Abstract:

Mitochondria play a vital role in plant life. Peanut (Arachis hypogaea L.) culitivars LH11 (Al-resistant) and R1549 (Al-sensitive) were selected through root elongation experiment, hematoxylin dying and Al³⁺ concentration detection in root tips. The concentration of mitochondrial MDA in two cultivars root tips increased after Al³⁺ treatment that of R1549 was higher than that of LH11. The difference between two cultivars in mitochondrial MDA concentration was very significant in 20ΔΨ decreased significantly, mitochondrial Cyt c/a ratio reduced, which was more obvious in R1549 than in LH11 with Al³⁺ concentration increasing. To sum up, high Al³⁺ concentration treatment induced mitochondrial permeability transition pore opening, increased mitochondrial membrane permeability, decreased mitochondrial membrane Ca²⁺ transit system activity so that cytoplasm Ca²⁺ concentration increased, cytochrome c released into the cytoplasm, which might induce PCD(programmed cell death) in root tip, and inhibit root growth. Compared with Al-sensitive cultivar, Al-resistant cultivar has less Al³⁺ absorption and membrane lipid peroxidation level, higher control ability of Ca²⁺-ATPase activity, MPTP opening and ΔΨ_m maintaining so that is not easy to produce PCD under low Al³⁺ concentration stress. It may be one of reasons for Al resistance mechanism in plant.

Key words: Aluminum stress, Peanut(Arachis hypogaea L.), Roottip, Mitochondria, Permeability physiology