A COMPREHENSIVE STUDY OF THE LIFE CYCLE OF A SOUTH-AMERICAN POPULATION OF STIGEOCLONIUM TENUE (CHAETOPHORALES, CHLOROPHYTA)

MICHETTI, KARINA MARIEL; LEONARDI, PATRICIA INÉS; CÁCERES, EDUARDO JORGE

JOURNAL OF PHYCOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: San Marcos, California, USA; Año: 2010 vol. 46 p. 997 - 1005

0022-3646

The diplobiontic-haplodiplontic life cycle with alternating isomorphic generations inStigeoclonium tenue is described for the first time. Sporophytes (2n=10) arise  fromtetraflagellate zoospores that are produced by meiosis. Sporic meiosis might be inferred from the cruciform divisions formed during zoosporogenesis and is confirmed through observationsof prophase I substages. Zoospores do not germinate directly, but produce a haploid cyst that germinate to give rise to a gametophyte (n=5). Gametophytes produce biflagellate isogametes which fuse to produce zygotes that germinate by mitosis into the sporophytic stage.Gametophytes and sporophytes reproduce asexually both via mitotic tetraflagellate zoospores and by thallus fragmentation. Results from this study indicate that both the cosmopolitandistribution and dominance of S. tenue in many periphytic communities might be due to its multiple reproductive strategies.