Revisiting yield in terms of phloem transport to grains suggests phloem sap movement might be homeostatic.

Autor: Tcherkez G; Research School of Biology, Australian National University, Canberra, Australia.; Institut de Recherche en Horticulture et Semences, Université d'Angers, Beaucouzé, France., Holloway-Phillips M; Department of Environmental Sciences, Bernoulli Straße 32, University of Basel, Basel, Switzerland., Lothier J; Institut de Recherche en Horticulture et Semences, Université d'Angers, Beaucouzé, France., Limami A; Institut de Recherche en Horticulture et Semences, Université d'Angers, Beaucouzé, France., Ball MC; Research School of Biology, Australian National University, Canberra, Australia.
Jazyk: angličtina
Zdroj: Plant, cell & environment [Plant Cell Environ] 2023 Sep; Vol. 46 (9), pp. 2667-2679. Date of Electronic Publication: 2023 Jun 11.
DOI: 10.1111/pce.14646
Abstrakt: Phloem sap transport, velocity and allocation have been proposed to play a role in physiological limitations of crop yield, along with photosynthetic activity or water use efficiency. Although there is clear evidence that carbon allocation to grains effectively drives yield in cereals like wheat (as reflected by the harvest index), the influence of phloem transport rate and velocity is less clear. Here, we took advantage of previously published data on yield, respiration, carbon isotope composition, nitrogen content and water consumption in winter wheat cultivars grown across several sites with or without irrigation, to express grain production in terms of phloem sucrose transport and compare with xylem water transport. Our results suggest that phloem sucrose transport rate follows the same relationship with phloem N transport regardless of irrigation conditions and cultivars, and seems to depend mostly on grain weight (i.e., mg per grain). Depending on the assumption made for phloem sap sucrose concentration, either phloem sap velocity or its proportionality coefficient to xylem velocity change little with environmental conditions. Taken as a whole, phloem transport from leaves to grains seems to be homeostatic within a narrow range of values and following relationships with other plant physiological parameters across cultivars and conditions. This suggests that phloem transport per se is not a limitation for yield in wheat but rather, is controlled to sustain grain filling.
(© 2023 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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