A stress-responsive caleosin-like protein, AtCLO4, Acts as a Negative Regulator of ABA Responses in Arabidopsis

Yun Young Kim, Kwang Wook Jung, Kyoung Shin Yoo, Ji Ung Jeung, Jeong Sheop Shin

Research output: Contribution to journalArticlepeer-review

60 Citations (Scopus)


Caleosins or related sequences have been found in a wide range of higher plants. In Arabidopsis, seed-specific caleosins are viewed as oil-body (OB)-associated proteins that possess Ca2+-dependent peroxygenase activity and are involved in processes of lipid degradation. Recent experimental evidence suggests that one of the Arabidopsis non-seed caleosins, AtCLO3, is involved in controlling stomatal aperture during the drought response; the roles of the other caleosin-like proteins in Arabidopsis remain largely uncharacterized. We have demonstrated that a novel stress-responsive and OB-associated Ca2+-binding caleosin-like protein, AtCLO4, is expressed in non-seed tissues of Arabidopsis, including guard cells, and down-regulated following exposure to exogenous ABA and salt stress. At the seed germination stage, a loss-of-function mutant (atclo4) was hypersensitive to ABA, salt and mannitol stresses, whereas AtCLO4-overexpressing (Ox) lines were more hyposensitive to those stresses than the wild type. In adult stage, atclo4 mutant and AtCLO4-Ox plants showed enhanced and decreased drought tolerance, respectively. Following exposure to exogenous ABA, the expression of key ABA-dependent regulatory genes, such as ABF3 and ABF4, was up-regulated in the atclo4 mutant, while it was down-regulated in AtCLO4-Ox lines. Based on these results, we propose that the OB-associated Ca2+-binding AtCLO4 protein acts as a negative regulator of ABA responses in Arabidopsis.

Original languageEnglish
Pages (from-to)874-884
Number of pages11
JournalPlant and Cell Physiology
Issue number5
Publication statusPublished - 2011 May

Bibliographical note

Funding Information:
This work was supported by a grant (CG3112) from the Crop Functional Genomics Center of the 21st Century Frontier Research Program, by a grant (2011-0001105) from SIGNET funded by the National Research Foundation of Korea, and by a grant from the BioGreen21 program funded by the Rural Development Administration, Republic of Korea.


  • ABA response
  • Arabidopsis thaliana
  • CaBP
  • Caleosin
  • Drought tolerance
  • Stomatal control

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology


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