Cyclofarnesoids and methylhexanoids produced from β-carotene in Phycomyces blakesleeanus

LC-MS/MS-based targeted carotenoid and anthocyanidin metabolic profile of Auricularia cornea under blue and red LED light exposure

Light exposure significantly impacted the coloration and metabolism of Auricularia cornea, although the underlying mechanisms remain unclear. This study aimed to test the apparent color and pigment metabolic profiles of A. cornea in response to red (λp = 630 nm) and blue (λp = 463 nm) visible light exposure. Colorimeter analysis showed that fruiting bodies appeared bright-white under red-light and deeper-red under blue-light, both with a yellow tinge. On the 40th day of light-exposure, bodies were collected for metabolite detection. A total of 481 metabolites were targeted analysis, resulting in 18 carotenoids and 11 anthocyanins. Under red and blue light exposure, the total carotenoids levels were 1.1652 μg/g and 1.1576 μg/g, the total anthocyanins levels were 0.0799 μg/g and 0.1286 μg/g, respectively. Four differential metabolites and three putative gene linked to the visual coloration of A. cornea were identified. This pioneering study provides new insights into the role of light in regulating A. cornea pigmentation and metabolic profile.

Apocarotenoids produced from β-carotene by dioxygenases from Mucor circinelloides

Mucor circinelloides exhibits the complex sexual behaviour that is induced in other Mucoromycotina by a family of apocarotenoids called trisporoids. The genome of M. circinelloides contains four genes encoding putative carotenoid cleavage dioxygenases. The gene products of two of them were sufficient to convert β-carotene into the precursors of three families of apocarotenoids, both in vitro and in the Escherichia coli heterologous in vivo system. The first of these products, CarS, cleaved the C40 β-carotene into the C15 precursor of cyclofarnesoids and a C25 apocarotenal that was converted by the second enzyme, AcaA, into the C18 precursor of trisporoids and the C7 precursor of methylhexanoids. Apocarotenoids were not found in single or mixed cultures of the two strains of opposite sex, whose interaction readily produced zygospores, the sexual fusion cells.

Fungal Sex: The Mucoromycota

Although at the level of resolution of genes and molecules most information about mating in fungi is from a single lineage, the Dikarya, many fundamental discoveries about mating in fungi have been made in the earlier branches of the fungi. These are nonmonophyletic groups that were once classified into the chytrids and zygomycetes. Few species in these lineages offer the potential of genetic tractability, thereby hampering the ability to identify the genes that underlie those fundamental insights. Research performed during the past decade has now established the genes required for mating type determination and pheromone synthesis in some species in the phylum Mucoromycota, especially in the order Mucorales. These findings provide striking parallels with the evolution of mating systems in the Dikarya fungi. Other discoveries in the Mucorales provide the first examples of sex-cell type identity being driven directly by a gene that confers mating type, a trait considered more of relevance to animal sex determination but difficult to investigate in animals. Despite these discoveries, there remains much to be gleaned about mating systems from these fungi.

Occurrence and Chemical Synthesis of Apocarotenoids from Mucorales: A Review

Apocarotenoids are metabolites originated by degradation of carotenes through the loss of carbon atoms placed at the side chain of their structure as consequence of oxydative reactions. We present here the first review of apocarotenoids in the fungi mucorales Phycomyces blakesleeanus, Blakeslea trispora and Mucor mucedo. This review is divided into two parts: the first one presents their structures and sources, whereas the second part is dedicated to their chemical synthesis.

The inhibition of mating in Phycomyces blakesleeanus by light is dependent on the MadA-MadB complex that acts in a sex-specific manner

Light is an environmental signal that influences reproduction in the Mucoromycotina fungi, as it does in many other species of fungi. Mating in Phycomyces blakesleeanus is inhibited by light, but the molecular mechanisms for this inhibition are uncharacterized. In this analysis, the role of the light-sensing MadA-MadB complex in mating was tested. The MadA-MadB complex is homologous to the Neurospora crassa White Collar complex. Three genes required for cell type determination in the sex locus or pheromone biosynthesis are transcriptionally-regulated by light and are controlled by MadA and MadB. This regulation acts through the plus partner, indicating that the inhibitory effect of light on mating is executed through only one of the two sexes. These results are an example whereby the mating types of fungi have acquired sex-specific properties beyond their role in conferring cell-type identity, and provide insight into how sex-determining chromosomal regions can expand the traits they control.