Different color regulation mechanism in willow barks determined using integrated metabolomics and transcriptomics...

Area of Science:

• Plant biology
• Biochemistry
• Genetics

Background:

• Willow (Salix spp.) bark exhibits vibrant colors, holding significant ornamental and economic value.
• The genetic and biochemical mechanisms regulating willow bark coloration are not yet understood.

Purpose of the Study:

• To elucidate the molecular mechanisms behind the diverse coloration of willow barks.
• To investigate the roles of anthocyanins, carotenoids, and chlorophyll in bark color development.

Main Methods:

• Comparative metabolomics and transcriptomics analyses were performed on purple, green, and red willow barks.
• Integrated pathway analysis of flavonoid biosynthesis, carotenoid biosynthesis, and chlorophyll metabolism.

Main Results:

• Seven anthocyanins were identified, with pelargonidin, petunidin 3-O-rutinoside, and cyanin chloride abundant in red bark, and pelargonin chloride in purple bark.
• Purple bark showed high canthaxanthin levels (carotenoid), while red bark had high anthocyanin accumulation and green bark showed high malvidin and maintained chlorophyll synthesis.
• Gene expression analysis indicated ANS, ANR, and BZ1 are involved in anthocyanin synthesis in red bark, CrtZ in carotenoid synthesis in purple bark, and DVR, POR, CRD1 in chlorophyll synthesis.

Conclusions:

• Purple bark color is co-regulated by anthocyanins and carotenoids.
• Red bark color is characterized by anthocyanin accumulation and chlorophyll degradation.
• Candidate genes BZ1 and CrtZ are proposed to regulate anthocyanin and canthaxanthin accumulation, respectively, potentially aiding in breeding colorful willows.