Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada.
J Phycol. 2024 Apr;60(2):275-298. doi: 10.1111/jpy.13438. Epub 2024 Mar 4.
Thick-walled rosette-like snow algae were long thought to be a life stage of various other species of snow algae. Rosette-like cells have not been cultured, but by manually isolating cells from 38 field samples in southern British Columbia, we assigned a variety of rosette morphologies to DNA sequence. Phylogenetic analysis of Rubisco large-subunit (rbcL) gene, ribosomal internal transcribed spacer 2 (ITS2) rRNA region, and 18S rRNA gene revealed that the rosette-like cells form a new clade within the phylogroup Chloromonadinia. Based on these data, we designate a new genus, Rosetta, which comprises five novel species: R. castellata, R. floranivea, R. stellaria, R. rubriterra, and R. papavera. In a survey of 762 snow samples from British Columbia, we observed R. floranivea exclusively on snow overlying high-elevation glaciers, whereas R. castellata was observed at lower elevations, near the tree line. The other three species were rarely observed. Spherical red cells enveloped in a thin translucent sac were conspecific with Rosetta, possibly a developmental stage. These results highlight the unexplored diversity among snow algae and emphasize the utility of single-cell isolation to advance the centuries-old problem of disentangling life stages and cryptic species.
厚壁玫瑰花形雪藻曾长期被认为是各种其他雪藻物种的一个生命阶段。玫瑰花形细胞尚未被培养，但通过从不列颠哥伦比亚省南部的 38 个野外样本中手动分离细胞，我们将各种玫瑰花形形态分配给 DNA 序列。Rubisco 大亚基（rbcL）基因、核糖体内部转录间隔区 2（ITS2）rRNA 区和 18S rRNA 基因的系统发育分析表明，玫瑰花形细胞在 Chloromonadinia 菌组内形成一个新的分支。基于这些数据，我们指定了一个新属 Rosetta，它包含五个新物种：R. castellata、R. floranivea、R. stellaria、R. rubriterra 和 R. papavera。在对不列颠哥伦比亚省 762 个雪样本的调查中，我们观察到 R. floranivea 仅存在于高海拔冰川覆盖的雪上，而 R. castellata 则存在于较低海拔、靠近树线的地方。其他三个物种很少被观察到。被薄而半透明囊包围的球形红色细胞与 Rosetta 同种，可能是一个发育阶段。这些结果突出了雪藻中尚未被探索的多样性，并强调了单细胞分离在解决长期存在的生命阶段和隐种问题方面的效用。
