I hope this class is being as beneficial to your learning as it is to mine. Every week people ask good questions, I go away, think about it, do some reading and almost always find the answer is far more interesting than I had imagined.
How do the various processes that affect stomatal opening and closure coordinate their actions? What happens if the stomata get conflicting signals?
I just started to do some reading on this when I came across this amazing paper from 2006 describing how stomata close upon detection of potential microbial pathogens to prevent the infection of the leaf interior. That's pretty cool but they also show how pathogenic bacteria have evolved strategies to suppress the closure of stomata! This appears to be brand new research and I think it is both the first demonstration of the defensive role of stomata as well as the first demonstration of bacteria overcoming this defense.
The journal editors obviously thought was pretty cool too since there's a nice preview of the research.
Plant Stomata Function in Innate Immunity against Bacterial Invasion
Cell, Volume 126, Issue 5, 8 September 2006, Pages 969-980
Maeli Melotto, William Underwood, Jessica Koczan, Kinya Nomura and Sheng Yang He