亚种间杂交稻根系伤流液与地上部细胞分裂素的变化

本文以水稻亚种间杂交组合Ⅱ优2070及恢复系2070、Ⅱ优419及恢复系中419为材料．应用HPLC和ELISA法测定灌浆期间根系伤流液中根源细胞分裂素（CTKs）种类和数量以及稻叶和籽粒中细胞分裂素组分含量的变化．研究表明在亚种杂交稻及其恢复系灌浆起始阶段，玉米素（Z）占总CTKs的比例高达62．8％-89．1％，是根系伤流液中细胞分裂素的主要成分．而二氢玉米素（diHZ）和二氢玉米素核苷（diHZR）则在灌浆后期明显上升，这种变化动态与II优2070和2070剑叶中ZRs（Z＋ZR）、diHZRs（diHZ＋diHZR）的波动变化是相符合的。与根系伤流液的主要细胞分裂素组成不同，IPAs在叶片和籽粒中占总CTKs量的比例最高。说明在灌浆期间．根系伤流液中CTKs的种类及其活性存在着变化，这种变化可能与细胞分裂素代谢酶活性变化及其相关酶基因表达的不同有关。讨论了强、弱势粒的CTKs组分的变化与籽粒结实的可能关系。

CYTOKININ CHANGES OF ROOT EXUDATES, LEAVES AND GRAINS IN INTER-SUBSPECIFIC HYBRID RICE

Using inter-subspecific hybrid rice of IIyou 2070 and IIyou 419 , their restorer lines 2070 and Zhong419, the various forms and levels of root-derived cytokinins(CTKs) in root exudates, and changes of various forms of cytokinins in rice flag leaves and grains were analyzed by HPLC and ELISA after initial heading stage. The results indicated that zeatin had 62.8% to 89.1% of total cytokinins and was the dominant form of cytokinins in root exudates during early grain filling, whereas, the contents of diHZ and diHZR greatly increased during milk ripening. This change was consistent with the dynamic changes of ZRs (Z+ZR)and diHZRs (diHZ+diHZR)in flag leaves of IIyou 2070 and 2070. Different from main cytokinin composition in root exudates, IPAs took high proportion of total CTKs in leaf and grain. We suggested that there were changes of various forms and activities of root-derived cytokinins in root exudates, and this change was related to catabolic enzymes of cytokinins and the different expression of enzyme genes. Meanwhile, the relationship between cytokinin changes of vigorous and weak spikelets and grain filling was disscused.