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 relationships among potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) contents in milled rice (Oryza stavia L.) of 274 genotypes and the relationships between these mineral element contents and other rice quality traits including 3 cooking quality traits, 17 amino acid contents, and protein content were investigated. The results showed that there were significant correlations among most of mineral element contents. Mg, Fe, and Mn contents were significantly correlated with most of the other mineral element contents, while Cu content had significantly negative associations with the K and Mg contents of rice. The relationships between mineral element contents and cooking quality traits showed that gel consistency (GC) was significantly correlated with K, Cu, and Mn contents of rice. Amylose content (AC) was significantly associated with K, Na, Mg, Cu, and Mn contents. The alkali spreading value (ASV) had closely positive relationships with Ca, Mg, and Mn contents. In addition, 8 mineral element contents had obvious correlations with different amino acid contents. Mg, Ca, and Zn contents were significantly correlated with most of the 17 amino acid contents, but Na content did not correlate with amino acid contents except aspartic acid of rice. Furthermore, significant associations were found between protein content and Na, Mg, Zn, Cu, or Mn content. Six principal components were extracted to explain 84.50% of the total variances and contained the information provided by the original 29 variables according to the principal component analysis.

Using a newly developed mapping model with endosperm and maternal main effects and QTL environment interaction effects on quantitative quality traits of seed in cereal crops, the investigation of quantitative trait loci (QTLs) located on triploid endosperm and diploid maternal plant genomes for protein content and lysine content of rice grain under different environments was carried out with two backcross (BC1F1 and BC2F1) populations from a set of 241 recombinant inbred lines derived from an elite hybrid cross of Shanyou 63. The results showed a total of 18 QTLs to be associated with these two quality traits of rice, which were subsequently mapped on chromosomes 2, 3, 5, 6, 7, 10, 11 and 12. Three of these QTLs were also found havingQTL environment interaction effects. Therefore, the genetic main effects from QTLs located on chromosomes in endosperm and maternal plant genomes and their QTL environment interaction effects in different environments were all important for protein and lysine contents in rice. The influence of environmental factors on the expression of some QTLs located in different genetic systems could not be ignored for both nutrient quality traits.

The floral organs are formed from floral meristem with a regular initiation pattern in angiosperm species. Flowers of naked seed rice (nsr) were characterized by the overdeveloped lemma and palea, the transformation of lodicules to palea-/lemma-like organs, the decreased number of stamens and occasionally extra pistils. Some nsr spikelets contained additional floral organs of four whorls and/or abnormal internal florets. The floral primordium of nsr spikelet is differentiated under an irregular pattern and an incomplete determination. And molecular analysis indicated that nsr was a novel homeotic mutation in OsMADS1, suggesting that OsMADS1 played a distinct role in regulating the differentiation pattern of floral primordium and in conferring the determination of flower meristem. The gain-of-function of OsMADS1 transgenic lines presented the transformation of outer glumes to lemma-/ palea-like organs and no changes in length of lemma and palea, but loss-of-function of OsMADS1 transgenic lines displayed the overdeveloped lemma and palea. Both findings revealed that OsMADS1 played a role in specifying lemma and palea and acted as a repressor of overdevelopment of lemma and palea. Moreover, it was indicated that OsMADS1 upregulated the transcript level of AP3 homologue OsMADS16, using real-time PCR analysis on gain- and loss-of-function of Os- MADS1 transgenic lines.

Near-infrared reflectance spectroscopy was used to address the genetic potential for 990 rice lines for 26 quality traits. The predicted genotypic values for quality traits were calculated using the Mahalanobis distance method and used to measure the genetic similarities among rice varieties. To make the core collection, Manhalanobis distance was employed to calculate the genetic distance among the accessions, and the hierarchical clustering method was used to group the accessions, accompanied by sampling method under the pre-concerted sample proportion (i.e., the ratio of accessions in the core collection to those in the initial population). In this experiment, 24 core collections were developed by using eight hierarchical clustering methods, combined with random, preferred and deviation sampling at a sample proportion of 15% (i.e., 149 for the 15% core collection). These core collections were compared with others constructed at sample proportions of 10% and 20% (i.e., 99 for the 10% core and 198 for the 20% core, respectively). In addition, a trend at increasing sample proportion from 5% to 60% showed that core collection development could be achieved at a sample proportion range of 10–25%. Further results revealed that deviation sampling strategy in combination with the single linkage method retained the greatest degree of genetic diversity of the initial collection. The core collection developed using a sample size of 15% retained the highest degree of diversity, and was stable for all the cluster methods and, hence, the best in developing a core collection of rice quality traits.