A dwarf mutant, dwarf 62 (d62), was isolated from rice cultivar 93-11 by mutagenesis with c-rays. Under normal growth conditions, the mutant had multiple abnormal phenotypes, such as dwarfism, wide and dark-green leaf blades, reduced tiller numbers, late and asynchronous heading, short roots, partial male sterility, etc. Genetic analysis indicated that the abnormal phenotypes were controlled by the recessive mutation of a single nuclear gene. Using molecular markers, the D62 gene was fine mapped in 131-kb region at the short arm of chromosome 6. Positional cloning of D62 gene revealed that it was the same locus as DLT/OsGRAS-32, which encodes a member of the GRAS family. In previous studies, the DLT/OsGRAS-32 is confirmed to play positive roles in brassinosteroid (BR) signaling. Sequence analysis showed that the d62 carried a 2-bp deletion in ORF region of D62 gene which led to a loss-of-function mutation. The function of D62 gene was confirmed by complementation experiment. RT-PCR analysis and promoter activity analysis showed that the D62 gene expressed in all tested tissues including roots, stems, leaves and panicles of rice plant. The d62 mutant exhibited decreased activity of a-amylase in endosperm and reduced content of endogenous GA1. The expression levels of gibberellin (GA) biosynthetic genes including OsCPS1,

利用7射线和EMs溶液诱变处理籼稻“93lJ”种子，经过M：筛选和M,重复鉴定，分别获得465份和210份（共675份）叶、茎、穗和根等性状变异的突变体，突变频率为5．62％。7射线诱变群体的变异范围要大于EMs诱变群体，突变频率也较高，但紫色叶鞘和叶片类病斑等少数突变类型只在EMS诱变群体中出现。新构建的突变体库将有助于进一步开展水稻功能基因的研究。

The analysis of temporal patterns of genetic effects for thousand-seed weight (TSW) and oil content (OC) in rapeseed was conducted at five different seed development times using unconditional and conditional genetic models for diploid seed quantitative traits. Phenotypic means among generations and seed development times in 2 different years revealed considerable variation for both TSW and OC. The expression of genes from diploid embryo, cytoplasmic and maternal plant genetic systems were all found to be important for the F1 generation, with maternal effects playing a more prominent role for both traits at most times. The conditional analysis indicated that the stage-specific gene expression from the maternal plant was influenced by environment. Higher magnitudes of additive and cytoplasmic effects were observed for both traits. Narrow-sense heritability was high for both traits at all developmental times with maternal heritability being more prominent at most times. Genetic correlations between TSW and OC were mostly negative over developmental times.

Following the sequencing of rice genome, the functional analysis of unidentified genes is gaining wide importance. For these, mutant isolation is one of the effective ways to isolate and clone the target genes and analyze their functions. For finding the various mutants in the same genetic background, seeds of Oryza sativa cv. Nipponbare were treated with ethyl methane sulphonate (EMS). A total of 1056 mutants for five categories were screened in M2 generation with the seedling frequency of 26.29‰ at three-leaf stage, but only 264 mutants were verified in M3 generation with a frequency of 6.57‰. Among the mutants verified in M3 generation, the frequency of leaf mutation was highest (2.22‰), followed by seedling height (1.74‰) and abiotic stress tolerance mutant (1.47‰). Nineteen characteristic mutations, including a big group of abiotic stress tolerant mutants such as herbicide resistant, salt tolerance and drought tolerance were identified at this stage. By observation of rice growth characteristics at different developmental stages, another 220 mutants have been isolated and verified in the M3 generation with the mutant frequency of 53.9‰ covering about 28 mutant taits. Among those identified, the highest frequency were obtained for appearance of brown rice mutant with 18.37‰ followed by panicle mutant with 13.47‰ and grain mutants with 9.06‰, respectively. All the mutants screened above were suitable for gene function analysis and for utilization in agronomy.

The potential of near-infrared reflectance spectroscopy (NIRS) for simultaneous analysis of grain weight (mg), brown rice weight (mg) and milled rice amylose content (AC, %) in single rice grains was studied. Calibration equations were developed using 474 single grain samples, scanned as both rice grain and brown rice. An independent set containing 90 F2 generation grains was used to validate the equations. In general, equations developed using the first derivative resulted in superior calibration and validation statistics compared with the second derivative and those developed using brown rice were superior to those developed from the rice grain. Fitting equations were developed and monitored with an external validation set. The standard error of prediction (corrected for bias) SEP(C) for AC, brown rice weight and rice grain weight for equations developed using brown rice were 2.82, 1.09 and 1.30, with corresponding coefficient of determinations (r2) of 0.85, 0.71 and 0.67, and SEP(C)/S.D. of 0.39, 0.57 and 0.59, respectively. It was demonstrated that NIRS provides a convenient way to screen single intact grains. This will be advantageous in early generation selection in rice breeding programs.