Comprehensive analysis of MYB gene family and their expression under various stress conditions in Lilium pumilum

The MYB family proteins play crucial roles in regulating the metabolism for plant growth and development as well as stress responses, thus, have great potential in breeding novel plant varieties with improved traits such as abiotic stress tolerance. Although the MYB genes have extensively studied in various plant species, they have not yet largely explored in Lilium species, which has high ornamental and medicinal values, limiting the practices for breeding abiotic stress tolerant Lilium species. For improving the abiotic stress tolerance of Lilium species, we identified 23 MYB genes in Lilium pumilum (salt-tolerant Lilium species) and performed comprehensive characterization of structure prediction, phylogenetic relationships, conserved motifs, and time- and tissue-specific expression patterns. Phylogenetic relationships of the LpMYB transcription factors showed their diverse roles related to various developmental processes and environmental interactions in L. pumilum. Structure prediction and conserved motif analysis revealed that LpMYB transcription factors have the conserved domain such as SANT domain in common. The LpMYB genes revealed explicit time- and tissue-specific induction pattern upon ABA, cold, PEG, and salt treatment. Particularly, LpMYB1 showed the strongest induction response upon salt in roots of L. pumilum. LpMYB1 overexpression tobacco lines further exhibited the improved salt tolerance phenotypes, such as higher levels of chlorophyll, proline, SOD, POD, and CAT enzymes while lower levels of MDA. Taken together, this study identified novel LpMYB gene family in L. pumilum and contributed to building the preliminary knowledge for further in-depth characterization of the LpMYB transcription factors as well as breeding stress-tolerant Lilium species.