Coenogonium: A Green Algal Lichen Without Photosynthetic Depression at High Water Contents

Thomas, Michael A.; Nash, Thomas H.; Tucker, Shirley C.

doi:10.1017/s0024282996000448

Cited by 3 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4j). This thallus structure is probably the morphological–anatomical reason why photosynthetic limitation by suprasaturation hardly occurred in Coenogonium interplexum in the study of Thomas et al . (1996) and occurred only to a small extent in the present study.…”

mentioning

confidence: 75%

Functional characteristics of corticolous lichens in the understory of a tropical lowland rain forest

2006

View full text Add to dashboard Cite

Summary• In tropical lowland forests, corticolous crustose green algal lichens are abundant and highly diverse. This may be related to adaptation to prevailing microenvironmental conditions including, for example, high precipitation and low light intensities.• In the understory of a tropical lowland rain forest in French Guiana, we studied the morphology of crustose green algal lichens and measured gas exchange and chlorophyll a fluorescence.• We found that (i) periods of thallus suprasaturation with water were reduced by the presence of water-repelling surface structures of mycobiont hyphae at the thallus surface and the medulla; (ii) photosynthesis was adapted to the low light intensities present in the understory; and (iii) photosynthesis was rapidly activated in fluctuating light.• The combination of these three mechanisms enables corticolous lichens to implement specific morphological and physiological strategies, which may favour growth in the limiting understory habitat of tropical lowland rain forests.

show abstract

mentioning

confidence: 75%

Functional characteristics of corticolous lichens in the understory of a tropical lowland rain forest

2006

View full text Add to dashboard Cite

show abstract

“…However, the extent of this depression diers from species to species and there are lichens which do not show it at all (see Lange et al 1995). The reason for this variation in performance is not known; structural, physical and biochemical features have been discussed as possible contributors (see Green et al 1985;Lange et al 1994;Thomas et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Do secondary substances in the thallus of a lichen promote CO 2 diffusion and prevent depression of net photosynthesis at high water content?

et al. 1997

View full text Add to dashboard Cite

Many lichens show seriously depressed net photosynthesis (NP) at high thallus water contents due to increased carbon dioxide diusion resistance through blockage of diusion pathways by water. The soil lichen Diploschistes muscorum, however, shows no depression and NP is close to maximal even at the highest thallus water content. We investigated whether lichen substances (lecanoric and diploschistesic acids) in the cortex and medulla contributed to this ability to maintain high NP. Dry thalli were extracted with water-free acetone and, after this treatment, were found to be fully viable to the extent of continued growth after replanting in the ®eld. No dierences were found in the response of NP to thallus water content between the normal and extracted thalli, in fact the response curves were often nearly identical. Thus, in this species it seems that lichen substances did not maintain the water-free diusion pathways and some other explanation, possibly structural, needs to be sought.

show abstract

Water Storage in the Lichen Family Umbilicariaceae

Valladares¹,

Sancho

Ascaso³

1998

Botanica Acta

View full text Add to dashboard Cite

Quantitative relationships between thallus structure and water storage and retention capacities in 12 species of the lichen family Umbilicariaceae were explored using three recent techniques for plant structure analysis: stereology (3D quantification of microscopic images), mercury intrusion porosimetry (determination of pore size distribution of tissues) and lowtemperature scanning electron microscopy (LTSEM). Water storage capacity of the thallus was related neither to thallus density nor surface area of the thallus; it was directly related to the total porosity of the thallus and inversely related to the proportion of thallus volume occupied by cell walls and gelatinous substances. Water retention capacity increased with increasing thallus density and was decreased by slight increases in the surface area of the upper side of the thallus. Water storage and retention capacities exhibited a positive correlation only when the storage capacity was expressed on a surface area basis. LTSEM study of fully hydrated specimens revealed that many intercellular spaces of the upper cortex and upper parts of the algal layer contained liquid water. Intercellular spaces of the lower part of the algal layer and medulla were in general either airfilled or partially occupied by gelatinous substances. Species with rhizinomorphs and substrate-hygrophytic (water uptake from surface run-offs) stored more water and retained it longer than aerohygrophytic species (water uptake from the atmosphere) lacking rhlzlnornorphs. Thallus structure of aerohygrophytic species seems to facilitate rapid gas exchange with the environment, improving water uptake and carbon gain when atmospheric moisture is available but accelerating dehydration when the atmosphere becomes dry.

show abstract

Coenogonium: A Green Algal Lichen Without Photosynthetic Depression at High Water Contents

Cited by 3 publications

References 0 publications

Functional characteristics of corticolous lichens in the understory of a tropical lowland rain forest

Functional characteristics of corticolous lichens in the understory of a tropical lowland rain forest

Do secondary substances in the thallus of a lichen promote CO 2 diffusion and prevent depression of net photosynthesis at high water content?

Water Storage in the Lichen Family Umbilicariaceae

Contact Info

Product

Resources

About