An efficient method for constructing a random insertional mutant library for forward genetics in Nannochloropsis oceanica

Insertional mutation, phenotypic evaluation, and mutated gene cloning are widely used to clone genes from scratch. Exogenous genes can be integrated into the genome during non-homologous end joining (NHEJ) of the double-strand breaks of DNA, causing insertional mutation. The random insertional mutant library constructed using this method has become a method of forward genetics for gene cloning. However, the establishment of a random insertional mutant library requires a high transformation efficiency of exogenous genes. Many microalgal species show a low transformation efficiency, making constructing random insertional mutant libraries difficult. In this study, we established a highly efficient transformation method for constructing a random insertional mutant library of Nannochloropsis oceanica , and tentatively tried to isolate its genes to prove the feasibility of the method. A gene that may control the growth rate and cell size was identified. This method will facilitate the genetic studies of N. oceanica , which should also be a reference for other microalgal species.