Unh1, an Ustilago maydis Ndt80-like protein, controls completion of tumor maturation, teliospore development, and meiosis

Abstract

In this study, Ustilago maydis Ndt80 homolog one, unh1, of the obligate sexual pathogen U. maydis,is described. Unh1 is the sole Ndt80-like DNA-binding protein inU. maydis. In this model basidiomycete, Unh1 plays a role in sexual development, influencing tumor maturation, teliospore development and subsequent meiotic completion. Teliospore formation was reduced in deletion mutants, and those that did form had unpigmented, hyaline cell walls, and germinated without completing meiosis. Constitutively expressing unh1 in haploid cells resulted in abnormal pigmentation, when grown in both potato dextrose broth and minimal medium, suggesting that pigmentation may be triggered by unh1 in U. maydis. The function of Unh1 in sexual development and pigment production depends on the presence of the Ndt80-like DNA-binding domain, identified within Unh1. In the absence of this domain, or when the binding domain was altered with targeted amino acid changes, ectopic expression of Unh1 failed to complement the unh1 deletion with regards to pigment production and sexual development. An investigation of U. maydis genes with upstream motifs similar to Ndt80 recognition sequences revealed that some have altered transcript levels in Δunh1 strains. We propose that the first characterized Ndt80-like DNA-binding protein in a basidiomycete, Unh1, acts as a transcription factor that is required for teliospore maturation and the completion of meiosis in U. maydis.

Natural antisense transcripts are linked to the modulation of mitochondrial function and teliospore dormancy in Ustilago maydis

“…). This timing coincides with the transition from dikaryotic hyphae to teliospore, as teliospore initials are present by 9 dpi and visually mature teliospores are present by 12 dpi (Doyle et al ., ). The presence of as‐ssm1 is also detected in isolated teliospores that are dormant.…”

“…Seven-day old seedlings were planted and infected as above with SG200 and SG200 otef:as-ssm1 s strains. Microscopy samples were harvested at 14 dpi following guidelines outlined in Banuett and Herskowitz (1996) with the following modifications by Doyle et al (2016). Doubleedged uncoated razors (American Safety Razor Company) were used to slice infected material horizontally.…”

“…In the tumours diploid unicellular teliospores develop (Snetselaar and Mims, 1994;Banuett and Herskowitz, 1996). The dikaryotic hyphae fragment and round, producing teliospore initials by approximately 9 days post infection (dpi; Banuett and Herskowitz, 1996;Doyle et al, 2016). As a specialized cell wall begins being deposited, these teliospore initials progress to mature teliospores, which appear at approximately 12 dpi and are characterized by melanized and echinulate cell walls.…”

Examining the role of the promoter region of het-6 in escape from heterokaryon incompatibility in Neurospora crassa

“…Furthermore, the number of NDT80-like genes varies from as few as 1 in S. cerevisiae and U. maydis, to as many as 7 in R. oryzae (Katz et al, 2013). In general, in species carrying more than one Ndt80-like DNA-binding protein, those involved in sexual reproduction and those involved in other responses to environmental conditions branch separately, with one notable exception being C. albicans (Doyle et al, 2016) Members of the Ndt80 family perform diverse functions in different fungal species.…”

“…However, Ndt80-like proteins share a conserved nutrient-sensing feature, but it is unclear whether this feature is linked to the regulation of other cellular processes like pigmentation and meiosis (Doyle et al, 2016). In A. nidulans, XprG acts as a regulator of extracellular protease production in response to carbon, nitrogen or sulfur starvation.…”