Rice Physiology Research Sub-Team, Hokuriku Research Center, National Agricultural Research Center, National Agriculture and Food Research Organization, 1-2-1, Inada, Joetsu, Niigata, 943-0193, Japan.
Theor Appl Genet. 2010 Mar;120(5):875-93. doi: 10.1007/s00122-009-1218-8. Epub 2009 Nov 22.
The quantitative trait locus controlling the number of primary rachis branches (PRBs) in rice was identified using backcrossed inbred lines of Sasanishiki/Habataki//Sasanishiki///Sasanishiki. The resultant gene was ABERRANT PANICLE ORGANIZATION 1 (APO1). Habataki-genotype segregated reciprocal recombinant lines for the APO1 locus increased both the number of PRB (12-13%) and the number of grains per panicle (9-12%), which increased the grain yield per plant (5-7%). Further recombination dividing this region revealed that different alleles regulated the number of PRB and the number of grains per panicle. The PRB1 allele, which includes the APO1 open reading frame (ORF) and the proximal promoter region, controlled only the number of PRB but not the number of grains per panicle. In contrast, the HI1 allele, which includes only the distal promoter region, increased the grain yield and harvest index in Habataki-genotype plants, nevertheless, the ORF expressed was Sasanishiki type. It also increased the number of large vascular bundles in the peduncle. APO1 expression occurred not only in developing panicles but also in the developing vascular bundle systems. In addition, Habataki plants displayed increased APO1 expression in comparison to Sasanishiki plants. It suggests that APO1 enhances the formation of vascular bundle systems which, consequently, promote carbohydrate translocation to panicles. The HI1 allele is suggested to regulate the amount of APO1 expression, and thereby control the development of vascular bundle systems. These findings may be useful to improve grain yield as well as quality through the improvement of translocation efficiency.
利用 backcrossed 自交系 Sasanishiki/Habataki//Sasanishiki///Sasanishiki 鉴定了控制水稻初级穗轴分支（PRB）数量的数量性状位点。所得基因是异常穗组织基因 1（APO1）。Habataki 基因型分离出 APO1 基因座的相互重组系增加了 PRB 的数量（12-13%）和每穗粒数（9-12%），从而增加了每株植物的粒产量（5-7%）。进一步的重组将该区域划分，发现不同的等位基因调控 PRB 的数量和每穗粒数。包含 APO1 开放阅读框（ORF）和近端启动子区的 PRB1 等位基因仅控制 PRB 的数量，而不控制每穗粒数。相比之下，仅包含远端启动子区的 HI1 等位基因增加了 Habataki 基因型植物的粒产量和收获指数，然而，表达的 ORF 是 Sasanishiki 型。它还增加了花梗中大维管束的数量。APO1 表达不仅发生在发育中的穗中，也发生在发育中的维管束系统中。此外，与 Sasanishiki 植物相比，Habataki 植物显示出 APO1 表达增加。这表明 APO1 增强了维管束系统的形成，从而促进了碳水化合物向穗的转移。HI1 等位基因被认为调节 APO1 表达的量，从而控制维管束系统的发育。这些发现可能有助于通过提高转运效率来提高粒产量和品质。
