Experimental evidence for photosynthetic dependency of phloem sap generation in minor veins

Experimental evidence for photosynthetic dependency of phloem sap generation in minor veins | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 12 March 2025 V1 Latest version Share on Experimental evidence for photosynthetic dependency of phloem sap generation in minor veins Authors : Guillaume Tcherkez 0000-0002-3339-956X [email protected] , Louis Broussard , Corentin Dourmap , Cyril Abadie , Eric Gomès 0000-0003-2582-1203 , Sylvie Dinant , Joan Doidy 0000-0003-3966-3218 , Nathalie Pourtau , and Marilyn Ball 0000-0001-9170-940X Authors Info & Affiliations https://doi.org/10.22541/au.174175937.76431721/v1 Published Plant, Cell & Environment Version of record Peer review timeline 378 views 222 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Factors controlling plant photosynthesis and primary production include parameters dictating photosynthetic activity together with export and allocation properties. In fact, phloem loading activity as well as phloem sap redistribution and velocity are considered as important players in plant carbon acquisition. But surprisingly, there is almost no information about how phloem sap properties such as sugar concentration and velocity, are controlled by photosynthetic rate. Here, we carried out gas exchange experiments coupled to isotopic labelling on sunflower leaves to monitor photosynthate export rate when photosynthesis was varied with CO 2 mole fraction. We took advantage of a compartmental isotope model to obtain an experimental estimate of phloem sugar pool size and thus sap concentration and velocity. Phloem sugar concentration was found to increase relatively slowly (from very low values to about 1 mol L -1 ) with photosynthesis and export rate, while sap velocity remained in the same order of magnitude (0.2-0.6 mm s -1 ). This phenomenon could be explained using a simple one-dimensional model of phloem sap generation and movement suggesting that at fixed photosynthesis, phloem sap was in a steady-state reflecting the balance between xylem-to-phloem and sieve tube hydraulic conductance, turgor pressure and osmotic pressure due to loading. Our study also shows that phloem sap composition was not invariant with photosynthetic conditions but rather, adjusted to leaf export while maintaining sap flow even at very low CO 2 . Supplementary Material File (paper modelling minor vein mergedfigures1.docx) Download 3.07 MB Information & Authors Information Version history V1 Version 1 12 March 2025 Peer review timeline Published Plant, Cell & Environment Version of Record 4 Nov 2025 Published Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords export phloem sap phloem transport photosynthesis photosynthesis: carbon reactions sieve tube Authors Affiliations Guillaume Tcherkez 0000-0002-3339-956X [email protected] Australian National University Research School of Biology View all articles by this author Louis Broussard Institut de Recherche en Horticulture et Semences View all articles by this author Corentin Dourmap Institut de Recherche en Horticulture et Semences View all articles by this author Cyril Abadie Ecophysiologie et Genomique Fonctionnelle de la Vigne View all articles by this author Eric Gomès 0000-0003-2582-1203 Ecophysiologie et Genomique Fonctionnelle de la Vigne View all articles by this author Sylvie Dinant Institut Jean-Pierre Bourgin View all articles by this author Joan Doidy 0000-0003-3966-3218 Universite de Poitiers View all articles by this author Nathalie Pourtau Universite de Poitiers View all articles by this author Marilyn Ball 0000-0001-9170-940X Australian National University Research School of Biology View all articles by this author Metrics & Citations Metrics Article Usage 378 views 222 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Guillaume Tcherkez, Louis Broussard, Corentin Dourmap, et al. Experimental evidence for photosynthetic dependency of phloem sap generation in minor veins. Authorea . 12 March 2025. DOI: https://doi.org/10.22541/au.174175937.76431721/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . 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