Search

Japonica rice variety Kanto 194 as the donor of resistance gene Stv-bi and low-amylose content gene Wx-mq was used to improve the resistance and eating quality of Wuyujing 3 by the breeding strategy of backcross. In continuous backcross and selfcross generations, the related molecular markers with Stv-bi and Wx-mq genes were utilized for genotypic detection by associated with resistance identification of rice stripe disease and agronomic traits selection. Finally, 10 improved lines with homozygous genotype Stv-biStv-biWx-mqWx-mq were obtained from BC3F4 generation. The results of comparative analysis indicated that most characters of these lines were consistent with those of recipient parent Wuyujing 3, except for the improved resistance, appearance and eating quality. By evaluation of the comprehensive performance of them, two excellent lines K01 and K04 were selected for further experiments.

GW2 is an important gene that regulates grain width and weight. We used cDNA clone to obtain the sequences of GW2 from large- and small-grained rice varieties, TD70 and Kasalath, respectively. Then, we developed a dCAPS (derived cleaved amplified polymorphic sequence) marker on the basis of the sequence difference between functional and nonfunctional GW2 genes to analyze the genotypes and phenotypes of recombinant inbred lines. Results showed that the sequence of GW2TD70 had a single nucleotide deletion at site 316 that generates a termination codon. This codon terminated the GW2 protein in advance. By contrast, the sequence of GW2Kasalath encoded an intact protein. A novel dCAPS marker was designed in accordance with a base A deletion at site 316 of the sequence. After the PCR product was digested by ApoI, TD70 showed 21 and 30 bp fragments, and Kasalath showed a 51 bp fragment. Up to 82 lines contained GW2TD70, and 158 lines contained GW2Kasalath. The lines that contained TD70 alleles displayed substantial increases in width and 1000-grain weight. This result suggested that GW2 played a critical role in rice breeding.

In order to develop a variety of japonica rice with good eating quality suitable for planting in Jiangsu Province, the genetic basis of high quality, disease resistance and high yield japonica rice varieties in Jiangsu Province was systematically studied. The relationship among different rice qualities of cooking, nutrition, and eating was studied by association analysis. It was clear that amylose content was the key factor affecting eating quality. The semi waxy rice with amylose content of 10%~14% has bright surface, soft texture, and elasticity, combining the softness of glutinous rice and the elasticity of japonica rice. The cold rice is not hard, and the taste is excellent. It meets the taste requirements of people in Yangtze River Delta region who like to eat soft fragrant japonica rice. The semi waxy japonica rice variety "Kantou 194" with a low expression of amylose content gene Wx mp and an amylose content of about 10% was selected as the core germplasm for improving eating quality. Pyramiding breeding of japonica rice variety with good eating quality, disease resistance and high yield was carried out by examining the development of Wx mp gene molecular markers and the use of closely linked molecular markers with disease resistance and high yield genes. A series of new japonica rice varieties with good taste such as Nanjing 46, Nanjing 5055, Nanjing 9108, and Nanjing 5718, suitable for different rice areas of Jiangsu Province, have been bred and approved by Jiangsu Provincial Variety Approval Committee. The layout of japonica rice varieties with good taste covering different rice areas in Jiangsu Province has been formed. These varieties have been planted with an accumulated area of more than 5.3 million hectares, which has effectively promoted the development of high quality rice industry in Jiangsu Province and its surrounding areas, and made important contributions to the structural adjustment of the supply side of rice industry, improving quality and efficiency, and ensuring food security.

Browning phenomena are ubiquitous in plant cell cultures that severely hamper scientific research and widespread application of plant cell cultures. Up to now, this problem still has not been well controlled due to the unclear browning mechanisms in plant cell cultures. In this paper, the mechanisms were investigated using two typical materials with severe browning phenomena, Taxus chinensis and Glycyrrhiza inflata cells. Our results illustrated that the browning is attributed to a physiological enzymatic reaction, and phenolic biosynthesis regulated by sugar plays a decisive role in the browning. Furthermore, to confirm the specific compounds which participate in the enzymatic browning reaction, transcriptional profile and metabolites of T. chinensis cells, and UV scanning and high-performance liquid chromatography-mass spectrometry (HPLC-MS) profile of the browning compounds extracted from the brown-turned medium were analyzed, flavonoids derived from phenylpropanoid pathway were found to be the main compounds, and myricetin and quercetin were deduced to be the main substrates of the browning reaction. Inhibition of flavonoid biosynthesis can prevent the browning occurrence, and the browning is effectively controlled via blocking flavonoid biosynthesis by gibberellic acid (GA3 ) as an inhibitor, which further confirms that flavonoids mainly contribute to the browning. On the basis above, a model elucidating enzymatic browning mechanisms in plant cell cultures was put forward, and effective control approaches were presented., (© 2015 Scandinavian Plant Physiology Society.)