Abstract

The continuing rise in atmospheric CO2 causes stomatal pores in leaves to close and thus globally affects CO2 influx into plants, water use efficiency and leaf heat stress(1-4). However, the CO2-binding proteins that control this response remain unknown. Moreover, which cell type responds to CO2, mesophyll or guard cells, and whether photosynthesis mediates this response are matters of debate(5-8). We demonstrate that Arabidopsis thaliana double-mutant plants in the beta-carbonic anhydrases beta CA1 and beta CA4 show impaired CO2-regulation of stomatal movements and increased stomatal density, but retain functional abscisic-acid and blue-light responses. beta CA-mediated CO2-triggered stomatal movements are not, in first-order, linked to whole leaf photosynthesis and can function in guard cells. Furthermore, guard cell beta CA-overexpressing plants exhibit instantaneous enhanced water use efficiency. Guard cell expression of mammalian alpha CAII complements the reduced sensitivity of ca1 ca4 plants, showing that carbonic anhydrase-mediated catalysis is an important mechanism for beta CA-mediated CO2 induced stomatal closure and patch clamp analyses indicate that CO2/HCO3-transfers the signal to anion channel regulation. These findings, together with ht1-2 (ref.9) epistasis analysis demonstrate that carbonic anhydrases function early in the CO2 signalling pathway, which controls gas-exchange between plants and the atmosphere.

Published in

Nature Cell Biology
2010, Volume: 12, number: 1, pages: 87-93
Publisher: NATURE PORTFOLIO

UKÄ Subject classification

Cell Biology


Publication identifier

DOI: https://doi.org/10.1038/ncb2009

Permanent link to this page (URI)

https://res.slu.se/id/publ/128996