Reduced Expression of Gongdae Ring Zinc Finger 1 (GdRZF1) Enhances Drought Stress Tolerance in Watermelon (Citrullus lanatus)

Abstract

Watermelon is a major fruit vegetable around the world. Drought is an abiotic stress factor that affects the productivity and growth of crop plants. To improve the tolerance of watermelon to drought stress, it is important to isolate stress tolerance-related genes. Recently, we characterized the gene for a ubiquitin E3 ligase protein named Lagenaria siceraria RING Zinc Finger 1 (LsRZF1). In Arabidopsis, LsRZF1 is involved in the drought response through the proline metabolism-mediated pathway. In this study, we identified and characterized a watermelon (Citrullus lanatus cv. Gongdae) homolog of LsRZF1, designated GdRZF1. LsRZF1 antisense (lsrzf1) transgenic watermelon lines showed reduced GdRZF1 expression, and were less sensitive to drought stress than the wild type. Reduced expression of GdRZF1 was also significantly influential in changes in drought-sensitive parameters including relative water content, ion leakage, chlorophyll content, malondialdehyde levels, proline content, and the expression of drought stress-associated genes. Taken together, these findings suggest that GdRZF1 is important for water deficit tolerance in watermelon.