| Rice is one of the most important crops in the world. It's a major staple food to people around world; approximately half have feed on it. It's also a monocots model plant for worldwide genomic research. Various mutants are becoming an important germplasm of rice genomic studies.A set of different mutants have been obtained through irradiation of a representative upland rice variety IRAT109 in this study. An extremely narrow leaf mutant (TB-56) and an elongated uppermost inter-node (eui) of recessive tall stalk mutant (TB-72) were selected from the fifth generation (M5) of 260 IRAT109 mutants for molecular markers locating research. The main results are as follows:1. TB-56 exhibited characteristics of dwarf plant, only 72.25cm,32.34% shorter than the parent IRAT109, delayed heading date, extremely narrow leaves, shorter panicle length and lower seed setting ratio in paddy field, but no significant differences in grain size and 100-grain weight in comparison with the wild type; leaf showing a defective vascular system and an irregular arrangement of outer parenchyma cells. For the defective vascular system affecting polar auxin transport, physiological metabolism and so on, the mutant TB-56 eventually showed dwarf plant, narrow leaves, decreased seed setting ratio;2. TB-56 has been crossed with normal plants IRAT109 and indica cultivar 9311 respectively. In TB-56/IRAT109 hybrid (F1) had normal leaves; F2 population appeared separation of leaf size (normal and narrow). Separation ratio fitted for 9:3:4 (normal/narrow/extremely narrow leaves) both in Hainan and Shanghai, in accordance with genetic model with two recessive epistatic genes by x2-test. It meant the extremely-narrow-leaf gene named enll may be epitasis effects to the narrow-leaf gene nl7. While in TB-56/9311 hybrid combination, seedling of F1 also behaved like normal plants, the segregation of F2 fitted 3:1 Mendelian segregation ratio. It indicated the narrow leaf trait is controlled by narrow-leaf gene nl7 in this population;3. The two independent F2 populations mentioned above were used for the mapping populations. The extremely-narrow-leaf gene enll was located near RM3615 on chromosome 1; the narrow-leaf gene nl7 was located between RM8245 and RM21433 on chromosome 7 with genetic distances of 1.6cM and 4.8cM, respectively;4. TB-72 exhibited characteristics of obviously increasing plant height,50.78% higher than the parent IRAT109, especially 94.35% increasing at 1st fall internode, decreased tillers number, significant differences in the grain size and the contents of chlorophyll;5. TB-72 has been crossed with the wild type IRAT109. All of F1 plants had normal plant heights; the segregation of F2 population also fitted 3:1 (χ2(0.0457)<χ2(3.84)) Mendelian segregation ratio. It indicated the eui trait is controlled by a single recessive gene;6. There is no polymorphism between the eui mutant TB-72 and IRAT109 when detected with the primers designed according to the sequences of euil and eui2 genes. We inferred the eui mutant TB-72 may carried a new gene, tentatively named as eui3. F2 population was also used for the mapping population. We screened a large set of SSR markers which were well-distributed on 12 chromosomes. Preliminary result showed a linkage between eui3 gene and the SSR marker RM528 on chromosome 6.
|
PDF Full Text Request