Genetic Analysis Of Heading Date And Mapping Of A Heading Date QTL In Rice

Heading date is one of the important agronomic traits in rice, which determine the suitability of geographical and seasonal, and it closely related to yield of rice. In this study, two accession of Guangxi common wild rice{Oryza rufipogon Griff.) DP30 and DP 15 were used as donor parent, and an indica rice varieties 9311 was used as receptor parent, two set of rice chromosome segment substitution lines has been established, from which we characterized two early heading line CSSL13 and CSSL26. Genetic analysis of early heading characters and mapped the QTL of heading date in CSSL13, the following results were obtained:(1)We obtained 408 molecular markers which have polymorphic between DP30 and 9311 and 425 molecular markers which have polymorphic between DP 15 and 9311 from 1663 molecular markers. These marks covered the 12 chromosomes. We detected substitution segment from donor parent in 12 chromosomes of CSSL13 and CSSL26 through these polymorphic molecular markers. There were five substitution segment from DP30 in 12 chromosomes of CSSL13, and six substitution segment from DP 15 in 12 chromosomes of CSSL26.(2) The heading date of CSSL13, CSSL26 and 9311 were investigated: Compared to 9311, the heading date of CSSL13 advance about 14 days, and the heading date of CSSL26 advanced about 9 days. Genetic analysis revealed:In a BC5F2 segregating population derived from CSSL13 and 9311, the ratio of early heading plants to late heading plants showed a 3:1 frequency distribution. In a BC5F2 segregating population derived from CSSL26 and 9311, the ratio of early heading plants to late heading plants showed a 3:1 frequency distribution. These results suggested that the early heading date phenotype in CSSL13 and CSSL26 was controlled by a pair of dominant gene.(3) In this study, We adopted the method of progeny test, The plants with stable inheritance of heading date in F2 population was obtained through the F2 population derived into F2:3 population. The qHD8.3 locus was further narrowed down to approximately 1.6 Mb DNA fragment defined by molecular markers M07 and M13 by using 76 early heading lines and 52 late heading lines which stable inheritance of heading date. The qHD8.3 locus is a new QTL of heading date.(4) Analysis of light & temperature characteristic showed:The qHD8.3 is a QTL which insensitive to light and temperature.(5) Four agronomic traits that include tillers, plant height, grains per spike and 1000-grain weight of CSSL13 and 9311 were investigated. The result revealed have not difference in there four agronomic traits between CSSL13 and 9311.The result of this study establishes a basic for fine mapping, cloning and function analysis of qHD8.3, it is great significance Enrich and improve the mechanism of heading date in rice and promote the application of qHD8.3 in rice breeding.