Study On The System Of Microspore Culture And DH-line Productivity In Brassica Napus L.

The system of isolated microspore culture and DH-line productivity were systematicly studied with cultivars(lines) and crossing combinations in Brassica napus L from the ordinary greenhouses and the field environment of Hybrid Rapeseed Research Center of Shaanxi Province in nearly years, with microspore culture ways of Coventry J et al(1988)and Teresa C T et al(1999)as basic ways. The main results are as following: 1. The technical system of isolated microspore culture and DH-line productivity were established in Brassica napus L to suit the conditions of ordinary greenhouses and field environment in the area. This system can make the genotype rate of microspore embryogenesis of ordinary greenhouses and field materials attain 50% or so, and make the microspore culture of ordinary greenhouses and field materials reach practicalization. Plants more than 200 of valuable DH-lines were acquired throught microspore culture in Brassica napus L . These plants are further being used in the genetic research and rapeseed breeding in Brassica napus L. 2. Affection of ways and time of low temperature pretreatment, lengths of inflorescences and genotypes of materials on embryogenesis of microspores were systemicly studied by isolated microspore culture firstly in Brassica napus L from the field environment. The result shows that microspores still had certain embryogenesis capability when the inflorescences with 30~40 cm lengths were in the cold pretreatment for 10 d. In 0~40 cm lengths of inflorescences, inflorescences pretreated were longer at length, and the efficient pretreatment time of in florescences in which microspores can conduct embryogenesis was longer. However,the embryoid yield trended to decline with the prolongation of pretreatment time of inflorescences. This result provides the basis for broadening the scale of material-collected, prolonging the time of sampling and culturing to materials from the field environment, efficient respiting the contradiction between the short and aggregate bud season of donor materials in open field as high temperature and bud-collected for culturing, making more materials cultured obtain plantlets, and getting buds and culturing their microspores for some important materials from far other places. 3. The effect that antibiotics are used in rapeseed microspore culture is given preliminary evaluation. The result shows that antibiotics can not only prevent contamination by microbes from culturing materials but also affect the embryoid yield through three kinds of antibiotics including Penicillin G sodium, Cefotaxime sodium and Streptomycin sulfate. Generally, the embryoid yield is gradually descent,even no embryogenesis capability with increase of antibiotic concentration, but the number of deformity embryoids are increasing. 4. The ways of subculture and preservation of tube-shoots are offered, the rooting medium of tube-shoots is selected and the key technique of transplant of plenty of tube-shoots is provided in Brassica napus. The result shows that the ways to perserve rapeseed haploid tube-shoots are easy and practicable throught decreasing the frequency of subculture, storing in cold condition and adding the growth retardant MET, the ways can ensure tube-shoots to live through the summer successfully. The better rooting medium of tube-shoots is B5+IBA 0.5 mg/l +Suc 2%+Agar 0.9%, tube-shoots can be transplanted when they are cultured in this medium in half month. A system to ensure high survival rates of transplant of plenty of tube-shoots is set up, the program efficient concert the conditions including temperature,humidity and light in transplant of tube-shoots, and make survival rate of transplant of tube-shoots over 95%, the program offers reliable guarantee to the further utilization of tube-shoots. 5. The efficient doubling ways of colchicine were offered. Rapeseed microspore doubling uses the ways adding 50mg/l colchicine to NLN13 medium. The average doubling rate was 81.56%. This way raises the doubling rate of colchicine and saves the chemical reagents and funds. Moreover, the effect of chromosome doubling of roots-soaked in solutions is better for shoots and plants doubling. In the experiment of colchicine doubling, the affection on doubling treatment to the survival rates and agronomic traits of plants needs to be considered when we try to improve the doubling rate of plants. In addition, the floral organ indexes of the doubled and no doubled branches of the same plants were firstly compared and statisticed. These floral organ indexes can be regarded as the morphological quantification indexes of the multiple discrimination of microspore-derived plants,and provided reference basis for identifying multiple of microspore-derived plants in Brassica napus L in early stage throught the morphological indexes.