Effect of abscisic acid on cold tolerance in Brassica napus shoots cultured in vitro

Abstract

Freezing periods cause considerable yield decreases in crops and produce severe damage in wild plant species, limiting the distribution and growth of plants. One of the most important agronomic traits in winter rapeseed (Brassica napus L.) is winter-hardiness or freezing tolerance, which can be enhanced by cold acclimation. Abscisic acid (ABA) has been implicated as a regulatory factor in plant cold acclimation. Investigations were carried out in the laboratory of Agrobiotechnology of Lithuanian University of Agriculture. Changes in proline and soluble sugars levels in response to cold acclimation and exogenous abscisic acid were monitored in vitro in winter rapeseed shoots. Shoots of variety Sunday were acclimated at 4°C for 7, 14 and 21 days. Exogenous ABA caused significant increase in proline and soluble sugars contents. The membrane injury for leaf discs under freezing stress was estimated by the electrolyte leakage test. The degree of cold tolerance of the shoots from the different treatments was substantially increased with increasing acclimation duration. The addition of exogenous ABA to the culture medium significantly decreased electrolyte leakage, however, ABA alone was less effective than the combination of ABA and low (acclimation) temperature.