Induction Of The Resistance Against Potato Virus Y By β-aminobutyric Acid And Its Mechanism

Potato Virus Y (PVY) is one of the most serious virus in the plant production process of potato and tobacco. Because of the extensive hosts, quick spread and complicated field symptoms, PVY was difficult to be identified and controlled. PVY could also mix-infected plants associated with other virus and caused serious decline in plant production and quality. So it is imminent to search for some efficient and practical measures as well as biological resistance inducer of PVY. β-aminobutyric acid (BABA) has been found as a valuable plant resistance inducer. In this experiment, the resistance against PVY induced by BABA in tobacco and its mechanism was analyzed. The main results showed as follows:1. The effects of BABA on tobacco resistance against PVY(1) BABA could induce resistance against PVY effectively. Considering the effect of resistance induction and the injury on tobacco of BABA,5mmol· L-1 is the optimal concentration of BABA in resistance induction on tobacco.(2) Treatment with 5mmol · L-1 BABA could obviously induce resistance against PVY on tobacco. It can delayed the virus-induced vein clearing in leaves by 3 to 4 days, inhibited the virus-induced necrosis in stems and the accumulation of PVY in plants. And the physiological symptoms are consistent with the results of molecular tests.2. The effects of BABA on hydrogen peroxide expression and gene expression of antioxidant enzymes in PVY-challenged tobacco plants.(1) BABA treatment could effectively regulate the reactive oxygen species homeostasis in tobacco, and activated the defense system of the plants while reducing the contents of H2O2.(2) BABA treatment could improve plants resistance against PVY via regulated the enzyme activities of POD, CAT in vivo.3. The effects of BABA on PR gene expression in PVY-challenged tobacco plantsBABA treatment could influence the gene expression of PR-la, PR-2a and PR-4a. And the Expression Levels of PR are correlated with the infection progress of PVY. The results suggested that BABA could improve resistance against PVY effectively by inducing the synthesis and expression of PR gene on tobacco.4. The effects of BABA on SA contents in PVY-challenged tobacco plantsThe peak occur time of SA content was earlier than the expression of protective enzyme gene and PR gene in tobacco with BABA treatment. The result suggested that SA act as a signaling molecule in the induction of defense gene expression in tobacco plants by BABA.