Evaluation of Growth Indices and Expression of Some Genes Involved in Response to Cold Stress in Corn

Cold stress is one of the most important factors limiting the early cultivation of most crops, including corn. Cold causes oxidative stress through the production of reactive oxygen species (ROS) in plants. This study was conducted in order to investigate the expression pattern of some genes involved in the response to cold stress (catalase, superoxide dismutase and metallothionein) in corn plants.

This experiment was conducted as a factorial in the form of a randomized complete block design with four replications and with three varieties of corn singlecross 260, singlecross 302 and doublecross 370. Planting was done in pots with a capacity of 4 kg of soil. qPCR technique was used to check gene expression pattern.

The results of the analysis of the gene expression pattern showed that among the examined cultivars, singlecross 260 had the highest expression of catalase and superoxide dismutase genes, and singlecross 302 had the lowest expression of these genes. Examining the metallothionein gene expression pattern also showed that the expression level of this gene is the lowest in singlecross 260 and the highest in singlecross 302. The high expression of metallothionein gene in singlecross 302 is probably due to the occurrence of oxidative stress due to cold stress, accumulation of hydrogen peroxide and low expression of catalase gene. Also, growth indices including germination percentage, germination speed, leaf surface and chlorophyll a and b showed a good correlation with the expression level of catalase and superoxide dismutase genes.

Singlecross 260 and Singlecross 302 had the highest and lowest levels of expression of superoxide dismutase and catalase genes, germination percentage, germination speed, leaf area and chlorophyll, respectively. The activity of antioxidant genes such as catalase and superoxide dismutase prevent the reduction of chlorophyll and damage to the plant's photosynthetic apparatus.