The importance of light and photoperiod in sexual reproduction and geographical distribution in the green snow alga,Chloromonas sp.-D (Chlorophyceae, Volvocales)

Abstract

The effects of premating light regimes on sexual reproduction and the production of spherical cells in Chloromonas sp.-D, a unicellular green snow alga, were studied using cross-mating strains 582C and 582D isolated from snowpacks associated with mixed hardwood-softwood forests in Whetstone Gulf State Park, Tughill Plateau, NY. Two preacclimation regimes were used, Vita-Lite as controls (530-700 nm peak) and blue light as experimentals (430-460 nm peak) prior to the mating experiments. In blue light, an increase in the number of matings and spherical cells (spheres) produced in the life cycle was observed as the photoperiod increased. This implies that longer photoperiods of blue light are more optimal for sexual reproduction in Chloromonas sp.-D than shorter ones. Under Vita-Lite, there was a significant increase in the number of matings and spheres with the extended 20 : 4 photoperiod compared with the shorter 14 : 10 photoperiod. Under blue light, significantly more matings and spheres occurred than under Vita-Lite using the same irradiance level of 95 µmol photons m 2 s 1 (photosynthetically active radiation [PAR] of 400-700 nm) for the 14 : 10 and 20 : 4 photoperiods. The results of these experiments suggest that Chloromonas sp.-D, known only from the Tughill Plateau, NY, is not reproducing optimally at this site where it grows and reproduces under an approximate 14 : 10 photoperiod in early April. However, in the upper 10 cm of snow in the Tughill Plateau, a blue light irradiance level of 95 µmol photons m 2 s 1 occurs, which is optimal for this species. When these conditions are combined with a 14 : 10 photoperiod, the Tughill Plateau appears to be sub-optimal for mating and production of spherical cells. Since Chloromonas sp.-D does not appear to have a dependence on a dark cycle, this would allow it to expand its geographical distribution. It may reproduce more optimally under blue light (95 µmol photons m 2 s 1 ) with an extended photoperiod (>20 : 4 h, light:dark) in high latitude field sites such as Lake Bienville, Québec, in eastern North America where other species of Chloromonas are known in snow associated with coniferous forests. Copyright

Re-examination of the snow algal speciesChloromonas miwae(Fukushima) Muramotoet al., comb. nov. (Volvocales, Chlorophyceae) from Japan, based on molecular phylogeny and cultured material

“…Swimming cell packs with flagella extending beyond the cell wall (Fig. 13) were very occasionally observed in the present cultures, as in all Chloromonas species in subclade 2 of clade A (Hoham et al, 2000(Hoham et al, , 2006. TEM did not reveal morphological differences between the two strains.…”

Effect of culturing parameters on the vegetative growth of Haematococcus alpinus (strain lcr‐cc‐261f) and modeling of its growth kinetics

“…Previous studies have shown that blue wavelengths of light promoted sexual reproduction in the green snow algae Chloromonas sp., which are near relatives of Haematococcus (Hoham et al. ). Therefore, it could be speculated that blue LED wavelength put the Haematococcus cells in a stress condition that triggered sexual reproduction in them.…”

A COMBINED 18S rDNA AND rbcL PHYLOGENETIC ANALYSIS OF CHLOROMONAS AND CHLAMYDOMONAS (CHLOROPHYCEAE, VOLVOCALES) EMPHASIZING SNOW AND OTHER COLD‐TEMPERATURE HABITATS1

“…pichinchae (Hoham 1975) retained their flagella on parental cells at the time of cell pack formation (cell pack is used here instead of zoosporangia or gametangia because it is not possible to distinguish zoospores from gametes when cell divisions occur). Chloromonas sp.‐D has a unique cell transformation from oblong to spherical during sexual reproduction, and the number of transformed cells increases under extended photoperiods of more than 20 h of light (Hoham et al 2000, Hoham and Duval 2001). Whereas the position of Cr.…”