Ligniera

Although the genus Ligniera remains a valid genus, molecular evidence has led to what was previously known as L. verrucosa to be reclassified as Pseudoligniera verrucosa (Maire and Tison) Neuhauser, Hittorf, Kirchmair (Hittorf et al 2020). What is referred to in the following personal comments as L. verrucosa is the organism that is now named Pseudoligniera verrucosa.

Personal Comments

I was interested in karyotyping Ligniera because of its similarity to Polymyxa. We had easy access to L. verrucosa on the Ohio University campus, but I held off with my karyological study because I knew some of Charles Miller's students were working on the ultrastructure of general development of L. verrucosa. Once their paper was accepted for publication, however, I felt free to take a walk around campus and pull up some Veronica in an area where I knew it would be infected with L. verrucosa. Since stages of development of Sorosphaera veronicae also could be in roots of Veronica, I spent hours sifting through fresh material with compound light microscopy to select only sections of roots that had sporogenic stages of Ligniera.

Transitional sporogenic plasmodia were easy to locate with techniques described in Meiosis & Karyotyping: I would cut a 1/2 µm "thick" section and examine it with light microscopy. When I found a transitional plasmodium, I would trim the block down to it and make serial sections for electron microscopy.

Images of Pseudoligniera

• Sporosori, LMG
• Pseudoligniera transitional sporogenic plasmodium, TEMG

Selected References for Ligniera & Pseudoligniera

• Barr, D. J. S. 1979. Morphology and host range of Polymyxa graminis, Polymyxa betae, and Ligniera pilorum from Ontario and some other areas. Can. J. Plant Path. 1: 85-94.
• Braselton, J. P. 1989. Karyotypic analysis of Ligniera verrucosa (Plasmodiophoromycetes). Can. J. Bot. 67: 1216-1218.
• Cook, W. R. I. 1926. The genus Ligniera Maire and Tison. Trans. British Mycol. Soc. 11: 196-213.
• Hittorf, M. et al (2020). Revised taxonomy and expanded biodiversity of the Phytomyxea (Rhizaria, Endomyxa). J. Eukaryot. Microbiol. Doi: 10.1111/jeu.12817
• Maire, R. & A. Tison. 1911. Nouvelles recherches sur les Plasmodiophoracees. Ann. Mycol. 9: 226-246.
• Miller, C. E. 1959. Studies on the life cycle and taxonomy of Ligniera verrucosa. Amer. J. Bot. 46: 725-729.
• _____, R. W. Martin, & D. P. Dylewski. 1985. The ultrastructure of plasmodia, sporangia, and cystosori of Ligniera verrucosa (Plasmodiophoromycetes). Can. J. Bot. 63: 263-273.
• Neuhauser, S. & M. Kirchmair. 2009. Ligniera junci, a plasmodiophorid re-discovered in roots of Juncus in Austria. Österr. Z. Pilzk. 18: 151-157.