Mapping QTLs Of Plant Height And Flowering Time And Identification Of Molecular Markers For Yellow Seed Trait In Brassica Napus

Oilseed rape is an important oilcrop planted extensively in the world.Plant height, flowering time and seed coad colour play important roles in lodging resistance, yield formation and seed quality respectively. Results obtained from previous studies on those three traits couldn't meet the present breeding demand. In this study, a Brassica napus mutant line with dwarf and early flowering characteristics was used to study the inheritance of plant height and flowering time, and to identify quantitative trait loci (QTLs) of these two traits; An F₂ population from a cross of a yellow-seeded and a black-seeded lines was used to screen molecular markers tightly linked to yellow-seed genes; Futher more, a yellow-seeded doubled haploid (DH) population was established for genetics and molecular studies of yellow seed character. The main results are summarized as following:1. A high stalk and later bloom Brassica napus line 2091 was crossed with a dwarf and early bloom mutant line 99CDAM. Genetic analysis on F₁, F₂, BC₁ populations indicated that the dwarf trait was controlled by three pairs of recessive genes, with maternal effect. Early flowering was mainly controlled by one pair of recessive genes. There was significant correlation between plant height and flowering time (r =0.2194*).2. A linkage map was constructed from a segregating population with 145 F₂:3 family lines derived from the cross of 99CDAM ×2091. It was consisted of 199 AFLP and 34 SSR loci in 20 main linkage groups, plus eight markers in four linkage pairs, covering 2094.6 cM of the genome.3.When F₂:3 family lines were used to map QTLs of plant height, one QTL on linkage group (LG) 13 was identified by single marker analysis method. Five QTLs were identified by both of interval mapping (1M) and composite interval mapping (CIM) methods. These loci accounted for 10.1-26.4% (IM) and 11.3-28.6%(CIM) of phenotypic variation respectively.4. When F₂:3 family lines were used to map QTLs of flowering time, two QTLs was identified by single marker analysis method. IM and CIM methods both result in four QTLs. These loci explained 8.9-30.4% of phenotypic variation. When phenotypes of F₂ single plants were used to detect QTLs of flowering time, a common QTL (fl13) was found by all three methods. IM method also identified one QTL on LG3, which accounted for 9.8% of phenotypic variation. Another QTL on LG6 with 9.5% contribution rate was detected by CIM method. In total, five QTLs related to flowering time were identified in two populations by three mapping methods.5.The QTL mapping results showed that main QTLs of plant height and flowering time were both mapped on LG13, and their QTL creditable regions were overlapped. QTLs of plant height and flowering time were both found on LG6, however they were not closely linked.6. DNA samples from nine blacked-seeded and 12 yellow-seeded F₂ plants of a B. napus hybrid Yuhuang No.1 from a yellow-seeded and a black-seeded parental lines, were mixed respectively to make blacked-seeded bulk and yellow-seeded bulk. Ninety-six AFLP primer combinations and 173...