UV radiation is the primary factor driving the variation in leaf phenolics across Chinese grasslands.

Litong Chen,Yan Geng,Jin-Sheng He,Zhaorong Mi,Yi Wu,Kechang Niu,Dan Fb Flynn

doi:10.1002/ece3.862

Abstract

Due to the role leaf phenolics in defending against ultraviolet B (UVB) under previously controlled conditions, we hypothesize that ultraviolet radiation (UVR) could be a primary factor driving the variation in leaf phenolics in plants over a large geographic scale. We measured leaf total phenolics, ultraviolet-absorbing compounds (UVAC), and corresponding leaf N, P, and specific leaf area (SLA) in 151 common species. These species were from 84 sites across the Tibetan Plateau and Inner Mongolian grasslands of China with contrasting UVR (354 vs. 161 mW/cm2 on average). Overall, leaf phenolics and UVAC were all significantly higher on the Tibetan Plateau than in the Inner Mongolian grasslands, independent of phylogenetic relationships between species. Regression analyses showed that the variation in leaf phenolics was strongly affected by climatic factors, particularly UVR, and soil attributes across all sites. Structural equation modeling (SEM) identified the primary role of UVR in determining leaf phenolic concentrations, after accounting for colinearities with altitude, climatic, and edaphic factors. In addition, phenolics correlated positively with UVAC and SLA, and negatively with leaf N and N: P. These relationships were steeper in the lower-elevation Inner Mongolian than on the Tibetan Plateau grasslands. Our data support that the variation in leaf phenolics is controlled mainly by UV radiation, implying high leaf phenolics facilitates the adaptation of plants to strong irradiation via its UV-screening and/or antioxidation functions, particularly on the Tibetan Plateau. Importantly, our results also suggest that leaf phenolics may influence on vegetation attributes and indirectly affect ecosystem processes by covarying with leaf functional traits.

Highlights

As a broad class of carbon-based secondary metabolites, leaf phenolics have received much attention due to their functional significances in plant ecological adaptation and evolution (Fraenkel 1959; Stafford 1991; Rozema et al.1997; Jansen et al 1998; Cockell and Knowland 1999; Agrawal and Fishbein 2008)
In the Inner Mongolian grasslands, leaf phenolics and ultraviolet-absorbing compounds (UVAC) ranged between 0.61–35.80 and 1.65–13.52 mg/g with an average of 7.44 and 6.08 mg/g, respectively
The mean of leaf phenolics on the Tibetan Plateau grasslands was over four time higher than those in the Inner Mongolian grasslands (32.36 vs. 7.44 mg/g) (Fig. 3A), and the mean of leaf UVAC on the Tibetan Plateau grasslands was almost two time higher than that in the Inner Mongolian grasslands (11.30 vs. 6.08 mg/g) (Fig. 3C)

Summary

Introduction

As a broad class of carbon-based secondary metabolites, leaf phenolics have received much attention due to their functional significances in plant ecological adaptation and evolution (Fraenkel 1959; Stafford 1991; Rozema et al.1997; Jansen et al 1998; Cockell and Knowland 1999; Agrawal and Fishbein 2008). Owing to their important roles in protecting plants from UV radiation, the functions of leaf phenolics have gained new interest (Agati and Tattini 2010; Pollastri and Tattini 2011). Leaf phenolics are likely to be key in the response of ecosystems to ongoing and future climate changes

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