Genetic Analysis Of Grain Weight And Toward Map-based Cloning Of A Major Gene In Rice

IAs an important determinant factor of rice appearance quality, grain length also has close relationship with thousand-grain weight. Cloning major genes controlling grain length can lead to uncovering molecular mechanism of floret (fruit) development, thus bringing facility to yield improvement and quality enhancement. In this research, a major grain length controlling gene, named 1k-4(t), was genetically analysed and fine-mapped. The main results were as follows:1. Though background investigation of minute-grain Shuhui 527 near-isogenetic lines with 35 polymorphic SSR marker and 11 RAPD markers, we found that the near-isogenetic lines had a genetic frequency of 0. 0086 or 0.0091 on the SSR locus or RAPD locus of Xiaoli genetic background. The result indicate that the genetic background of the minute gene donor parent had been largely screeded away during construction of near-isogenetic lines, which had a genetic background very near to shuhui 527.2. Though observing grain weight growth of caryopsis and photosynthesis rate analysis, the caryopsis of short grain phenotype of 1k-4(t) was found slowing growth 9 days after anthesis, earlier than that of the Shuhui527. 15 days after anthesis, the caryopsis growth of the short grain phenotype almost stopped; at the same time, its photosynthesis rate was found much lower than that of Shuhui527.3. The distribution frequency result of agronomic traits in F₂ and BC₂F₂ generations XiaoLi/Shuhui 527 suggested that only one major gene that was accounted for the grain length variation (the segregation ratio was in accordance with the classic ratio of 3:1). To get a clearer...