用单片段代换系研究水稻产量和籽粒充实对花后不同土壤干旱的响应

以介入巴西陆稻IAPAR9抗性基因片段的单片段代换系(single segment substitution line, SSSL)和受体亲本华粳籼74为材料，设置正常灌水(CK)、中度干旱胁迫(MD)、重度干旱胁迫(SD) 3种土壤水分处理，分析SSSL和受体亲本籽粒灌浆特征、蔗糖及淀粉代谢中相关酶活性动态，探讨了水稻籽粒充实和产量对花后干旱胁迫响应的生理机制。结果表明，与受体亲本相比，携带抗旱基因的SSSL在MD和SD处理下其耐旱性的表现更为明显，减产幅度明显小于受体亲本。在花后7 d开始的中、重度干旱胁迫处理下，灌浆中后期SSSL叶片相对含水量、叶绿素含量和光合速率下降幅度明显小于受体亲本，其籽粒中蔗糖合酶(sucrose synthase, SS)、酸性蔗糖转化酶(acid invertase, AINV)、腺苷二磷酸葡萄糖焦磷酸化酶(ADP glucose pyrophosphorylase, AGPP)﹑可溶性淀粉合酶(soluble starch synthase, SSS)﹑Q酶活性在灌浆前(中)期也明显上升，增强了SSSL籽粒灌浆中前期库活性。虽然持续的干旱胁迫使得上述酶活性在灌浆的中后期快速下降，导致同化物积累的活跃灌浆期缩短，但SSSL籽粒平均灌浆速率和最大灌浆速率明显高于受体亲本，这在一定程度上可弥补因灌浆期缩短导致的同化物积累损失，干旱胁迫下SSSL产量高于受体亲本，这一趋势在重度干旱胁迫下更为明显。

Responses of the Yield and the Grain Filling to Different Post-Anthesis Soil Drought Analyzed with Single Segment Substitution Line (SSSL) in Rice (Oryzasativa L.)

To explore the physiological mechanisms of the yield and the grain filling in rice affected by post-anthesis soil drought, we analyzed the characters of grain filling and the activities of enzymes involved in sucrose metabolism and starch synthesis in the single segment substitution line (SSSL) and its receptor parent Huajingxian 74 under normal (CK), moderate deficit (SD) and severe deficit (MD) water conditions after flowering were analyzed. The result showed that the SSSL, containing the resistance gene segment provided by Brazil upland rice, presented higher drought resistance than its receptor parent Huajingxian 74 under the MD and SD treatments. The yield reduction in SSSL was much less than that in Huajingxian 74. SPAD values and net photosynthetic rate of flag leaf in SSSL under the MD and SD treatments applied at 7 day after anthesis (DAA) were less than its receptor parent during mid and late grain-filling period, and the activities of sucrose synthase (SS), acid invertase (AINV), ADP glucose pyrophosphorylase (AGPP), soluble starch synthase (SSS), and Q enzymes in SSSL grains were elevated remarkably, resulting in the enhancement of grain sink activities under MD and SD at early and mid grain-filling stages. Although the activities of the above mentioned enzymes were descended much quickly during late grain-filling period under the continuous drought stress, which could shorten the duration of active grain-filling significantly, the average and the maximum grain-filling rates of SSSL under MD and SD were increased much more those that of the receptor parent during mid and early filling period, which could compensate for the loss of assimilate accumulation in grain by the abatement of active grain-filling duration, consequently the yield of SSSL under drought stress was higher than that of receptor parent, especially under SD.