A New Genetic Linkage Map of the Zygomycete Fungus Phycomyces blakesleeanus

Author: mycolabadmin
2013-03-14
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Summary

This research created a detailed genetic map of the fungus Phycomyces blakesleeanus, providing new insights into how this organism reproduces sexually and passes genetic material to offspring. The study helps scientists better understand evolution of sexual reproduction in fungi and provides tools for identifying genes controlling important biological processes. Impacts on everyday life: – Advances understanding of fundamental processes in fungal reproduction and evolution – Provides tools for identifying genes controlling responses to light and gravity – Helps understand production of β-carotene, an important nutrient and industrial compound – Contributes to basic knowledge about inheritance and genetic recombination – May lead to applications in biotechnology using fungi

Background

Phycomyces blakesleeanus is a member of the order Mucorales in the subphylum Mucoromycotina. The basal lineages in the fungal kingdom represent less than 5% of all fungal species yet hold the majority of evolutionary history. Despite a long research history with some Mucoromycotina species, particularly regarding mating properties, the genes required for mating are poorly understood and completing sexual cycles under laboratory conditions is challenging.

Objective

The primary goal was to develop a genetic map covering the genome that could be used for map-based cloning to identify unknown genes controlling traits like phototropism, gravitropism, and metabolism. Additional objectives were to estimate chromosome numbers, provide higher order genome scaffold assembly, and examine genetic reduction processes within zygospores.

Results

Analysis revealed nine or 12 linkage groups depending on the log of the odds (LOD) score, across 1583.4 cM at LOD 5. The markers covered more than 97% of the genome. The new map provides a genome-wide recombination estimate averaging 33.2 kb per cM. The molecular marker map, phenotype map and genome sequence showed overall congruence with some exceptions. Evidence for both meiotic recombination and transmission of non-recombinant chromosomes was found during the mating process.

Conclusion

The new genetic map provides scaffold ordering for the genome sequence and enables identification of genes affecting traits of interest through positional cloning. The recombination frequency observed is comparable to other sexual fungal species, providing evidence for meiosis in Phycomyces and potentially broadly in the Mucorales order. The map demonstrates that while genetic reduction occurs during zygospore development, the process appears to combine both meiotic recombination and non-recombinational transmission of chromosomes.

Published in:PLoS One,
Study Type:Genetic Mapping Study,
Source: 10.1371/journal.pone.0058931