What Makes the Wood? Exploring the Molecular Mechanisms of Xylem Acclimation in Hardwoods to an Ever-Changing Environment

Abstract

Wood, also designated as secondary xylem, is the major structure that gives trees and other woody plants stability for upright growth and maintains the water supply from the roots to all other plant tissues. Over recent decades, our understanding of the cellular processes of wood formation (xylogenesis) has substantially increased. Plants as sessile organisms face a multitude of abiotic stresses, e.g., heat, drought, salinity and limiting nutrient availability that require them to adjust their wood structure to maintain stability and water conductivity. Because of global climate change, more drastic and sudden changes in temperature and longer periods without precipitation are expected to impact tree productivity in the near future. Thus, it is essential to understand the process of wood formation in trees under stress. Many traits, such as vessel frequency and size, fiber thickness and density change in response to different environmental stimuli. Here, we provide an overview of our current understanding of how abiotic stress factors affect wood formation on the molecular level focussing on the genes that have been identified in these processes.

Response of Merlot Grapevine to Drought Is Associated to Adjustments of Growth and Nonstructural Carbohydrates Allocation in above and Underground Organs

“…This was confirmed by the lack of any significant correlation of root DMC (or any other morphological traits) with neither root starch nor soluble NSC content, respectively (Figure S2). Nevertheless, it is also conceivable that root DMC increased in Merlot grapevines under water deficit due to xylem anatomical changes, as it is well-known that drought affects xylogenesis by reducing cambial cell layers and vessel lumen [50][51][52]. These acclimatory modifications have been already demonstrated to occur in some grapevine varieties in organs such as dormant cane stem [53], mature stem [54,55] or leaf petiole [25,56].…”

Synergies and Entanglement in Secondary Cell Wall Development and Abiotic Stress Response in Trees

“…The effects of abiotic stresses on SCW biogenesis and wood formation have been covered in other reviews ( Moura et al, 2010 ; Houston et al, 2016 ; Camargo et al, 2019 ; Eckert et al, 2019 ). Although few studies have investigated the role of SCW synthesis genes in stress responses in trees, many transcriptomic studies suggest roles for SCW biosynthesis in both seasonal adaptations and abiotic stress responses, with consequential effects on biomass utilization ( Fox et al, 2017 ; Ployet et al, 2017 ; Wildhagen et al, 2017 ; Jokipii-Lukkari et al, 2018 ).…”

Physiological Responses to Abiotic and Biotic Stress in Forest Trees

“…The most likely reasons for sudden tree death are carbohydrate depletion or hydraulic failure. Here, Eckert et al [9] provide an overview on how hardwoods acclimate their hydraulic system to cope with environmental stresses. They explain the production of basic wood structures, focusing mainly on molecular regulation, and compile information on how these structures are influenced to maintain water flow under environmental constraints.…”