Role of stomata in plant-microbiota interaction

Li Zhang, Sheng-Yang He
MOE Key Laboratory of Geriatric Diseases and Immunology, School of Life Sciences, Soochow University, China; Department of Biology, Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA;

Pathogen entry into host tissue is a critical first step in causing infection. For foliar bacterial plant pathogens, such as Pseudomonas syringae pv. tomato (Pst) DC3000, stomata are important entry sites into the leaf apoplast. We previously showed that stomatal closure is a plant immune response to bacteria invasion. We then conducted a genetic screen to identify Arabidopsis mutants that are defective in stomatal closure during Pst DC3000 infection. These mutants were named scord (for susceptible to coronatine-deficient Pst DC3000). We have since cloned several SCORD genes. SCORD5 encodes an ATP-binding cassette protein, AtGCN20 (GENERAL CONTROL NONDEREPRESSIBLE 20) , predicted to be involved in stress-associated protein translation control. SCORD7 encodes TRICHOME BIREFRINGENCE (TBR), which is related to proteins involved in cell wall polymer O-acetylation. As expected, scord5 and scord7 mutant plants show increased disease susceptibility due to defects in stomatal closure. Interestingly, further characterization of the scord5 and scord7 mutants showed normal levels of endophytic and total phyllosphere microbiota compared to wild-type plants. However, differences in endophytic leaf microbiota composition were observed between wild-type plants vs. the scord5 or scord7 mutant. These results begin to provider evidence that, in addition to regulating pathogen invasion, stomata may contribute to shaping the composition of endophytic microbiota in the phyllosphere.