Differences in the sexual aposymbiotic phase of the reproductive cycles of Parmelina carporrhizans and P. quercina. Possible implications for their reproductive biology

Abstract

Our knowledge of ontogenetic development and reproductive biology in lichen-forming fungi is rather poor. Here, we aim to advance our understanding of the reproductive biology of Parmelina carporrhizans and P. quercina for which mycobiont fungi of both species were cultured in aposymbiotic conditions from ascospores. For P. carporrhizans 48 hours were necessary for 98·6% of apothecia to eject spores, while for P. quercina 100% of apothecia ejected spores in the first 24 hours. In P. quercina, large apothecia ejected more spores than smaller ones. In both species the percentage of spores germinating seemed independent of apothecium size. The percentage germination was higher in P. carporrhizans (72·4%) than in P. quercina (14·3%). Moreover, P. carporrhizans was grown more successfully on culture media than P. quercina. These results suggest that these species have different reproductive strategies, given that P. carporrhizans expels larger spores and in greater numbers than P. quercina as well as having different nutritional requirements (since P. carporrhizans grew successfully in the selected media but P. quercina did not). These characteristics may explain the sympatric speciation of these species.

The Temporal Variation of Secondary Metabolites in the Mycobiont Culture and Thallus of Parmelina carporrhizans and Parmelina quercina Analyzed using High-Performance Liquid Chromatography

“…The Petri dishes were covered with aluminum foil to ensure the total absence of photobionts, kept at 18-20 • C in the dark, and mycobiont cultures were periodically examined using a Nikon SMZ800 stereomicroscope and an Olympus CX40 microscope. The spores were ejected in groups of eight ascospores, and germination tubes were observed at four days after spore discharge [47]. Twenty-five to thirty days after spore discharge, a total of 90 agar pieces containing plurisporic mycelia of P. carporrhizans and a total of 35 agar pieces containing plurisporic mycelia of P. quercina were transferred to new plates containing three different types of nutrient-rich culture media: 0.2% glucose malt-yeast extract (0.2G-MY) prepared according to Molina et al [44], cornmeal agar (CMA) prepared following the manufacturer's instructions (Difco Laboratories, Detroit, MI, USA), and Lilly Barnett medium (LBM, [50]).…”

“…These two foliose and morphochemically similar species have differentiated ecological distributions and different reproductive behavior. The sexual reproduction of P. quercina is based on the production of higher and smaller sizes spores with lower germination rates compared with P. carporrhizans [47]. It has been suggested that the different reproductive strategies of these species are related to their distribution.…”

Axenic culture and biosynthesis of secondary compounds in lichen symbiotic fungi, the Parmeliaceae

“…Three samples from each species where used to select the apothecia. They had a size of 2-7 mm to ensure sexual maturity (Molina et al 1997;Alors et al 2019) and were carefully cleaned following the protocol described by Molina and Crespo (2000). Twenty apothecia per species (6 or 7 by thalli or sample) were used.…”