The advent of dwarf statured rice varieties enabled a major breakthrough in yield and production, but raising the ceiling of genetically determined yield potential even further has been the breeding priority. Grain filling is asynchronous in the rice panicle; the inferior spikelets particularly on secondary branches of the basal part do not produce grains of a quality suitable for human consumption. Of the various strategies being considered, the control of ethylene production at anthesis has been a valuable route to potentially enhance genetic yield level of rice. The physiology underlying spikelet development has revealed spikelet position-specific ethylene levels determine the extent of grain filling, with higher levels resulting in ill-developed spikelet embodying poor endosperm starch content. To break the yield barrier, breeders have increased spikelet number per panicle in new large-panicle rice plants. However, the advantage of panicles with numerous spikelets has not resulted in enhanced yield because of poor filling of inferior spikelets. High spikelet number stimulates ethylene production and downgrading of starch synthesis, suggesting a trade-off between spikelet number and grain filling. High ethylene production in inferior spikelets suppresses expression of genes encoding endosperm starch synthesising enzymes. Hence, ethylene could be a retrograde signal that dictates the transcriptome dynamics for the cross talk between spikelet number and grain filling in the rice panicle, so attenuation of its activity may provide a solution to the problem of poor grain filling in large-panicle rice. This physiological linkage that reduces starch biosynthesis of inferior kernels is not genetically constitutive and amenable for modification through chemical, biotechnological, surgical and allelic manipulations. Studies on plant genotypes with different panicle architecture have opened up possibilities of selectively improving starch biosynthesis of inferior spikelets and thereby increasing grain yield through a physiological route.

中文翻译：

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更正为：控制小穗数量与籽粒充实之间的折衷：水稻穗小穗中淀粉合成与激素动力学相关的层次结构。

矮定稻品种的问世使产量和产量有了重大突破，但将基因决定的单产潜力的上限进一步提高已成为育种工作的重点。水稻穗中的籽粒灌浆是异步的。下小穗，特别是在基部次要分支上的小穗，不会产生适合人类食用的品质的谷粒。在考虑的各种策略中，控制花期乙烯产量一直是潜在提高水稻遗传产量水平的重要途径。小穗发育的生理学基础已经揭示，小穗特定位置的乙烯水平决定了谷物的充实程度，较高的水平导致发育不良的小穗表现出较差的胚乳淀粉含量。为了打破产量障碍，在新的大穗型水稻植物中，育种者增加了每穗的小穗数。然而，由于劣质小穗的填充较差，具有许多小穗的穗的优势并未导致产量提高。小穗数量高会刺激乙烯的产生和淀粉合成的降级，这表明小穗数量与谷物填充之间需要权衡。下小穗的高乙烯产量抑制了编码胚乳淀粉合成酶的基因的表达。因此，乙烯可能是逆行信号，决定了小穗数和水稻穗粒灌浆之间串扰的转录组动力学，因此，降低其活性可能为解决大穗水稻粒灌浆不良的问题提供解决方案。减少下粒淀粉生物合成的这种生理联系不是遗传构成的，不能通过化学，生物技术，外科手术和等位基因操作进行修饰。对具有不同穗型结构的植物基因型的研究为选择性改善下小穗的淀粉生物合成从而通过生理途径提高谷物产量开辟了可能性。