Null mutants of a tomato Rho of plants exhibit enhanced water use efficiency without a penalty to yield

Mallikarjuna R. Puli, Purity Muchoki, Adi Yaaran, Noga Gershon, Ahan Dalal, Felista Nalufunjo, Yoav Dagan, Leah Rosental, Shiran Abadi, Zachary Haber, Lucas Silva, Yariv Brotman, Nir Sade*, Shaul Yalovsky*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Improving water use efficiency in crops is a significant challenge as it involves balancing water transpiration and CO2 uptake through stomatal pores. This study investigates the role of SlROP9, a tomato Rho of Plants protein, in guard cells and its impact on plant transpiration. The results reveal that SlROP9 null mutants exhibit reduced stomatal conductance while photosynthetic CO2 assimilation remains largely unaffected. Notably, there is a notable decrease in whole-plant transpiration in the rop9 mutants compared to the wild type, especially during noon hours when the water pressure deficit is high. The elevated stomatal closure observed in rop9 mutants is linked to an increase in reactive oxygen species formation. This is very likely dependent on the respiratory burst oxidase homolog (RBOH) NADPH oxidase and is not influenced by abscisic acid (ABA). Consistently, activated ROP9 can interact with RBOHB in both yeast and plants. In diverse tomato accessions, drought stress represses ROP9 expression, and in Arabidopsis stomatal guard cells, ABA suppresses ROP signaling. Therefore, the phenotype of the rop9 mutants may arise from a disruption in ROP9-regulated RBOH activity. Remarkably, large-scale field experiments demonstrate that the rop9 mutants display improved water use efficiency without compromising fruit yield. These findings provide insights into the role of ROPs in guard cells and their potential as targets for enhancing water use efficiency in crops.

Original languageAmerican English
Article numbere2309006120
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number4
StatePublished - 2024
Externally publishedYes

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  • RBOH
  • ROP
  • ROS
  • stomata
  • water use efficiency


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