CDF family of zinc transporters ZRC-1, MSC-2, and ZRG-17 are involved in survival at high zinc conditions, vegetative development, and cellulase utilization in Neurospora crassa .

The cation diffusion facilitator (CDF) family of zinc transporters plays a crucial role in zinc homeostasis in eukaryotes, including fungi. Here, we investigated the cell functions and genetic interactions of CDF zinc transporters zrc -1 and msc -2 in Neurospora crassa . The Δ zrc -1 mutant could not grow in a high-zinc environment, indicating that the zinc transporter protein ZRC-1 was essential for growth in high-zinc conditions. However, the deletion of msc -2 did not show any severe phenotypic defects. Furthermore, we studied the genetic interactions of the zinc transporters using the CDF double mutants. Previously, zrg -17 was reported to be critical, where the Δ zrg -17 mutant showed defects in both vegetative development and asexual sporulation. Interestingly, the Δ msc -2;Δ zrg -17 double mutant showed phenotypes similar to the wild type, and restored the phenotypic defects of the Δzrg-17 mutation. However, the Δ zrc-1 ;Δ msc-2 and Δ zrc-1 ;Δ zrg-17 double mutants continue to display phenotypic defects like their parental single mutants. The double mutant Δzrc-1;Δzrg-17 showed severe vegetative growth defects, including slow growth, short aerial hyphae, narrowed septation, and defective asexual sporulation. In addition, aerial hyphae development of the Δzrc-1;Δmsc-2 and Δzrc-1;Δzrg-17 double mutants were reduced under endoplasmic reticulum stress. Thus, this study revealed the cell functions and genetic interactions of zrc-1, msc-2, and zrg-17 for vegetative development and tolerance to stress conditions in N. crassa.