The First Line of Defense: Receptor-like Protein Kinase-Mediated Stomatal Immunity

Abstract

Stomata regulate gas and water exchange between the plant and external atmosphere, which are vital for photosynthesis and transpiration. Stomata are also the natural entrance for pathogens invading into the apoplast. Therefore, stomata play an important role in plants against pathogens. The pattern recognition receptors (PRRs) locate in guard cells to perceive pathogen/microbe-associated molecular patterns (PAMPs) and trigger a series of plant innate immune responses, including rapid closure of stomata to limit bacterial invasion, which is termed stomatal immunity. Many PRRs involved in stomatal immunity are plasma membrane-located receptor-like protein kinases (RLKs). This review focuses on the current research progress of RLK-mediated signaling pathways involved in stomatal immunity, and discusses questions that need to be addressed in future research.

Tomato brassinosteroid-signaling kinase Bsk830 is a component of flagellin signaling that regulates pre-invasion immunity

“…For example, Arabidopsis plants mutated in FLS2 or in both PEPR1 and PEPR2 PRRs fail to close stomata when challenged with the respective MAMPs, and are more susceptible to Pst DC3000 when dip-inoculated, but not when syringe-infiltrated (Zipfel et al, 2004; Melotto et al, 2006; Zheng et al, 2018). In Arabidopsis, the RLCKs BIK1 and PBL27 act downstream of PRRs in signaling pathways that lead to stomata closure (Wang and Gou, 2021). BIK1 transduces the signal generated by recognition of flg22 and pep1 by their respective PRRs and activates anion channels that cause stomata closure (Kadota et al, 2014; Li et al, 2014; Guzel Deger et al, 2015; Zheng et al, 2018; Thor et al, 2020).…”

“…Similar to BIK1, additional members of the RLCK subfamily VII contribute to PTI (Rao et al, 2018). RLCKs regulate stomatal immunity and are essential for the initial closure step (Wang and Gou, 2021). For example, BIK1 and PBL27 regulate stomatal closure by promoting activation of ion channels (Zheng et al, 2018; Liu et al, 2019; Thor et al, 2020).…”

“…Stomatal movement is modulated by ROS accumulation that controls the activity of ion pumps, plasma membrane channels, and transporters (Sierla et al, 2016). In Arabidopsis ROS molecules have been shown to be generated by the NADPH oxidase RBOHD that is activated by phosphorylation upon MAMPs perception by PRRs (Wang and Gou, 2021). MAMP perception also triggers the activation of signaling pathways involving the hormones salicylic acid (SA) and abscisic acid (ABA), which contribute to stomatal closure.…”

Fresh Produce as a Potential Vector and Reservoir for Human Bacterial Pathogens: Revealing the Ambiguity of Interaction and Transmission

“…Stomata also serve as an active innate immunological agent against plants and HMP in Arabidopsis leaves [ 43 ]. According to previous studies, O157:H7 cannot withstand the closure of stomata, resulting in protracted stimulation of the stomatal immune response [ 43 ].…”

“…Stomata also serve as an active innate immunological agent against plants and HMP in Arabidopsis leaves [ 43 ]. According to previous studies, O157:H7 cannot withstand the closure of stomata, resulting in protracted stimulation of the stomatal immune response [ 43 ]. In contrast, a recent study found that S. enterica serovar Typhimurium SL1344 migrated toward stomata and internalized without stimulating an immune response [ 18 ].…”