CstMYB1R1, a REVEILLE-8-like transcription factor, regulates diurnal clock-specific anthocyanin biosynthesis and response to abiotic stress in Crocus sativus L.

CstMYB1R1 acts as a positive regulator of Crocus anthocyanin biosynthesis and abiotic stress tolerance which was experimentally demonstrated through molecular analysis and over-expression studies in Crocus and Nicotiana. Regulatory mechanics of flavonoid/anthocyanin biosynthesis in Crocus floral tissues along the diurnal clock has not been studied to date. MYB proteins represent the most dominant, functionally diverse and versatile type of plant transcription factors which regulate key metabolic and physiological processes in planta.

CstPIF4 Integrates Temperature and Circadian Signals and Interacts with CstMYB16 to Repress Anthocyanins in Crocus.

Crocus sativus has emerged as an important crop because it is the only commercial source of saffron that contains unique apocarotenoids. Saffron is composed of dried stigmas of Crocus flower and constitutes the most priced spice of the world. Crocus floral organs are dominated by different classes of metabolites.

Crocus transcription factors CstMYB1 and CstMYB1R2 modulate apocarotenoid metabolism by regulating carotenogenic genes.

Two MYB genes have been identified which regulate apocarotenoid metabolism in Crocus sativus. Apocarotenoids like crocin, picrocrocin and safranal are restricted to genus Crocus and are synthesized by oxidative cleavage of zeaxanthin followed by glycosylation reactions. In Crocus sativus, these apocarotenoids are synthesized in stigma part of the flower in developmentally regulated manner.