Cloning and expression analysis of four DELLA genes in peanut

Peanut (Arachis hypogaea L.), as a source of oil and protein, is the second-most important grain legume cultivated in the world. Peanut is a relatively drought-tolerant crop; however, the molecular biology research of peanut is far behind other crops; the molecular mechanisms of its stress resistance are poorly understood. DELLA proteins, negative regulators of gibberellin signaling pathway in plants, promote survival of plants in adverse environments. In this study, four DELLA homologue genes were isolated using peanut transcriptome sequences. Molecular phylogenetic analysis revealed that these four AhDELLAs fall into three distinct groups: AhDELLA1 and AhDELLA2 clustered into two distinct groups, while AhDELLA3 and AhDELLA4 were in one group, which was separated from other DELLAs. qRT-PCR results showed that these four DELLA genes were expressed differentially in various peanut tissues. The AhDELLA1 and AhDELLA2 genes were expressed ubiquitously in different tissues. AhDELLA3 and AhDELLA4 showed much higher expression level in flowers and seeds as compared with other organs. The expression of four AhDELLA genes was temporally induced by PEG 6000 treatment. The AhDELLA3 and AhDELLA4 transcripts were significantly induced by NaCl treatment, while the expression of AhDELLA1 and AhDELLA2 did not change much under salt stress. The possible role of DELLA proteins in peanut development and responses to abiotic stresses is discussed.