Diverse Heat Tolerance of the Yeast Symbionts of Platycerus Stag Beetles in Japan

Xue-Jiao Zhu; Sheng-Nan Zhang; Kana Watanabe; Kako Kawakami; Noriko Kubota; Etsuro Takagi; Masahiko Tanahashi; Xiu-Jun Wen; Kôhei Kubota

doi:10.3389/fmicb.2021.793592

Diverse Heat Tolerance of the Yeast Symbionts of Platycerus Stag Beetles in Japan

Front Microbiol. 2022 Jan 7:12:793592. doi: 10.3389/fmicb.2021.793592. eCollection 2021.

Authors

Xue-Jiao Zhu^{1

2}, Sheng-Nan Zhang¹, Kana Watanabe¹, Kako Kawakami³, Noriko Kubota⁴, Etsuro Takagi^{3

5}, Masahiko Tanahashi^{6

7}, Xiu-Jun Wen², Kôhei Kubota¹

Affiliations

¹ Laboratory of Forest Zoology, Department of Forest Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
² Guandong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China.
³ Laboratory of Forest Zoology, Course of Applied Life Sciences, Faculty of Agriculture, The University of Tokyo, Tokyo, Japan.
⁴ Independent Researcher, Kashiwa, Japan.
⁵ Department of Tourism Science, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, Hachioji, Japan.
⁶ Department of Life Science, National Taiwan Normal University, Taipei, Taiwan.
⁷ Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.

Abstract

The genus Platycerus (Coleoptera: Lucanidae) is a small stag beetle group, which is adapted to cool-temperate deciduous broad-leaved forests in East Asia. Ten Platycerus species in Japan form a monophyletic clade endemic to Japan and inhabit species-specific climatic zones. They are reported to have co-evolutionary associations with their yeast symbionts of the genus Sheffersomyces based on host cytochrome oxidase subunit I (COI) and yeast intergenic spacer (IGS) phylogenies. Here we examined the heat tolerances of the yeast colonies isolated from the mycangia of 37 females belonging ten Japanese Platycerus species. The upper limits of growth and survival temperatures of each colony were decided by cultivating it at ten temperature levels between 17.5 and 40°C. Although both temperatures varied during 25.0-31.25°C, the maximum survival temperatures (MSTs) were a little higher than the maximum growth temperatures (MGTs) in 16 colonies. Pearson's correlations between these temperatures and environmental factors (elevation and 19 bioclimatic variables from Worldclim database) of host beetle collection sites were calculated. These temperatures were significantly correlated with elevation negatively, the maximum temperature of the warmest month (Bio5) positively, and some precipitative variables, especially in the warm season (Bio12, 13, 16, 18) negatively. Sympatric Platycerus kawadai and Platycerus albisomni share the same lineage of yeast symbionts that exhibit the same heat tolerance, but the elevational lower range limit of P. kawadai is higher than that of P. albisomni. Based on the field survey in their sympatric site, the maximum temperature of host wood of P. kawadai larvae is higher about 2-3°C than that of P. albisomni larvae in the summer, which may restrict the elevational range of P. kawadai to higher area. In conclusion, it is suggested that the heat tolerance of yeast symbionts restricts the habitat range of their host Platycerus species or/and that the environmental condition that host Platycerus species prefers affect the heat tolerance of its yeast symbionts.

Keywords: Scheffersomyces; environmental factor; host wood material; maximum growth temperature; maximum survival temperature.