Experimental inoculation of Terminalia catappa seedlings with an environmental isolate of Cryptococcus neoformans var. gattii serotype C .

Abstract

In 1997, our laboratory reported for the first time the isolation of Cryptococcus neoformans var. gattii serotype C associated with almond tree (Terminalia catappa) detritus. This finding led to a more detailed follow up of the association between the plant and the yeast. Preliminary data have shown that survival of the yeast in almond trees seedlings goes beyond 100 days. The aim of the present study was to establish if under the conditions previously studied, C. neoformans var. gattii would remain viable for longer periods. A total of 83 almond tree seedings, 20-40 cm high, were inoculated with C. neoformans var. gattii serotype C (INS-755). Assays were carried out inoculating the stem or the soil where the seedlings were planted. Observations were undertaken for a period of up to 12 months. As processing techniques we employed the endophytic fungi procedure (stems), maceration (roots, leaves) and standard suspension method (soils). Additionally, microscopic visualization of the yeast in plant tissues was done with trypan blue plus lactophenol. C. neoformans var. gattii was recovered from the inoculated plants for a period of up to 12 months post-inoculation; additionally, the fungus had the capacity to migrate from the stem to the soil and viceversa, without causing macroscopic or microscopic alterations in the plant tissues. This finding suggests that there appears to be an association between the host plant and C. neoformans var. gattii in the environment.