下节间直径（UID）是与小麦穗部发育和丰产性相关的重要形态性状。而我们对其遗传基础的了解知之甚少。本文在5个小麦重组自交系（RIL）群体中利用高密度遗传图谱鉴定了控制UID的数量性状位点（QTL）。在5个RIL群体中共检测到25个UID QTL，分别位于1A、1D（3个QTL）、2B（2）、2D（3）、3B、3D、4A、4B（3）、4D、5A（5）、5B（2）、6B、7D染色体上。其中，5个主效且稳定的QTL：QUid.sau-2CN-1D.1、QUid.sau-2SY-1D、QUid.sau-QZ-2D、QUid.sau-SC-3D和QUid.sau-AS-4B分别在5个RIL群体的多个环境中检测到。QUid.sau-2CN-1D、QUid.sau-2SY-1D与QUid.sau-SC-3D 为三个新的UID 位点。我们进一步开发了与主效QTL紧密连锁的竞争性等位基因特异性PCR（KASP）标记，用于构建近等基因系（NILs）。此外，我们还在主效QTL的物理区间内预测了候选基因，这些候选基因大多与植物发育和水分运输有关。以中国春为参考基因组，我们对定位到的主效QTL的物理区间进行了比较，结果表明，QUid.sau-2CN-1D.1和QUid.sau-2SY-1D可能是等位基因，进一步证实了它们的真实性和有效性。本文也对UID与其他农艺性状的相关关系及UID的大小进行了讨论。总体而言，我们的研究结果剖析了小麦UID的潜在遗传基础，为这些QTL的进一步精细定位和图位克隆奠定了基础。

Starch is the major carbohydrate in oat (Avena sativa L.) and starch formation requires the coordinated actions of several synthesis enzymes. In this study, the granule morphology, composition and physicochemical properties of oat starch, as well as the expressions of starch synthesis genes were investigated during oat endosperm development. Under the scanning electron microscopy (SEM), we observed that the unique compound granules were developed in oat endosperms at 10 days post anthesis (DPA) and then fragmented into irregular or polygonal simple granules from 12 DPA until seed maturity. The amylose content, branch chain length of degree of polymerization (DP=13–24), gelatinization temperature and percentage of retrogradation were gradually increased during the endosperm development; whereas the distribution of short chains (DP=6–12) were gradually decreased. The relative expressions of 4 classes of 13 starch synthesis genes characterized in this study indicated that three expression pattern groups were significantly different among gene classes as well as among varied isoforms, in which the first group of starch synthesis genes may play a key role on the initiation of starch synthesis in oat endosperms.