Investigating the functions of the RIN4 protein complex during plant innate immune responses

Pathogen recognition by the plant innate immune system invokes a sophisticated signal transduction network that culminates in disease resistance. The Arabidopsis protein RIN4 is a well-known regulator of plant immunity. However, the molecular mechanisms by which RIN4 controls multiple immune responses have remained elusive. In our recently published study, we purified components of the RIN4 protein complex from A. thaliana and identified several novel RIN4-associated proteins. 1 We found that one class of RIN4-associated proteins, the plasma membrane H+-ATPases AHA1 and AHA2, play a crucial role in resisting pathogen invasion. Plants use RIN4 to regulate H+-ATPase activity during immune responses, thereby controlling stomatal apertures during pathogen attack. Stomata were previously identified as active regulators of plant immune responses during pathogen invasion, but how the plant innate immune system coordinates this response was unknown. 2,3 Our investigations have revealed a novel function of RIN4 during pathogenesis. Here, we discuss the RIN4-AHA1/2 interaction and highlight additional RIN4-associated proteins (RAPs) as well as speculate on their potential roles in plant innate immunity.