Climate sensitivity of Cryptomeria japonica in two contrasting environments: Perspectives from QTL mapping

RESEARCH ARTICLE Climate sensitivity of Cryptomeria japonica in two contrasting environments: Perspectives from QTL mapping Hideki MoriID*, Kana Yamashita, Shin-Taro Saiki, Asako Matsumoto, Tokuko Ujino-Ihara Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan * morih@ffpri.affrc.go.jp Abstract Long-lived forest tree species experience a wide range of environmental conditions through- out their lifespan. Evaluation of the underlying growth and development mechanisms of these species is essential to predict tree growth under climate change. This study investi- gated climate sensitivity to temperature, precipitation, dry periods, and the associated geno- mic regions in Cryptomeria japonica, Japan’s most commercially important tree. We used tree rings and common garden experiments with three clonal replicates planted in two con- trasting environments in Kyushu (Kumamoto site) and Honshu (Chiba site), Japan. Tree growth showed a significant negative correlation with the dry period (>4 days) in March of the year of tree-ring formation at the Chiba site. In contrast, temperature and precipitation had little influence on tree growth. Quantitative trait locus (QTL) analysis was performed to investigate climate sensitivity to dry periods at the Chiba site, revealing 13 significant QTLs. One QTL showed a substantially large contribution to the overall climate sensitivity, accounting for 12.4% of the total phenotypic variation. The phenotypic variance explained (PVE) by other QTLs ranged from 0.9% to 2.9%, and the total PVE by all QTLs was 35.6%.

These findings indicate that the tree population at the Chiba site could be vulnerable to drought in early spring and that the QTL showing the greatest impact on climate sensitivity may be closely related to genes associated with tolerance or adaptation to drought stress. The QTLs identified in this study could be useful for molecular breeding, forest manage- ment, and predicting the growth of C. japonica under a changing climate. 1. Introduction Longed-lived forest tree species, with their limited dispersal ability, experience various envi- ronmental changes throughout their lifespan. As extreme climatic events such as droughts and heatwaves are expected to increase as a result of ongoing climate change [1], evaluating the underlying genetic mechanisms that control growth and development of these species under changing climatic conditions is essential to understand the local adaptation abilities of tree species to predict tree growth, which is necessary for the effective forest management and breeding programs [2,3]. PLOS ONE | https://doi.org/10.1371/journal.pone.0228278 January 28, 2020 1 / 14 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Mori H, Yamashita K, Saiki S-T, Matsumoto A, Ujino-Ihara T (2020) Climate sensitivity of Cryptomeria japonica in two contrasting environments: Perspectives from QTL mapping. PLoS ONE 15(1): e0228278. https://doi. org/10.1371/journal.pone.0228278 Editor: Filippos A. Aravanopoulos, Aristotle University of Thessaloniki, GREECE Received: October 3, 2019 Accepted: January 12, 2020

Published: January 28, 2020 Copyright: © 2020 Mori et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: This study was supported by the Research Grant #201421 of the Forestry and Forest Products Research Institute to AM. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist.