杂交水稻的根呼吸——四种耗氧途径的活力和P/O比

Root Respiration of Hybrid Rice——Activities of Four O 2 Uptake Pathways and Apparent P/O Ratio

对杂交水稻赣化 7号和其亲本之一广抗粳 2号的根系耗氧特征进行了研究。稻株种植在通气的营养液中 ,4种耗氧途径的活力被量化分析。过氧化物酶耗氧占了较大的比例 ,龙胆酸可抑制稻根中的过氧化物酶活力。杂交水稻的过氧化物酶和抗氰酸呼吸途径耗氧率比其亲本高 5 0 %以上 ,杂交水稻和其亲本根系过氧化物酶的耗氧分别占总量的 2 6 .5 %和 2 2 .6 % ,细胞色素氧化酶途径分别占 35 .5 %和 40 .5 % ,抗氰酸呼吸途径分别占 2 7.8%和 2 1 .7% ,剩余呼吸分别占 9.8%和 1 4 .9%。按根系耗氧总量计算 ,杂交水稻和其亲本的P/O比分别是 1 .35和 1 .44。杂交组合的根系和植株相对生长率比其亲本大 6 0 %左右 ,但根系耗氧量和ATP生产率比其亲本仅分别高 1 8.7%和 1 4 .2 %。因此 ,水稻品种的生长率差异不能用根系呼吸耗氧及P/O比来解释。本研究结果显示 。

The O 2 uptake characteristics of roots of Ganhua 7 (F 1 hybrid) and one of its parents Guangkang Geng 2 were studied. Plants were grown in aerated nutrient solution. The activities of four O 2-consuming pathways in the roots were quantified. A significant fraction of root O 2 uptake was mediated by a peroxidase. Gentisic acid inhibited this activity in the rice root. Rates of O 2 uptake via peroxidase and alternative path were 50% higher in the F 1 hybrid than in its parents. In roots of the F 1 hybrid and its parents, peroxidase contributed 26.5% and 22.6%, the Cyt path 35.5% and 40.5%, the alternative path 27.8% and 21.7%, and the residual component 9.8% and 14.9% to total O 2 uptake, respectively. The P/O ratios, as calculated from these data, were 1.35 and 1.44 in te F 1 hybrid and its parents, respectively. The fastgrowing F1 hybrid combined a 60% higher root and plant RGR with a 18.7% higher O 2 uptake and a 14.2% higher root ATP production rate, as compared to its parents. The variety differences in growth rate cannot be ascribed to root O 2 uptake and different P/O ratios of root respiration. The present data suggest intra-specific variation in energy costs of root processes in relation to growth rate.