Seasonal dynamics of xanthophyll cycle pigments in lichen Xanthoria parietina.
| Authors | |
|---|---|
| Year of publication | 2005 |
| Type | Article in Proceedings |
| Conference | 11th Congress of the European Society for Photobiology, September 3-8 - Book of Abstracts |
| MU Faculty or unit | |
| Citation | |
| Field | Botany |
| Keywords | zeaxanthin chlorophyll fluorescence photoinhibition field study photoprotection |
| Description | Lichen photobionts possess various photoprotective mechanisms. One of these is xanthophyll cycle. Protective roles of xanthophylls include heat dissipation of excess energy and scavenging of reactive oxygen species. Zeaxanthin (Z) content and total xanthophyll pool content (violaxanthin, antheraxanthin, zeaxanthin - VAZ) rise under such conditions when the amount of absorbed light energy exceeds the energy that can be utilized in metabolic processes. To evaluate seasonal dynamics, we collected thalli of X. parietina on 10 collection dates during the period from March 2003 to February 2004 and determined xanthophyll cycle pigments and chlorophyll (Chl) a and b, by HPLC. Additionally, the functionality of photosynthetic apparatus was monitored by several Chl fluorescence parameters. The thalli collected in winter contained low amounts of VAZ. During spring, VAZ pool increased, with a peak found in early May. In summer and early autumn, the VAZ content was constant, followed by a decrease from late autumn until winter solstice. The de-epoxidation state of xanthophyll cycle pigments (DEPS, calculated as Z/(V+A+Z)) and maximal quantum yield of photosystem II (FV/FM) showed similar dynamics during majority of the year. The Z content closely followed the DEPS. Total Chl content increased from the end of March to a maximum found in winter. The Chl a/b ratio rose from winter to summer. Obtained data show that the X. parietina photobiont acclimates to seasonal changes in the site microclimate of well-lit habitats. |
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