Discovery of Essential MPK Genes in Rice by Studying CRISPR Knock-out Mutants

The CRISPR-Cas9 system depends on a guide RNA (gRNA) to specify its target. By co-expressing multiple gRNAs, the CRISPR-Cas9 system can perform multiple gene editing. The team of Bastian Minkenberg from Pennsylvania State University identified the rice genes MPK1 and MPK6, homologs of Arabidopsis genes AtMPK6 and AtMPK4, respectively, in rice (Oryza sativa) as essential genes for rice development via CRISPR-edited mutants.

The team found that MPK1 knock-out mutants were severely dwarfed and sterile, and the homozygous mpk1 seeds from heterozygous parents were defective in embryo development. Meanwhile, heterozygous mpk6 mutant plants failed to produce homozygous mpk6 seeds. Both these findings prove the importance of MPK genes in rice embryo development. However, unlike Arabidopsis MPK genes where individual MPK genes can be turned off and have no distinguishable effect on the phenotype, a knockout of an individual MPK gene in rice has lethal consequences to the embryo.

This study revealed the importance of MPK1 and MPK6 in rice development. It enables future functional studies to specify the function of each MPK gene.

For more information on the study, read the article in The Plant Journal.