Genetic Study On Apetalous Trait In Brassica Napus And Brassica Campestris

Oilseed rape is an important oilcrop extensively planted in the world. In the past and the near future, canola breeders still face the common and major goal of improving the productivity level of rapeseed and increasing disease resistance of rapeseed. Special apetalous germplasm has important effect on improving productivity and disease resistance of rapeseed. The access to knowledge of genetic model and molecular mechanism of petal-loss mutation rapeseed, together with the availability of closely associated DNA markers, will facilitate the exploitation of petal-loss trait in breeding program. Also, genetic study on the mechanism underlining petal-loss mutation will provide a chance for better understanding of the developmental process of floral organs in plant.In this study, 'APT02', an apetalous germplasm of Brassica napus and 'AM032', an apetalous germplasm of Brassica campestris, were used as main materials to study: comparison of morphological characteristics; genetic analysis of apetalous trait; allelism and interaction of petal-loss genes; molecular markers for apetalous trait. Main results of the present studies are as follow:1. Morphological characteristics of two mutant materials were compared. The result suggested that the mechanism of petal loss in Brassica campestris was different from that in Brassica napus. Floral organs of 'APT02' showed mainly petal loss, But the material 'AM032' showed mainly stamenoid petal and leaf curled.2. Three wild type Brassica napus varieties were crossed with apetalous mutant of Brassica napus 'APT02'. Genetic analysis on their progenies indicated that apetalous trait of 'APT02' was controlled by two major recessive gene pairs and a third modifying recessive gene pair, maternal effect wasn't found in this trait.3. Two wild type Brassica campestris varieties were crossed with apetalous mutant of Brassica campestris 'AM032'. Genetic analysis on their progenies indicated that apetalous trait of 'AM032' was controlled by one recessive gene pair, maternal effect wasn't found in this trait.4. By crossing 'APT02' with 'AM032', the relationship of petal loss mechanism for two mutants was studied. Double-mutation (petal loss and petal stamenoid) plants were found in F₁ populations and segregating populations derived from the cross of 'APT02' with 'AM032'. Petal-loss genes of two mutants occurred complicated genetic interaction.5. Male sterile plants were found for the first time in segregating populations derived from the cross of 'APT02' with 'AM032'. It appeared segregation of sterile plants and fertile plants in three populations i.e. [ (AM032 × APT02) × (AM032 × APT02) ], [ (AM032 × APT02) × APT02 ] and [(APT02xAM032)x(APT02xAM032)]. But it didn't appear segregation of sterile plants and fertile plants in two populations i.e. [(APT02×AM032)×APT02] and [(APT02×AM032)×AM032].6. One F₂ population derived from the cross between 'APT02' and 'ZS NO.4' was used for identifying molecular markers linked to the apetalous trait of Brassica napus. 20 pairs of AFLP...