Isolation and applied genetic study of rice mutant genes controlling the internode elongation pattern.

水稻秆由一些伸长的节间组成，这些相对长度比受遗传控制。这种特性被称为“节间伸长模式”，它是一个重要的农艺性状，因为不仅秆长，而且这种模式的差异参与水稻植株的抗倒伏性。本研究通过图位克隆的方法检测了部分矮秆或半矮秆基因，并研究了这些基因对水稻茎秆和节间伸长的影响。结果表明：1.sd1是赤霉素生物合成酶基因的功能缺失基因，GA 20氧化酶（GA 20 ox-2）抑制了水稻的茎伸长，但节间伸长模式和穗伸长与野生型没有差异; 2.d35编码赤霉素生物合成酶基因，内贝壳杉烯氧化酶也抑制了水稻的茎伸长。而d35突变体的秆和穗上部节间相对减少的幅度较大，其抗倒效果低于sd1.3。d2和d 61分别是油菜素内酯生物合成和感知功能的丧失，这些轻度突变体选择了叶片，使秆下部节间相对减少。从而导致更高的抗倒伏性。但这些突变基因对产量的负面影响使其不足以作为一个实用的半矮秆基因。4.通过对水稻d 61的一系列研究，分离出了大麦的实用半矮秆基因'uz'。

Rice culm is consisted of some elongated internodes and these relative length ratios to culm are under genetic control. Such characteristics is so-called ‘internode elongation pattern' and it is an important agronomic trait because that not only the culm length but also the difference of such pattern are involvement in lodging resistance of rice plant. So many dwarf or semi-dwarf genes were known to regulate the culm and internode elongations.We have detected some dwarf or semi-dwarf genes by map-based cloning and examined the effects of these genes action on culm and internode elongation pattern. The results are as follows.1.sd1 which is loss of function in gibberellin biosynthetic enzyme gene, GA20 oxidase (GA20ox-2) reduced culm elongation but internode elongation pattern and panicle elongation were not different from those of wild type.2.d35 encoding the gibberellin biosynthesis enzyme gene, ent-kaurene oxidase also reduced the culm elongation. However, in d35 mutant, the upper side internodes of culm and panicle were relatively reduced more intensely and thus the effect of d35 mutation on lodging resistance was lower than that of sd1.3.d2 and d61 are a loss of function in brassinosteroid biosynthesis and perception respectively, and these mild mutations had elected leaves and reduced relatively the lower side internodes of culm, resulting the higher lodging resistance. However, the effect of these mutant genes was thought to be inadequate for the use as a practical semi-dwarf gene because of the negative effect to grain yield.4.A series of our studies in d61 of rice contributed the isolation of barley's practical semi-dwarf gene, ‘uz'.