As one of the most important transcription factors regulating plant anthocyanin biosynthesis, MYB has attracted great attentions. In this study, we identified fifteen candidate anthocyanin biosynthesis related MYB (ABRM) proteins, including twelve R2R3-MYBs and three 1R-MYBs, from highbush blueberry. The subcellular localization prediction results showed that, with the exception of VcRVE8 (localized in chloroplast and nucleus), all of the blueberry ABRMs were nucleus-localized. The gene structure analysis revealed that the exon numbers of the blueberry ABRM genes varied greatly, ranging between one and eight. There are many light-responsive, phytohormone-responsive, abiotic stress-responsive and plant growth and development related cis-acting elements in the promoters of the blueberry ABRM genes. It is noteworthy that almost all of their promoters contain light-, ABA- and MeJA-responsive elements, which is consistent with the well-established results that anthocyanin accumulation and the expression of MYBs are influenced significantly by many factors, such as light, ABA and JA. The gene expression analysis revealed that VcMYB, VcMYB6, VcMYB23, VcMYBL2 and VcPH4 are expressed abundantly in blueberry fruits, and VcMYB is expressed the highest in the red, purple and blue fruits among all blueberry ABRMs. VcMYB shared high similarity with functionally proven ABRMs from many other plant species. The gene cloning results showed that VcMYB had three variable transcripts, but only the transient overexpression of VcMYB-1 promoted anthocyanin accumulation in the green fruits. Our study can provide a basis for future research on the anthocyanin biosynthesis related MYBs in blueberry.

Gerbera hybrida, a model plant for studying the development and evolution of complex inflorescences, has been recognized as a valuable source of colorants and natural coatings. Previously, we demonstrated that inoculation with Piriformospora indica, an endophytic fungus, could enhance the resistance of gerbera to Phytophthora cryptogea, which causes root rot disease. Here, to dissect the underlying molecular mechanism, comparative transcriptomic analyses of gerbera roots from P. indica-colonized (PI), P. cryptogea-inoculated (PC), and P. cryptogea-inoculated P. indica-colonized (PP), along with the non-inoculated control (CK) groups were conducted. In total, we identified 15,763 differentially expressed genes (DEGs) among CK vs. PI, CK vs. PC, and PI vs. PP comparisons, together with PC vs. PP comparisons. Of them, 743 DEGs encode transcription factor (TF) proteins, with the AP2/ERF family members occupying the majority. An ERF gene (GhERF) was identified as one of the 30 common DEGs among the four comparisons. Notably, its transient overexpression in tobacco leaves reduced the lesion area caused by P. cryptogea inoculation to 65.36% of the empty vector control. Many defense response- and secondary metabolism-related DEGs were expressed higher in the PP group than in the PC group. Moreover, P. indica-colonization up-regulated the expression of hormone signaling- and MAPK signaling-related genes, thereby activating the defense responses against the pathogen infection. Our study is helpful for understanding the molecular mechanism underlying P. indica-enhanced root rot resistance in gerbera.