title: Carbon isotope composition of latex does not reflect temporal variations of photosynthetic carbon isotope discrimination in rubber trees (Hevea brasiliensis).
abstract: Latex, the cytoplasm of laticiferous cells localized in the inner bark of rubber trees (Hevea brasiliensis Müll. Arg.), is collected by tapping the bark. Following tapping, latex flows out of the trunk and is regenerated, whereas in untapped trees, there is no natural exudation. It is still unknown whether the carbohydrates used for latex regeneration in tapped trees is coming from recent photosynthates or from stored carbohydrates, and in the former case, it is expected that latex carbon isotope composition of tapped trees will vary seasonally, whereas latex isotope composition of untapped trees will be more stable. Temporal variations of carbon isotope composition of trunk latex (δ(13)C-L), leaf soluble compounds (δ(13)C-S) and bulk leaf material (δ(13)C-B) collected from tapped and untapped 20-year-old trees were compared. A marked difference in δ(13)C-L was observed between tapped and untapped trees whatever the season. Trunk latex from tapped trees was more depleted (1.6‰ on average) with more variable δ(13)C values than those of untapped trees. δ(13)C-L was higher and more stable across seasons than δ(13)C-S and δ(13)C-B, with a maximum seasonal difference of 0.7‰ for tapped trees and 0.3‰ for untapped trees. δ(13)C-B was lower in tapped than in untapped trees, increasing from August (middle of the rainy season) to April (end of the dry season). Differences in δ(13)C-L and δ(13)C-B between tapped and untapped trees indicated that tapping affects the metabolism of both laticiferous cells and leaves. The lack of correlation between δ(13)C-L and δ(13)C-S suggests that recent photosynthates are mixed in the large pool of stored carbohydrates that are involved in latex regeneration after tapping.
authors.affiliation: Department of Horticulture, Faculty of Agriculture, Kasetsart University, 10900 Bangkok, Thailand Ecologie et Ecophysiologie Forestières, Faculté des Sciences, Université de Lorraine, UMR 1137, F-54506 Vandoeuvre-les-Nancy, France Ecologie et Ecophysiologie Forestières, Centre de Nancy - Lorraine, INRA, UMR 1137, F-54280 Champenoux, France.
authors.forename: Nicha
authors.initials: N
authors.lastname: Kanpanon
authors.affiliation: Department of Horticulture, Faculty of Agriculture, Kasetsart University, 10900 Bangkok, Thailand.
authors.forename: Poonpipope
authors.initials: P
authors.lastname: Kasemsap
authors.affiliation: CIRAD, UMR Eco&Sols, F-34060 Montpellier, France Hevea Research Platform in Partnership, Kasetsart University, Centre of Thai-French Cooperation on Higher Education and Research, 10900 Bangkok, Thailand.
authors.forename: Philippe
authors.initials: P
authors.lastname: Thaler
authors.affiliation: Department of Botany, Faculty of Science, Chulalongkorn University, 10330 Bangkok, Thailand.
authors.forename: Boonthida
authors.initials: B
authors.lastname: Kositsup
authors.affiliation: CIRAD, UMR Eco&Sols, F-34060 Montpellier, France Hevea Research Platform in Partnership, Kasetsart University, Centre of Thai-French Cooperation on Higher Education and Research, 10900 Bangkok, Thailand.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gay
authors.affiliation: Hevea Research Platform in Partnership, Kasetsart University, Centre of Thai-French Cooperation on Higher Education and Research, 10900 Bangkok, Thailand CIRAD, UPR Tree Crop-Based Systems, F-34000 Montpellier, France.
authors.forename: Régis
authors.initials: R
authors.lastname: Lacote
authors.affiliation: Ecologie et Ecophysiologie Forestières, Faculté des Sciences, Université de Lorraine, UMR 1137, F-54506 Vandoeuvre-les-Nancy, France Ecologie et Ecophysiologie Forestières, Centre de Nancy - Lorraine, INRA, UMR 1137, F-54280 Champenoux, France CIRAD, UMR Eco&Sols, F-34060 Montpellier, France daniel.epron@univ-lorraine.fr.
authors.forename: Daniel
authors.initials: D
authors.lastname: Epron
mesh_terms: D002244:Carbon / Q000737:chemistry / Q000378:metabolism*; D002247:Carbon Isotopes; D028482:Hevea / Q000737:chemistry* / Q000502:physiology*; D007840:Latex / Q000737:chemistry*; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000737:chemistry; D011891:Rain; D012621:Seasons; D013997:Time Factors
chemical_list: D002247:Carbon Isotopes; D007840:Latex; D002244:Carbon
keywords: latex regeneration; seasonality; storage; tapping; δ13C