Study On β-amino Butyric Acid Induce Tobacco Against Low Potassium Stress And TMV Infection

β-amino-butyric acid （BABA） is a non-protein amino acid with asimple structure that can induce plant resist various biotic and abioticstresses in plants. This paper studied on BABA protecting tobacco againstlow potassium stress and infection of TMV with tobacco yunyan87and97asmaterials. The results showed that the effect of BABA is highlycorresponding to its concentration. The concentration of BABA both safeand effective to tobacco is5mmol/L.The study of BABA inducing tobacco against low potassium stressdemonstrated that, after BABA treated, root length, fresh weight andChlorophyll content of tobacco increased compared with the control. All theresults showed that BABA promotes tobacco growth. Under low potassiumstress, Potassium content in the tobacco leaves increased after BABAtreatment. QRT-PCR analysis showed that potassium up-taking relatedprotein genes NtHAK, NtLKS, NKT1and NtKC were induced to expressincreasingly by low potassium stress and BABA induction. The resultshowed that the increased expressions of the NtHAK, NtLKS, NKTI, NKCgenes via BABA induction are consistented with potassium content increase.Tobacco free proline content, peroxidase activity and catalase activity wereimproved after BABA treatment, and the effect is more obvious under lowpotassium stress. The results, DAB histochemical staining and quantificationanalysis of H₂O₂,showed that both BABA and low potassium stress couldlead to H₂O₂formation, BABA induced the protection effect of theantioxidant enzymes system and enhanced the resistance to low potassiumstress. Together, BABA may via molecular regulation of potassiumup-taking related genes and mechanism of reactive oxygenspecies-dependened induce tobacco against low potassium stress.With yunyan87as materials, BABA to TMV inhibition rate andmorbidity rate were investigated under the conditions of both artificialinoculation of TMV in the laboratory and natural incidence in the field. Theresults showed that5mmol/L BABA could effectively reduce the incidenceof tobacco. After BABA treatment, the allergic reaction induced by BABAwas measured with histochemistry method, the generation of H₂O₂was measured by DAB histochemical position staining and the activity of PALwas measured. Pathogenesis related （PR） proteins was measured bySDS-PAGE, and PR protein gene expression was detected by QRT-PCR. Allresults suggested that BABA treatment could obviously induce oxygen toburst, cause hypersensitive response. The activity of PAL in leaves wasimproved remarkably after BABA treatment, and a possible PR protein,whose molecular weight is20KD, was found. Besides, the expression of PR1and PR3genes were induced. In conclusion, appropriate concentrationBABA enhances the resistance to TMV, protecting tobacco against infectionof TMV.