Role of potassium in proline metabolism. I. Conversion of precursors into proline under stress conditions in K-sufficient and K-deficient plants

Abstract

The role of potassium in the biosynthesis of proline in excised leaves of finger-millet and groundnut under moisture stress conditions was studied. In finger-millet leaves, a synergistic interaction with potassium and arginine as seen by the increased amounts of proline accumulation was observed. In groundnut, ornithine was a preferred precursor. Further, in leaves of K-deficient finger-millet when subjected to stress, proline accumulation was lower by 78% compared to K-sufficient plants. However, in groundnut leaves in which the K content was reduced by 73%, did not result in lower proline accumulation under stress. Leaves of K-deficient plants of finger-millet did not convert arginine into proline, but pretreatment with potassium restored the capacity. It is concluded that species differ in the proline biosynthetic pathway and in finger-millet potassium has a role in proline biosynthesis.