Rice Under Salt Stress Related Physiological Traits Analysis

In this study, a linkage map consisting of250DNA markers were constructed by using247recombinant inbred lines derived from an indica-indica rice cross Zhenshan97B/Milyang46. Quantitative trait loci(QTL) conditioning physiological traits of rice under normal and salt stress conditions were determined by composite interval mapping. The main results were summaried as follows.1On the basis of the former linkage map,11markers were positioned on the gap of12rice chromosomes by SSR marker selection. At present, a linkage map consisting of250DNA markers and spanning1710.9cM was constructed in.this RIL population.2At rice seeding, plant height、root length、root dry weight and relative water content were measured respectively under normal and salt stress (0.7%NaCl). Five QTLs of these agronomic traits were indentified and mapped to chromosome1,3,6,11and12under salt stress, with6.01%～16.50%phenotypic variations. Six QTLs for these agronomic traits were indentified and mapped to chromosome1,2,3,6and11under normal conditions, with4.39%～18.50%phenotypic variations. Meanwhile, root length and relative water content were simultaneously affected by two QTLs located in the interval RM246-RG101on chromosome1and the interval RZ399-RG393on chromosome3. These chromosome regions showed tightly linked or pleiotropism, and easily affected by the environment.3Seven QTLs for parameter of chlorophyll fluorescence (F0、Fm and φPSⅡ of rice leaf were detected on the chromosome1,4,5and11under normal and salt stress, with5.98%to10.74%phenotypic variations. One QTL for Fm under normal condition and one QTL for F0under salt stress were located in the same interval CDO82-RG413on chromosome5.The result indicated that this chromosome region had pleiotropism, and could affect Fm and Fo.4Under salt stress, three QTLs for proline content, ascorbic acid content and protein content were detected to have significant additive effects. One QTL for proline content and one QTL for ascorbic acid content were located in the interval RG81-S13126and RM309-RG543both on chromosome12respectively, the phenotypic variations were9.09%and7.97%. One QTL for protein content was located in the interval RM237-RM246on chromosome1, and the phenotypic variations was13.14%.On comparison with the detected QTLs for different traits in Zhenshan97B/Milyang46RIL populations, it was found that some QTLs conditioning different traits often located in the same intervals. For example, the QTLs for root dry weight, starch braching enzyme activities at10d after flowering, number of panicles per plant and total number of spikelets per plant were detected to be located in the interval RZ588-RG138on chromosome6. Then, these different agronomic and physiological traits were mapped in the same molecular linkage map to construct a functional map. We could intergrate the agronomy and physiology research by molecular markers in the functional map and identify the key or controling loci for the expression of quantitative traits. The genetic relationship between agronomic and physiological traits could be analysed.