A bacterial effector protein targets plant ferredoxin-NADP+ reductase to promote infection.

Pathogenic bacteria utilize a type III secretion system to translocate effector proteins into plant cells, where they inhibit plant immunity or interfere with normal cellular functions to facilitate infection. Whether and how pathogen effectors manipulate plant adenosine 5'-triphosphate (ATP) to facilitate infection remains largely unknown. In this work, we show that an effector protein, RipAF1, from the plant pathogen Ralstonia solanacearum suppresses flg22-induced immune activation and contributes to virulence. RipAF1 physically interacts with plant ferredoxin-NADP+ reductase (FNR), which is involved in NADPH and ATP production, in chloroplast. Transient expression of FNR leads to increased ATP accumulation and resistance against R. solanacearum, while co-expression of FNR with RipAF1 significantly reduced ATP levels. We further show that exogenous application of ATP enhances plant resistance to R. solanacearum infection. Our findings indicate a key role of ATP in plant resistance against R. solanacearum, and elucidate a bacterial virulence strategy wherein pathogenicity is enhanced through targeted modification of host ATP homeostasis via bacterial effector proteins.