Evaluation And Analysis Of Rapeseed Introgression Lines Derived From The Interspecific Cross B.juncea×B.napus

Compared with Brasscia napus, the species B. juncea has many goodhereditary properties, such as a higher number of siliques, indigenous yellow seedcoat, high oil content (over 45%), resistance to diseases and lodging. Theintrogression lines (ILs), which have some genetic components of B.juncea, havebeen derived from the interspecific cross (B. juncea Sichuan Yellow×B. napus cv.Stellar) F₁×B. napus inbred 1047. This study was carried out in order to determinethe agronomic and the quality characters of BC₁F₆, BC₁F₇, and to analyse thecomposition and origin of genetic material in BC₁F₇ inbred lines using the RAPDmarkers.The following results and conclusions were drawn from these researches:1 Obsrvation of 13 BC₁F₆, BC₁F₇ ILs showed that their flower buds werevisible 92-98 days after direct seeding in autumn and the plants were flowering155-167 days after direct seeding in autumn. Four short-stature, three branchy, fivesilique-rich and three high-yielding ILs have been identified. Four double-low, onelow-erucic, and two high oil ILs have also been found. These novel germplasm willlay the foundation for rapeseed breeding.2 Among 503 10-mer random primers used 141 primers displayedpolymorphism of the three parents, of which the 46 primers were used to examine the18 BC₁F₇ ILs. The bands common to all parents were transmitted into introgressionlines with high frequency, for example, 94% in IL4, IL7 and IL8. The bands commonto B. napus parents 1047 and Stellar were similarly transmiteed into introgressionlines with high frequency, above 70% on average, but up to 87.5% in IL17. A fewbands were found to be common to B. juncea Sichuan Yellow and Stellar or 1047because of the difference between B. juncea and B. napus genomes. 3 B. juncea-specific bands were transmitted into the introgression lines withlower frequency compared with B. napus-specific bands. Only 22.1% and 7.4% of B.juncea-specific bands were respectively maintained in IL5 and IL7, while 50.0%-56.7% and 46.7%-71.4% of B.napus-specific bands were miantained in respectivelines.4 Novel RAPD bands absent in all the three parents occurred in someintrogression lines. Five new bands, ie, S20₉₀₀, S197₁₀₀₀, S204₁₆₀₀, S429₁₀₀₀, S481₉₅₀were amplified in IL9 using five primers. This indicated that new genetic variationwas caused by recombination through crossing and selection after successiveself-pollitation.5 The genetic distances of 18 ILs and their parents were estimated to rangefrom 0.0284(between IL4 and IL5) to 1.3055(between Sichuan Yellow and 1047).Clustering analysis showed that accessions studied were grouped into five classes by asimilarity coefficient of 0.1387-0.1399.