Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou, Jiangsu, China.
J Exp Bot. 2012 Jan;63(1):215-27. doi: 10.1093/jxb/err263. Epub 2011 Sep 16.
This study tested the hypothesis that a post-anthesis moderate soil drying can improve grain filling through regulating the key enzymes in the sucrose-to-starch pathway in the grains of rice (Oryza sativa L.). Two rice cultivars were field grown and two irrigation regimes, alternate wetting and moderate soil drying (WMD) and conventional irrigation (CI, continuously flooded), were imposed during the grain-filling period. The grain-filling rate and activities of four key enzymes in sucrose-to-starch conversion, sucrose synthase (SuSase), adenosine diphosphate-glucose pyrophosphorylase (AGPase), starch synthase (StSase), and starch branching enzyme (SBE), showed no significant difference between WMD and CI regimes for the earlier flowering superior spikelets. However, they were significantly enhanced by the WMD for the later flowering inferior spikelets. The activities of both soluble and insoluble acid invertase in the grains were little affected by the WMD. The two cultivars showed the same tendencies. The activities of SuSase, AGPase, StSase, and SBE in grains were very significantly correlated with the grain-filling rate. The abscisic acid (ABA) concentration in inferior spikelets was remarkably increased in the WMD and very significantly correlated with activities of SuSase, AGPase, StSase, and SBE. Application of ABA on plants under CI produced similar results to those seen in plants receiving WMD. Applying fluridone, an indirect inhibitor of ABA synthesis, produced the opposite effect. The results suggest that post-anthesis WMD could enhance sink strength by regulating the key enzymes involved, and consequently, increase the grain-filling rate and grain weight of inferior spikelets. ABA plays an important role in this process.
抽穗后适度土壤干旱可通过调节籽粒中蔗糖向淀粉转化的关键酶来提高灌浆。在灌浆期，田间种植了两个水稻品种，并采用两种灌溉制度，即交替湿润和适度土壤干旱（WMD）与常规灌溉（CI，持续淹水）。对于较早开花的优势小穗，WMD 和 CI 处理之间的灌浆速率和蔗糖向淀粉转化的四个关键酶（蔗糖合酶（SuSase）、腺苷二磷酸葡萄糖焦磷酸化酶（AGPase）、淀粉合酶（StSase）和淀粉分支酶（SBE））的活性没有显著差异。然而，对于较晚开花的劣势小穗，WMD 显著提高了它们的活性。WMD 对籽粒中可溶性和不可溶性酸性转化酶的活性影响不大。两个品种均表现出相同的趋势。SuSase、AGPase、StSase 和 SBE 的活性与灌浆速率呈极显著正相关。WMD 显著增加了劣势小穗中的脱落酸（ABA）浓度，且与 SuSase、AGPase、StSase 和 SBE 的活性呈极显著相关。在 CI 条件下给植物施加 ABA 可产生与 WMD 条件下相似的结果。施加 fluridone，ABA 合成的间接抑制剂，可产生相反的效果。结果表明，抽穗后 WMD 可以通过调节参与的关键酶来增强库强度，从而提高劣势小穗的灌浆速率和粒重。ABA 在这个过程中起重要作用。
