Mutations in the BoPQL2 gene enhance the sensitivity to low temperature and affect the leaf margin coloration in ornamental kale

•The BoPQL2 gene exhibits 4 amino acid substitutions between white-green variegated leaf and white leaf ornamental kale.•Three BoPQL2-deficient mutants were generated using CRISPR/Cas9 technology.•The BoPQL2-deficient mutants showed increased sensitivity to low temperature.•Inner leaves of BoPQL2-deficient mutants were free of green margins at low temperatures below 16 °C. Leaf color is an important ornamental trait for ornamental kale. In our previous study, the BoPQL2 gene was identified to exhibit significant differential expression between white and green leaf tissues of ornamental kale. In this study, the gene BoPQL2 was cloned from 'D11′ with white-green variegated inner leaves and '1631′ with fully white inner leaves. Five SNPs were identified between the two above materials, of which four lead to four amino acid substitutions. To elucidate the function of the BoPQL2 gene in ornamental kale, the CRISPR-BoPQL2 vector was constructed and transformed into the 'D11′. Three BoPQL2-deficient mutants were generated, including two homozygous mutants and one double allelic mutant. Compared to the wildtype, the three mutants exhibited full white inner leaves without green margins under the same low temperature condition. These results indicate that the mutations in the BoPQL2 gene increased sensitivity to the low temperature of ornamental kale, thus affecting leaf margin coloration. This study lays the foundation for improving ornamental kale genotypes by editing the BoPQL2 gene.