铝胁迫对花生根尖线粒体膜生理特性的影响

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

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,筛选到耐铝品种鲁花11(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20μmolL-1和100μmolL?1时,两品种的MDA含量差异显著,但在400μmolL-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,ΔΨm明显降低,线粒体中Cytc/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ΔΨm调控能力强,不易发生细胞程序性死亡,从而表现出较强的耐铝能力。

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 Al^3＋ concentration detection in root tips. The concentration of mitochondrial MDA in two cultivars root tips increased after Al^3＋ treatment, that of R1549 was higher than that of LH11. The difference between two cultivars in mitochondrial MDA concentration was very significant in 20 and 100 μmol L^-1 Al^3＋ treatment, but not significant in 400 μmol L^-1 treatment. With the increase of Al^3＋ concentration, mitochondrial Ca^2＋-ATPase activity and Ca^2＋ concentration in two cultivars root tips decreased, and Ca^2＋ concentration of R1549 decreased faster than that of LH11. Under Al^＋~ stress, mitochondrial optical density decreased continuously, （mitochondrial permeability transition pore MPTP） enlarged, mitochondria ΔΨ decreased significantly, mitochondrial Cyt c/a ratio reduced, which was more obvious in R1549 than in LH11 with Al^3＋ concentration increasing. To sum up, high Al^3＋ concentration treatment induced mitochondrial permeability transition pore opening, increased mitochondrial membrane permeability, decreased mitochondrial membrane Ca^2＋ transit system activity so that cytoplasm Ca^2＋ 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 Al^3＋ absorption and membrane lipid peroxidation level, higher control ability of Ca^2＋-ATPase activity, MPTP opening and ΔΨm maintaining so that is not easy to produce PCD under low Al^3＋ concentration stress. It may be one of reasons for Al resistance mechanism in plant.