Proline metabolism-related gene expression in four potato genotypes in response to drought stress

Abstract

Drought severely limits potato yield. The aim of this work was to study a response of plantlets of four potato genotypes to polyethylene glycol (PEG 6000)-induced drought stress in both physiological and molecular levels. The drought-tolerant and drought-sensitive genotypes were identified based on plantlet growth, chlorophyll content, lipid peroxidation, free proline content, and proline metabolism-related gene expressions. We found that PEG-induced stress increased malondialdehyde (MDA) and proline content, and drought-tolerant plantlets exhibited lower MDA and proline content than sensitive genotypes. In addition, PEG up-regulated ∆-1-pyrroline-5-carboxylate synthase (P5CS) and pyrroline- 5-carboxylate reductase (P5CR) gene expressions and down-regulated pyrroline dehydrogenase (PDH) and ∆-1-pyrroline-5-carboxylate dehydrogenase (P5CDH) gene expressions. Genotype B plantlets exhibited lower P5CS and P5CR expressions and higher PDH and P5CDH expressions compared with the other plantlets. The results suggest that significant cultivar differences among potato plantlets in response to PEG-induced drought stress are exhibited in root length, MDA content, proline accumulation, and proline metabolism-related gene expressions.