DCA1 Acts as a Transcriptional Co-activator of DST and Contributes to Drought and Salt Tolerance in Rice.

Long-Gang Cui,Hong-Xuan Lin,Jun-Xiang Shan,Min Shi,Ji-Ping Gao,Gregory P Copenhaver

doi:10.1371/journal.pgen.1005617

Abstract

Natural disasters, including drought and salt stress, seriously threaten food security. In previous work we cloned a key zinc finger transcription factor gene, Drought and Salt Tolerance (DST), a negative regulator of drought and salt tolerance that controls stomatal aperture in rice. However, the exact mechanism by which DST regulates the expression of target genes remains unknown. In the present study, we demonstrated that DST Co-activator 1 (DCA1), a previously unknown CHY zinc finger protein, acts as an interacting co-activator of DST. DST was found to physically interact with itself and to form a heterologous tetramer with DCA1. This transcriptional complex appears to regulate the expression of peroxidase 24 precursor (Prx 24), a gene encoding an H2O2 scavenger that is more highly expressed in guard cells. Downregulation of DCA1 significantly enhanced drought and salt tolerance in rice, and overexpression of DCA1 increased sensitivity to stress treatment. These phenotypes were mainly influenced by DCA1 and negatively regulated stomatal closure through the direct modulation of genes associated with H2O2 homeostasis. Our findings establish a framework for plant drought and salt stress tolerance through the DCA1-DST-Prx24 pathway. Moreover, due to the evolutionary and functional conservation of DCA1 and DST in plants, engineering of this pathway has the potential to improve tolerance to abiotic stress in other important crop species.

Highlights

How to feed a growing population that is expected to reach roughly 9 billion by the middle of this century is among the major challenges of our time [1]
Drought and salt are two of the most serious threats to food production worldwide, and research on stress tolerance in crops is important for future food security
DST Co-activator 1 (DCA1) participates in stress tolerance by controlling stomatal aperture through modulation of H2O2 homeostasis in guard cells

Summary

Introduction

How to feed a growing population that is expected to reach roughly 9 billion by the middle of this century is among the major challenges of our time [1]. Droughts are likely to be more frequent as global warming accelerates, and rising sea levels will result in the loss of productive agricultural land to water infiltration and increased soil salinity. Together these unfavorable factors pose a huge threat to food security, and studying drought and salt tolerance in crops is becoming increasingly urgent. The main function of stomata, which are formed from pairs of guard cells, is to allow gases to move rapidly into and out of the leaf This evolved trait poses a problem for plants since they face the predicament of taking up CO2 through stomata while attempting to minimize water loss through these pores. The ability to effectively control the balance between photosynthesis and transpiration in accordance with the external environment is an impressive evolutionary achievement

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Discussion

Conclusion