Submitted to: European Journal of Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/8/2011
Publication Date: 1/17/2012
Citation: Vittal, R., Yang, H., Hartman, G.L. 2012. Anastomosis of germ tubes and nuclear migration of nuclei in germ tube networks of the soybean rust pathogen, Phakopsora pachyrhizi. European Journal of Plant Pathology. 132:163-167. Interpretive Summary: Asexual recombination is an important mechanism for genetic diversity for many fungi. In this study, fusion of germ tubes in germinating spores of Phakopsora pachyrhizi, the causal fungus of soybean rust, resulted in a complex network of fused germ tubes. Staining of the spore germ tubes showed the migration of nuclei through the network of germ tubes resulting in multinucleate germ tubes. Short bridges connecting the germ tubes, with nuclei migrating through them, were also observed. This study provides the first evidence of germ tube fusion, and contributes to a better understanding of how this fungus may generate genetic variability through an asexual process. This information will be useful for fungal geneticists and plant pathologists studying variability of fungi that attack plants.
Technical Abstract: Parasexual recombination through hyphal anastomosis is an important mechanism for genetic diversity in filamentous fungi. In this study, we observed fusion of germ tubes in germinating urediniospores of Phakopsora pachyrhizi resulting in a complex hyphal network. Staining of the germinating urediniospores with 4’,6-diamindino-2-phenlindole showed the migration of nuclei through the network of germ tubes resulting in multinucleate germ tubes. Short bridges connecting the germ tubes, with nuclei migrating through them, were also observed. Our study provides the first evidence of germ tube anastomosis in the urediniospores of P. pachyrhizi, which may in part be an explanation for virulence diversity among populations of P. pachyrhizi.