Calcium partitioning and allocation and blossom-end rot development in tomato plants in response to whole-plant and fruit-specific abscisic acid treatments.
The mechanisms regulating Ca(2+) partitioning and allocation in plants and fruit remain poorly understood. The objectives of this study were to determine Ca(2+) partitioning and allocation in tomato plants and fruit in response to whole-plant and fruit-specific abscisic acid (ABA) treatments, as well as to analyse the effect of changes in Ca(2+) partitioning and allocation on fruit susceptibility to the Ca(2+) deficiency disorder blossom-end rot (BER) under water stress conditions. Tomato plants of the cultivar Ace 55 (Vf) were grown in a greenhouse and exposed to low Ca(2+) conditions during fruit growth and development. Starting 1 day after pollination (DAP), the following treatments were initiated: (i) whole plants were sprayed weekly with deionized water (control) or (ii) with 500mg l(-1) ABA; or fruit on each plant were dipped weekly (iii) in deionized water (control) or (iv) in 500mg l(-1) ABA. At 15 DAP, BER was completely prevented by whole-plant or fruit-specific ABA treatments, whereas plants or fruit treated with water had 16-19% BER incidence. At 30 DAP, BER was prevented by the whole-plant ABA treatment, whereas fruit dipped in ABA had a 16% and water-treated plants or fruit had a 36-40% incidence of BER. The results showed that spraying the whole plant with ABA increases xylem sap flow and Ca(2+) movement into the fruit, resulting in higher fruit tissue and water-soluble apoplastic Ca(2+) concentrations that prevent BER development. Although fruit-specific ABA treatment had no effect on xylem sap flow rates or Ca(2+) movement into the fruit, it increased fruit tissue water-soluble apoplastic Ca(2+) concentrations and reduced fruit susceptibility to BER to a lesser extent.
Brazilian Agricultural Research Corporation, Embrapa Semiárido, Petrolina, PE, 56302-970, Brazil.
Sergio
S
Tonetto de Freitas
Andrew J
AJ
McElrone
Kenneth A
KA
Shackel
Elizabeth J
EJ
Mitcham
D000040:Abscisic Acid / Q000494:pharmacology*; D001692:Biological Transport; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D003681:Dehydration; D035264:Flowers; D005638:Fruit / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D018551:Solanum lycopersicum / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D010935:Plant Diseases / Q000517:prevention & control*; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D018547:Plant Stems / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D052584:Xylem / Q000187:drug effects / Q000254:growth & development / Q000502:physiology
D000040:Abscisic Acid; D002118:Calcium
ABA; apoplast; blossom-end rot; leakage; membrane; xylem sap.