Juvenility of tobacco induced by cytokinin gene introduction decreases susceptibility to Tobacco necrosis virus and confers tolerance to oxidative stress

• DOI: 10.1016/j.pmpp.2004.10.006
• Publication Date: 2005-01-26T04:16:30Z
• Authors: Miklós Pogány; Julia Koehl; Ingrid Heiser; Erich F. Elstner; Balázs Barna
• Keywords: 0301 basic medicine; 03 medical and health sciences; 3. Good health

Abstract Tobacco necrosis virus (TNV) susceptibility of a cytokinin overproducing tobacco line (CTKm) transformed with a CaMV 35S :ipt gene construct was studied. Expression of the ipt gene was confirmed by RT-PCR. As a result of cytokinin excess caused by the transgene, senescence of CTKm plants was greatly delayed. The number of virus-induced necrotic lesions as well as the coat protein content were significantly lower in the transgenic tobacco, as compared with the control. Leaf discs of CTKm tobacco produced less ethylene and ethane upon inoculation with TNV, which indicated higher stress tolerance and lower level of lipid peroxidation. Diminished H 2 O 2 accumulation was observed in both uninoculated and TNV-infected CTKm tobacco leaves as compared to the SR 1 control line. The activity of three antioxidant enzymes (ascorbate peroxidase, glutathione S-transferase, catalase) and the amount of the non-enzymatic antioxidant ascorbic acid were markedly higher in healthy CTKm tobacco leaves and accordingly, CTKm tobacco leaves exhibited tolerance to oxidative stress induced by the herbicide paraquat as compared to control tobacco leaves. Therefore, inhibition of senescence resulting from cytokinin gene introduction confers more efficient reactive oxygen species (ROS) scavenging ability, which may attenuate lipid peroxidation and presumably contributes to the resistance against TNV-induced necrosis development.