³³P translocation in the thallus of the mat‐forming lichen Cladonia portentosa

Abstract

The extent of vertical migration of $$P in thalli of the heathland lichen Cladonia portentosa was investigated under field conditions. $$P-labelled orthophosphate was introduced into the bottom 25 mm of podetia cut to a length of 50 mm from the apices. The distribution of label was scanned using a molecular imager immediately after incubation, and after growing for 8 wk and 6 months. Differences in the relative distribution of label between podetia harvested at the beginning and the end of the experiment showed that there had been a significant migration of $$P upwards out of the labelled 25 mm stratum towards the apex. This was confirmed by statistically significant changes in the median (md) and the 90 percentile of total relative distribution of $$P label. In a control treatment in which label was introduced into the apical 25 mm of podetia, which were then grown inverted (top down), no upward movement of label was detected. By contrast, a statistically significant reduction in the md of the distribution indicated migration downwards towards the thallus apex. The results are consistent with the hypothesis that P is recycled within podetia of mat-forming lichens, migrating from degrading basal regions upwards to the growing apices following a source-sink relationship.

Response of the lichen-eating moth Cleorodes lichenaria larvae to varying amounts of usnic acid in the lichens

“…Many authors reported similar effects of lichen secondary metabolites by using polyphagus or generalist model species (Zukal 1895;Slansky 1979;Reutimann and Scheidegger 1987;Blewitt and Cooper-Driver 1990;Fahselt 1994;Giez et al 1994;Hyvärinen and Crittenden 2000;Gauslaa 2005;Pöykkö et al 2005;Lawrey 1983;Blewitt and Cooper-Driver 1990;Emmerich et al 1993;Giez et al 1994). Though in good accordance with these studies, our experiments are among the first to show that even specialized lichen feeders are negatively affected by usnic acid concentrations, which are typically found in widely distributed lichens (see also Pöykkö 2006Pöykkö , 2011a.…”

Growth, nitrogen uptake, and resource allocation in the two tripartite lichens Nephroma arcticum and Peltigera aphthosa during nitrogen stress

“…Alternatively, assimilation of externally added N might have been more active in the margins of the thallus compared to the main body. In support of the former hypothesis it has previously been found that phosphorus is reallocated from the basal zone to the growing apex of the lichen Cladonia portentosa (Hyvärinen & Crittenden, 2000), suggesting a symplastic movement of nutrients within lichens. These authors also put forward the hypothesis of re‐circulation of nutrients within lichen thalli, allocating N and phosphorus from older, nonactive, parts towards more actively growing parts following a sink/source model.…”

A single phosphorus treatment doubles growth of cyanobacterial lichen transplants

“…Our results also suggest further research into cyanolichen physiology by exploring Hyva¨rinen and Crittenden's (2000) suggestion of long-term within-thallus recycling of P. For example, how long can a pulse of P stimulate growth? How do N-fixation rates of cyanolichens respond to supplemental P?…”