Analysis Of Physiological Characteristics And Candidate Gene Mining Of Stem Lodging Resistance In Brassica Napu

Brassica napus is the main oil crop in China and one of its important breeding goals is the genetic improvement of stem lodging resistance at present.In this study,germplasm resources of 200 rapeseed accessions were evaluated by stem breaking resistance to screen out the stem lodging-resistant and stem lodging-sensitive inbred lines.The physical and chemical components of the mature stems of selected stem lodging-resistant and-sensitive lines were detected.microscopic sections of the stems of the differential materials were also observed at the seedling,bud,bloom and maturity stages,and the transcriptome sequencing analysis was used to compare transcriptomes of the stems of the stem lodging-resistant and-sensitive lines at the budding and full blooming periods.The results showed that:(1)The stem breaking resistance and stem diameter of 200 Brassica napus germplasm resources were all normal distribution,which belonged to quantitative genetic traits.The extremely non resistant stem fall material GY172 and anti stem fall material GY199,which had similar birth dates,plant types and stem diameter,but significant differences in stem breaking resistance,were screened based on stem breaking resistance and agronomic traits.(2)The phloem of GY199 was denser than that of GY172,while the content of hemicellulose,lignin,neutral detergent fiber and total soluble sugar in the mature stem of GY172 was significantly higher than that of GY199,while the content of cellulose in the mature stem was extremely significantly lower than that of GY199,the content of cellulose in the mature stem was positively correlated with the stem bending resistance of the two materials.(3)Microscopic sections revealed that there were no significant differences in epidermal thickness and cortical thickness between the failure-prone material GY172 and the failure-resistant material GY199 at seedling,bud,flowering and maturity stages,but the number of vascular bundles of GY199 was higher than that of GY172 at flowering and maturity stages,and the number of vascular bundles of GY199 reached a significant level of difference between the two,and the vascular bundles of GY199 were relatively closely arranged,and the percentage of vascular bundle area of the failure-resistant material GY199 was significantly higher than that of the failure-prone material at each reproductive stage.The percentage of vascular bundles in the area of GY199 was significantly higher than that of the crop-prone material,indicating that the outstanding mechanical strength of GY199 is closely related to its characteristic culm structure,such as tightly arranged,thick-walled cells with more layers,a higher number of vascular bundles and the percentage of vascular bundles in the area of the culm.(4)Sequencing of stem transcriptome at bud moss stage and full bloom stage rev ealed that carbon metabolism,carbon fixation,pentose phosphate pathway,amino acid biosynthesis 14 genes(Bna A10G0056100 ZS,Bna C08G0455100 ZS,Bna A08G0262400 ZS,Bna C08G0239700 ZS,Bna A07G0362300 ZS,Bna C02G0081300 ZS,Bna C04G0273000 ZS,etc.)were resistant to stem.The expression was significantly up-regulated in metamaterial GY199,these genes may be involved in regulating stem strength traits a nd serve as candidate genes for stem lodging resistance in rapeseed.