Differences in monoterpene emission characteristics after ozone exposure between three clones representing major gene pools of <I>Cryptomeria japonica</I>

Abstract

Tropospheric ozone O 3 concentration has been increasing. The aim of this study was to compare the effect of O 3 exposure on monoterpene emission rate and the components of Japanese cedar Cryptomeria japonica between three major gene pools identified by population genetic structure analysis. At the O 3 -FACE Free-Air O 3 and CO 2 Enrichment facility, 1-year saplings of three clones of Japanese cedar Donden, Kawazu, and Yakushima were exposed to ambient double concentrations of O 3 . After 15 months of O 3 exposure experiment, monoterpene emission characteristics were evaluated by branch enclosure method using cutting samples of current-year leaves. Basal biogenic volatile organic compound emission rate E s was higher in the O 3 exposure plots, and two-way analysis of variance revealed an effect of the O 3 exposure p < 0.05 and an interaction between the O 3 exposure and clone p < 0.05 . Especially, high E s values were observed in the Yakushima after the O 3 exposure. In addition, the coefficient related to temperature sensitivity increased in the O 3 exposure plots p < 0.05 . Our findings supported the fact that there are large inter-clone variations in C. japonica. It is important to evaluate the differences in clones considering the genetic diversity and to clarify the mechanism of the differences after long-term moderate O 3 exposure.

Seasonal Changes in Interclone Variation Following Ozone Exposure on Three Major Gene Pools: An Analysis of Cryptomeria Japonica Clones

“…The ozone exposure experiment was conducted from May 2016 to January 2018. Since the monoterpene emission rate of the current-year leaves was significantly higher compared to the one-year leaves and because current-year leaves were sensitive to ozone exposure [11], current-year leaves (n = 6, approximately 100 mm in length, 0.5-1.0 g dry weight) in the control and ozone exposure groups were sampled in August 2017 and January 2018 [11].…”

“…In field measurement, current-year needle leaves were easily injured by the wind, and the injured leaves irregularly emitted high levels of monoterpene [11]. To evaluate the sensitivity of the monoterpene emission to temperature increases, it was necessary to adjust the temperature over a wide range.…”

“…The needle leaves were cut at the experimental facility, quickly supplied with water, and carried to the laboratory within 10 min for measurement of the monoterpene emission rate using the branch enclosure method ( Figure 2) [11,13]. Briefly, a transparent perfluoroalkoxy alkane bag was used for the branch enclosure method (JPBP0610; TGK, Japan, L = 150 mm × W = 250 mm).…”

“…Thus, it is important to evaluate the effect of ozone exposure on the monoterpene emission rate of C. japonica for human health in urban areas. Our previous report revealed that the monoterpene emission rate of a C. japonica clone of Yakushima remarkably increased after ozone exposure in the summer [11]. However, the influence of seasonal changes on interclone variation after ozone exposure has not been investigated.…”

“…In this study, we hypothesized that there is a difference in the ozone exposure effect on monoterpene emissions between the summer and winter for the three clones of C. japonica. Thus, we conducted ozone exposure experiments using the free-air ozone enrichment experimental facility in the winter and compared the results with those previously reported from the summer [11].…”