Ultrastructure Changes Of Tobacco Leaf After Glyphosate Treatment And EPSPS Ⅰ Cloning

EPSPS which is Encoded by gene of EPSPS(5-enolpyruvlyshikimate-3-phyosphate synthase)is a key enzyme in the aromatic amino acid biosynthesis pathway in microorganisms and plants.EPSPS catalyzes the transfer of the en -olpyruvyl moiety ofphosphoenol pyruvate(PEP)to the 5-hydroxyl of shikim -ate-3-phosphate(S3P).Glyphosate is nonselective broad spectrum herbicide, which is harmful to plants and microorganisms and even lead death.EPSPS is is the target of the herbicide glyphosate.Glyphosate is a competitive inhibitor with respect to PEP and binds adjacent to S3P in the active-site of EPSPS,and block the production of aromatic amino acids.In this paper,3 research projects were proformed,and the results were summarized as follows:1,To study the effects of Glyphosate on tobacco leaf(Nicotiana tabacum L.cv.C176),we sprayed 30mmol/L Glyphosate and checked its effect on tobacco leaf at 2,6,12,24,48h after treatment,respectively.No significant damage was observed before the first 12h treatment.However,24 and 48h treatment resulted in bleached leaf with necrosis.Ultrastructure studies suggested that glyphosate mainly effects on leaf chloroplasts and mitochond -ria.Chloroplasts showed disorganized grana lamellae,while mitochondria were of low electron density.These results indicated that glyphosate affected photosynthesis and respiration,which might result in necrosis.2,Full CDS of TOBEPSPS I was cloned,next is sequence analysis and transformation.3,Optimised tobacco callus induction.The results suggested that leaf was the best explant.