Evaluation Of Agronomy And Stress Resistance And Screening Of Excellent Germplasms In Brassica Napus L.

Brassica napus is the main cultivation type of rapeseed in China,but it has a short history of introduction from Europe and Japan,with only 80 years of cultivation history,and the overall genetic background is weak.Therefore,it is urgent to identify a batch of high-yield,good resistance,early maturity,and outstanding agronomic traits from the existing B.napus germplasm resources to enrich the basic resource base of B.napus.In this study,821 B.napus germplasm resources were collected by the Oil Crop Research Institute of the Chinese Academy of Agricultural Sciences from home and abroad for many years,with rich genetic variation and large phenotypic differences.Through the phenotypic identification and germplasm evaluation of 821 B.napus during the whole growth period,a batch of phenotypic differences,high yield,early maturity,and good resistance varieties were selected for follow-up basic research.The identification and evaluation of traditional germplasm resources are mostly based on morphological character evaluation,ignoring the identification and evaluation of germplasm resources at the molecular level.Therefore,this study not only carried out the field phenotype evaluation,but also used molecular biology technology to clone and analyze some related genes,providing a new idea and method for the identification and evaluation of germplasm resources.The main results are as follows:(1)The analysis of agronomic traits during the seedling and growth periods showed that 91.2%of the germplasms had semi-upright seedling habits,5.1%had creeping seedling habits,and 3.7%had erect seedling habits.The basal leaf type of 97.59%germplasm is split leaf,1.56%is intact leaf,and 0.84%is mosaic.18SA-875 has the shortest bolting period of 147 days,18SA-830 has the longest bolting period of 191 days;18SA-875 has the shortest initial flowering period of 175 days,and 18SA-1648 has the longest initial flowering period of 199 days;18SA-875 entered the final flowering period,which was the shortest at 192 days,18SA-829 entered the terminal flowering period,which was the longest,at 226 days;18SA-968 entered the maturity period,which was the shortest,at 220 days;18SA-829 germplasm entered the mature period the longest at 256 days.(2)The field stress resistance analysis of B.napus showed that the lodging resistance of 18SA-860,18SA-937,18SA-1029,18SA-1241,and 18SA-1305 were the best,with a level of 3(strong).The cold resistance of 18SA-873,18SA-1584,and 18SA-1325 were the best,with a grade of 3(strong).18SA-839,18SA-957,18SA-1351,18SA-1423 have the lowest incidence of sclerotinia disease,with an incidence of 0-10%.(3)The analysis of plant type and yield traits of B.napus showed that twelve agronomic traits were riched in variation,Such as biological yield per plant and effective number of siliques on the spindle,belonged to normal and partial normal distributions.The twelve agronomic traits have correlation at different grade.Among them,the agronomic trait closely related to yield was the grain yield per plant,which had a very significant positive correlation(0.272**),followed by thousand-grain weight(0.215**);while the silique was long,there was a positive correlation with the number of grains per horn and the thousand-grain weight.In the process of breeding,we can select varieties(accessions)with long siliques,which may effectively increase the thousand-grain weight and the number of grains per horn,so as to achieve the purpose of increasing production.(4)A total of 52 germplasms with outstanding single traits were selected from 821 B.napus germplasms based on the phenotypic data of agronomic traits,which can be used as the original materials for the follow-up research.According to the actual needs of production,ten germplasms with balanced and excellent comprehensive characters were selected.The average plant height of these germplasms was 152-162 cm,the number of effective pods in the main axis was more than 50,and the grain yield of the plot was between 2500-3000 kg/hm2,which were 18SA-840,18SA-868,18SA-1012,18SA-1030,18SA-1110,18SA-1199,18SA-1239,18SA-1286,18SA-1103 and 18SA-1535.(5)The CDS sequence of the BnaSVB gene was cloned from the salt-tolerant accession 18-SA862 of B napus.The total length of CDS is 468 bp,encoding 155 amino acids.Analysis of the conserved domain of the protein encoded by this gene revealed that there is a conserved segment of 109 amino acids at the 28th to 138th amino acid positions,which is the DUF538 domain;78 DUF538 gene family members from the whole genome of B.napus.was identified by bioinformatics analysis method.(6)In this study,an overexpression vector of the BnaSVB gene was constructed to lay the foundation for the subsequent transgenic creation of salt-tolerant rapeseed germplasms.In order to verify the relationship between the BnaSVB gene and abiotic stress,a 1500 bp fragment upstream of the BnaSVB gene was selected,and it was found that the upstream promoter element of the gene was related to low temperature stress,drought stress and other abiotic stresses.