Proline Accumulation as a Symptom of Drought Stress in Maize: A Tissue Differentiation Requirement

Abstract

Ibarra-Caballero, J., Villanueva-Verduzco, C., Molina-Galan, J. and Sanchez-de-Jimenez, E. 1988. Proline accumulation as a symptom of drought stress in maize: a tissue differentiation requirement.—J. exp. Bot. 39: 889–897. Seedlings and callus tissue of maize (Zea mays L.) were tested for proline accumulation under drought stress. A variety from a tropical humid region, a semi-desertic variety and its improved population selected for drought stress resistance, were used for this study. Proline accumulation was found in green leaves of maize seedlings under drought stress; no correlation was found between proline accumulation in leaves and the variety or population tested. White tissue, callus and leaves of etiolated seedlings did not show this response to drought stress, nor did green callus or detached leaves (green or etiolated), even when stress caused a loss of water from leaves similar to that observed when whole seedlings were drought-stressed. Addition of abscisic acid to green or white tissue did not result in proline accumulation. The above data indicate that proline accumulation caused by drought stress does not seem to be an indication of drought stress resistance, but rather a symptom of it. For this accumulation to take place it seems that fully organized chloroplasts are required as well as the systemic development of the plant.