Maize is a widely cultivated crop. Whereas maize seeds are edible, the maize leaves and stems are a promising renewable feedstock for the chemicals industry. As such, maize could act as a dual-use crop, i.e., for food and materials.
However, the non-edible biomass of maize is currently difficult to process, mainly due to the presence of the lignin polymer. To overcome this problem, attempts are undertaken to engineer maize with lower lignin content. Previous work showed that reducing CINNAMOYL-CoA REDUCTASE (CCR) activity can successfully lower lignin amounts in plants. Recent research from our group showed that by deactivating two genes in the CCR gene family via CRISPR/Cas9, the amount of lignin in the stem (-20%) and leaves (-11%) was reduced, as compared to wild-type plants. Consequently, processing efficiency was improved. In fact, the ccr double mutants displayed a higher processing efficiency in comparison to the ccr single mutants. Importantly, the plant yield was not negatively affected by the engineering strategy. To determine whether the findings observed under greenhouse conditions could be confirmed when plants were grown in the field, the ccr double and respective single mutants were evaluated in a field trial. Preliminary results show that the lignin levels are decreased in the double mutant, compared to the wild type plants. No significant differences were observed in the biomass of the field-grown double mutants, as compared to their respective control lines. These findings can provide us new insights into the role of the CCR gene family members in maize, as well as lead to development of new maize varieties with enhanced processability for the chemical industry.
