CarNAC4, a NAC-type chickpea transcription factor conferring enhanced drought and salt stress tolerances in Arabidopsis

Abstract

Key message: CarNAC4 is a typical stress-responsive NAC transcription factor and enhances drought and salt stress tolerances in transgenicArabidopsis. Abstract: Chickpea (Cicer arietinum L.) is relatively vulnerable to abiotic stress conditions, but the tolerance mechanisms for such stresses in chickpea are largely unknown. To identify stress-related factors in chickpea, we previously constructed a cDNA library of chickpea leaves exposed to drought stress conditions. A cDNA encoding a putative NAC transcription factor (CarNAC4) was identified as a putative stress-responsive gene. Our study indicated that the transcript levels of CarNAC4 were enhanced in response to several abiotic stresses and phytohormones. Promoter analysis demonstrated that multiple stress-related cis-acting elements exist in promoter region of CarNAC4. CarNAC4 is localized in the nucleus and binds to the DNA sequence containing CGT[G/A], while the C-terminal region of CarNAC4 contains a transcriptional activation domain. Over-expression of CarNAC4 in Arabidopsis plants improved tolerance to drought and salt stresses. Transgenic plants exhibited greater reduced rates of water loss and more proline accumulation than Col-0 plants under drought stress and less MDA contents than Col-0 plants under salt stress. In addition, over-expression of CarNAC4 enhanced the expression of stress-responsive genes such as RD29A, ERD10, COR15A, COR47, KIN1 and DREB2A. These results indicated that CarNAC4 functions as a transcription factor involved in the regulation of drought and salt stress response.