The isolation and characterization of genes that control tillering in rice

在水稻栽培中，分蘖的遗传控制一直是重要的。本研究旨在阐明哪些基因参与了栽培稻分蘖的自然变异。在玉米中，已知tb1（toesinte branched 1）是控制分蘖的基因，包括其天然变体。为了这个研究项目，我瞄准了这个基因的水稻直系同源物。以Asominori水稻× IR 24水稻重组自交系为作图群体，对玉米tb1探针进行了比较定位。tb1探针定位在水稻3号染色体上标记C1351附近。由于水稻染色体的这一区域与玉米1号染色体长臂tb1所在的位置同线，因此定位的基因被认为是玉米tb1基因的水稻直向同源物。共分离分析表明，水稻tb1基因与一个分蘖旺盛的突变体的表型紧密连锁。这一事实，结合tb1功能丧失突变体大量分蘖的事实，表明水稻tb1像玉米tb1一样控制分蘖。由于已报道的分蘖数QTL之一位于水稻tb1位点附近，该基因极有可能是引起分蘖自然变异的原因。

In rice cultivation, the genetic control of the tillering has been important. The present research project was conducted to elucidate what genes are involved in the natural variant in tillering in cultivated rice. In maize, the tb1 (toesinte branched 1) has been known as a gene that control the tillering including its natural variants. I targeted the rice ortholog of this gene for this research project. Using Asominori rice x IR24 rice recombinant inbred lines as a mappin population the comparative mapping of the maize tb1 probe was performed. The tb1 probe was mapped near the marker C1351 in the rice chromosome 3. Since this region of rice chromosomes is syntenic with the long arm of the maize chromosome 1 where the tb1 is located, the mapped gene is considered to be the rice ortholog of the maize tb1 gene. A co-segregation analysis revealed that this rice tb1 gene is tightly linked to the phenotype of a mutant that tillers profusely. This fact, in combination with the fact that the loss-of-function mutant of tb1 tillers profusely, suggests that the rice tb1 controls tillering like maize tb1. Since one of the reported QTLs for tiller number is located near the locus of the rice tb1, it is highly probable that this gene is a cause of natural variant of tillering.