Overexpression of Reduces Resistance against .

Plant triterpenoids play a critical role in plant resistance against de Bary, the causal pathogen of potato and tomato late blight. However, different triterpenoids could have contrasting functions on plant resistance against . In this study, we targeted the key biosynthetic gene of all plant triterpenoids, (), to examine the function of this gene in plant- interactions. A post-inoculation, time-course gene expression analysis revealed that expression was induced in but was transiently suppressed in . Consistent with the host-specific changes in expression, concentrations of major triterpenoid compounds were only induced in . A stable overexpression of in reduced plant resistance against and induced the hyperaccumulation of stigmasterol. A comparative transcriptomics analysis of the transgenic lines showed that diverse plant physiological processes were influenced by overexpression, suggesting that phytosterol content regulation may not be the sole mechanism through which promotes plant susceptibility towards . This study provides experimental evidence for the host-specific transcriptional regulation and function of in plant interactions with , offering a novel perspective in examining the quantitative disease resistance against late blight.