A glycoprotein elicitor from a hypovirulent strain of Alternaria alternata activates pathogen defense pathway in tobacco

Tobacco plants treated with a glycoprotein elicitor from the hypovirulent strain TBA 16 of Alternaria alternata, the pathogen that causes brown spot in tobacco,displayed a decreased catalase (CAT) activity and an increased hydrogen peroxide (H 2O 2) content,similarly as did plants treated with salicylic acid(a positive control), compared with the negative control (treatment with sterilized water).CAT activity began to decline one day and got to the lowest level at the sixth day,while H 2O 2 content elevated continuously and reached to the highest level ten days after induction.Application of the elicitor to tobacco induced expression of PR 1b ,a gene encoding basic pathogenesis related protein 1b.Treatment of tobacco with the elicitor induced systemic resistance to the virulent strain TBA28 of the pathogen.