NorWood: a gene expression resource for evo-devo studies of conifer wood development.

Soile Jokipii-Lukkari,David Sundell,Ove Nilsson,Nathaniel R Street,Torgeir R Hvidsten,Hannele Tuominen

doi:10.1111/nph.14458

Soile Jokipii-Lukkari, David Sundell + Show 4 more

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https://doi.org/10.1111/nph.14458

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Abstract

Summary The secondary xylem of conifers is composed mainly of tracheids that differ anatomically and chemically from angiosperm xylem cells. There is currently no high‐spatial‐resolution data available profiling gene expression during wood formation for any coniferous species, which limits insight into tracheid development.RNA‐sequencing data from replicated, high‐spatial‐resolution section series throughout the cambial and woody tissues of Picea abies were used to generate the NorWood.conGenIE.org web resource, which facilitates exploration of the associated gene expression profiles and co‐expression networks.Integration within PlantGenIE.org enabled a comparative regulomics analysis, revealing divergent co‐expression networks between P. abies and the two angiosperm species Arabidopsis thaliana and Populus tremula for the secondary cell wall (SCW) master regulator NAC Class IIB transcription factors. The SCW cellulose synthase genes (CesAs) were located in the neighbourhoods of the NAC factors in A. thaliana and P. tremula, but not in P. abies. The NorWood co‐expression network enabled identification of potential SCW CesA regulators in P. abies.The NorWood web resource represents a powerful community tool for generating evo‐devo insights into the divergence of wood formation between angiosperms and gymnosperms and for advancing understanding of the regulation of wood development in P. abies.

Highlights

Conifers are woody plants representing the largest lineage of the ancient seed plant group of gymnosperms (Wang & Ran, 2014)
Gene expression analysis across P. abies wood revealed expression clusters associated with developmental transitions during wood formation
A high-spatial-resolution gene expression data resource was created in P. abies woody tissues representing developmental stages of cambial through to secondary xylem formation (Fig. 1a; Table S1)

Summary

Introduction

Conifers are woody plants representing the largest lineage of the ancient seed plant group of gymnosperms (Wang & Ran, 2014). Conifers are important producers of raw material for paper, solid fuels, liquid biofuels and biomaterials (Guo et al, 2015; Isikgor & Becer, 2015). The majority of conifer species are large, slow-growing trees. They share several properties with angiosperm trees, such as the formation of extensive secondary xylem (the ‘wood’), which facilitates water and nutrient transport in addition to mechanical support. There are striking anatomical differences in how these functions are achieved: while conifer wood consists mainly of single-celled tracheids that serve both water transport and physical support functions, angiosperm wood is composed of water-transporting multicellular conduits called vessels and libriform fibres, which provide structural support

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