VelC Positively Controls Sexual Development in Aspergillus nidulans

Abstract

Fungal development and secondary metabolism is intimately associated via activities of the fungi-specific velvet family proteins including VeA, VosA, VelB and VelC. Among these, VelC has not been characterized in Aspergillus nidulans. In this study, we characterize the role of VelC in asexual and sexual development in A. nidulans. The velC mRNA specifically accumulates during the early phase of sexual development. The deletion of velC leads to increased number of conidia and reduced production of sexual fruiting bodies (cleistothecia). In the velC deletion mutant, mRNA levels of the brlA, abaA, wetA and vosA genes that control sequential activation of asexual sporulation increase. Overexpression of velC causes increased formation of cleistothecia. These results suggest that VelC functions as a positive regulator of sexual development. VelC is one of the five proteins that physically interact with VosA in yeast two-hybrid and GST pull down analyses. The ΔvelC ΔvosA double mutant produced fewer cleistothecia and behaved similar to the ΔvosA mutant, suggesting that VosA is epistatic to VelC in sexual development, and that VelC might mediate control of sex through interacting with VosA at specific life stages for sexual fruiting.

Coordinated and Distinct Functions of Velvet Proteins in Fusarium verticillioides

“…Since the transportation of VelB into nuclei depends on the formation of heterodimers with other velvet proteins with the nuclear localization signal (14,16), the absence of VosA might make VeA more important in Fusarium than in Aspergillus. Although VelC negatively regulates conidial production in A. nidulans (20), similar to our observation for F. verticillioides, deletion of VelC caused less phenotypic alteration than that of VeA and VelB in A. nidulans and Aspergillus flavus (16,18), indicating that VelC is less important than other velvet proteins.…”

“…In A. nidulans, VeA can interact with VelB (14), VelB can interact with VosA (16), and VosA can interact with VelC (20). Yeast twohybrid experiments demonstrated that all velvet proteins, including VeA, VelB, and VelC, can interact with each other in Fusarium oxysporum (21).…”

“…All of these velvet-domain-containing proteins form the velvet family (10,18,19). Previous studies demonstrated that VelB can interact with VeA and VosA (14,16), and VelC can interact with VosA in A. nidulans (20). Unlike the case with A. nidulans, VosA is not present in Fusarium oxysporum, in which all three velvet proteins, VeA, VelB, and VelC, can interact with each other (21).…”

Vel2 and Vos1 hold essential roles in ascospore and asexual spore development of the heterothallic maize pathogen Cochliobolus heterostrophus

“…Phylogenetic analysis indicated that these two proteins group with A. nidulans VosA and VelB, respectively, and confirms that C. heterostrophus Vel1 groups with A. nidulans VeA, as shown earlier (Wu et al, 2012). The fourth protein (ID 151118) is the ortholog of A. nidulans VelC (Park et al, 2014), Fig. S4).…”

“…Velvet family proteins (four members VeA, VelB, VelC and VosA in A. nidulans) partner with the LaeA (Lae1) protein to regulate morphological development and secondary metabolism in response to light, in numerous filamentous fungi (Amaike and Keller, 2009;Bayram and Braus, 2012;Bayram et al, 2008;Calvo et al, 2004Calvo et al, , 2002Hoff et al, 2010;Kim et al, 2014;Park et al, 2014;Schumacher et al, 2012;Wiemann et al, 2010;Wu et al, 2012). All velvet family members possess a novel DNA-binding domain structurally similar to the Rel homolog domain (RHD) of the mammalian transcription factor NF-kB (Ahmed et al, 2013 In A. nidulans, VelB plays a positive role in production of conidia and a negative role in regulating conidial germination (Park et al, 2012).…”