Anthocyanin inheritance and instability in purple basil (Ocimum basilicum L.)

Area of Science:

• Plant genetics and breeding
• Horticultural science
• Biochemistry

Background:

• Anthocyanin instability in purple basil (Ocimum basilicum L.) restricts its use as an ornamental plant and anthocyanin source.
• Previous attempts to stabilize anthocyanin expression through self-pollination were unsuccessful.

Purpose of the Study:

• Investigate the inheritance and stability of leaf traits in the Purple Ruffles basil variety.
• Determine the genetic basis for anthocyanin expression and leaf texture.
• Explore potential mechanisms behind color reversion.

Main Methods:

• Complete diallele crosses were performed on Purple Ruffles basil.
• Leaf traits, anthocyanin expression, and essential oil constituents were analyzed.
• Reverse-phase high-performance liquid chromatography (HPLC) was used to detect secondary metabolites.

Main Results:

• Anthocyanin expression is controlled by two dominant genes; ruffled leaf texture by a single recessive gene.
• Leaf margin and base structures are linked to leaf texture.
• Green-reverted sectors showed accumulation of secondary metabolites, suggesting an anthocyanin pathway block.
• Essential oil composition remained unchanged despite color reversion.

Conclusions:

• Anthocyanin instability in purple basil is likely due to a mutation in an anthocyanin regulatory gene.
• Environmental factors and cutting location influence color stability.
• Understanding these genetic and environmental factors is crucial for improving purple basil varieties.