Molecular and evolutionary conservation of Abscisic acid and blue light signalling in stomatal regulation

Cai S1,2, Chen G2, Franks P3 and Chen ZH2

  1. School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
  2. College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
  3. School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia.

Evolutionary trajectories of land plants have led to structurally complex and functionally active stomata for terrestrial life. The unique morphology, development and molecular regulation of stomata enable their rapid environmental response. Growing evidence has shown that signals controlling stomatal opening and closure may have evolved in some species of mosses. Here, comparative genomic study showed that many of abscisic acid (ABA) signalling, photoreceptor, membrane transporter, reactive oxygen species (ROS) and nitric oxide (NO) signalling, and protein kinase gene families are conserved over the evolutionary history of green plants (Viridiplantae). Phylogenetic analysis indicated an evolutionarily conserved stomatal response to ABA. Moreover, comparative transcriptomic analysis has identified a suite of ABA responsive differentially expressed genes encoding proteins associated with ABA biosynthesis, transport, reception, transcription, signalling, and ion and sugar transport, which fit the general ABA signalling pathway constructed from Arabidopsis thaliana and Hordeum vulgare. Furthermore, stomatal assays on epidermal peels showed ABA-induced stomatal closure in two fern species (Polystichum proliferum and Nephrolepis exaltata) and blue light-induced stomatal opening of a wide range of fern species in the Orders of Polypodiales, Schizaeales, Psilotales, and Ophioglossales. Stomata of fern species in the Polypodiales and Schizaeales are more responsive to blue light, generating higher ROS production and H+ pumping to the apoplast as compared to other fern species and Arabidopsis. Understanding the evolution stomatal regulation will inform functional manipulation of water use efficiency for plant productivity and will benefit future efforts towards sustainable food production and ecological diversity.