Effects of Jasmonic Acid on Cold Stress Tolerance of Potato at Seedling Stage

Objective The research was carried out to explore the effects of different jasmonic acid(JA) concentrations on the content of reactive oxygen species(ROS)and its scavenging enzyme activity as well as the expression of key cold resistance gene CBF of potato, and to identify the optimal application concentration of JA, which contributed to enhance cold tolerance of potato, with a view to providing a theoretical basis for the development of potato industry.

Method Taking the potato variety Favorita as the research object, the method of spraying JA on potato leaves was used to explore the content of ROS, the activities of catalase(CAT), peroxidase(POD)and superoxide dismutase SOD, and the expression of CBF genes of potato leaves under the normal and low temperature conditions.

Result As the increase of JA concentration, the content of ROS of potato leaves at seedling stage decreased gradually, and the content of ROS could be maintained at a low level upon cold stress. The appropriate concentration range was 100 μmol/L to 400 μmol/L, among which 200 μmol/L had the most significant effect, and the ROS content was reduced by 47.6% compared with control. JA could enhance the activities of ROS scavenging enzymes - CAT and POD, and the effect became more significant with the increase of JA concentration. After cold stress, 200 μmol/L JA treatment could significantly increase the activities of CAT and POD by 1.30 and 2.53 times, respectively. However, under the normal condition, JA treatment inhibited SOD activity to a minimum of 70.7%, while JA may increase SOD activity to a maximum of 2.11 times through other ways under the condition of cold stress. Exogenous JA could induce the expression of StCBF1-3, and cold stress could promote the synthesis of endogenous JA which might induce the expression of StCBF1-3 and improve the cold tolerance of potato.

Conclusion The cold tolerance of potato is significantly correlated with the concentration of exogenous JA. The appropriate concentration can promote the expression of key gene StCBF1-3 for cold tolerance, significantly enhance the activities of CAT, POD and SOD, inhibit the generation of ROS induced by cold stress, and improve the cold tolerance of potato. The optimal concentration of JA is 100 μmol/L to 400 μmol/L, and 200 μmol/L has the best effect.