边缘细胞对水稻生长和细胞壁组分的影响及其与耐铝性的关系

以水稻II优3027 (耐铝基因型)和红良优166 (铝敏感基因型)为材料，采用悬空培养法，在根尖附着和移除边缘细胞(root border cell, RBCs)条件下，比较研究水稻生长、根尖铝含量和细胞壁组分含量变化及其与耐铝性的关系。结果表明，铝抑制水稻根系伸长，导致根尖和细胞壁铝积累。移除根尖边缘细胞令根伸长抑制率、根尖胼胝质含量、根尖和细胞壁铝含量及细胞壁单核铝含量显著低于保留边缘细胞的根。此外，对比于根尖移除边缘细胞，保留边缘细胞降低了细胞壁中果胶和半纤维素1含量，而对半纤维素2含量无影响。表明铝毒胁迫下水稻根尖由于附着边缘细胞，阻止了根系铝吸收，并维持较低的细胞壁果胶和半纤维素1含量，减少细胞壁吸附铝的位点。同时也减少了根尖毒性形态铝的含量，降低了铝的生物有效性，从而提高了水稻的耐铝性。

Effects of Root Border Cells on Root Growth and Cell Wall Polysaccharide Contents in Rice Seedlings and Their Relation to Aluminum Tolerance

Most plant root tips are sheathed by large populations of root border cells(RBCs).One of suggested roles of RBCs is to defend from toxic metal cations,including Al,in the rhizosphere.Using rice genotypes "Ⅱ You 3027"(Al-resistant)and "Hongliangyou 166"(Al-sensitive)with treatments of different concentrations of Al3+,acroponic culture with RBCs adhered to or removed from root tips was conducted to study the effects of RBCs on root growth,Al content and cell wall polysaccharide contents in root tips of rice seedlings under Al toxicity.Al treatment inhibited root elongation and increased Al accumulation in the root tips.Removal of RBCs from root tips significantly enhanced Al-induced root growth inhibition and increased callose content,Al accumulation in root tips and root tip cell walls,and monomeric Al content in root tips.The removal of RBCs from root tips also significantly increased pectin and hemicellulose 1 contents in the cell walls of root tips,but did not affect the hemicellulose 2 contents.These results suggested that RBCs adhered to the root tips enhance Al tolerance of rice by decreasing Al,pectin and hemicellulose 1 contents in the cell walls of root tips,and contents of toxic species of Al in root tips.