Wang Zhiqin, Xu Yunji, Chen Tingting, Zhang Hao, Yang Jianchang, Zhang Jianhua
Jiangsu Key Laboratory of Crop Genetics and Physiology, Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, 225009, China.
Planta. 2015 May;241(5):1091-107. doi: 10.1007/s00425-015-2245-0. Epub 2015 Jan 15.
Abscisic acid mediates the effect of post-anthesis soil drying on grain filling through regulating the activities of key enzymes and expressions of genes involved in sucrose-to-starch conversion in rice spikelets. This study investigated if abscisic acid (ABA) would mediate the effect of post-anthesis soil drying on grain filling through regulating the key enzymes in sucrose-to-starch conversion in rice (Oryza sativa L.) spikelets. Two rice cultivars were field-grown. Three treatments, well-watered (WW), moderate soil drying (MD), and severe soil drying (SD), were imposed from 6 days after full heading until maturity. When compared with those under the WW, grain filling rate, grain weight, and sink activity, in terms of the activities and gene expression levels of sucrose synthase, ADP glucose pyrophosphorylase, starch synthase, and starch branching enzyme, in inferior spikelets were substantially increased under the MD, whereas they were markedly decreased in both superior and inferior spikelets under the SD. The two cultivars showed the same tendencies. Both MD and SD increased ABA content and expression levels of its biosynthesis genes in spikelets, with more increase under the SD than the MD. ABA content was significantly correlated with grain filling rate and sink activities under both WW and MD, while the correlations were not significant under the SD. Application of a low concentration ABA to WW plants imitated the results under the MD, and applying with a high concentration ABA showed the effect of the SD. The results suggest that ABA plays a vital role in grain filling through regulating sink activity and functions in a dose-dependent manner. An elevated ABA level under the MD enhances, whereas a too high level of ABA under the SD decreases, sink activity.
脱落酸通过调节水稻小穗中蔗糖向淀粉转化的关键酶活性和相关基因的表达，介导花后土壤干旱对籽粒灌浆的影响。本研究探讨脱落酸（ABA）是否会通过调节水稻（Oryza sativa L.）小穗中蔗糖向淀粉转化的关键酶，介导花后土壤干旱对籽粒灌浆的影响。选用两个水稻品种进行田间种植。从齐穗后6天至成熟设置3种处理：充分灌溉（WW）、适度土壤干燥（MD）和重度土壤干燥（SD）。与WW处理相比，MD处理下弱势小穗的籽粒灌浆速率、粒重和库活性（以蔗糖合酶、ADP葡萄糖焦磷酸化酶、淀粉合酶和淀粉分支酶的活性及基因表达水平衡量）显著增加，而SD处理下强势和弱势小穗的上述指标均显著降低。两个品种表现出相同趋势。MD和SD处理均提高了小穗中ABA含量及其生物合成基因的表达水平，且SD处理的增幅大于MD处理。在WW和MD处理下，ABA含量与籽粒灌浆速率和库活性显著相关，而在SD处理下相关性不显著。对WW植株施用低浓度ABA可模拟MD处理的结果，施用高浓度ABA则表现出SD处理的效果。结果表明，ABA通过调节库活性在籽粒灌浆中起关键作用，且呈剂量依赖性。MD处理下升高的ABA水平增强了库活性，而SD处理下过高的ABA水平则降低了库活性。
