The transcriptome of Aspergillus niger was analysed during germination of conidia in the absence or presence of the antifungal compound natamycin. Early germination was accompanied by a reduction in cellular microviscosity and a drop in mannitol and trehalose levels. During 8 hours, normal germlings grew isotropically, followed by polarized growth (germ tube formation) and performed 1 cycle of mitosis. With 3Â μM natamycin, germination was arrested at the stage of mitosis and germ tube formation and at 10Â μM natamycin conidia even did not swell and accumulated some mannitol. After 2 h of germination, upregulation in the transcriptome of natamycin treated conidia was very similar to untreated conidia, especially protein synthesis, energy and rRNA translation. Correlation of the RNA profiles between 28208;Â and 8 h indicated that all conidia change extensively, but highest in 10Â μM natamycin, despite the lack of morphological change. The RNA profiles of these cells were slightly more similar to dormant conidia then all other samples. After 28208;Â and 8 h, natamycin8208;treated cells contained increased numbers of expressed genes compared to the controls in a dose8208;dependent manner. Transcripts of a number of protective compounds specific for dormant conidia were highly accumulated in 8 hour old treated spores. These habits have developed secondary after a large shift in the transcriptome. All these cues point into the direction that germinating conidia that are confronted with adverse conditions have no focus on strong vegetative development, but regain relatively high stress resistance, absence of growth and prolonged survival.
Full conference title:
11 th European Conference on Fungal Genetics
- ECFG 11th (2012)