Cold-induced Changes of Proline, Malondialdehyde and Chlorophyll in Spring Canola Cultivars

Low temperature (LT) is an important environmental factor that limits the survival, productivity and geographical distribution of plants. Oil seeds are the second global food resources among which Brassica napus L. is the third annual oil seed in the world. In cold stress, some biochemical and physiological reactions occur in response to reactive oxygen species (ROS). Hence, the quantitative changes of proline, malondialdehyde (MDA) and chlorophyll (a, b, total) content were assessed in two spring canola (cv. Zarfam, cold tolerant and cv. Option 500, cold sensitive) seedlings exposed to early spring cold stress. They were first grown in a controlled growth room at 22/16 °C (day/night) and then at the 4th fully expanded leafy stage seedlings weretransferred to a cold environment (10/3 °C) for 7 d, or they were maintained continuously at 22/16 °C (Control). Leaf samples were harvested at days 0 (transferred day), 2, 4 and 7 of cold exposure period. Analysis of variance showed significant differences between the temperature treatments and also cultivars for all physiological traits. The cold tolerant cultivar showed remarkable less LT-induced decrease in chlorophylls (a, b, total) and increase in MDA and accumulation of proline compared to the cold sensitive cultivar. This assay verified the superior response of cold tolerant Zarfam canola to cold temperature.