Functional differences between two homologous MYB transcription factors in regulating fruit color in octoploid strawberry (Fragaria×ananassa)

• Two highly homologous MYB transcription factors FaMYB44.1 and FaMYB44.3 have distinct roles in strawberries. • Both FaMYB44.1 and FaMYB44.3 are nuclear-localized transcription factors significantly induced by weak light. • FaMYB44.1 significantly inhibits anthocyanin synthesis by transcriptionally repressing FaF3H , a key anthocyanin pathway gene, while FaMYB44.3 lacks this function. • FaMYB44.1’s suppression of anthocyanin synthesis is consistent across strawberry varieties ‘BeniHoppe’ and ‘JianDe-Hong’, demonstrating its conserved regulatory role. Anthocyanins are the flavonoid pigments responsible for vibrant fruit and flower colors, and they also play key roles in both plant physiology and human health. MYB transcription factors are crucial regulators of anthocyanin biosynthesis and accumulation, but the functional differences of homologous MYB transcription factors in regulating anthocyanin content are still unclear. In strawberry ( Fragaria × ananassa ), FaMYB44.1 and FaMYB44.3 are highly homologous MYB transcription factors localized in the nucleus and can be significantly induced by weak light. However, they differ in their effects on anthocyanin accumulation in the fruits. FaMYB44.1 inhibits anthocyanin synthesis by transcriptionally suppressing FaF3H , which is essential for anthocyanin regulation, in the ‘BeniHoppe’ and ‘JianDe-Hong’ strawberry varieties. In contrast, FaMYB44.3 does not affect anthocyanin levels. This study provides a comprehensive overview of the roles of FaMYB44.1 and FaMYB44.3 in anthocyanin regulation in strawberry fruits. By elucidating the molecular mechanisms underlying their regulation, this study enhances our understanding of how the interactions between genetic and environmental factors control fruit pigmentation and enhance the nutritional value of the fruit.