会议名称：“2021世界木材日”研讨会暨第三届国际林联（IUFRO） 林产品文化研究组讨论会
会议时间：2021年3月21日

报告嘉宾：Roni Aloni
嘉宾简介：Professor emeritus of School of Plant Sciences and Food Security, Tel Aviv University

摘要：
The secondary xylem, namely, the wood, in trees is induced and controlled by streams of inductive hormonal signals which shape wood quality and quantity. Auxin is the primary hormonal signal that controls wood formation; it is mainly produced in young leaves, moves downward through the cambium and induces the wood. Cytokinin, from root tips moves upward, promotes cambial cell division activity, and increases the sensitivity of the cambium to the auxin signal. Gibberellin from maturing leaves promotes shoot elongation and induces long fibers and tracheids. Centrifugal movement of ethylene from differentiating-xylem cells outwards to the bark induces the radial vascular rays. In conifer trees, jasmonate-induced defence response, which is mediated by ethylene, induces the traumatic resin ducts. Large traumatic resin cavities that damage the wood in response to wounding and stress can be prevented by lowering the sensitivity to ethylene. Along the tree axis, gradients of decreasing auxin concentrations from leaves to roots induce gradients of increasing cell size. The juvenile wood in trees is induced by young leaves, while the adult wood is produced further away from these leaves. Therefore, to swift the transition from juvenile wood to the high-quality adult wood at the base of the trunk, fast stem elongation of young trees should be promoted. This can be achieved by growing young trees in high densities and by minimizing competition with annuals. Likewise, as root tips provoke juvenile effects in the shoot, fast root growth should be endorsed to minimize their effects. Rapid stem elongation and wood production can also be achieved by manipulating endogenous hormonal concentrations in transgenic trees. Elevating endogenous bioactive gibberellin concentrations in transgenic trees promotes stem elongation, increases fiber and tracheid growth, promotes wood production, and can modify lignin biosynthesis.

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