水稻生育后期根系氮代谢生理活性变化的研究
Dynamics of nitrogen metabolism activity in rice root at the late development stage
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摘要: 以“两优培九”及其父本“9311”和“汕优63”为材料, 测定不同水稻品种花后根系氮代谢相关酶谷氨酰胺合成酶(GS)、谷-丙转氨酶(GPT)、谷草转氨酶(GOT)和谷氨酸脱氢酶(GDH)及蛋白水解酶活性、蛋白质和游离氨基酸含量、根系伤流液量以及伤流液游离氨基酸及糖含量。结果表明,“9311”的GPT和GDH活性高峰出现在开花前, GS和GOT峰值分别出现在花后第1、2周; “两优培九”除GS高峰在开花前, 其余3种酶活性高峰均出现在花后1周;“汕优63”的4种酶活性高峰均出现在花后第2周。“9311”和“两优培九”根系可溶性蛋白、游离氨基酸含量高峰出现在花后1周左右, “汕优63”的两峰值滞后于前两品种, 分别推至花后第2周和第3周, 这与3品种根系酶活性的变化趋势基本一致。“两优培九”根系伤流液量的最大值出现在花后两周, 早于“9311”和“汕优63”1周。伤流液的高峰和根系中游离氨基酸峰值相差1周, 且滞后时间在品种间有所差别,“两优培九”相差1周,“9311”相差两周, 而“汕优63”二者基本一致。3品种伤流液中“汕优63”糖含量显著高于其他两品种(P<0.01), 而“9311”的氨基酸含量显著高于其他两品种(P<0.05)。本试验结果表明,“两优培九”根系的氮代谢高峰早于其他两个品种, 而峰值低于其他两品种, 说明生育后期“两优培九”根系生理活性衰退早于其他两个品种; 品种间根系的代谢高峰具有明显的强度和时间性差异; 根系组织代谢高峰和伤流液峰值具有时间差, 其差值因品种而异。Abstract: Rice cultivars “Liangyoupeijiu”, “9311” and “Shanyou63” were used to investigate the activities of glutamine synthetase (GS), glutamic acid-pyruvic acid transaminase (GPT), glutamic acid oxaloacetate transaminase (GOT), glutamate dehydrogenase (GDH) and protease in rice root during the late development stage. Also the content of soluble protein and free amino acids in rice root, and that of sugar and free amino acids of root bleeding-sap of rice after blooming were analyzed. The results show that GPT and GDH activity peak precedes blooming while that of GS and GOT occurs after one and two weeks of blossom in “9311”. In “Liangyoupeijiu”, GPT, GDH and GOT activity peaks in the first week after blooming while that of GS occurs before blossom. In “Shanyou63”, the four enzymes reach their highest activity two weeks after blossom. The content of soluble protein and free amino acids in “9311” and “Liangyoupeijiu” peaks in the first week after blossom while that in “Shanyou63” delays to the second and third weeks. Peak of root bleeding-sap occurs in the second week after blossom in “Liangyoupeijiu”, which is one week earlier than in “9311” and “Shanyou63”. Peak time difference between bleeding sap and free amino acids in roots is one week, but the lag-time is different for the three cultivars — one week for “Liangyoupeijiu”, two weeks for “9311” and insignificant for “Shanyou63”. Bleeding-sap sugar content in “Shanyou63” is remarkably higher than in the other two cultivars (P<0.01), while the content of free amino acids in “9311” is significantly higher than in the other two cultivars (P<0.05). It is inferred from the results that nitrogen metabolism in “Liangyoupeijiu” peaks earlier, but at a lower value than in the other two cultivars. This indicates an earlier decline in root physiological activity at late development stage in “Liangyoupeijiu” than in the other two cultivars. Notable differences exist in the strength and peak time of metabolism among the three cultivars. Tissue metabolism and bleeding-sap peak occurs at different times and with different strength, and at varying time-lags among the cultivars.
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