| Rice is one of the most important crops in the world, providing the staple food for almost half of the word’s population. As one of the most important agronomic characters of rice, heading date is responsible for the regional and seasonal adaptation of rice varieties. It is vital to map QTLs for heading date and study the genetic effect in rice breeding. The traits of heading date show continuous phenotypic variation in progeny, controlled by multiple quantitative trait loci (QTLs). At present, near-isogenic lines is considered as an ideal tool to QTLs detecting, mapping and cloning in rice.This study focused on fine mapping of one heading-date QTL,which located on chromosome3,with the material of near-isogenetic lines (NILs) population that derived from a cross between two rice varieties:japonica variety Ⅱ-32B cultivar as the recipient, indica variety Azucena cultivar as the donor.1Through field traits investigation, heading date segregation was found in the populations of BC4F2during the construction of NILs. The plants of early heading are51while the late plants are138. the segregation was fitted for the ratio of1:3during the heading.(χ2=0.4744<χ20.05=3.841)2After testing recessive plants, qHd3-1was primarily narrowed down to an61.8kb genomic DNA region between marker RM3443and RM3894, with the genetic distance of1.92cM and0.96cM, respectively. 3Testing the population of BC4F2, heterozygote plants were gotten and sowed.69lines of enlarged population of BC4F3were obtained for fine mapping. By detecting1150recessive plants with STS markers, qHd3-1was finely mapped between the molecular markers GS3-47and G3-52with the genetic distance of0.13cM and0.087cM, respectively.The molecular markers of GS3-47and G3-52were located at the same BAC clone. In accordance with the sequence of marker GS3-47and G3-52, qHd3-1was finally limited on the region with physical distance of61.8Kb on the website of http://www.gramene.org. The qHd3-1was limited in this region. |
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