Changes in ploidy affect vascular allometry and hydraulic function in Mangifera indica trees |
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Authors: | Miguel Barceló-Anguiano N Michele Holbrook José I Hormaza Juan M Losada |
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Institution: | 1. Institute for Mediterranean and Subtropical Horticulture ‘La Mayora’ – CSIC – UMA, Avda. Dr. Wienberg s/n, Málaga, 29750 Spain;2. Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts, 02138 USA |
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Abstract: | The enucleated vascular elements of the xylem and the phloem offer an excellent system to test the effect of ploidy on plant function because variation in vascular geometry has a direct influence on transport efficiency. However, evaluations of conduit sizes in polyploid plants have remained elusive, most remarkably in woody species. We used a combination of molecular, physiological and microscopy techniques to model the hydraulic resistance between source and sinks in tetraploid and diploid mango trees. Tetraploids exhibited larger chloroplasts, mesophyll cells and stomatal guard cells, resulting in higher leaf elastic modulus and lower dehydration rates, despite the high water potentials of both ploidies in the field. Both the xylem and the phloem displayed a scaling of conduits with ploidy, revealing attenuated hydraulic resistance in tetraploids. Conspicuous wall hygroscopic moieties in the cells involved in transpiration and transport indicate a role in volumetric adjustments as a result of turgor change in both ploidies. In autotetraploids, the enlargement of organelles, cells and tissues, which are critical for water and photoassimilate transport at long distances, point to major physiological novelties associated with whole-genome duplication. |
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Keywords: | autotetraploid hydraulic resistance pectin phloem polyploidy xylem Mangifera indica |
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