[Mapping and cloning of GAD1-2 for long awn using CSSLs in rice (Oryza sativa L.)].

Rice is an important food crop in the world. The awn may protect rice seeds from being cut by birds, which is important in rice domestication, survival and diffusion. However, the characteristic of awn is gradually washed out during rice domestication and artificial selection. Mapping and cloning of rice awn genes is the basis of studying the genetic mechanism of awn domestication. In this study, 146 chromosome segment substitution lines (CSSLs) derived from DongNanHui 810/ZhangPu wild rice with DongNanHui 810 as the recurrent parent were used to analyze the quantitative trait loci (QTL) controlling the long awn of rice. The results showed that four CSSLs contained one QTL for the long awn. Using substitution mapping, the GAD1-2 gene was mapped between two markers (Ind8-10 and RM4936) on chromosome 8, with a genetic distance of about 4.75 Mb. Using the dominant individuals of segregating populations, the GAD1-2 gene was eventually located between two Indel markers, with a physical distance of about 27 kb, which contained only two candidate genes Os08g0485500 and Os08g0485400. Sequencing analysis showed that Os08g0485500 was the candidate gene of GAD1-2. Further analysis showed that there were six bases missing in the conservative ORF region, resulting in the absence of serine and cysteine that led to the long awn of the four CSSLs. The GAD1 gene was also cloned in this position, suggesting that GAD1-2 and GAD1 were allelic. This study laid a foundation for further understanding of the genetic regulation mechanism and genetic evolution of the awn gene in rice.

[Morphological characteristics and gene mapping of a palea degradation(pd2) mutant in rice].

The yield and quality of rice are directly impacted by floral organ development in rice. Understanding of the floral development mechanism will be useful in genetic improvement of yield and quality. In this study, a rice mutant palea degradation 2 (pd2) in an indica cultivar '8PW33' was obtained after 60Co γ-ray treatment. Analysis of the mutant showed that, compared to the wild type, plant height, total grain number per panicle, and sword leaf width were significantly increased, but the seed setting rate were significantly decreased. The florets of the mutant exhibited degraded palea and sickle-shaped tortuous lemma. Detail examination using scanning electron microscopy revealed that when epidermis of the vane and lemma were normal, epidermis of the palea were arranged tightly, which might result from degraded palea. Genetic analysis supported that this mutation phenotype was controlled by a single recessive gene. Polymorphic analysis of simple sequence repeat markers demonstrated that PD2 gene is located on chromosome 9. With a larger mapping population and more indel markers, we further mapped PD2 gene between 2 indel markers with a physical region of about 82 kb. Within this region, there is a cloned gene REP1 known to control rice palea development. By comparing the DNA sequences of REP1 from pd2 and 8PW33, in combination with the results of phenotypic analysis, we concluded that PD2 is an allele of REP1.

[Study of the pH sensitive polymer].

A pH sensitive polymer was prepared by copolymerization of methacrylic acid as monomer, diethylene glycol dimethacrylate as cross-linking reagent, heptane as porogen, and fluorescent dye eosin as indicator. The factors of influence on the preparation, and the character of the pH sensitive polymer for pH were studied. The maximal emission wavelength of eosin was red shifted in the polymer than in solution, the apparent Ka largened, and the dissociation equilibrium of indicator was shifted to acidity direction, because the polarity of polymer diminished. Under the optimal condition, the calibration curve of the pH sensitive polymer covered the range of pH 0-3.0 with good reproduction and reversibility.