Identificate Genes For Flowering Time Trait In Rapeseed Based On The Contiguous Insertion Lines

Brassica napus L. is one of the very important oil crops in Brassica genus. Flowering is one manifestation of higher plants transiting from vegetative to reproductive growth. During all lifelong of rapeseed, flowering time affects the harvest and the yield. This research is based on an achievement that a Chromosome Insertion Lines (CILs) have been built. The CILs have a genome background of ZY821, a traditional black-seed cultivar in China, and each of the lines harbors a segment from No.2127-17, a synthesized yellow-seed cultivar. In this study, the gene controlling flowering time was primarily tagged by using two populations BC3F2and BC4F3. Main results are as follows:1. The CILs contained93lines with a total of281substitution segments. These281segments can cover the whole genome of Brassica napus L. In the19chromosomes, Chromosome C4had only one segment while Chromosome A3had eight, with an average of4.9segments in each. Among all the281segments, the longest segment was117.9centi-Morgan (cM) and the shortest was3.04cM, with an average of43.57cM and a total length of.4052cM. Each line had the genome proportion of the recurrent parent ranging from95.3%to99.7%, with an average of97.5%.2. We recorded flowering data of758individuals of the BC3F2population. Among them,575flowered early or semi early, while only183flowered late. The segregation fitted the Mendel inheritance ratio of3:1by Chi-square test, indicating early flower was controlled by a single dominant gene.3.108SSR markers were used to screen DNA bulked pools of the BC3F2population,16of which had shown polymorphism between the pools. Subsequently, we could locate flowering-trait locus on chromosome C2, which was designated as qFT-C02. When making BLASTn of these16markers with the B.olerace chromosomes, we tagged qFT-C02in a1.5-Mb distance. Then BoFLC2, one of the four clones of FLC in B. napus, was detected as a candidate gene. However, there was no difference when screening DNA pools using BoFLC2primer. Therefore, BoFLC2was not our target gene. 4.111SSR markers were used to screen DNA bulked pools of the BC4F3population,18of which had shown polymorphism between the pools. We located this locus on chromosome A2. To find more linked markers, the screening work is continuing. Considering the two loci, we made a BLASTn among these two parts of markers and then found that the two loci were regulated by different genes.