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Root-synthesized cytokinins improve shoot growth and fruit yield in salinized tomato (Solanum lycopersicum L.) plants

Ghanem, Michel Edmond and Albacete, Alfonso and Smigocki, Ann C. and Frebort, Ivo and Pospisilova, Hana and Martinez-Andujar, Cristina and Acosta, Manuel and Sanchez-Bravo, Jose and Lutts, Stanley and Dodd, Ian C. and Perez-Alfocea, Francisco (2011) Root-synthesized cytokinins improve shoot growth and fruit yield in salinized tomato (Solanum lycopersicum L.) plants. Journal of Experimental Botany, 62 (1). pp. 125-140. ISSN 1460-2431

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Abstract

Salinity limits crop productivity, in part by decreasing shoot concentrations of the growth-promoting and senescence-delaying hormones cytokinins. Since constitutive cytokinin overproduction may have pleiotropic effects on plant development, two approaches assessed whether specific root-localized transgenic IPT (a key enzyme for cytokinin biosynthesis) gene expression could substantially improve tomato plant growth and yield under salinity: transient root IPT induction (HSP70::IPT) and grafting wild-type (WT) shoots onto a constitutive IPT-expressing rootstock (WT/35S::IPT). Transient root IPT induction increased root, xylem sap, and leaf bioactive cytokinin concentrations 2- to 3-fold without shoot IPT gene expression. Although IPT induction reduced root biomass (by 15%) in control (non-salinized) plants, in salinized plants (100 mM NaCl for 22 d), increased cytokinin concentrations delayed stomatal closure and leaf senescence and almost doubled shoot growth (compared with WT plants), with concomitant increases in the essential nutrient K+ (20%) and decreases in the toxic ion Na+ (by 30%) and abscisic acid (by 20-40%) concentrations in transpiring mature leaves. Similarly, WT/35S::IPT plants (scion/rootstock) grown with 75 mM NaCl for 90 d had higher fruit trans-zeatin concentrations (1.5- to 2-fold) and yielded 30% more than WT/non-transformed plants. Enhancing root cytokinin synthesis modified both shoot hormonal and ionic status, thus ameliorating salinity-induced decreases in growth and yield.

Item Type: Article
Journal or Publication Title: Journal of Experimental Botany
Uncontrolled Keywords: ABA ; cytokinins ; grafting ; IPT ; root zone temperature ; root to shoot signalling ; salinity ; Solanum lycopersicum ; DELAYED LEAF SENESCENCE ; ISOPENTENYL TRANSFERASE GENE ; TOBACCO PLANTS ; IPT GENE ; CUCUMBER COTYLEDONS ; MASS-SPECTROMETRY ; TRANSGENIC PLANTS ; HORMONAL CHANGES ; PLASMA-MEMBRANE ; SALT-TOLERANCE
Subjects: UNSPECIFIED
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 50442
Deposited By: ep_importer_pure
Deposited On: 19 Oct 2011 15:30
Refereed?: Yes
Published?: Published
Last Modified: 26 Oct 2013 00:04
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/50442

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