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Desiccation‐induced changes in photochemical processes of photosynthesis and spectral reflectance in Nostoc commune ( C yanobacteria, N ostocales) colonies from polar regions
Author(s) -
Trnková Kateřina,
Barták Miloš
Publication year - 2017
Publication title -
phycological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.438
H-Index - 44
eISSN - 1440-1835
pISSN - 1322-0829
DOI - 10.1111/pre.12157
Subject(s) - desiccation , biology , photosynthesis , phycobiliprotein , dehydration , photosystem ii , nostoc , botany , relative humidity , cyanobacteria , chlorophyll fluorescence , reflectivity , bacteria , physics , biochemistry , genetics , thermodynamics , optics
SUMMARY Cyanobacterium Nostoc commune is a species highly resistant against desiccation. In this study, we investigated changes in photochemical processes of photosynthesis and spectral reflectance indices during controlled desiccation of the colonies from A ntarctica. In a dehydration process, water potential ( WP ) reached −3 MP a and values of potential ( F v / F m ) and effective quantum yields ( ΦPSII ) of photosystem II were kept to high value until 90% of water was lost from the colony, and these values decreased rapidly by further loss of water. This indicates that the colony loses water mostly from the exopolysaccharidic envelope, not from cells during the initial part of dehydration (relative water content, RWC = 100–10%). Other suggestions of inhibition of photosynthetic processes after 90% loss of water were the increase of the chlorophyll fluorescence parameter F p / F s . The F m ′ was higher than F m in hydrated colonies because of state transition which change energy distribution between PS I and PS II , but decreased to same level as F m in dehydrated colonies. The N ormalized D ifference V egetation I ndex ( NDVI ) and P hotochemical R eflectance I ndex ( PRI ) showed concave‐ and convex‐curvilinear relationship with RWC , respectively. The changes of NDVI values were, however, statistically insignificant. PRI values were predominantly below 0 because of phycobiliprotein involvement. These results were compared with the same species in the A rctic region. This is, according to our best knowledge, the first measurement of changes in spectral reflectance indices during desiccation of cyanobacteria.