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Non-hydraulic regulation of fruit growth of tomato plants rooted in drying soil.

Mingo, Darren M. and Bacon, Mark A. and Davies, William J. (2003) Non-hydraulic regulation of fruit growth of tomato plants rooted in drying soil. Journal of Experimental Botany, 54 (385). pp. 1205-1212. ISSN 1460-2431

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Abstract

Tomato (Lycopersicon esculentum cv. Solairo) fruit growth, fruit mesocarp and leaf epidermal cell turgor, and fruit and leaf sub-epidermal apoplastic pH were monitored as plants were allowed to dry the soil in which they were rooted. Soil drying regimes involved splitting the root system of plants between two halves of a single pot separated by a solid impervious membrane to form a split-root system. Plants were then allowed to dry the soil in both halves of the pot (a soil-drying (SD) treatment) or water was supplied to one-half of the pot (a partial root-drying (PRD) treatment), allowing only one-half of the root system to dry the soil. A well-watered control treatment watered the soil on both halves of the pot. The rate of fruit growth was highly correlated with the soil water content of both sides of the SD treatment and the dry side of the PRD treatment. Soil drying caused a significant restriction in fruit growth rate, which was independent of any changes in the turgor of expanding fruit mesocarp cells in the PRD treatment. By supplying water to half of the root system, the turgors of mesocarp cells were maintained at values above those recorded in well-watered controls. The turgor of leaf epidermal cells exhibited a similar response. The pH of the sub-epidermal apoplastic compartment in leaves and fruit increased with soil drying. The dynamics of this increase in leaves and fruit were identical, suggesting free transport of this signal from shoot to fruit. Fruit growth rate and sub-epidermal pH within the fruit showed a strong correlation. The similarity of fruit growth response in the SD and PRD treatment, suggests that tomato plants respond to a discrete measure of soil water status and do not integrate measures to determine total soil water availability. The results of this study are not consistent with Lockhartian models of growth regulation in expanding fruit of a higher plant. A non-hydraulic, chemical-based signalling control of fruit growth in plants growing in drying soil is proposed.

Item Type: Article
Journal or Publication Title: Journal of Experimental Botany
Uncontrolled Keywords: ABA ; chemical signalling ; hydraulic regulation ; pH ; PRD ; tomato ; turgor.
Subjects: Q Science > QH Natural history > QH301 Biology
Departments: Faculty of Science and Technology > Lancaster Environment Centre
Faculty of Science and Technology
VC's Office
ID Code: 8887
Deposited By: Prof William J Davies
Deposited On: 16 May 2008 13:18
Refereed?: Yes
Published?: Published
Last Modified: 06 Sep 2013 21:12
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/8887

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