Zygnema cf. cylindricum SAG 698-1a [Image credit: Xuehuan Feng]

The Zygnema cf. cylindricum SAG 698-1a 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 cf. cylindricum SAG 698-1a

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 cf. cylindricum SAG 698-1a is a member of family Zygnemataceae, order Zygnematales, and class Zygnematophyceae. Z. cf. cylindricum was first isolated by V. Czurda from Bohemia ditch of Czech Republic in 1929. This strain was first deposited in the Culture Collection of Algae at the University of Göttingen, Germany in 1954. SAG 698-1a is identical to CCAP 698/1a from the Culture Collection of Algae and Protozoa (CCAP). A recent study found that SAG 698-1a has a larger nuclei size and cell size than Z. circumcarinatum SAG 698-1b (Feng et al., 2021). The cell width of SAG 698-1a is 26~29 µm and cell length is 40~120 µm. The algae have 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.
Miller RD. (1973) A development and physiological comparison of two mating strains of Zygnema circumcarinatum (Czurda). [Ph.D. Thesis]. Tucson, AZ: University of Arizona.
Miller RD and Hoshaw R. (1974) Cell width as a taxonomic character with special reference to Zygnema circumcarinatum Czurda. Br. Phycol. J. 9, 145-148. doi: 10.1080/00071617400650181
Feng X, Holzinger A, Permann C, Anderson D, Yin Y. (2021) Characterization of two Zygnema strains (Zygnema circumcarinatum SAG 698-1a and SAG 698-1b) and a rapid method to estimate nuclear genome size of Zygnematophycean green algae. Front Plant Sci. 12:610381. doi: 10.3389/fpls.2021.610381.