Zygnema circumcarinatum UTEX 1559 [Image credit: Xuehuan Feng]

The Zygnema circumcarinatum UTEX 1559 genome assembly and gene models have not been determined by the JGI, but were downloaded from https://bcb.unl.edu/Zygnema_4genomes/ (Yanbin Yin Lab, University of Nebraska - Lincoln) on January 24, 2023. Please note that this copy of the genome is not maintained by the Yin Lab and is therefore not automatically updated. In order to allow comparative analyses with other algal genomes sequenced by the JGI, a copy of this genome is incorporated into PhycoCosm. The JGI Annotation Pipeline was used to add functional annotation to this genome.

Zygnema circumcarinatum UTEX 1559

The class of Zygnematophyceae has been pinpointed as the algal sister lineage to land plants. This class is named for filamentous algae of the genus Zygnema, which are known to occur in challenging environments and are desiccation resistant. Four strains (SAG 698-1a, SAG 698-1b, UTEX 1559, UTEX 1560) were sequenced, capturing the strain history of the + and - mating types derived from the Zygnema circumcarinatum sample of 1929 by Czurda. Of these, SAG 698-1a likely now represents a different species, Zygnema cf. cylindricum. Owing to their key phylogenetic position, genome data on these organisms shed light on the evolution of the genetic toolbox for multicellular growth and response to environmental challenges.

The filamentous green alga Zygnema circumcarinatum UTEX 1559 is a member of family Zygnemataceae, order Zygnematales, and class Zygnematophyceae. UTEX 1559 was reported to be a spontaneous mutant of IUCC 42 with an increased cell size and chloroplast numbers (Gauch, 1966). IUCC 42 was originally isolated by V. Czurda and maintained at the University of Texas at Austin’s Culture Collection of algae. Both UTEX 1559 and IUCC 42 were unable to conjugate with SAG 698-1b, and was labeled as an non-functional mating (+) strain (Gauch, 1966). UTEX 1559 has a cell width of 22~24 µm that is similar to that of SAG 698-1b. UTEX 1559 and SAG 698-1b have identical plastomes, but their mitogenomes are slightly different. UTEX 1559 has unbranched filaments and each cell contains a single nucleus located between the two star-shaped chloroplasts.

References

Gauch HG. (1966) Studies on the life cycle and genetics of Zygnema. [Master’s Thesis]. Ithaca, NY: Cornell University.