Reversal of osmotic stress effects by gibberellic acid in Brassica campestris. Recovery of hypocotyl growth, protein and RNA levels in the presence of GA

Inhibition of hypocotyl growth by water stress and the antagonistic effect of gibberellic acid was studied in Brassica campestris L. cv. Varuna. Water stress alone inhibited increases in length and fresh weight of the hypocotyl. Increasing levels of GA applied simultaneously reversed the effect of water stress. Growth was related directly to water status and inversely to water saturation deficit. However, in severely stressed seedlings GA increased the length of hypocotyls, while fresh weight showed either no change or was even reduced. Thus a distinct ‘uncoupling’ between increases in length and water status was observed. GA appears to act partially by increasing the water status of the seedlings and partially by sustaining protein and RNA levels.