CRISPR-Cas9 Used in Reverse Genetics Studies of Parasponia

Parasponia represents five tropical tree species in the Cannabeaceae family and is the only plant lineage besides legumes that can produce nitrogen-fixing nodules with rhizobium. Analyses between legumes and Parasponia allow identification of genetic networks controlling this symbiosis. However, these studies are lacking due to the absence of reverse genetic tools for Parasponia.

The team of Arjan van Zeijl from Wageningen University and Research in the Netherlands reported the use of CRISPR-Cas9 mutagenesis on Parasponia andersonii. Using CRISPR, the team mutated four genes, PanHK4, PanEIN2, PanNSP1, and PanNSP2, which control cytokinin, ethylene or strigolactone hormonal networks. These same set of genes is also responsible for essential symbiotic functions in legumes.

Knockout mutants in Panhk4 and Panein2 displayed developmental phenotypes, namely reduced procambium activity in Panhk4 and disturbed sex differentiation in Panein2 mutants. The symbiotic phenotypes of these two mutant lines also differ from those in legumes. In contrast, PanNSP1 and PanNSP2 were found to be essential for nodule formation, a phenotype similar as reported for legumes.

This study presents the application of CRISPR-Cas9 on Parasponia species as well as its use in reverse genetics studies.

For more on this study, read the article in Frontiers in Plant Science.