title: A global analysis of parenchyma tissue fractions in secondary xylem of seed plants.
abstract: Parenchyma is an important tissue in secondary xylem of seed plants, with functions ranging from storage to defence and with effects on the physical and mechanical properties of wood. Currently, we lack a large-scale quantitative analysis of ray parenchyma (RP) and axial parenchyma (AP) tissue fractions. Here, we use data from the literature on AP and RP fractions to investigate the potential relationships of climate and growth form with total ray and axial parenchyma fractions (RAP). We found a 29-fold variation in RAP fraction, which was more strongly related to temperature than with precipitation. Stem succulents had the highest RAP values (mean ± SD: 70.2 ± 22.0%), followed by lianas (50.1 ± 16.3%), angiosperm trees and shrubs (26.3 ± 12.4%), and conifers (7.6 ± 2.6%). Differences in RAP fraction between temperate and tropical angiosperm trees (21.1 ± 7.9% vs 36.2 ± 13.4%, respectively) are due to differences in the AP fraction, which is typically three times higher in tropical than in temperate trees, but not in RP fraction. Our results illustrate that both temperature and growth form are important drivers of RAP fractions. These findings should help pave the way to better understand the various functions of RAP in plants.
authors.affiliation: Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, D-89081, Ulm, Germany.
authors.forename: Hugh
authors.initials: H
authors.lastname: Morris
authors.affiliation: Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, D-89081, Ulm, Germany.
authors.forename: Lenka
authors.initials: L
authors.lastname: Plavcová
authors.affiliation: Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Albert-Einstein-Allee 11, D-89069, Ulm, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Cvecko
authors.affiliation: Institute of Agronomy in the Tropics, University of Göttingen, Grisebachstrasse 6, 37077, Göttingen, Germany.
authors.forename: Esther
authors.initials: E
authors.lastname: Fichtler
authors.affiliation: Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Albert-Einstein-Allee 11, D-89069, Ulm, Germany.
authors.forename: Mark A F
authors.initials: MA
authors.lastname: Gillingham
authors.affiliation: Département des Sciences Biologiques, Université du Québec à Montréal, UQÁM, CP 8888, Succ. Centre Ville Montréal, Montréal, QC, H3C 3P8, Canada.
authors.forename: Hugo I
authors.initials: HI
authors.lastname: Martínez-Cabrera
authors.affiliation: Department of Biology, College of Charleston, Charleston, SC, 29424, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: McGlinn
authors.affiliation: Department of Forest Biomaterials, NC State University Raleigh, Raleigh, NC, 27695-8005, USA.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Wheeler
authors.affiliation: Key Laboratory for Silviculture and Conservation of the Ministry of Education, Beijing Forestry University, Beijing, 100083, China.
authors.forename: Jingming
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
authors.forename: Kasia
authors.initials: K
authors.lastname: Ziemińska
authors.affiliation: Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, D-89081, Ulm, Germany.
authors.forename: Steven
authors.initials: S
authors.lastname: Jansen
mesh_terms: D002980:Climate; D019992:Databases as Topic; D019684:Magnoliopsida / Q000254:growth & development / Q000502:physiology; D058503:Mesophyll Cells / Q000166:cytology / Q000502:physiology*; D011891:Rain; D012639:Seeds / Q000502:physiology*; D018709:Statistics, Nonparametric; D013696:Temperature; D064028:Tracheophyta / Q000254:growth & development / Q000502:physiology; D014197:Trees / Q000502:physiology*; D014934:Wood / Q000502:physiology; D052584:Xylem / Q000166:cytology / Q000502:physiology*
keywords: angiosperms; axial parenchyma; conifers; growth form; mean annual precipitation; mean annual temperature; ray parenchyma; secondary xylem