A bird’s-eye view of the endoplasmic reticulum in filamentous fungi

The endoplasmic reticulum (ER) is one of the most extensive organelles in eukaryotic cells. It performs crucial roles in protein and lipid synthesis and Ca²⁺ homeostasis. Most information on ER types, functions, organization, and domains comes from studies in uninucleate animal, plant, and yeast cells. In contrast, there is limited information on the multinucleate cells of filamentous fungi, i.e., hyphae. We provide an analytical review of existing literature to categorize different types of ER described in filamentous fungi while emphasizing the research techniques and markers used. Additionally, we identify the knowledge gaps that need to be resolved better to understand the structure-function correlation of ER in filamentous fungi. Finally, advanced technologies that can provide breakthroughs in understanding the ER in filamentous fungi are discussed.