Dissipation of excess excitation energy of the needle leaves in Pinus trees during cold winters.

Ao Zhang,Zi-Ling Hu,Zhen-Hai Cui,Rui Ding,Da-Ming Ren,Jia-Lin Yu,Li-Jun Zhang

doi:10.1007/s00484-016-1182-3

Abstract

Photooxidative damage to the needle leaves of evergreen trees results from the absorption of excess excitation energy. Efficient dissipation of this energy is essential to prevent photodamage. In this study, we determined the fluorescence transients, absorption spectra, chlorophyll contents, chlorophyll a/b ratios, and relative membrane permeabilities of needle leaves of Pinus koraiensis, Pinus tabulaeformis, and Pinus armandi in both cold winter and summer. We observed a dramatic decrease in the maximum fluorescence (F m) and substantial absorption of light energy in winter leaves of all three species. The F m decline was not correlated with a decrease in light absorption or with changes in chlorophyll content and chlorophyll a/b ratio. The results suggested that the winter leaves dissipated a large amount of excess energy as heat. Because the cold winter leaves had lost normal physiological function, the heat dissipation depended solely on changes in the photosystem II supercomplex rather than the xanthophyll cycle. These findings imply that more attention should be paid to heat dissipation via changes in the photosystem complex structure during the growing season.

Highlights

Evergreen pine (Pinus spp.) trees are widely distributed throughout the world and play important ecological roles
For heat dissipation during the growth season, the excess energy is released via the xanthophyll cycle (Eskling et al 1997; Jahns and Holzwarth 2012), which involves the enzymatic interconversion between violaxanthin and zeaxanthin in higher plants and depends on the pH differential across the thylakoid membrane (Bratt et al 1995; Büch et al 1995)
The plants used in this study were specimens of Pinus koraiensis, Pinus tabulaeformis, and Pinus armandi growing in the botanic garden of Shenyang Agricultural University, Shenyang city, Liaoning Province, China (41° 82′ N, 123° 56′ E)

Summary

Introduction

Evergreen pine (Pinus spp.) trees are widely distributed throughout the world and play important ecological roles. The excess energy absorbed by plant leaves is dissipated as fluorescence and heat (Allahverdiyeva and Aro 2012). For heat dissipation during the growth season, the excess energy is released via the xanthophyll cycle (Eskling et al 1997; Jahns and Holzwarth 2012), which involves the enzymatic interconversion between violaxanthin and zeaxanthin in higher plants and depends on the pH differential across the thylakoid membrane (Bratt et al 1995; Büch et al 1995).

Results

Conclusion