Journal Article

Hormonal changes during salinity-induced leaf senescence in tomato (<i>Solanum lycopersicum</i> L.)

Michel Edmond Ghanem, Alfonso Albacete, Cristina Martínez-Andújar, Manuel Acosta, Remedios Romero-Aranda, Ian C. Dodd, Stanley Lutts and Francisco Pérez-Alfocea

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 11, pages 3039-3050
Published in print August 2008 | ISSN: 0022-0957
Published online June 2008 | e-ISSN: 1460-2431 | DOI:

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Leaf senescence is one of the most limiting factors to plant productivity under salinity. Both the accumulation of specific toxic ions (e.g. Na+) and changes in leaf hormone relations are involved in the regulation of this process. Tomato plants (Solanum lycopersicum L. cv Moneymaker) were cultivated for 3 weeks under high salinity (100 mM NaCl) and leaf senescence-related parameters were studied during leaf development in relation to Na+ and K+ contents and changes in abscisic acid (ABA), cytokinins, the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), and the auxin indole-3-acetic acid (IAA). Na+ accumulated to a similar extent in both leaves 4 and 5 (numbering from the base of the plant) and more quickly during the third week, while concurrently K+ contents sharply decreased. However, photosystem II efficiency, measured as the Fv/Fm ratio, decreased from the second week of salinization in leaf 4 but only at the end of the third week in the younger leaf 5. In the prematurely senescent leaf 4, ABA content increased linearly while IAA strongly decreased with salinization time. Although zeatin (Z) levels were scarcely affected by salinity, zeatin-riboside (ZR) and the total cytokinin content (Z+ZR) progressively decreased by 50% from the imposition of the stress. ACC was the only hormonal compound that increased in leaf tissue coincident with the onset of oxidative damage and the decline in chlorophyll fluorescence, and prior to massive Na+ accumulation. Indeed, (Z+ZR) and ACC contents and their ratio (Z+ZR/ACC) were the hormonal parameters best correlated with the onset and progression of leaf senescence. The influence of different hormonal changes on salt-induced leaf senescence is discussed.

Keywords: Abscisic acid; 1-aminocyclopropane-1-carboxylic acid; indole-3-acetic acid; plant hormones; salt stress; senescence; sodium chloride; tomato (Solanum lycopersicum L.); zeatin; zeatin-riboside

Journal Article.  7214 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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