Breeding For Two Type Lines And Temporary Maintainer Lines With High Oleic Acid Through Marker-assisted Selection In Brassica Napus L.

Rapeseed is an important oil crop in China,and rapeseed oil is one of the main sources of edible oil in China.Breeding of high oleic acid hybrids is an important part of rapeseed quality breeding.Recessive nuclear sterility is widely used in rapeseed hybrid breeding in recent years.In this study,based on the latest results of recessive nuclear sterile system,molecular markers were developed and applied to assist the breeding of two-type lines and temporary maintainer lines with high oleic acid in rapeseed.The main results are as follows:1)Two INDEL markers Ms3-1F/2R and Ms3-3F/4R and one KASP marker Ms3-T45a/T45b/T45c were developed according to Bnms3 gene mutation from T45.The Bn MS3 genotypes of F₂（No.20J2000）,F₃and BC₁F₁populations（No.21J4000）derived from T45 recessive genic male sterile line with high oleic acid were detected.The results showed that the marker could effectively distinguish the Bnms3 mutation and its wild type from different genetic backgrounds with T45 origin.The specific marker m3c9-4F/2R for mutation and M3C9-1F/1R for wild-type developed in our previous study for gene Bnms3from 9012A were used for duplex PCR,and the Bn MS3/ms3 genotypes in BC₂F₁materials with high oleic acid（No.20J9000）and BC₃F₁materials with two types（No.21J6000 and 21J9000）derived from recessive genic male sterile system 9012A line could be accurately identified.2)Several pair markers of Bnms4 locus developed previously were evaluated under different genetic backgrounds.Among them,the single dominant marker C-1F/1R can be used to identify the genotype of Bnms4^c,but there is no polymorphism when the double PCR consisting of this marker and M4A1-1F/b-1R were used to detect the high oleic acid F₂material of recessive genic male sterile system from T45（No.20J2000）.Codominant marker 7P-2F/2R can distinguish the three genotypes of Bnms4^bms4^c,Bnms4^bms4^band Bnms4^cms4^cand has good polymorphism under different genetic backgrounds,but there are errors in the identification of Bnms4^cms4^cgenotype.The codominant markers M4A1-5F/M4A1-1R and M4A1-1F/1R were optimized and recombined so that the genotypes of Bnms4^ams4^b,Bnms4^ams4^aand Bnms4^bms4^bcould be well identified.3)A pair of Holly oleic acid markers and a pair of 254 oleic acid markers developed before were used to identify the oleic acid locus of 5210 individuals of high oleic acid F₃and BC₁F₁materials（No.21J4000）derived from the recessive genic male sterile line T45.A total of 472 homozygous genotypes and 1305 heterozygous genotypes with oleic acid sites were identified.4)Phenotypic observation on flowering of recessive genic male sterile lines of Brassica napus from different sources and temporary maintainer lines showed that recessive genic male sterile plants showed empty buds,stamen abortion,stigma exposure,complete sterility and self-infertility.According to the degree of dead buds from light to heavy,the sterile plants were divided into A0,A1,A2 and A3 grades.The survey found that most sterile plants were type A1 and type A2.The sterile plants without dead buds were selected to cross with the maintainer plants,and the dead buds of offspring were significantly reduced.The breeding priority of sterile plants was A0>A1>A2>A3.By comparison,it was found that the growth vigor and bud performance of sterile plants from T45 were better than those from 9012A,and the growth vigor of the two types of lines from the same source was same.5)SNP genotyping was carried out in 26 sterile plants,38 maintainers,27temporary maintainers and 14 double heterozygous plants of high oleic acid F₂material（No.20J2000）derived from T45 recessive nuclear sterile system of Brassica napus using60K chip array.We analyzed the genetic similarity of these materials by clustering and SNP genetic linkage distribution,and obtained two groups of 20J2026 and 20J2069materials with similar genetic relationship between the two groups of materials.The genetic similarity between the two groups of materials was high,93%and 95%,respectively.We produce three-line group of high oleic acid with homozygous breeding background and excellent comprehensive traits through two types of lines with similar genetic relationship and temporary maintainer lines.6)This study provides new germplasm resources for the cultivation of high oleic acid rapeseed hybrid varieties,which is of great significance to accelerate the breeding and utilization of strong heterosis combinations and promote the research on rapeseed quality breeding.