University, Gwangju, Korea.
authors.forename: Sangkyu
authors.initials: S
authors.lastname: Park
authors.affiliation: Kumho Life Science Laboratory, Chonnam National University, Gwangju, Korea.
authors.forename: Ae Ran
authors.initials: AR
authors.lastname: Park
authors.affiliation: Kumho Life Science Laboratory, Chonnam National University, Gwangju, Korea.
authors.forename: Soonduk
authors.initials: S
authors.lastname: Im
authors.affiliation: Kumho Life Science Laboratory, Chonnam National University, Gwangju, Korea.
authors.forename: Yun-Jeong
authors.initials: YJ
authors.lastname: Han
authors.affiliation: Research Division for Biotechnology, Advanced Radiation Technology Institute, Jeongeup, Korea.
authors.forename: Sungbeom
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, Chonnam National University, Gwangju, Korea.
authors.forename: Kyoungwhan
authors.initials: K
authors.lastname: Back
authors.affiliation: Department of Biotechnology, Chonnam National University, Gwangju, Korea; Kumho Life Science Laboratory, Chonnam National University, Gwangju, Korea.
authors.forename: Jeong-Il
authors.initials: JI
authors.lastname: Kim
authors.affiliation: Kumho Life Science Laboratory, Chonnam National University, Gwangju, Korea.
authors.forename: Young Soon
authors.initials: YS
authors.lastname: Kim
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000378:metabolism; D000935:Antifungal Agents / Q000378:metabolism*; D002212:Capsicum / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology* / Q000502:physiology; D020231:Colletotrichum / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D013186:Farnesyl-Diphosphate Farnesyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism; D005638:Fruit / Q000254:growth & development* / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D054884:Host-Pathogen Interactions; D012717:Sesquiterpenes / Q000378:metabolism* / Q000494:pharmacology; D013185:Squalene / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D004791:Enzyme Inhibitors; D012717:Sesquiterpenes; C081843:capsidiol; D013185:Squalene; D019883:Alkyl and Aryl Transferases; C078217:5-epi-aristolochene synthase; D013186:Farnesyl-Diphosphate Farnesyltransferase