Mosaic fungal individuals have the potential to evolve within a single generation

Although cells of mushroom-producing fungi typically contain paired haploid nuclei (n + n), most Armillaria gallica vegetative cells are uninucleate. As vegetative nuclei are produced by fusions of paired haploid nuclei, they are thought to be diploid (2n). Here we report finding haploid vegetative nuclei in A. gallica at multiple sites in southeastern Massachusetts, USA. Sequencing multiple clones of a single-copy gene isolated from single hyphal filaments revealed nuclear heterogeneity both among and within hyphae. Cytoplasmic bridges connected hyphae in field-collected and cultured samples, and we propose nuclear migration through bridges maintains this nuclear heterogeneity. Growth studies demonstrate among- and within-hypha phenotypic variation for growth in response to gallic acid, a plant-produced antifungal compound. The existence of both genetic and phenotypic variation within vegetative hyphae suggests that fungal individuals have the potential to evolve within a single generation in response to environmental variation over time and space

The Effect of Management Practices on Bacterial, Fungal, and Nematode Communities on Cool Season Turfgrass

Golf courses comprise 50 million acres in the United States of highly managed turf susceptible to abiotic and biotic stressors. A growing area of interest is utilizing microbes to improve plant growth, increase disease and stress tolerance, and reduce pathogens. In order to develop these new practices, we must gain an understanding of turfgrass microbial communities and how they are affected by management practices. We characterized bacteria, fungi, and nematodes on three golf courses: one organic, one with reduced inputs, and one conventional. We took samples from three management areas on each course representing different management intensities (roughs, fairways, and putting greens). This is the first study to our knowledge to use metagenomics to describe bacteria and fungi on all three management areas of golf courses. The conventional and hybrid putting green were most similar to one another in nematode and microbe community composition than to the roughs and fairways of their respective courses or of the organic putting green. The organic putting green differed markedly in the high number of beneficial bacterivore nematodes and low number of herbivore nematodes compared to the conventional and hybrid putting greens. Management intensity affected fungal but not bacterial abundance, diversity, and richness. Canonical correspondence analysis and multiple stepwise regression analyses revealed pH, phosphorous, and organic matter were positively related to increased herbivore nematodes and negatively related to increased bacterivore nematodes, however there was no separation of fungal or bacterial communities based on soil properties. Lastly, we investigated the abundance of bacteria, fungi, and specifically the turf pathogen Sclerotinia homoeocarpa in the soil and thatch of the three golf courses on the three management areas and determined that fungal abundance is always greater in the thatch. S. homoeocarpa abundance did not vary among management areas on the soil or thatch, suggesting the fungal inoculum is unaffected by different management intensities. The results of our study provide baseline data on the nematode, bacterial, and fungal communities on golf courses under different management intensities. The results will help in developing future research studies to examine how cultural practices can be used to increase turf health and decrease disease severity, optimizing biocontrol organism activity, and decreasing herbivore nematode populations while increasing beneficial bacterivores

DESS deconstructed: Is EDTA solely responsible for protection of high molecular weight DNA in this common tissue preservative?

DESS is a formulation widely used to preserve DNA in biological tissue samples. Although it contains three ingredients, dimethyl sulfoxide (DMSO), ethylenediaminetetraacetic acid (EDTA) and sodium chloride (NaCl), it is frequently referred to as a DMSO-based preservative. The effectiveness of DESS has been confirmed for a variety of taxa and tissues, however, to our knowledge, the contributions of each component of DESS to DNA preservation have not been evaluated. To address this question, we stored tissues of three aquatic taxa, Mytilus edulis (blue mussel), Faxonius virilis (virile crayfish) and Alitta virens (clam worm) in DESS, each component of DESS individually and solutions containing all combinations of two components of DESS. After storage at room temperature for intervals ranging from one day to six months, we extracted DNA from each tissue and measured the percentage of high molecular weight (HMW) DNA recovered (%R) and normalized HMW DNA yield (nY). Here, HMW DNA is defined as fragments >10 kb. For comparison, we also measured the %R and nY of HMW DNA from extracts of fresh tissues and those stored in 95% EtOH over the same time intervals. We found that in cases where DESS performed most effectively (yielding ≥ 20%R of HMW DNA), all solutions containing EDTA were as or more effective than DESS. Conversely, in cases where DESS performed more poorly, none of the six DESS-variant storage solutions provided better protection of HMW DNA than DESS. Moreover, for all taxa and storage intervals longer than one day, tissues stored in solutions containing DMSO alone, NaCl alone or DMSO and NaCl in combination resulted in %R and nY of HMW DNA significantly lower than those of fresh tissues. These results indicate that for the taxa, solutions and time intervals examined, only EDTA contributed directly to preservation of high molecular weight DNA