Genetic And QTL Mapping Analysis Of Seed Germination Related Traits In Brassica Napus L.

Rapeseed is one of the most important oil crops in China which accounting for about 20% of global production.Previous rapeseed cultivation has the problems of low seed germination rate and large consumption,while the seeds with high germination quality show the advantages of strong seedlings,strong heterosis and high stress resistance.Rapid and uniform germination of seeds is the prerequisite for high yields in crop production.Therefore,studying the genetic basis of seed germination and exploring the excellent alleles regulating seed germination related traits is essential for the development of breeding program and the selection of new rapeseed varieties with high germination quality.In order to analyze the genetic basis of the high germination quality of rapeseed,the DH population include 280 lines were constructed with the microspore culture technology by ZhongShuang 11 and R11,the parents of the excellent chemical emasculation cultivar of DaDi 199.With the high-throughput,automated phenotypic acquisition platform,the seed germination related traits were collected for phenotypic data of this study,and the QTL mapping of seed germination related traits in three environments was carried out in combination with a high-density genetic linkage map constructed by a large number of bin markers obtained based on Whole Genome Resequencing.The main results are as follows:1.A high-throughput seed germination quality detection platform was constructed.The seed germination quality detection platform mainly includes 24 germination boxes,and the image acquisition of the seed germination process is acquired by using the Raspberry Pi microcomputer.The Germinator software was used to detect the accumulation germination curve of each lines in the DH population.Extraction of germination quality evaluation indicators,including Hypocotyl Length(HL),Radicle Length(RL),Area under Germination Curve(AUC),Mean Germination Time(MGT),Germination Uniformity(U8416),Germination Speed(T50).Compared with the traditional seed germination quality detection method,the seed germination quality detection platform has the advantages of high throughput,automation,low cost an d good repeatability.2.Correlation analysis of six germination traits in three different environments showed that the germination traits of hypocotyl length and radicle length has significant correlation with germination traits except the trait of Germination Uniformity in E3 environment.The significant correlation was found between the four seed germination quality evaluation indicators(AUC,MGT,U8416,T50)derived from the cumulative germination results.In E1 environment,thousands seed weight(TSW)was significantly positively correlated with the hypocotyl length and radicle length,and was significantly positively correlated with the area under the germination curve,and was negative correlation the germination rate.No significant correlation between thousands seed weight and germination traits has been detected in E2 environment.Thousands seed weight was significantly positively correlated with hypocotyl length and was positively correlated with radicle length and germination uniformity.3.The genetic analysis of the six germination traits in E1 environment showed that the main gene effect of germination traits include hypocotyl length and radicle length was not obvious,and it was greatly affected by the environment.The four seed germination quality evaluation indicators(AUC,MGT,U8416,T50)derived from the cumulative germination results were regulated by the major gene plus polygene,and the genes of each germination trait showed an interaction effect.In order to make more opportunities for recombination between the interaction genes,the selection intensity in the lower generation should not be too strict.4.Totally 72 QTLs were detected about HL,RL,AUC,MGT,U8416,T50.The QTLs related to the six germination traits were widely distributed on 15 chromosomes except that A08,C02,C05 and C06.The source of the synergistic gene was different,showing the quantitative traits of micro-effect and multi-gene control.The phenotypic variation of a single QTL interpretation ranged from 2.21% to 21.88%.Four consistent QTLs distributed on the A09 chromosome in the range of Block16014-Block16039 marker interval were identified show multi-effect.Meanwhile,two codominant markers and one dominant marker were developed,which provided an effective technical tools for further development of molecular marker-assisted selection breeding in Brassica napus L.