Formation, chemical composition and function of suberin in poplar (Populus trichocarpa) roots
Plant Physiology
Final Report Abstract
We were able to establish an experimental pipeline including the propagation of plants in tissue culture, transplantation in soil with acclimatization, and the subsequent hydroponic cultivation by rooting of stem cuttings. The benefits of this procedure are the precise definition of root ages and developmental stages, growth of roots in the dark, and easy access to the developing root systems resulting in a high reproducibility of experimental results. Available protocols for histochemistry, chemical suberin analysis, and root transport investigation could successfully be adapted to be used with primary poplar roots cultivated in hydroponic conditions. Furthermore, we identified a significantly lower if not even missing endodermal suberization reaction of dicotyledonous poplar roots as a response to abiotic stress (drought and salt). This is very different from monocotyledonous and highly drought‐tolerant barley. If at all, it was especially the developing younger root tip region that showed a stress‐responsive endodermal suberization, which was not suberized in hydroponic control conditions. This phenomenon has not been described previously and it is very different from monocotyledonous species. This unique but surprisingly low overall suberization reaction of poplar in response to drought and salt stress as well as the significantly different reaction compared to drought‐ and salt‐tolerant barley, leads us to conclude that an enhancement of poplar root suberization in reaction to stress obtained by breeding or genetic modification should result in poplar cultivars being more stress‐tolerant. It was the low degree of endodermal suberization, also in response to abiotic drought and salt stress, which was most surprising. Available literature with a number of different species and especially experiments performed in our own laboratory with barley suggested that the employed stress treatments should result in a significant increase of suberization. However, this low stress‐responsiveness of root suberization processes in poplar might, in parts, explain its high drought and salt sensitivity. A second unforeseen phenomenon was the exclusive full suberization of root tips in response to high salt treatments. Root suberization is usually described as continuously increasing suberin deposition over the root length. This remarkable reaction in response to salt excess but not water deficit might point towards a pivotal role of suberin in conveying ionic stress rather than water loss resistance.
Publications
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Hydroponic cultivation conditions allowing the reproducible investigation of poplar root suberization and water transport. Plant Methods, 17(1).
Grünhofer, Paul; Guo, Yayu; Li, Ruili; Lin, Jinxing & Schreiber, Lukas
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Leaf morphology, wax composition, and residual (cuticular) transpiration of four poplar clones. Trees, 36(2), 645-658.
Grünhofer, Paul; Herzig, Lena & Schreiber, Lukas
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Suberin in Monocotyledonous Crop Plants: Structure and Function in Response to Abiotic Stresses. Signaling and Communication in Plants, 333-378. Springer International Publishing.
Grünhofer, Paul; Schreiber, Lukas & Kreszies, Tino
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Transcriptomic and epigenomic remodeling occurs during vascular cambium periodicity in Populus tomentosa. Horticulture Research, 8(1).
Chen, Bo; Xu, Huimin; Guo, Yayu; Grünhofer, Paul; Schreiber, Lukas; Lin, Jinxing & Li, Ruili
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Genome-wide analysis of long non-coding RNAs in shoot apical meristem and vascular cambium in Populus tomentosa. Journal of Plant Physiology, 275, 153759.
Guo, Yayu; Xu, Huimin; Chen, Bo; Grünhofer, Paul; Schreiber, Lukas; Lin, Jinxing & Zhao, Yuanyuan
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Increased cuticular wax deposition does not change residual foliar transpiration. Plant, Cell & Environment, 45(4), 1157-1171.
Grünhofer, Paul; Herzig, Lena; Sent, Sophie; Zeisler‐Diehl, Viktoria V. & Schreiber, Lukas
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Populus × canescens root suberization in reaction to osmotic and salt stress is limited to the developing younger root tip region. Physiologia Plantarum, 174(5).
Grünhofer, Paul; Stöcker, Tyll; Guo, Yayu; Li, Ruili; Lin, Jinxing; Ranathunge, Kosala; Schoof, Heiko & Schreiber, Lukas
