Development Of The Recessive Genic Male Sterility Maintainers By Marker-Assisted Selection And Microspore Culture In Rapeseed(Brassica Napus)

Heterosis utilization is one of important approaches to improve the yield and quality of rapeseed varieties. As the recessive genic male sterility(RGMS) system of 9012 AB types can obtain 100% male sterile lines by maintainer lines, it has become one of the most potential pollination control system. In this system, it is crucial to develop the maintainer lines. Because of the complicated genetic model, the development of maintainer line by traditional methods is a time-consuming and low efficiency work, but the combination of marker-assisted selection and microspore culture can accelerate the development of homozygous maintainer lines.Several Brassica napus lines of spring type with better comprehensive characters(recessive nuclear male sterility materials yu127 and yu128, recessive nuclear male sterility homozygous two type line T45 AB and its homonuclear maintainer T45, pol-cytoplasmic male sterile line 303A) were used in this study. The purpose were to quickly obtain new maintainer with better comprehensive characters and genetic stability through the combination of traditional hybridization, marker-assisted selection and microspore culture, providing more basic breeding materials for utilizing this nuclear male sterility system in hybrid breeding. The main results were as follows:1. Through marker-assisted selection, 40 and 37 plants with genotype of ms3ms3 Rf cRf c and 47 and 51 plants with genotype of Ms3ms3 Rf cRf c were selected out from the BC1 populations of yu127×(yu127×T45B) and yu128×(yu128×T45B) respectively.2. Through microspore culture for the plants with genotype of ms3ms3 Rf cRf c and Ms3ms3 Rf cRf c selected out in the BC1 populations of yu127×(yu127×T45B) and yu128×(yu128×T45B) and F1 plants of T45×303A, 20, 984 and 3200 seedlings were acquired respectively. After the ploidy identification of seedlings, W1, W2 and W3 DH populations consisting of 9, 199 and 360 DH lines were finally obtained respectively, with the chromosome doubling rates of 45%, 20.2% and 11.3% respectively.3. After molecular marker aided-selection, 4, 126, 205 DH lines with genotype of ms3ms3 Rf cRf c from W1, W2 and W3 DH populations were obtained respectively. Statistical analysis showed that the rate of ms3ms3 Rf cRf c genotype was higher than 1/2 of the theoretical value, indicating that the rate of embryo-bearing ovules, seedling surviving or chromosome doubling might be different in different genotypes gametes in microspore culture with colchicines.4. The results of flowering time of three DH populations showed that the flowering time of each plant in W1 DH population was between that of two parents and presented a mid-parent separation. The separation degree of flowering time in W2 and W3 DH populations were bigger and appeared to be a transgressive segregation, that is, the flowering time of most plants were earlier than that of two parents.5. 15 DH lines with better agronomic traits were selected through the preliminary investigation of three DH populations. And based on the survey of yield-related traits and oil content, one DH line(8X-5969) from W1 population with higher 1000-grain weight and higher oil content was found compared with its two parents; In W2 population, one DH line(8X-5984) with its 1000-grain weight slightly lower than high value parent was obtained of which number of Siliques of main infloresence, Seeds per silique and oil content were higher than two partents; In W3 population, one DH line(8X-5734) was obtained with its higher number of Siliques of main infloresence, Seeds per silique, 1000-grain weight and oil content than two parents.