Tobacco susceptibility to Potato virus YNTN infection is affected by grafting and endogenous cytokinin content

• Published in: Plant science (Limerick) Vol. 235; pp. 25 - 36
• Main Authors: Spoustová, Petra, Hýsková, Veronika, Müller, Karel, Schnablová, Renata, Ryšlavá, Helena, Čeřovská, Noemi, Malbeck, Jiří, Cvikrová, Milena, Synková, Helena
• Format: Journal Article
• Language: English
• Published: Elsevier Ireland Ltd 01.06.2015
• Subjects: Antioxidant system; Cytokinin; cytokinins; enzyme activity; genetically modified organisms; hydrogen peroxide; ipt gene; Malic enzyme; pathogens; Peroxidase; plant development; Potato virus A; roots; Salicylic acid; synergism; tobacco; viruses; Antioxidant system; C; T/C; PEPC; SA; BR; NADP-ME; R; ipt gene; SPOD; T; AOE; IBR; OG; APOD; Peroxidase; WCMV; GPOD; NBT; Salicylic acid; PPDK; Pssu; DAB; CK; SOD; F1; GR; F2; ipt; CMV; DAI; F3; Cytokinin; F4; Malic enzyme; CKX; C/C; CAT; ROS; NG; PVYNTN; TMV
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2015.02.017

•We studied response mechanisms of ipt tobacco to PVY infection from different views.•Overproduction of cytokinins increases plant tolerance to PVY.•Grafting plants prior infection increases plant tolerance to PVY.•Interaction of various plant response mechanisms to viral infection is suggested. Faster or stronger response to pathogen occurs if plants undergo prior priming. Cytokinins seem to be also involved in plant priming and in response to pathogens. Susceptibility to Potato virus YNTN (PVYNTN) was studied in transgenic cytokinin overproducing (Pssu-ipt) tobacco and compared with nontransgenic plants. Since cytokinin overproduction inhibits development of plant roots and grafting overcomes this limitation, both types were grown as rooted and/or grafted plants to check also the effect of grafting. Control rooted tobacco (C), the most susceptible to PVYNTN, showed always symptoms during the infection together with the rising virus content and a systemic response, such as accumulation of H2O2, salicylic acid (SA) and other phenolic acids, and stress-induced enzyme activities. In transgenic and grafted plants, the response to PVYNTN was dependent on protective mechanisms activated prior to the inoculation. In Pssu-ipt tobacco, cytokinin active forms and SA contents exceeded manifold their content in C. Grafting promoted the accumulation of phenolics, but SA, and stimulated peroxidase activities. Thus, the pre-infection barrier established in both transgenic and grafted plants helped to suppress partly the virus multiplication and resulted in milder symptom development. However, only the synergic effect of both grafting and the high cytokinins led to PVYNTN tolerance in transgenic grafts. Possible mechanisms were discussed.