Light-Dependent Functions of the Fusarium fujikuroi CryD DASH Cryptochrome in Development and Secondary Metabolism

Abstract

DASH (Drosophila, Arabidopsis, Synechocystis, human) cryptochromes (cry-DASHs) constitute a subgroup of the photolyase cryptochrome family with diverse light-sensing roles, found in most taxonomical groups. The genome of Fusarium fujikuroi, a phytopathogenic fungus with a rich secondary metabolism, contains a gene encoding a putative cry-DASH, named CryD. The expression of the cryD gene is induced by light in the wild type, but not in mutants of the "white collar" gene wcoA. Targeted ⌬cryD mutants show light-dependent phenotypic alterations, including changes in morphology and pigmentation, which disappear upon reintroduction of a wild-type cryD allele. In addition to microconidia, the colonies of the ⌬cryD mutants produced under illumination and nitrogen starvation large septated spores called macroconidia, absent in wild-type colonies. The ⌬cryD mutants accumulated similar amounts of carotenoids to the control strain under constant illumination, but produced much larger amounts of bikaverin under nitrogen starvation, indicating a repressing role for CryD in this biosynthetic pathway. Additionally, a moderate photoinduction of gibberellin production was exhibited by the wild type but not by the ⌬cryD mutants. The phenotypic alterations of the ⌬cryD mutants were only noticeable in the light, as expected from the low expression of cryD in the dark, but did not correlate with mRNA levels for structural genes of the bikaverin or gibberellin biosynthetic pathways, suggesting the participation of CryD in posttranscriptional regulatory mechanisms. This is the first report on the participation of a cry-DASH protein in the regulation of fungal secondary metabolism.

Fungal cryptochrome with DNA repair activity reveals an early stage in cryptochrome evolution

“…Sensory roles have been proposed for fungal CPF members (16,17,28,29), and it is possible that Phycomyces CryA plays an additional role as a photoreceptor. However, none of the mutants affected in phototropism have a mutation in cryA, arguing against a sensory role for CryA, at least for the phototropism of the fruiting body, and suggesting that the main role of CryA is to act as a photolyase.…”

“…Cry-DASH have been described in other fungi and they have minor sensory roles. They participate in the regulation by light of development in Sclerotinia sclerotiorum and Fusarium fujikuroi (28,29), and pigment accumulation in F. fujikuroi (29).…”

The gene cutA of Fusarium fujikuroi, encoding a protein of the haloacid dehalogenase family, is involved in osmotic stress and glycerol metabolism

“…5b). Significant photoinduction was also observed in mutants of the gene cryD, which encodes a DASH cryptochrome photoreceptor involved in the regulation of secondary metabolism of this fungus (Castrillo et al, 2013). However, photoinduction was not apparent in mutants of the WC-1 gene of F. fujikuroi, wcoA (Estrada & Avalos, 2008), indicating that Role of CutA HAD protein in Fusarium fujikuroi this photoreceptor mediates cutA and gldB photoinduction.…”

“…The wild-type strain of Fusarium fujikuroi, FKMC1995 (Gibberella fujikuroi mating population C) was kindly provided by J. F. Leslie (Kansas State University Collection, Manhattan, KS, USA). The DwcoA mutants SF225 and SF226 and the DcryD mutants SF236 and SF237 were described previously: DwcoA (Estrada & Avalos, 2008); DcryD (Castrillo et al, 2013).…”

Carotenoids

“…In contrast, mutants of the WC-1 gene of F. fujikuroi wcoA and F. oxysporum wc1 maintained a signifi cant carotenoid photoinduction [ 200 , 201 ], indicating the participation of other photoreceptors for carotenogenesis in both species. Mutants of putative F. fujikuroi photoreceptors, such as the DASH cryptochrome CryD [ 202 ] or the rhodopsins CarO [ 172 ] and OpsA [ 173 ] also exhibited light-induced carotenogenesis. As formerly proposed for V. agaricinum photocarotenogenesis [ 134 ], the participation of more than one photoreceptor is not discarded.…”