Strain breeding and gene complementation strategies for filamentous fungi

Filamentous fungi produce a variety of unique bioactive metabolites, which are important to food, medical and agricultural industries. In order to better utilize filamentous fungi for synthesizing their valuable products, platform technologies, which include gene disruption and complementation methods, are increasingly expected for editing and analyzing gene functions involved in their metabolic pathways. As more and more genomes of filamentous fungi have been sequenced and the efficient clustered regularly interspaced short palindromic re-peats (CRISPR)/Cas9 system has been widely utilized for the genetic manipulation of filamentous fungi, gene modification and gene function analyses become more feasible. However, gene function studies on some species of filamentous fungi are still limited by gene editing or complemented strategies. In this review, we summarized the current strain breeding methods, gene complementation strategies and biotechnological application of gene complementation for filamentous fungi. In addition, we discuss the challenges to current gene complementation for biotechnological application and show perspectives on its future technological development and application to biotechnology studies on filamentous fungi.