Received  14 August, 2017    Accepted  20 December, 2017

In this study we report the results of a decade-long breeding program for japonica super rice made by Nanjing Branch of Chinese National Center for Rice Improvement in Jiangsu Academy of Agricultural Sciences.  We concluded that selection of parents with good comprehensive traits and complementary advantages and disadvantages of both parents in the hybrid combination, and early selection of high heritability traits in earlier segregating generations could significantly improve the breeding efficiency.  The use of closely-linked functional markers in pyramiding of multiple genes could greatly increase breeding efficiency, avoiding time-consuming and laborious steps that were used in traditional breeding program.  It is also important to coordinate the yield components with variety characteristics such as yield stability, wide adaptability, lodging resistance, and an attractive grain appearance during late growth stage of rice.

To establish a suitable and effective protocol of protein extraction for two-dimensional gel electrophoresis (2-DE) analysis in kenaf leaf tissues, three extraction methods (trichloroacetic acid/acetone, urea/thiourea, and phenol extraction methods) were applied to the extraction of kenaf leaf protein. The results were compared in regard to protein extraction efficiency, sodiumdodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and 2-DE gels. Furthermore, the 2-DE system was optimized for four aspects: the pH range of IPG (immobilized pH gradient) stripes, sampling methods, sample volumes, and concentration of polyacrylamide gels. The data presented showed that the phenol extraction method is the best method to perform 2-DE analysis of kenaf leaf protein. The protein extracted from phenol extraction method reached the purity of (26.40±0.859)%, showed (25.67±1.53) protein bands in one dimension SDS-PAGE gels, and (1 374±54.44) protein spots on 2-DE gels. The research also indicates that kenaf leaf protein spots were distributed mainly within the pH range of 4-8. More clear background with a better distribution effect and many protein spots could be obtained on 2-DE gels under the conditions of active rehydration loading, 24 cm IPG strips (linear pH gradient of 4-7), 1.4 mg samples, and 12% SDS-PAGE gels.