Study On Molecular Marker And Supplementary Breeding Of White-Petal Gene In Brassica Napus L.

The petal color of rapeseed is yellow generally, but there are also a few of different colors, such as golden, orange, white, and milk-white. This kind of floral color character comes from natural mutation, and artificial cross between species or genera. White petal which is an important trait and easy to be distinguished from yellow petal has a vast application foreground in determining variety's purity and nature cross-pollination rate as well as traits transferring, and so on. At the same time, as a sign trait, the white petal can play an important role in the system of the heterosis utilization of rapeseed. But for the later identification during flowering period and limitation of study to white-petal trait, so the utilization of this trait is not in focus. The goal of this study is to find the molecular marker linked to white-petal gene and use the marker in supplementary breeding.White-petal rapeseed (Brassica napus L.) and its segregation population were used as the experiment materials to study the genetic law of white-petal traits in Brassical napus L.. The procedure of RAPD reaction system was optimized. The RAPD marker linked to white-petal gene was found using bulked segregation analysis. The possibility that the RAPD marker would be utilized in molecular supplementary breeding was discussed. The main results are as follow.1. The white-petal trait in Brassica Napus L. was controlled by one pair of incompletedominant nuclear genes (Ww) . The genetic pattern is as follow:White petal(WW)× White petal(WW) → White petal(WW)White petal(WW)× Yellow petal(ww) → Milk-white petal(Ww) (?)1 White petal(WW): 2 Milk-white petal(Ww): 1 Yellow petal(ww)2. The quality of DNA from different extraction methods and its effect on RAPDanalysis were studied. A simple and rapid method of DNA extraction on rapeseed was established.3. The procedure of RAPD reaction system was optimized, and the new procedure ismore economical and stable.4. BSA was employed to identify RAPD markers linked to the white-petal gene. A totalof 1 200 arbitrary 10-mer oligonucleotide primers were screened on the DNA of W and Y bulks. Only one primer Sio92(5-CCC AGG CTA C-3) gives repeatable polymorphism between the two bulks. In bulk W a specific 1.25 Kb DNA segment was amplified with primer S1092, but not corresponding segment in bulk Y, and the same result was obtained on different single plants of segregation population with the primer Si029. The result can be repeated.5. The other four white-petal varieties in Brassica napus L. were analyzed by primerS1092 and the specific 1.25 Kb DNA segments were all amplified. The result proved that the RAPD marker S-lO92i2so is linked to the white-petal gene. The genetic distance is 0.84 cM between RAPD maker and the white-petal gene.6. The utilization approach of white petal was discussed, and the molecular markerlinked to the white-petal gene can be used in determining variety's purity and nature cross-pollination rate, identifying varieties, as well as molecular supplementary breeding.