AUTHOR=Hernandez Jonathan O. , An Ji Young , Combalicer Marilyn S. , Chun Jong-Pil , Oh Sang-Keun , Park Byung Bae 

TITLE=Morpho-Anatomical Traits and Soluble Sugar Concentration Largely Explain the Responses of Three Deciduous Tree Species to Progressive Water Stress

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.738301

DOI=10.3389/fpls.2021.738301

ISSN=1664-462X

ABSTRACT=<p>A better understanding of plant drought responses is essential to improve plant water use efficiency, productivity, and resilience to ever-changing climatic conditions. Here, we investigated the growth, morpho-anatomical, physiological, and biochemical responses of <italic>Quercus acutissima</italic> Carruth., <italic>Quercus serrata</italic> Murray, and <italic>Betula schmidtii</italic> Regel to progressive water-stress. Seedlings were subjected to well-watered (WW) and water-stressed (WS) conditions while regularly monitoring the soil volumetric water content, stem diameter (SD), height, biomass, stomatal conductance (g<sub>s</sub>), intercellular CO<sub>2</sub> concentration (C<sub>i</sub>), and leaf relative water content (RWC). We also investigated the variation in stomatal pore (SP) area, specific leaf area (SLA), root xylem vessel diameter (VD), and total soluble sugar (TSS) concentration between treatments. After 2 months, WS significantly suppressed SD growth of <italic>Q. acutissima</italic> and <italic>B. schmidtii</italic> but had no impact on <italic>Q. serrata</italic>. Total biomass significantly declined at WS-treated seedlings in all species. WS resulted in a smaller SLA than WW in all species. The SP of WS-treated seedlings of <italic>Q. acutissima</italic> and <italic>B. schmidtii</italic> significantly decreased, whereas it increased significantly with time in <italic>Q. serrata</italic>. Larger vessels (i.e., &gt;100 to ≤ 130) were more frequent at WS for <italic>Q. acutissima</italic> and <italic>B. schmidtii</italic>, whereas smaller vessels (i.e., &gt;40 to ≤ 90) were more frequent at WS than at WW for <italic>Q. serrata</italic> after 8 weeks. Tylosis was more frequent at WS than WW for <italic>Q. serrata</italic> and <italic>B. schmidtii</italic> at eighth week. WS seedlings showed lower g<sub>s</sub>, C<sub>i</sub>, and RWC compared with WW-treated ones in <italic>Q. acutissima</italic> and <italic>B. schmidtii</italic>. TSS concentration was also higher at WS-treated seedlings in two <italic>Quercus</italic> species. Overall, principal component analysis (PCA) showed that SLA and SP are associated with WS seedlings of <italic>Q. serrata</italic> and <italic>B. schmidtii</italic> and the tylosis frequency, TSS, and VD are associated with WS seedlings of <italic>Q. acutissima</italic>. Therefore, water-stressed plants from all species responded positively to water stress with increasing experimental duration and stress intensity, and that is largely explained by morpho-anatomical traits and soluble sugar concentration. The present study should enhance our understanding of drought-induced tree growth and short-term tree-seedling responses to drought.</p>