Effect of exogenous amino acids on electrolyte leakage in rapeseed shoots cultured in vitro

Abstract

Rapeseed (Brassica napus L.) is one of the most important oil crops worldwide and has a significant potential for cultivation in Lithuania. One of the most important agronomic traits in winter rapeseed (Brassica napus L.) is winter-hardiness or freezing tolerance, which can be enhanced by various exogenous factors. Investigations were carried out in the laboratory of Agrobiotechnology of Aleksandras Stulginskis University. Changes in proline and soluble sugars levels in response to cold de-acclimation and exogenous amino acids were monitored in vitro in winter rapeseed shoots. Shoots of variety ‘Sunday’ were acclimated at 4°C for 14 days and de-acclimated under temperatures of 18/16ºC, photoperiod 16/8 h (day/night) for 1, 3, 5 and 7 days. Exposure of cold-acclimated shoots to normal growth temperature significantly reduced cold tolerance as well as soluble sugars and proline contents. Exogenous amino acids caused significant increase in proline 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 treatment was substantially decreased with increasing de-acclimation duration. The addition of exogenous amino acids to the culture medium resulted in significant decrease in electrolyte leakage. On the medium supplemented with exogenous amino acids after de-acclimation treatment electrolyte leakage of proline-treated shoots was from 6.97 to 11.93% lower in comparison with non-treated shoots.