Mapping And Identification Of The Dwarf Gene BnRGA1 In Rapeseed (Brassica Napus)

The oil seed is one of the most important oil crops and Brassica napus is the mainly cultivar in our country.Now,the improvement of plant form and loding resistance is the key of increased yield.So to isolate and characterize new dwarf genes reveal substantial significance in accelerating plant breeding and implementing the "Green Revolution" in Brassica.The materials of the dwarf mutantion(Brassica napus) LB821-1 and the high material (Brassica napus) 9369-1 were used.The inheritance of the dwarf trait for LB821-1 was studied.The molecular markers were used to tag the dwarf gene,and finally sieved the dwarf gene by identifying the candidate gene.The main results are as follows:1.Genetic analysis showed that the plant heights of F₁ population was intermediate of two parents,but partial to dwarf parent,F₁ and RF₁ had no significant difference.The segregation ratio of short plants:mid-strains:tall plants in F₂ population accorded with 1: 2:1.The segregation analysis revealed that LB821-1 was a demi-dwarf mutantion and the dwarf character was controlled by a single partial dominance gene and without cytoplasmic effect.2.The bulked segregant analysis(BSA) method was used in identifying the linked markers.Totally 640 SSR primers were screened and only one polymorphic band SR12156 was found linked to the dwarf gene BnRGA1 and mapped on linkage group N6(Chen et al.,2007).Then another marker SCAR07 was found on linkage group N6. Finally,the dwarf gene BnRGA1 was located between SR12156 and SCAR07.The genetic distance of SR12156 is 2.8cM and SCAR07 is 1.9cM.3.Based on the date of the dwarf gene BnRGA1,the primers AX49,AX1270 and AX910,AX1740 were quoted to amplify the gene in mutation LB821-1.Surprisingly,we found that a novel P-to-L mutation in the TVHYNP motif of the N-terminal DELLA domain.And we found that there was an additional nine bases insertion behind the TVHYNP motif in mutation LB821-1.There was difference between the parents when the PCR products ampolified by the primer AX49 and AX1270 were digested with the restriction enzyme Hpaâ…¡or Xhoâ… .So the primer BrRGAT covering the discrepant region was designed and used to amplify the F₂ individuals which contained 384 hight plants and 148 dwarf plants.The result showed that the primer BrRGAT was co-segregated with the dwarf phenotype.