RRC ID 36716
Author Lai D, Pičmanová M, Abou Hachem M, Motawia MS, Olsen CE, Møller BL, Rook F, Takos AM.
Title Lotus japonicus flowers are defended by a cyanogenic β-glucosidase with highly restricted expression to essential reproductive organs.
Journal Plant Mol Biol
Abstract Flowers and leaves of Lotus japonicus contain α-, β-, and γ-hydroxynitrile glucoside (HNG) defense compounds, which are bioactivated by β-glucosidase enzymes (BGDs). The α-HNGs are referred to as cyanogenic glucosides because their hydrolysis upon tissue disruption leads to release of toxic hydrogen cyanide gas, which can deter herbivore feeding. BGD2 and BGD4 are HNG metabolizing BGD enzymes expressed in leaves. Only BGD2 is able to hydrolyse the α-HNGs. Loss of function mutants of BGD2 are acyanogenic in leaves but fully retain cyanogenesis in flowers pointing to the existence of an alternative cyanogenic BGD in flowers. This enzyme, named BGD3, is identified and characterized in this study. Whereas all floral tissues contain α-HNGs, only those tissues in which BGD3 is expressed, the keel and the enclosed reproductive organs, are cyanogenic. Biochemical analysis, active site architecture molecular modelling, and the observation that L. japonicus accessions lacking cyanogenic flowers contain a non-functional BGD3 gene, all support the key role of BGD3 in floral cyanogenesis. The nectar of L. japonicus flowers was also found to contain HNGs and additionally their diglycosides. The observed specialisation in HNG based defence in L. japonicus flowers is discussed in the context of balancing the attraction of pollinators with the protection of reproductive structures against herbivores.
Volume 89(1-2)
Pages 21-34
Published 2015-9-1
DOI 10.1007/s11103-015-0348-4
PII 10.1007/s11103-015-0348-4
PMID 26249044
MeSH Amino Acid Sequence Cellulases / analysis Cellulases / genetics Cellulases / physiology Cyanides / metabolism* Flowers / chemistry Flowers / metabolism Flowers / physiology* Gene Expression Regulation, Plant / genetics Gene Expression Regulation, Plant / physiology* Glucosides / analysis Herbivory Lotus / genetics Lotus / physiology* Molecular Sequence Data Nitriles / analysis Plant Leaves / chemistry Plants, Genetically Modified / genetics Real-Time Polymerase Chain Reaction Tobacco / genetics beta-Glucosidase / genetics beta-Glucosidase / physiology*
IF 3.302
Times Cited 9
Lotus / Glycine Miyakojima MG-20