Species-specific responses of spectral reflectance and the photosynthetic characteristics in two selected Antarctic mosses to thallus desiccation
| Authors | |
|---|---|
| Year of publication | 2022 |
| Type | Article in Periodical |
| Magazine / Source | Acta Physiologiae Plantarum |
| MU Faculty or unit | |
| Citation | |
| web | článek ve formátu PDF |
| Doi | http://dx.doi.org/10.1007/s11738-021-03339-6 |
| Keywords | Antarctica; Dehydration; Rehydration; Chlorophyll fluorescence; Light response curves; Brachythecium austro-glareosum; Bryum pseudotriquetrum |
| Description | Mosses are considered highly resistant against desiccation because they maintain photosynthetic activity even when severely dehydrated. In our study, we investigated changes in the photochemical processes of photosynthesis, as well as the spectral reflectance parameters during controlled rehydration and desiccation in two Antarctic species, i.e. Brachythecium austro-glareosum and Bryum pseudotriquetrum. Changes in primary photochemical processes were evaluated by chlorophyll fluorescence, i.e. slow Kautsky kinetics supplemented with saturation light pulses. In desiccating thalli, an effective quantum yield of photosynthetic processes in PS II (phi(PSII)) remained unchanged within low to moderate desiccation, i.e. with a relative water content (RWC) decrease from fully wet (100%) to semidry (30%). Below 20% RWC, phi(PSII) showed a species-specific decline, as well as steady-state fluorescence (F-S). A half-decrease in phi(PSII) was reached at an RWC of 12.6% (B. austro-glareosum) and 9.8% (B. pseudotriquetrum). Rapid light-response curves showed a strong limitation of photosynthetic electron transport (ETR) at an RWC below 20% in both species. The phi(PSII) and ETR data suggested that both species were desiccation-tolerant and well adapted to harsh Antarctic environments. However, B. pseudotriquetrum was more resistant in a state of severe dehydration (RWC below 20%) than B. austro-glareosum. Spectral reflectance indices responded to desiccation either (a) similarly in the two species (normalised difference vegetation index [NDVI]), (b) with similar trends but different values (modified chlorophyll absorption in reflectance index [MCARI] and greenness index [GI]) and (c) species-specifically (photochemical reflectance index [PRI]). |
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