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HOMOTHALLIC AUXOSPORULATION IN PSEUDO‐NITZSCHIA BRASILIANA (BACILLARIOPHYTA) 1
Author(s) -
QuijanoScheggia Sonia,
Garcés Esther,
Andree K.,
Fortuño Jose Manuel,
Camp Jordi
Publication year - 2009
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2008.00636.x
Subject(s) - homothallism , biology , frustule , sexual reproduction , heterothallic , zygote , botany , gamete , genus , evolutionary biology , diatom , genetics , mating type , gene , sperm , embryogenesis
Most pennate diatoms are allogamous, and various types of mating systems have been described. In Pseudo‐nitzschia , reproductive stages have been identified in some species, and it is generally accepted that the genus is mainly heterothallic. Here we report homothallic auxosporulation of Pseudo‐nitzschia brasiliana Lundholm, Hasle et G. A. Fryxell. To our knowledge, this is the first verified description of homothallic sexual reproduction in the genus. Auxospore formation was observed in all 16 subclones derived from three initial clonal cultures of P. brasiliana . Pairing was followed by production of two gametes per gametangium, which fused to give two zygotes. Each zygote (early auxospore) was initially spherical and adhered to one girdle band of the parental frustule. The two auxospores tended to expand parallel to each other and perpendicular to the parental frustule. Elongation was synchronous, slightly asynchronous, or totally asynchronous. The entire process of sexual reproduction, from gamete formation to the appearance of the initial vegetative cells, took 2–4 d. The occurrence of sex in a homothallic species seems an advantageous life strategy for this species in that any encounter between cells of the right size class is potentially sexual.