title: Rootstock-mediated changes in xylem ionic and hormonal status are correlated with delayed leaf senescence, and increased leaf area and crop productivity in salinized tomato.
abstract: Tomato crop productivity under salinity can be improved by grafting cultivars onto salt-tolerant wild relatives, thus mediating the supply of root-derived ionic and hormonal factors that regulate leaf area and senescence. A tomato cultivar was grafted onto rootstocks from a population of recombinant inbred lines (RILs) derived from a Solanum lycopersicum x Solanum cheesmaniae cross and cultivated under moderate salinity (75 mM NaCl). Concentrations of Na(+), K(+) and several phytohormones [abscisic acid (ABA); the cytokinins (CKs) zeatin, Z; zeatin riboside, ZR; and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC)] were analysed in leaf xylem sap in graft combinations of contrasting vigour. Scion leaf area correlated with photosystem II (PSII) efficiency (F(v)/F(m)) and determined fruit productivity. Xylem K(+) (but not Na(+)), K(+)/Na(+), the active CK Z, the ratio with its storage form Z/ZR and especially the ratio between CKs and ACC (Z/ACC and Z + ZR/ACC) were positively loaded into the first principal component (PC) determining both leaf growth and PSII efficiency. In contrast, the ratio ACC/ABA was negatively correlated with leaf biomass. Although the underlying physiological mechanisms by which rootstocks mediate leaf area or chlorophyll fluorescence (and thus influence tomato salt tolerance) seem complex, a putative potassium-CK interaction involved in regulating both processes merits further attention.
authors.affiliation: CEBAS-CSIC, Campus de Espinardo, Espinardo, Murcia, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Albacete
authors.forename: Cristina
authors.initials: C
authors.lastname: Martínez-Andújar
authors.forename: Michel Edmond
authors.initials: ME
authors.lastname: Ghanem
authors.forename: Manuel
authors.initials: M
authors.lastname: Acosta
authors.forename: José
authors.initials: J
authors.lastname: Sánchez-Bravo
authors.forename: María J
authors.initials: MJ
authors.lastname: Asins
authors.forename: Jesús
authors.initials: J
authors.lastname: Cuartero
authors.forename: Stanley
authors.initials: S
authors.lastname: Lutts
authors.forename: Ian C
authors.initials: IC
authors.lastname: Dodd
authors.forename: Francisco
authors.initials: F
authors.lastname: Pérez-Alfocea
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000598:Amino Acids, Cyclic / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism; D018551:Solanum lycopersicum / Q000254:growth & development* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D025341:Principal Component Analysis; D055051:Salt-Tolerant Plants / Q000254:growth & development* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D052584:Xylem / Q000378:metabolism*
chemical_list: D000598:Amino Acids, Cyclic; D003583:Cytokinins; D010937:Plant Growth Regulators; C023863:1-aminocyclopropane-1-carboxylic acid; D000040:Abscisic Acid; D012964:Sodium; D011188:Potassium