The α subunit of the heterotrimeric G protein regulates mesophyll CO2 conductance and drought tolerance in rice

Yotam Zait*, Ángel Ferrero-Serrano, Sarah M. Assmann*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Mesophyll conductance gm determines CO2 diffusion rates from mesophyll intercellular air spaces to the chloroplasts and is an important factor limiting photosynthesis. Increasing gm in cultivated plants is a potential strategy to increase photosynthesis and intrinsic water use efficiency (WUEi). The anatomy of the leaf and metabolic factors such as aquaporins and carbonic anhydrases have been identified as important determinants of gm. However, genes involved in the regulation and modulation of gm remain largely unknown. In this work, we investigated the role of heterotrimeric G proteins in gm and drought tolerance in rice d1 mutants, which harbor a null mutation in the Gα subunit gene, RGA1. d1 mutants in both cv Nipponbare and cv Taichung 65 exhibited increased gm, fostering improvement in photosynthesis, WUEi, and drought tolerance compared with wild-type. The increased surface area of mesophyll cells and chloroplasts exposed to intercellular airspaces and the reduced cell wall and chloroplast thickness in the d1 mutant are evident contributors to the increase in gm. Our results indicate that manipulation of heterotrimeric G protein signaling has the potential to improve crop WUEi and productivity under drought.

Original languageAmerican English
Pages (from-to)2324-2338
Number of pages15
JournalNew Phytologist
Issue number6
StatePublished - Dec 2021
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2021 The Authors. New Phytologist © 2021 New Phytologist Foundation


  • CO assimilation
  • Oryza sativa
  • d1
  • drought
  • heterotrimeric G protein
  • mesophyll conductance
  • stomatal conductance


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