Artificial Resynthesis of Thalli of the Cyanobacterial Lichen <i>Peltigera Praetextata</i> Under Laboratory Conditions

Stocker-Wörgötter, Elfie; Türk, Roman

doi:10.1017/s0024282991000294

Cited by 34 publications

(26 citation statements)

References 34 publications

(46 reference statements)

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“…New cephalodia can develop from hormogonia released by earlier cephalodia (Stocker-Wo$ rgo$ tter, 1995), ensuring cyanobiont homogeneity among cephalodia of a thallus. However, in a laboratory synthesis, cephalodia were formed by the attachment of hyphae from primordia (containing cyanobiont and mycobiont) to the green thallus (Stocker-Wo$ rgo$ tter & Turk, 1994). The latter mode of cephalodia development, if prevalent in nature, would cause considerable heterogeneity in symbiont populations within a single thallus, but this is not the case (see section IV.6).…”

Section: Cyanolichensmentioning

confidence: 99%

Tansley Review No. 116

2000

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Summary 449 I. INTRODUCTION 450 II. THE PARTNERS 451 1. Cyanobionts and their role 451 2. Hosts and their role 453 3. Location of cyanobionts in their hosts 455 III. INITIATION AND DEVELOPMENT OF SYMBIOSES 458 1. Initiation of symbioses 458 2. Geosiphon pyriforme 458 3. Cyanolichens 459 4. Liverworts and hornworts 460 5. Azolla 460 6. Cycads 461 7. Gunnera 461 IV. THE SYMBIOSES 462 1. Geographical distribution and ecological significance 462 2. Benefits to the partners 462 (a) Benefits to the cyanobionts 462 (b) Benefits to the hosts 463 3. Duration and stability 463 4. Mode of transmission and perpetuation 463 5. Recognition between the partners 464 6. Specificity and diversity 464 7. Symbiosis‐related genes 465 8. Modifications of the cyanobiont 466 (a) Growth and morphology 466 (b) Photosynthesis and carbon metabolism 467 (c) Glutamine synthetase 467 (d) Heterocysts 469 (e) N2fixation 470 9. Nutrient exchange 471 (a) Carbon 471 (b) Nitrogen 472 V. EVOLUTIONARY ASPECTS 472 VI. ARTIFICIAL SYMBIOSES 474 VII. FUTURE OUTLOOK AND PERSPECTIVES 475 1. Cryptic symbioses 476 2. Developmental profile of symbiotic tissues 476 3. Sensing and signalling 476 4. Genetic aspects 476 5. Physiological and biochemical aspects of nutrient exchange 477 6. Microaerobiosis 477 7. Potential applications 477 Acknowledgements 477 References 477 Cyanobacteria are an ancient, morphologically diverse group of prokaryotes with an oxygenic photosynthesis. Many cyanobacteria also possess the ability to fix N2. Although well suited to an independent existence in nature, some cyanobacteria occur in symbiosis with a wide range of hosts (protists, animals and plants). Among plants, such symbioses have independently evolved in phylogenetically diverse genera belonging to the algae, fungi, bryophytes, pteridophytes, gymnosperms and angiosperms. These are N2‐fixing symbioses involving heterocystous cyanobacteria, particularly Nostoc, as cyanobionts (cyanobacterial partners). A given host species associates with only a particular cyanobiont genus but such specificity does not extend to the strain level. The cyanobiont is located under a microaerobic environment in a variety of host organs and tissues (bladder, thalli and cephalodia in fungi; cavities in gametophytes of hornworts and liverworts or fronds of the Azolla sporophyte; coralloid roots in cycads; stem glands in Gunnera). Except for fungi, the hosts form these structures ahead of the cyanobiont infection. The symbiosis lasts for one generation except in Azolla and diatoms, in which it is perpetuated from generation to generation. Within each generation, multiple fresh infections occur as new symbiotic tissues and organs develop. The symbioses are stable over a wide range of environmental conditions, and sensing–signalling between partners ensures their synchronized growth and development. The cyanobiont population is kept constant in relation to the host biomass through controlled initiation and infection, nutrient supply and cell division. In most cases, the partners have remaine...

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Section: Cyanolichensmentioning

confidence: 99%

Tansley Review No. 116

2000

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“…In resynthesis studies both chlorosymbiodemes and cyanosymbiodemes have been obtained from isolated lichen bionts, and such studies have provided new information on the lichenization process (Stocker Woergoetter & Tuerk, 1994 ;Yoshimura et al, 1994). Natural photosymbiodemes have also been used as experimental models in comparing the ecophysiological performances of lichenized green algae and cyanobacteria under almost identical conditions of habitat, history and fungal association.…”

Section: mentioning

confidence: 99%

Cyanobiont specificity in some Nostoc‐containing lichens and in a Peltigera aphthosa photosymbiodeme

1998

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The cyanobacterial symbionts in some Nostoc-containing lichens were investigated using the nucleotide sequence of the highly variable cyanobacterial tRNA Leu (UAA) intron. When comparing different Nostoc-containing lichens, identical intron sequences were found in different samples of the same lichen species collected from two remote areas. This was true for all species where this comparison was made (Peltigera aphthosa (L.) Willd., P. canina (L.) Willd. and Nephroma arcticum (L.) Torss.). With one exception, a specific intron sequence was never found in more than one lichen species. However, for two of the species, Peltigera aphthosa and Nephroma arcticum, two different cyanobionts were found in different samples. By examining a P. aphthosa photosymbiodeme it could be shown that the same Nostoc is present in both bipartite and tripartite lobes of this lichen. It is thus possible for one cyanobiont\Nostoc to form the physiologically different symbioses that are found in bipartite and tripartite lichens. The connection between photobiont identity and secondary chemistry is discussed, as a correlation between differences in secondary chemistry and different cyanobionts\Nostocs in the species Peltigera neopolydactyla (Gyeln.) Gyeln. was observed. It is concluded that more knowledge concerning the photobiont will give us valuable information on many aspects of lichen biology.

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“…and P. leucophlebia (Nyl.) Gyelnik reveal that the development of the main, green cephalodiate thallus is initiated from a prothallus including Nostoc as the sole photobiont (Stocker-Wö rgö tter and Tü rk, 1994;Yoshimura et al, 1994), and this initial symbiotic stage involving cyanobacteria seems obligatory for all chlorophilous Peltigerineae (Holtan-Hartwig, 1996). The simultaneous symbioses between a mycobiont and one prokaryotic and one eukaryotic photobiont, combined with the exclusive or preferential symbiosis at different stages of the life history, with the cyanobacterium or the green alga, respectively, suggests that the selection of a photobiont is genetically controlled.…”

Section: Figmentioning

confidence: 99%

Characterization of Mycobionts of Photomorph Pairs in the Peltigerineae (Lichenized Ascomycetes) Based on Internal Transcribed Spacer Sequences of the Nuclear Ribosomal DNA

Goffinet

Bayer

1997

Fungal Genetics and Biology

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Goffinet, B., and Bayer, R. J. 1997. Characterization of mycobionts of photomorph pairs in the Peltigerineae (lichenized ascomycetes) based on internal transcribed spacer sequences of the nuclear ribosomal DNA. Fungal Genetics and Biology 21, 228-237. The The ''one fungus-two photomorphs'' hypothesis suggests that certain lichenized fungi can establish a symbiotic relationship with either a eukaryotic or a prokaryotic photobiont. Such pairs of photomorphs are well know from cephalodiate Peltigerineae. Using an ascomycete-specific primer we amplified the internal transcribed spacer region of the nrDNA repeat of the mycobiont from total ''lichen DNA'' extracts of Peltigera malacea, photomorphs of P. aphthosa, P. britannica, and P. leucophlebia, Nephroma expallidum, and photomorphs of N. arcticum. Comparisons of 5.8S sequences suggest that the sequences obtained belong to the mycobiont and thus, that the ascomycetespecific primer is adequate for amplifying fungal DNA from total lichen-DNA extracts. The strict identity of nucleotide sequences of the internal transcribed spacer region of the nrDNA repeat between joined-photomorphs supports the one fungus-two photomorphs hypothesis. Photomorphs may thus primarily reflect phenotypic plasticity of photomorphic fungi in response to changing environmental conditions. The cyanomorph recently reported for P. leucophlebia is shown to be based on a misidentified specimen of P. aphthosa. Comparisons of the ITS sequences further supports recognizing P. aphthosa, P. britannica, and P. leucophlebia at the species rather than the infraspecific level. r 1997 Academic Press

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Artificial Resynthesis of Thalli of the Cyanobacterial Lichen Peltigera Praetextata Under Laboratory Conditions

Cited by 34 publications

References 34 publications

Tansley Review No. 116

Tansley Review No. 116

Cyanobiont specificity in some Nostoc‐containing lichens and in a Peltigera aphthosa photosymbiodeme

Characterization of Mycobionts of Photomorph Pairs in the Peltigerineae (Lichenized Ascomycetes) Based on Internal Transcribed Spacer Sequences of the Nuclear Ribosomal DNA

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