PHYSIOLOGICAL‐ENVIRONMENTAL INTERACTIONS IN LICHENS

• Published in: New Phytologist
• Main Authors: MACFARLANE, J. D., KERSHAW, K. A., WEBBER, M. R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1983
• Subjects: Cladonia rangiferina
• Online Access: http://dx.doi.org/10.1111/j.1469-8137.1983.tb04495.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1469-8137.1983.tb04495.x; https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.1983.tb04495.x

SUMMARY Despite the contrasting thermal and light environment of sun and shade ecotypes of Cladonia rangiferina , analysis of the pattern of net photosynthesis throughout the year as well as enzyme polymorphism in each morphotype has found little genotypic difference. The large disparity between photosynthetic capacity in the sun and shade replicates is shown to be due simply to a difference in chlorophyll content. There is a significant decline in photosynthetic capacity in November and this is found to be reversible uncoupling of photosynthetic units (PU's) during the winter period. The control of coupling and uncoupling of PU's is shown to be mediated by both daylength and thallus temperatures, and a double environmental signal in June and July of short days coupled to low temperature will initiate and finalize the event within 12 h. This response pattern is discussed in relation to identical capacity changes in other lichen species. Apart from a single isoenzyme difference in esterase polymorphism, no differences in the zymograms of leucine aminopeptidase, phosphoglucoisomerase, or acid phosphatase were detected and this overall genetic homogeneity was equally evident in a general protein gel. This unexpected degree of homogeneity is discussed in terms of the difficulties in assessing enzyme polymorphisms in different plant populations without maximum refinement of protein preparation methods and electrophoretic techniques. It is concluded that the two quite distinct sun and shade morphotypes only reflect phenotypic differences. In contrast however significant differences are reported in the distribution of specific enzymes between the tops and bases of the podetia.