铝胁迫对花生根尖线粒体膜生理特性的影响

线粒体在植物生命活动中发挥重要作用,以花生为材料,研究了在铝胁迫条件下,花生根尖细胞线粒体膜生理变化。结果表明,通过根长试验、苏木精染色和根尖铝离子含量测定,筛选到耐铝品种LH11,铝敏感品种R1549。铝胁迫后,两个品种根尖线粒体MDA含量增加,R1549的MDA含量均高于LH11,在处理浓度是20 μmol L^-1和100 μmol L^-1时,两品种的MDA含量差异显著,但在400 μmol L^-1时,差异不显著;两品种根尖线粒体Ca²⁺-ATP酶活性和Ca²⁺含量呈下降趋势,且随铝溶液浓度增加而加快,R1549的线粒体Ca²⁺含量下降较LH11快;随处理铝溶液浓度增加,线粒体光密度持续下降,MPT不断增大,ΔΨ_m明显降低,线粒体中Cyt c/a减少,R1549较LH11下降更明显。试验结果说明在较高铝浓度胁迫下,两品种线粒体透性转换孔开放,膜透性增加,跨线粒体膜Ca²⁺转运系统活性降低,使胞质Ca²⁺超载,细胞色素C释放到细胞质中,诱导根尖细胞发生程序性死亡,从而抑制根生长;在低铝浓度下,与铝敏感品种相比,耐铝品种吸收铝少,脂质过氧化水平低,线粒体膜Ca²⁺-ATPase活性、MPTP和ΔΨ_m调控能力强,不易发生PCD,从而表现出较强的耐铝能力。

Effects of Aluminum on Physiological Characteristics of Mitochondrial Membrane in Peanut Root Tips

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.