A Relationship between Carotenoid Accumulation and the Distribution of Species of the Fungus Neurospora in Spain

Abstract

The ascomycete fungus Neurospora is present in many parts of the world, in particular in tropical and subtropical areas, where it is found growing on recently burned vegetation. We have sampled the Neurospora population across Spain. The sampling sites were located in the region of Galicia (northwestern corner of the Iberian peninsula), the province of Cáceres, the city of Seville, and the two major islands of the Canary Islands archipelago (Tenerife and Gran Canaria, west coast of Africa). The sites covered a latitude interval between 27.88° and 42.74°. We have identified wild-type strains of N. discreta, N. tetrasperma, N. crassa, and N. sitophila and the frequency of each species varied from site to site. It has been shown that after exposure to light Neurospora accumulates the orange carotenoid neurosporaxanthin, presumably for protection from UV radiation. We have found that each Neurospora species accumulates a different amount of carotenoids after exposure to light, but these differences did not correlate with the expression of the carotenogenic genes al-1 or al-2. The accumulation of carotenoids in Neurospora shows a correlation with latitude, as Neurospora strains isolated from lower latitudes accumulate more carotenoids than strains isolated from higher latitudes. Since regions of low latitude receive high UV irradiation we propose that the increased carotenoid accumulation may protect Neurospora from high UV exposure. In support of this hypothesis, we have found that N. crassa, the species that accumulates more carotenoids, is more resistant to UV radiation than N. discreta or N. tetrasperma. The photoprotection provided by carotenoids and the capability to accumulate different amounts of carotenoids may be responsible, at least in part, for the distribution of Neurospora species that we have observed across a range of latitudes.

Fungal evolutionary genomics provides insight into the mechanisms of adaptive divergence in eukaryotes

“…In addition, carotenoid accumulation in Neurospora has been correlated with latitude (Luque et al . ). Carotenoids protect against UV irradiation and their production is induced by light.…”

“…Indeed, genome scans have detected islands of genomic differentiation including genes involved in both the response to cold temperatures and the circadian cycle, and growth rate assays have confirmed differences in fitness between populations ). In addition, carotenoid accumulation in Neurospora has been correlated with latitude (Luque et al 2012). Carotenoids protect against UV irradiation and their production is induced by light.…”

The Blue-Light Photoreceptor Sfwc-1 Gene Regulates the Phototropic Response and Fruiting-Body Development in the Homothallic Ascomycete Sordaria fimicola

“…Carotenoid pigments play a major role as an antioxidant by protecting the photosynthetic system of plant cells against excess light and the harmful effect of UV light (58). Similarly, light-induced carotenoid accumulation protects filamentous fungi, including N. crassa, against UV damage (59). Moreover, the ability to optimize carotenoid production in N. crassa is dependent on the UV radiation dose (59).…”

Carotenoids

“…Visible light negatively affects respiration of N. crassa hyphae, with no alteration in growth, and this effect is enhanced in an albino mutant, indicating a protective effect of carotenoids [ 267 ]. Additional evidence was provided by the correlation between carotenoid content in Neurospora wild type isolates and the latitude where they were isolated [ 268 ]. The strains found at higher latitudes contain less carotenoid, and their conidia are more sensitive to UV exposure.…”