Morphological change in the early stages of the mating process of Rhodosporidium toruloides

Abstract

The events which occur in the early stages of the mating process of the yeast Rhodosporidium toruloides between strains M-919 (mating type A) and M-1057 (mating type a) were investigated. In preliminary experiments we determined the frequency of mating by two newly designed methods: the liquid culture method and the membrane-filter microculture method. The mating frequencies of strains M-919 and M-1057 were 89% in the liquid culture method and 62% in the membrane-filter microculture method. The early stages in the mating process included the following events: (i) M-919 cells produce constitutively the extracellular inducing substance (A factor), (ii) M-1057 cells receive A factor, and in response to it they form mating tubes and secrete another inducing substance (a factor), (iii) M-919 cells receive a factor, and in response to it they form mating tubes, (iv) mating tubes elongate to the cells or the tubes of mating partner, (v) tips of the growing tubes recognize the opposite mating type cells or their tubes, followed by cell-to-cell fusion.

Fungal Sex: The Basidiomycota

“…), the MAT A1 pheromone precursor typically presents a greater number of repeats of the peptide moiety (up to six copies in some species), whereas the MAT A2 pheromone gene appears to encode only one or two copies of the mature pheromone (39,42,43,45). Interestingly, this increased production of pheromone per mole of precursor in MAT A1 cells, possibly allowing communication with A2 cells at longer distances, is consistent with the observed asymmetric growth of conjugation tubes in both R. toruloides (46) and Microbotryum spp. (43,47), which occurs earlier and to a greater extent from MAT A2 cells.…”

Nuclear Behavior of Rhodosporidium Toruloides, a Heterobasidiomycetous Yeast

“…Rhodosporidium toruloides IFO 0559-M919 (haploid yeast, mating type A, Met-, Pan-) and R. toruloides IFO 0880-M1057 (haploid yeast, mating type a, PABA-) were designated as A and a strains (or cells), respectively, and used in this paper. Phenotype abbreviations were described in our previous paper (1). These strains were obtained from Dr.…”

“…Media and cultivation. Yeast extract-sucrose medium (YS medium) and minimal medium (MM medium) used here were also described in our previous paper (1). The latter medium was a selection medium for the conjugant of A and a cells.…”

Transient increase of Ca2+ uptake as a signal for mating pheromone-induced differentiation in the heterobasidiomycetous yeast Rhodosporidium toruloides

“…In the life cycle of Rhodosporidium toruloides, a heterobasidiomycetous yeast, the vegetative haploid cells (mating type a or A) of a given mating type differentiate to gamete cells, responding to a mating pheromone secreted by cells of opposite mating types as a prelude to mating (1). The differentiation of a cells is induced by rhodotorucine A, a famesyl undecapeptide mating pheromone produced by A cells (3).…”

“…The differentiation of a cells is induced by rhodotorucine A, a famesyl undecapeptide mating pheromone produced by A cells (3). This sexual differentiation is characterized by the arrest of vegetative growth in the Gl phase of the cell division cycle and protrusion of a mating tube which grows toward the partner cell (1). To elucidate the signaling mechanism triggered by the pheromone, we have been studying the initial biochemical responses of the pheromone recipient cell (5,6).…”