Creation And Resistance Evaluation Of Phosphite Tolerant Transgenic Brassica Napus L

Weeds accompany the whole production process of Brassica napus,which seriously affects the yield and quality of Brassica napus.Long-term overuse of chemical herbicides has led to the emergence of herbicide-resistant weeds,and manual weeding is time-consuming and inefficient,so there is a great need to develop new weed control systems.Phosphite(Phi)is not directly available to plants and inhibits plant growth.The tyrosine mutation of ptx D(phosphite dehydrogenase)protein at position 139 to glutamine(Y139Q)in Raltsonia.sp.strain 4506 was able to improve its activity in catalyzing the conversion of Phi to orthophosphate(Pi).In this study,ptx D_Q was transferred into kale type Brassica napus by genetic transformation,and their growth characteristics under Phi conditions,and competition with weeds were analyzed.The results were as follows.(1)The growth and development of Brassica napus was inhibited by Phi.Phi inhibited the growth and development of Brassica napus.In this study,kale oilseed Brassica napus was treated with different gradients of Phi concentration and its phenotype was analyzed,and it was found that as the concentration of Phi increased,the growth inhibition of Brassica napus became more significant.(2)The use of ptx D_Q/Phi as a genetic transformation dominant screening marker in Brassica napus needs to be further explored.In this study,a plant expression vector p1300-35S::ptx D_Q containing ptx D_Q and hpt screening marker genes was constructed,and when 1 m M Phi was used as a screening agent in the transformation of Brassica napus,the explants only had healing wounds but could not be re-differentiated.When a trace amount of Pi was added,1.5 m M Phi+0.5 m M Pi as a screening agent,11 regenerated plants were obtained,but no positive strains were identified.A total of 6 positive transgenic lines were identified when Homomycin B was used as the screening agent.(3)The 35S::ptx D_Q transgenic Brassica napus had a stronger competitive advantage over WT and weeds under Phi conditions.The detection of ptx D_Q expression levels in 35S::ptx D_Q transgenic Brassica napus revealed that ptx D_Q was expressed in root,stem,and leaf tissues of the transgenic Brassica napus.When 35S::ptx D_Q transgenic Brassica napus was treated with wild-type Brassica napus(WT)and weeds with Phi or Pi as the sole source of phosphorus,it was found that the biomass of WT and weeds under Phi conditions decreased by about 72%and 58%,respectively,compared with Pi treatment,while there was no significant difference between35S::ptx D_Q transgenic Brassica napus and 35S::ptx D_Q transgenic Brassica napus phosphorus starvation response The expression of PT21,PT24,PT1:4 and PHR were not significantly up-regulated under Phi conditions,and moreover,35S::ptx D_Q transgenic Brassica napus accumulated more orthophosphate under Phi conditions.In conclusion,the 35S::ptx D_Qtransgenic Brassica napus has the ability to convert Phi to Pi,thus conferring a competitive growth advantage over wild-type Brassica napus and weeds under Phi conditions,indicating that ptx D_Q/Phi is an effective phosphorus utilization and weed control system for Brassica napus,providing a new feasible solution to effectively address phosphorus utilization and weed control in Brassica napus.