Monoxenic cultures of light sensitive arbuscular mycorrhizal fungi with Lunularia cruciata (Marchantiopsida)
Fonseca, Henrique M.A.C.; Berbara, Ricardo L.L.; Pereira, Maria L.
This study presents a new in vitro method to culture light-sensitive arbuscular mycorrhizal fungi with Lunularia cruciata. Mycothalli inoculated with Glomus clarum and Gigaspora margarita were successfully cultivated on 150 mL of dual-layer medium composed of macro- and micro-nutrients and without any of the growth promoters usually found in root organ cultures. The upper layer had the addition of 2 g L-1 of activated charcoal. Mature cultures of both fungi were obtained in less than 150 days and could be maintained viable for more than 500 days, with container size being the limiting factor for plant growth. Lunularia cruciata colonisation by both fungi showed the characteristic Paris -type morphology and was more abundant within the mycothalli's central midrib parenchyma cells than in other cells. For Gi. margarita the thallus colonisation was relatively small and shallow, suggesting a discrete distribution of the fungus within the plant and that penetration occurs mainly through new entry points of external hyphae, i.e., thallus-to-thallus penetration via appressorium. Conversely, for Gl. clarum higher colonisation was probably due to internal fungal growth along the midrib parenchyma, towards the new formed cells on the thallus' apical meristem.