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Initiation of meiotic recombination in Ustilago maydis.

TitleInitiation of meiotic recombination in Ustilago maydis.
Publication TypeJournal Article
Year of Publication2013
AuthorsKojic M, Sutherland JH, Pérez-Martín J, Holloman WK
JournalGenetics
Volume195
Issue4
Pagination1231-40
Date Published2013 Dec
ISSN1943-2631
Abstract

A central feature of meiosis is the pairing and recombination of homologous chromosomes. Ustilago maydis, a biotrophic fungus that parasitizes maize, has long been utilized as an experimental system for studying recombination, but it has not been clear when in the life cycle meiotic recombination initiates. U. maydis forms dormant diploid teliospores as the end product of the infection process. Upon germination, teliospores complete meiosis to produce four haploid basidiospores. Here we asked whether the meiotic process begins when teliospores germinate or at an earlier stage in development. When teliospores homozygous for a cdc45 mutation temperature sensitive for DNA synthesis were germinated at the restrictive temperature, four nuclei became visible. This implies that teliospores have already undergone premeiotic DNA synthesis and suggests that meiotic recombination initiates at a stage of infection before teliospores mature. Determination of homologous recombination in plant tissue infected with U. maydis strains heteroallelic for the nar1 gene revealed that Nar(+) recombinants were produced at a stage before teliospore maturation. Teliospores obtained from a spo11Δ cross were still able to germinate but the process was highly disturbed and the meiotic products were imbalanced in chromosomal complement. These results show that in U. maydis, homologous recombination initiates during the infection process and that meiosis can proceed even in the absence of Spo11, but with loss of genomic integrity.

DOI10.1534/genetics.113.156752
Alternate JournalGenetics
PubMed ID24077302
PubMed Central IDPMC3832269
Grant ListGM042482 / GM / NIGMS NIH HHS / United States
GM079859 / GM / NIGMS NIH HHS / United States
R01 GM042482 / GM / NIGMS NIH HHS / United States
R01 GM079859 / GM / NIGMS NIH HHS / United States

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