Metabolic Contributors to Drought-enhanced Accumulation of Sugars and Acids in Oranges

By B. Hockema, E. Etxeberria. 2001

83 citations recorded by the source corpus.

The nature of sink strength in orange fruit and changes occurring during drought stress were investigated. Potted trees of 'Hamlin' orange ( Citrus sinensis (L.) Osbeck) grafted on Troyer citrange (Citrus sinensis x Poncirus trifoliata (L.) Raf.) were irrigated using a microsprinkler system creating either well-watered or water-stressed conditions, as determined by stem water potentials. Fruit were harvested every other week from trees of both well- watered and drought-stressed treatments during the final stage of fruit development when sugars accumulate rapidly. Fruit quality indices and activities of sucrose synthase (SuSy), invertase, sucrose-P synthase, sucrose-P phosphatase, V- ATPase, and V-PPase were measured. Acids and soluble sugar concentrations were elevated in drought-stressed fruit, whereas juice pH decreased in those same fruit. Results indicate that increased sink strength in fruit from stressed trees was accompanied by an increase in SuSy activity and lowered juice pH. The remaining enzymes examined in this experiment showed no changes in activity between control and treated fruit, as was the case for plasmalemma and tonoplast sucrose carriers. Based on the present data, we conclude that SuSy and vacuolar pH are the predominant factors controlling photoassimilate accumulation in orange fruit under enhanced sink conditions brought about by imposition of a mild drought stress.

Subfields: Plant Science

View Paper: https://www.semanticscholar.org/paper/db427cce606b5fdc2f2a16dbc078305e048779f2

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In Plant Science

1. D. Iglesias
2. Manuel Talón
3. F. García-Sánchez
4. J. Syvertsen

Citations in the corpus

• Multiple abiotic stresses occurring with salinity stress in citrus (2014, background): “Mild drought stress can improve fruit quality (Hockema and Etxeberria, 2001).”
• Physiology of citrus fruiting (2007, background): “The physiological roles of organic acids are not clear; however, Hockema and Etxeberria (2001) suggested that low pH could result in enhanced sink strength, thus facilitating sugar accumulation.”
• Response of citrus trees to deficit irrigation during different phenological periods in relation to yield, fruit quality, and water productivity (2010, background): “Several works have shown that water stress exerts significant impact on some fruit organoleptic properties (Bielorai, 1982; Kuriyama et al., 1981; Yakushiji et al., 1998; Hockema and Etexeberria, 2001), showing that water stress increases TSS and TA in citrus.”
• Molecular physiology of development and quality of citrus (2008, background): “The physiological roles of organic acids are not clear; however, Hockema and Etxeberria (2001) suggested that low pH could result in enhanced sink strength, thus facilitating sugar accumulation.”
• Rootstocks and Plant Water Relations Affect Sugar Accumulation of Citrus Fruit Via Osmotic Adjustment (2004, background): “More recently, Hockema and Etxeberria (2001) demonstrated the involvement of sucrose hydrolyzing enzymes in this physiological process.”