477 / 2019-02-27 23:10:20

An important role of L-fucose biosynthesis and protein fucosylation genes in Arabidopsis immunity

coronatine, fucosylation, jasmonate, L-fucose, plant immunity, stomata.

全体主题 > Plant Microbe Interactions & Microbiomes

Plants mount coordinated immune responses to defend against pathogen infection. However, the cellular pathways and components that are required for plant immunity are not fully understood. The jasmonate-mimicking coronatine (COR) toxin produced by the bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000, is required for Pst DC3000 to overcome stomatal closure response against bacterial invasion, as well as defenses inside the apoplast of Arabidopsis leaves. We previously isolated eight Arabidopsis (scord) mutants that exhibit increased susceptibility to a COR-deficient mutant of Pst DC3000. In this study, we identified the SCORD6 gene via next-generation sequencing. SCORD6 encodes an isoform of GDP-D-mannose-4,6-dehydratase (GMD), GMD2, involving in the biosynthesis of GDP-L-fucose. Discovery of SCORD6 led to a series of experiments that revealed a multi-faceted role of L-fucose biosynthesis in stomatal and apoplastic defenses as well as in pattern-triggered immunity and effector-triggered immunity, including glycosylation of pattern-recognition receptors. Interestingly, compromised stomatal and/or apoplastic defenses were also observed in mutants of several fucosyltransferases with specific substrates (e.g., O-glycan, N-glycan or the DELLA transcriptional repressors). Collectively, these results demonstrate a broad and essential role of L-fucose biosynthesis and fucosylation of polysaccharides and proteins in executing multiple immune pathways in Arabidopsis.