Cytological studies on Pyropia suborbiculata

Abstract

In the present study, karyological observations on Pyropia suborbiculata (Bangiophycidae) at various stages of the life cycle were carried out. Living material of different life cycle stages of Py. suborbiculata were fixed in Carnoy’s fixative fluid and stored under the light conditions of 60–80 μmol photons m−2 s−1 to leach phycobilin pigments and then the samples were stained with Wittmann’s aceto-iron hematoxylin chloral hydrate and examined under a photomicroscope. The results indicated that vegetative cells, spermatangia, and carpogonia in gametophytic blade phase were haploids (n = 3), while zygotospores, vegetative cells, and conchosporangial branch cells in conchocelis phase were diploids (2n = 6). Meiosis occurred during the initial two-cell divisions of the germinating conchospores. Subsequently, the chromosome changed from diploid (2n = 6) to haploid (n = 3). When the blades released monospores for asexual reproduction, both the monospores and the cells of their germlings were haploid karyotypes (n = 3). In addition, when filamentous conchocelis cells at different developmental stages underwent mitosis, pairing of homologous chromosomes would occur in the nucleus during the prophase of division.