Gametocidal Effects Of Seven Sulfonylurea Herbicides And Transcriptome Changes Caused By Tribenuron-methyl Exposure In Rapeseed

Using the theory of heterosis is an important way to improve the quality and yield of rapeseed,chemical herbicide induced physiological male sterility of Brassica napus and then producing hybrid seed is one of the main approaches to utilize the heterosis.Tribenuron-methyl and other Acetolactate Synthase(ALS)activity inhibited herbicides have been successfully applied in the large-scale production of hybrid rapeseed.But now,there are still lacking chemical hybridizing agents(CHA)with stability effect that suit for different rapeseed varieties and different environment.Meanwhile,previous studies about the dynamic change processes of Acetolactate Synthase in response for chemical herbicides is little knew as well as the the transcriptome level changes of rapeseed buds affected by tribenuron-methyl.This article had screened new type of rapeseed CHA through field efficacy investigation and compared the influence on the activity of ALS,then we also had explored the effect of tribenuron-methyl on the transcriptome level and gene expression of rapeseed.The results obtained are:(1)All chemical herbicides of Sulfometuron-Methyl,Flazasulfuron,Halosulfuron-methyl,Hulfosulfuron,Triflulsulfuron-methyl and Oxasulfuron can induce the Brassica napus male sterility and the rate of male sterility can lead to more than 90% when rapeseed was treated with the two dilution concentrations of benchmark concentrations.The five rapeseed varieties treated with Sulfometuron-Methyl and Hulfosulfuron all had a high male sterility rate but the phytotoxicity of the two agents was serious.The difference of genotype selection of Brassica napus was obvious with Oxasulfuron and Flazasulfuron.The appropriate concentration of Halosulfuron-methyl is 1.95 mg/L,but the concentration of 3.9mg/L is easy to cause phytotoxicity.These 5 chemical herbicides need to be reduced in the spraying dosage and continue to search for suitable concentrations and varieties for the sake of their popularization and application.The gametocidal effect of Triflulsulfuron-methyl in two concentration of 1.5mg/L and 3mg/L are very good,investigation of field traits showed the lightest chemical injury.When the flower turned sterile,the plant phenotype was basically normal.Triflulsulfuron-methyl could be considered as a candidate CHA for extensive use.(2)The ALS enzyme activity in buds of rapeseed underwent the strongest inhibition,then was in the young leaves and the old leaves was the least.The ALS enzyme activity of buds and young leaves treated with Tribenuron-methyl,Halosulfuron-methyl and Oxasulfuron basically remained at 20%~40% and can turn to male sterility.Whereas,bispyribac and flumetsulam basically maintained at 40%~60%,but could not result in male sterility of rapeseed.The inhibitory effects of the 5 herbicides on old leaves were not obvious and fluctuated greatly.The sensitivity of inbred line 740 C to Tribenuron-methyl 、Halosulfuron-methyl and Oxasulfuron were higher than that of inbred lines Q8 C.It was preliminary found that there was a linear relationship between the activity of ALS enzyme and the spraying amount of chemical hybridizing agent,which could be used to determine whether the spraying amount of chemical hybridizing agent was enough.(3)Screening the buds transcriptome after Tribenuron-methyl treatment,727 differentially expressed transcripts were selected,including 437 up-regulated and 290 down regulated.432 Significant difference GO(Gene Ontology)and 35 biological pathway of KEGG(Kyoto Encyclopedia of Genes and Genomes)were enriched.GO terms interested mainly include(1)amino acid metabolite,(2)energy metabolite,(3)carbohydrate,lipid,protein metabolite,(4)cell division,growth and death,(5)stimulus and defense response,(6)chlorophyll and mitochondria,(7)hormone,(8)oxidoreductase,and(9)flavonoid bio-synthesis.Expression of the most genes in cell division,growth and death category,and flavonoid biosynthesis were down-regulated.Stimulus and defense response were obviously induced.The expression of fertility related genes,including BnSPL,BnROXY2,BnEMS1,BnTPD1,BnDYT1,BnTDF1,BnAMS,BnMYB103,BnMS1,were conducted through quantitative analysis and results found that the expression of all these genes were inhibited in different degrees.The results provide a basis for revealing the molecular mechanism of male sterility induced by chemical hybridizing agents.