磷对水稻耐铝性及根尖细胞壁组分的影响

 为阐明外源磷供应引起水稻体内磷代谢和根尖细胞壁组分变化进而阐述磷、铝间的相互作用，以水稻菲优多系1号(耐铝毒基因型)和红良优166(铝毒敏感基因型)为材料，水培条件下先用0.5、10和30 mg/L磷预处理9 d，然后用50 μmol/L Al处理48 h，研究铝毒胁迫下磷对水稻根尖的防护效应及磷作用下根尖细胞壁组分变化与水稻耐铝性的关系。结果表明，50 μmol/L Al处理抑制水稻总根长，尤其是在0.5 mg/L磷预处理后用铝交替处理时该作用更为明显。铝毒胁迫下，0.5 mg/L磷预处理时两基因型水稻叶片的丙二醛(MDA)、抗坏血酸(ASA)、游离脯氨酸(Pro)含量显著高于其他处理，10 mg/L和30 mg/L磷预处理显著降低两基因型水稻叶片的MDA、ASA和Pro含量，表明充足的磷供应减轻了铝对水稻的伤害。耐铝毒水稻根尖的果胶和半纤维素2含量在30 mg/L磷与铝交替处理时显著低于0.5 mg/L 和10 mg/L 磷与铝交替处理，根系的酸性磷酸酶(ACP)活性在0.5 mg/L磷与铝交替处理时显著高于10 mg/L与30 mg/L磷与铝交替处理。而铝毒敏感水稻的根尖细胞壁多糖组分含量、ACP活性在不同浓度的磷、铝交替处理间无显著差异。表明铝耐性水稻在缺磷条件下通过提高ACP活性以提供更多的Pi与铝结合钝化铝，在磷充足条件下通过降低细胞壁多糖含量以减少铝结合位点，进而提高铝毒耐性。

Effects of Phosphorous on Aluminum Tolerance and Cell Wall Polysaccharide Components in Rice Root Tips

To elucidate the possible interaction of phosphorus induced Al tolerance in rice by improving inorganic phosphorus metabolism and modifying cell wall polysaccharides of root tip cell walls,rice seedlings of two rice cultivars \Feiyouduoxi 1 (Al tolerant genotype) and Hongliangyou 166 (Al sensitive genotype)\]were pretreated with phosphorus (P) at concentrations of 0.5, 10 and 30 mg/L for 9 d, then   treated with 50 μmol/L Al for 48 h. The results showed that total root length of both rice genotypes decreased at 50 μmol/L Al , especially in 0.5 mg/L P and Al alternate processing. Under Al toxicity stress, the malonaldehyde (MDA), ascorbic acid (ASA) and proline (Pro) contents in rice leaves of two genotypes were significantly higher in 0.5 mg/L P pretreatment than other treatments, and 10 mg/L and 30 mg/L P pretreatment significantly decreased MDA, ASA and Pro contents. These results suggested that sufficient P supply ameliorated Al damage on rice. The contents of pectin and hemicellulose 2 in root apex of Feiyouduoxi 1 were significantly lower in 30 mg/L P pretreatment than in 0.5 mg/L and 10 mg/L P pretreatment under Al toxicity, and 0.5 mg/L P pretreatment increased Feiyouduoxi 1 root acid pohosphatase(ACP) activity more significantly than 10 mg/L, 30 mg/L P and aluminum alternate processing. However, no significant differences were observed in cell wall polysaccharides components and ACP activity in Hongliangyou 166. These results suggested that Al tolerant rice genotype detoxified Al via increasing the ACP activity in root tips to provide more Pi to combine with Al under P deficient condition, and decreasing the cell wall polysaccharide content to reduce Al binding sites in cell walls under P sufficient condition.