The Construction Of Mutant Population For Variety "9311" And Analysis For Some Mutant Traits In Rice (Oryza Sativa L.)

Rice (Oryza sativa L.) has become a model plant for the study of the cereal genomes in the last decade. Recent completion of the draft sequence for the rice genome has resulted in an explosion of information on rice genes. The challenge for the post-sequencing era is to identify the biological functions for these genes. Of all the approaches used for discovering the gene function, the more useful one is based on a saturated mutagenesis population, which is a straight and efficient way to understand the role of all the genes. Among the methods for constructing the mutant liberary, the physical and chemical mutangenesis might be the main methods, which were simple and effective. They can be used to produce a large number of mutants with high mutagenesis frequence in a short period and to establish a mutant population. The purpose of the present experiment is to screen different plant morphogenesis mutants and rice quality mutants by treating the seeds of the indica rice variety 9311 withγ-rays, of which has been completely sequenced in the whole genome. The mutant library created will be helpful for gene identity and gene functional analysis.For plant traits, 205 mutants with agronomic traits were identified and the total mutants frequence were 6.82% in M₂. Some mutants with the variations of leaf, stalk, panicle or root traits were found in progenies. Among these traits, the mutant frequence of sterilite, dwarf or stem-number was higher than that of growing-period or non-awn; while the frequences of plant type, leaf-style, panicle and hull were all low. The mutants of seedling were screened and 417 mutants with the variations of albino, albino-transfer-green, yellows, leaf-rolling, sheath, tiny-leaf-rolling, dwarf, short roots, no lateral root, long seminal root, gravity insensitive of root, salt-resistance, drought-resistance, herbicide-resistance and cold-resistance were found in 42852 M₂ plants. Among the mutants, the albino mutant frequence was higher than that for other traits. The frequence of short root mutants was higher than that for other root mutants. For the rice quality mutants, 160 mutants with rice cooking or nutrient quality traits were found in M₂ population and the mutant frequence was 5.32%. Among them, increased or reduced content variations of the quality traits could be found except for threonine of rice. The frequency of alkali spreading value or phenylalanine, which the frequency was 0.17% or 0.31 % of total M₂ plants, was lower than that for amylase, lysine, threonine or protein content, which the frequency was 0.54%, 0.50%, 0.50% or 0.63% of total M₂ plants, respectively. The range of amylase content was higher and the variation range was over 24 percent, mutants for protein content of rice was following. The mutant library created for indica rice variety 9311, which include different plant morphogenesis mutants and rice quality mutants, will be helpful for the research in rice founctional genomics and the relationship among the cereal genome.Anatomical observation revealed that the ovary number of the multi-ovary mutant variated from 1 to 6 or more at the flower period. But less than 3 ovaries could be further developped to seeds and other overies were all degenerated. The performance of F₁ showed that the multi-ovary trait might be a recessive trait. The leaves of CK (wild type) were rough and the thorns and flosses could be found through anatomical observation. But these thorns and flosses could not be found on glabrous leaf mutant. The leaves of the narrow-leaf mutant were palpably narrow than those of CK "9311". Cytological observation showed that the space number of nervure for the narrow-leaf mutant was two, just only equal to half of CK. The leaves of rolled-leaf mutant were observably rolled about one circle and the nervure of the mutant's leaf was also curved.. The leaves of wrinkled-leaf mutant were markedly wrinkled, transverse section revealed that the cell of the wrinked part ranked close. The leaves of lesion mimic mutant were normal except the brown lesion, which was enchased in the cells and made the leaf rigid and crisp, and the spaces distributing in nervure were also different from those of CK. The chlorophyll and net photosynthtic rates of some leaf mutants revealed that the net photosynthtic rates was not depended on the total chlorophyll amount. The net photosynthtic rate of mutat with deep green degree color was larger than that of mutants with green or tiny green.