Inositol hexakisphosphate biosynthesis underpins PAMP‐triggered immunity to Pseudomonas syringae pv. tomato in Arabidopsis thaliana but is dispensable for establishment of systemic acquired resistance

摘要

Phytic acid (inositol hexa phosphate, Ins ) is an important phosphate store and signal molecule necessary for maintenance of basal resistance to plant pathogens. (‘arabidopsis’) has three genes encoding ‐inositol phosphate synthases (IPS1–3), the enzymes that catalyse conversion of glucose‐6‐phosphate to Ins , the first step in Ins biosynthesis. There is one gene for inositol‐(1,3,4,5,6)‐penta phosphate 2‐kinase (IPK1), which catalyses the final step. Previously, we showed that mutation of and but not increased susceptibility to pathogens. Our aim was to better understand the Ins biosynthesis pathway in plant defence. Here we found that the susceptibility of arabidopsis (Col‐0) to virulent and avirulent pv. was also increased in and double mutants. Also, plants had compromised expression of local acquired resistance induced by treatment with the pathogen‐derived molecular pattern (PAMP) molecule flg22, but were unaffected in other responses to flg22, including Ca influx and the oxidative burst, seedling root growth inhibition, and transcriptional up‐regulation of the PAMP‐triggered genes ( ) , , , and . mutation did not prevent the induction of systemic acquired resistance by avirulent . Also, and double mutant plants, like , were hypersusceptible to but were not compromised in flg22‐induced local acquired resistance. The results support the role of Ins biosynthesis enzymes in effective basal resistance and indicate that there is more than one basal resistance mechanism dependent upon Ins biosynthesis.