Ascospore discharge, germination and culture of fungal partners of tropical lichens, including the use of a novel culture technique

Abstract

A total of 292 lichen samples, representing over 200 species and at least 65 genera and 26 families, were collected, mainly in Thailand; 170 of the specimens discharged ascospores in the laboratory. Generally, crustose lichens exhibited the highest discharge rates and percentage germination. In contrast, foliose lichen samples, although having a high discharge rate, had a lower percentage germination than crustose species tested. A correlation with season was indicated for a number of species. Continued development of germinated ascospores into recognizable colonies in pure culture was followed for a selection of species. The most successful medium tried was 2 % Malt-Yeast extract agar (MYA), and under static conditions using a liquid culture medium, a sponge proved to be the best of several physical carriers tested; this novel method has considerable potential for experimental work with lichen mycobionts.

High-throughput genome sequencing of lichenizing fungi to assess gene loss in the ammonium transporter/ammonia permease gene family

“…Lichens can be seen as micro-communities, hosting not just the mycobiont (fungal) and photobiont (algal or cyanobacterial symbionts), but a rich internal microbiota composed of bacteria and endolichenic fungi [64,65]. As lichenizing fungi have only infrequently been successfully cultured compared to other fungi (although see [66,67]), and because it can take up to three years to produce enough tissue to extract sufficient DNA for a genome sequence, sequencing a metagenome from thalli taken directly from nature would greatly reduce the time required for a genome project, were the final product of useful quality. The lichens used for metagenomes here included two cyanolichens symbiotic with cyanobacteria, and two lichens symbiotic with green algae, one of which has a very tight association with the algal symbiont, and one of which produces large fungal fruiting stalks (podetia) essentially devoid of the algal symbiont.…”

Interface between fungi and green algae in lichen associations

“…In addition, endolichenic fungi and external fungal and bacterial contaminants are common (Arnold et al 2009;U'Ren et al 2010), making isolation and identification of the lichen fungus difficult to confirm. With improvements in culturing techniques having facilitated the use of lichen symbionts in experimental studies (Oliver et al 1989;Jahns 1993;Crittenden et al 1995;Stocker-Wörgötter 2001, 2002Sangvichien et al 2011;McDonald et al 2013;Athukorala et al 2014aAthukorala et al , 2014bAthukorala et al 2015) and the resynthesis of the lichen thalli the reintroduction of the symbionts in culture to produce the original controlled parasitic interaction, or complete thallus resynthesis in culture has been elusive in lichenology (Grube et al 2014). Challenges persist in the resynthesis of lichen symbionts and further experimentation with the symbionts (Grube et al 2014).…”

“…As these isolation methods developed, the challenge to find optimal growing conditions became a focus, since conditions that have been optimized for symbionts from one lichen species may not be suitable for other species Yoshimura et al 1993;Crittenden et al 1995;Sangvichien et al 2011;McDonald et al 2013). Suitable growing conditions are currently unknown for the symbionts of some of the physiologically obligate species (McDonald et al 2013).…”

Five new species and one new record ofAstrothelium(Trypetheliaceae, Ascomycota) from Thailand

“…The lichen mycobionts were isolated from fresh material by the ascospore discharge technique (Sangvichien et al 2011). Ascospore germination and cultivation of the mycobiont was carried out on Malt-Yeast Extract medium incubated at room temperature (32-35°C).…”