| Breeding of extra-early-maturing,high-yield,and high-quality Brassica napus hybrids that can mature normally in high-altitude areas is of great significance for improving the yield of high-altitude spring rapeseed.The Spring Rape Research Institute of Qinghai Academy of Agriculture and Forestry has selected and bred a large number of extra-early-ripening Brassica napus restorer lines that can mature in high altitude areas through interspecific hybridization of Brassica napus and Chinese cabbage.In order to clarify the application value of these restorer lines in the breeding process of extra-early maturing hybrids and improve the breeding efficiency,the following work was carried out in this study: SLAF-seq high-throughput sequencing technology was used to construct 97 core germplasms of extra-early cabbage spring rapeseed restorer lines,and the genetics of restorer lines and a high-quality extra-earlymaturing Polima cytoplasmic male sterile line commonly used in breeding were determined.According to the genetic distance,cluster analysis was carried out.In each category,the restorer line and the sterile line were selected according to the proportion of 45%,and the hybrid performance,heterosis and heterotic pattern were analyzed.The Spring Rape Institute of Qinghai Academy of Agriculture and Forestry has located 4early-maturing genes,and identified the distribution of these early-maturing genes in98 materials by polyacrylamide gel electrophoresis.The main findings are as follows:Core germplasm construction results: The core collections of C30 and C40 spring Brassica napus L.extra-early restorer lines were constructed,containing 29 and38 materials,respectively,which can represent the variation degree of the entire resource.Among them,the average variability of C30 core germplasm was 99.89%,and the average variability of C40 was 99.96%.Analysis of genetic differences between restorer lines and sterile lines: The97 extra-early spring Brassica napus L.restorer lines were divided into five categories.The top ten genetic distances were mainly concentrated between the fourth and fifth categories,and the genetic distance ranged from 0.6229 to 0.6628.It shows that the genetic difference between the fourth and fifth restorer lines is relatively large;The 98 Brassica napus samples were also divided into five categories,among which the sterile lines were clustered in the fourth category,the genetic distance between the restorer lines and the sterile lines ranged from 0.0061 to 0.5241,the average genetic distance was 0.35221.The top ten restorer lines with large genetic distance differences from the sterile lines were all in the fifth category,and the genetic distances ranged from 0.4472 to 0.5241,indicating that the genetic differences between the sterile lines and the fifth category of restorer lines were large.Hybrid performance and heterosis analysis: The combination with the highest ranking of plot yield was(64-1)× 16D3(category 5).There are 29 combinations of BY’s OPH advantage and positive advantage,which are distributed in 1.29%～91.98%,and the combination with the strongest advantage is(64-1)× 26;There are 23 combinations in which BY’s OSH is a positive advantage,distributed in 4.26%～52.55%,and the combination with the strongest advantage is(64-1)× 3286;There are 41 combinations in which BY’s MPH is positive dominance,ranging from 1.56%～99.51%,and the combination with the strongest dominance is(64-1)×26.There was a significant positive correlation between genetic distance and plot yield in terms of mid-parental dominance,with a correlation coefficient of 0.319.Among the top 20 BY combinations,the genetic distances were distributed between 0.189 and 0.524,and there were 10 combinations of sterile lines × restorer lines of the fifth type,and the top five were all combinations of sterile lines × restorer lines of the fifth type.When the sterility line ×the fifth type restorer line is crossed,when the hybrid parents are combined,the progeny has a great potential to produce strong dominant hybrids.Identification of early flowering loci of extra-early-maturing cabbage type spring rapeseed varieties(lines): G1803(A7 site)has 27 materials that express AA and56 materials that express BB;12-51(A10 site)73 materials express AA,and 14 materials express BB;SNP 12(C8 site)has 82 materials that express AA,and 14 materials that express BB;CZ-32(A02 site)has 64 materials that express AA and 31 materials that express BB;In the four-site combination form,there are only 3 materials with single sites;25 materials with double sites;34 materials with three sites;9materials with four sites.These different loci materials were distributed in five different taxa,which provided the basis for parental selection for the aggregation of different early flowering loci to create extra-early spring rapeseed resources. |
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