Physiological and molecular responses of roots differ from those of leaves in spinach plants subjected to short-term drought stress

In this study, physiological responses as well as changes in expressions of specific proteins (dehydrin [DHN] and phospholipase Dα1 [PLDα1]) were determined in leaf and root tissues of Spinacia oleracea L.cv. Matador plants under different levels of drought stress. Spinach plants grown in the plant growth chamber were exposed to two levels of drought stress (Moderate Stress [MS]: 50% Field Capacity [FC] and Severe Stress [SS]: 25% FC) and compared with no stress conditions (Control: 100% [FC]) for a period of 10 days. Results revealed that the roots and leaves of spinach plants responded differently to drought stress, probably due to different antioxidant activities and accumulation of specific proteins (DHN and PLDα1). Moderate or severe drought stress did not alter the oxidation parameters in leaves of S. oleracea L. cv. Matador plants while significant changes associated with oxidative stress were observed in roots. Dehydrin polypeptides (75 and 50 kDa for leaves and 75 kDa for roots) and PLDα1 polypeptides (22 kDa in leaves; 52 kDa and 28 kDa in roots) have been observed to accumulate following drought exposure. The accumulation of these polypeptides was associated with physiological responses of spinach plants which provide evidence for their contribution to the acclimation process in early drought stress. These data suggest that tissues of spinach plant respond differently against different levels of drought stress and that the response is associated with altered expressions of DHN and PLDα1 polypeptides.