Phosphate limitation induces sporulation in the chytridiomycete  Blastocladiella emersonii.
The cell cycle is controlled by numerous mechanisms that ensure correct cell division. If growth is not possible, cells may eventually promote autophagy, differentiation, or apoptosis. Microorganisms interrupt their growth and differentiate under general nutrient limitation. We analyzed the effects of phosphate limitation on growth and sporulation in the chytridiomycete  Blastocladiella emersonii  using kinetic data, phase-contrast, and laser confocal microscopy. Under phosphate limitation, zoospores germinated and subsequently formed 2-4 spores, regardless of the nutritional content of the medium. The removal of phosphate at any time during growth induced sporulation of vegetative cells. If phosphate was later added to the same cultures, growth was restored if the cells were not yet committed to sporulation. The cycles of addition and withdrawal of phosphate from growth medium resulted in cycles of germination-growth, germination-sporulation, or germination-growth-sporulation. These results show that phosphate limitation is sufficient to interrupt cell growth and to induce complete sporulation in B. emersonii. We concluded that the determination of growth or sporulation in this microorganism is linked to phosphate availability when other nutrients are not limiting. This result provides a new tool for the dissection of nutrient-energy and signal pathways in cell growth and differentiation.
Departamento de Bioquímica, Universidade Estadual de Maringá, Maringá-PR, Brazil.
Vagner Alexandre
VA
Bongiorno
Angela
A
Ferreira da Cruz
Antonio
A
Nunis da Silva
Luiz Carlos
LC
Corrêa
D001754:Blastocladiella / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010710:Phosphates / Q000378:metabolism / Q000494:pharmacology*; D013172:Spores, Fungal / Q000187:drug effects / Q000502:physiology
D010710:Phosphates