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Title: Root-synthesised cytokinins induce salinity tolerance in tomato (Solanum lycopersicum L.)

Author
item GHANEM, MICHEL - Universite Catholique
item ALBACETE, ALFONSO - Centro De Edafologia Y Biologia Aplicada Del Segura (CEBAS)
item Smigocki, Anna
item FREBORT, IVO - Palacky University
item POSPISILOVA, HANA - Palacky University
item MARTINEZ-ANDUJAR, CRISTINA - Universite Catholique
item ACOSTA, MANUEL - Centro De Edafologia Y Biologia Aplicada Del Segura (CEBAS)
item SANCHEZ-BRAVO, JOSE - Centro De Edafologia Y Biologia Aplicada Del Segura (CEBAS)
item LUTTS, STANLEY - Universite Catholique
item DODD, IAN - Lancaster University
item PEREZ-ALFOCEA, FRANCISCO - Centro De Edafologia Y Biologia Aplicada Del Segura (CEBAS)

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2010
Publication Date: 10/19/2010
Citation: Ghanem, M.E., Albacete, A., Smigocki, A.C., Frebort, I., Pospisilova, H., Martinez-Andujar, C., Acosta, M., Sanchez-Bravo, J., Lutts, S., Dodd, I.C., Perez-Alfocea, F. 2010. Root-synthesised cytokinins induce salinity tolerance in tomato (Solanum lycopersicum L.). Journal of Experimental Botany. 62(1):125-140.

Interpretive Summary: Soil salinity decreases crop yield via multiple mechanisms. One of the mechanisms is a decrease in levels of a plant hormone that controls growth, death and insect resistance. Two approaches were used to evaluate whether extra production of this plant hormone in tomato roots could improve tomato growth in salty soils. Growing tomato plants that were capable of producing higher levels of the plant hormone in the roots increased their lifespan and almost doubled their growth rate that resulted in 30% higher tomato yields. This information will be used by scientists to develop genetically improved crops that can tolerate insect pests and increased soil salinity found in almost two billion acres worldwide.

Technical Abstract: Soil salinity decreases crop yield via multiple mechanisms, including decreasing concentrations of the growth-promoting, senescence-delaying and insect resistance-enhancing plant hormones cytokinins. Two approaches evaluated whether root-localised ipt (a key enzyme for cytokinin biosynthesis) gene expression could improve tomato growth under salinity: transient root ipt induction (hsp70::ipt plants exposed to elevated rootzone temperature-RZT) and grafting wild-type shoots onto an ipt-containing rootstock (WT/35S::ipt). Elevated RZT increased root, but not leaf, ipt expression and increased root and leaf bioactive cytokinin concentrations of induced hsp70::ipt plants 2-3 fold. Induction delayed leaf senescence and increased shoot growth (95%) of plants grown with 100 mM NaCl for 22 days, with concomitant increases (20%) and decreases (30%) in leaf K+ and Na+ concentrations, respectively. Similarly, WT/35S::ipt plants grown with 75 mM NaCl for 90 days had higher fruit cytokinin concentrations (50-100%) and yielded 30% more than self-grafted WT plants, indicating root-synthesised cytokinins improved yield of salinised tomato.