Artificial Reestablishment of Lichens. II. Secondary Products of Resynthesized Cladonia Cristatella and Lecanora Chrysoleuca

SUMMARYSuccessful resyntheses of the Cladonia cristatella mycobiont with its normal phycobiont and with Trebouxia isolates from 12 other species of lichens all produced the characteristic depside barbatic acid as the major secondary product. Many also produced the dibenzofuran didymic acid, but none yielded detectable amounts of the cortical pigment usnic acid. No characteristic lichen products were found in cultures of the C. cristatella mycobiont either alone, under a variety of cultural conditions, or mixed with Pseudotrebouxia phycobionts under the same conditions that led to successful resyntheses with Trebouxia phycobionts. Well-developed soredia from successful resyntheses of the Lecanora chrysoleuca mycobiont with Pseudotrebouxia phycobionts showed traces of usnic acid. The production of characteristic lichen products is affected primarily by the establishment of a successful symbiosis and secondarily by as yet poorly defined environmental factors. The formation of many characteristic lichen products may involve algal inhibition of fungal enzymes.