Gloeobacter violaceus: primitive reproductive scheme and its significance

• Published in: Plant systematics and evolution 2018-12, Vol.304 (10), p.1221-1229
• Main Authors: Montejano, Gustavo, Becerra-Absalón, Itzel, Gold-Morgan, Michele, Osorio-Santos, Karina
• Format: Article
• Language: English
• Subjects: Biological clocks; Biomedical and Life Sciences; Circadian rhythm; Circadian rhythms; Cyanobacteria; Life cycles; Life Sciences; Original Article; Plant Anatomy/Development; Plant Ecology; Plant Sciences; Plant Systematics/Taxonomy/Biogeography; Population studies; Thylakoids
• ISSN: 0378-2697; 1615-6110; 2199-6881
• DOI: 10.1007/s00606-018-1542-z

Gloeobacter violaceus is a simple unicellular cyanobacterium believed to be basal to all cyanobacteria. It is unique among the cyanobacteria in various features, but most significantly in the absence of thylakoids and a circadian clock. We found additional features which support the basal status of the clade of G. violaceus in samples from a wet wall in a waterfall cave in central Mexico. We encountered a high morphological and morphometric variability in the populations studied. In trying to explain the reasons for this, we discovered that it can be attributed basically to two phenomena: a lack of synchronicity, circadian or other, in the cell cycles of the organisms; and the presence of a scheme with three simultaneous reproductive options. These two characteristics interfere with the development of a life cycle comparable to that found in other organisms. We coined the term "reproductive routes" for the alternative to a life cycle and discuss the consequences of having several routes instead of a cycle. Our results open avenues for studies to understand how the rest of the cyanobacteria acquired circadian clocks, organized life cycles and evolved complex regulating mechanisms.