Physiological and Biochemical Properties of Cotton in Response to Copper Stress

Background: copper (Cu) is an essential micronutrient, required for plant growth and development. However, high concentrations of Cu can be extremely toxic to plant. This study investigate the tolerance mechanism of cotton under copper stress and its potential for soil pollution improvement. Results: The hybrid cotton variety (Zhongmian 63) and its two parent lines were selected as materials. Cotton seedling were treated with different Cu concentrations (0, 0.2, 50, 100, 200 μM) for 10 days in hydroponic condition. The results showed that the stem height, root length, and leaf area of cotton seedlings appear to have a down trend with the increase of Cu concentration. Increasing Cu concentration promoted Cu accumulation in roots, stems, and leaves of all the three cotton genotypes, however, the roots region was the main Cu storage organ, followed by leaves and stems regions. Compared with the parent lines, the roots of Zhongmian 63 are more capable of enriching Cu and have the least amount of Cu transported to the shoots. Therefore, the toxicity of Cu to cotton seedling is effectively alleviated. Cu-caused oxidative stress to cotton leaves was evident by over accumulation of H 2 O 2 and MDA. POD activity and soluble sugar content increased firstly and then decreased compared with the control group. GSH content increased and photosynthetic pigment content decreased with increasing copper concentration in nutrient solution. Conclusion: Our results suggest that the hybrid cotton variety Zhongmian 63 performed well under Cu stress. This lays the theoretical foundation for further analysis on molecular mechanism of cotton resistance to copper and promoting the large-scale planting Zhongmian 63 in the copper-contaminated area.