Optimizing wheat grain yield: Effects of Rht (gibberellin-insensitive) dwarfing genes
Optimizing wheat grain yield: Effects of Rht (gibberellin-insensitive) dwarfing genes
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DOI：
10.1017/s0021859696003942
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发表时间：
1997-02-01
影响因子：
2
通讯作者：
Gale, MD
中科院分区：
文献类型：
--
作者：
Flintham, JE;Borner, A;Gale, MD
利用赤霉素不敏感矮秆基因Rht-Blb、Rht-Dlb和Rht-Blc的不同组合，对四套六倍体小麦（Triticum aestivum L.）在英格兰东部和德国中部进行的一系列产量试验中，在所有四个品种背景中，Rht-Blb和Rht-Dlb的效果相似（株高分别约为高对照的86%和83%），并且在组合中将株高降低至c。百分之五十八Rht-Blc等位基因导致更严重的侏儒症（c. 50%），并且当与Rht-Dlb组合时，将植株高度进一步降低至c.来自试验的数据与高度/产量关系的模型一致，在该模型中，Rht等位基因对产量的多效性效应可以从它们的主要功能推断出来：对赤霉素的不敏感性限制了茎伸长生长，减少了对该器官的同化物需求，并将其转移到发育中的穗（其本身并不矮化）。收获指数的增加与株高和总茎产量之间的曲线关系之间的净平衡导致中等株高的最佳籽粒产量。在平均籽粒产量为200 - 760 g m（-2）的几次试验中，矮株的产量优势明显优于高株对照。在不同遗传背景下，Rht等位基因对产量的最佳贡献取决于背景品种的株高，即高基因型需要更多的Rht等位基因才能获得最大的潜在产量，穗粒数的增加是由于Rht基因多效性所致。由此推断，每穗粒数受花前同化物供应的限制。粒数的增加与平均每粒重的减少，根据不同的严重程度的矮化和品种背景，使每穗籽粒产量的净效应有时是积极的，有时是消极的，有时是中性的不同的Rht/品种组合。
Four sets of near-isogenic lines carrying different combinations of the alleles Rht-Blb, Rht-Dlb and Rht-Blc for gibberellin-insensitive dwarfism in hexaploid wheat (Triticum aestivum L.) were compared with tall controls in a series of yield trials in eastern England and central Germany. In all four varietal backgrounds the effects of Rht-Blb and Rht-Dlb were similar (plant height approximate to 86 and 83 % of tall controls respectively) and in combination reduced plant height to c. 58 %. The Rht-Blc allele caused more severe dwarfism (c. 50 %) and, when combined with Rht-Dlb, reduced plant height still further to c. 41 %.Data from the trials were consistent with a model for height/yield relationships in which the pleiotropic effects of the Rht alleles on yield can be inferred from their primary function: insensitivity to gibberellin limits stem extension growth, decreasing assimilate demand for this organ and diverting it to the developing ear (which is not itself dwarfed). The net balance between the resulting increase in harvest index and the curvilinear relationship observed between plant height and total shoot yield results in optimum grain yields at intermediate plant heights.Yield advantages of shorter plants over tall controls were evident over several trials with mean grain yields ranging from 200 to 760 g m(-2). The optimum plant height for yield improvement in different genetic backgrounds was achieved by different Rht alleles according to the background varietal height, such that intrinsically taller genotypes required more potent Rht alleles to achieve maximum potential grain yield.Ear yield components showed increases in grain number due to Rht pleiotropy, from which it is inferred that the number of grains per ear is limited by supply of assimilates pre-anthesis. Increases in grain number were associated with decreases in mean weight per grain which varied according to severity of dwarfism and varietal background, so that the net effect on grain yield per ear was sometimes positive, sometimes negative, and sometimes neutral in different Rht/variety combinations.