2,4-D and alkaloid accumulation in periwinkle cell suspensions

Area of Science:

• Plant cell culture
• Plant biochemistry
• Secondary metabolite production

Background:

• Catharanthus roseus is a valuable source of indole alkaloids.
• Plant growth regulators like 2,4-D influence plant cell metabolism and secondary metabolite production.
• Understanding the precise mechanisms of 2,4-D's effect is crucial for optimizing alkaloid yields.

Purpose of the Study:

• To investigate the impact of 2,4-D omission and feeding on alkaloid accumulation in Catharanthus roseus cell cultures.
• To determine whether 2,4-D affects cell growth or alkaloid biosynthesis more significantly.
• To elucidate the specific pathways and timing of 2,4-D's inhibitory action on alkaloid production.

Main Methods:

• Culturing Catharanthus roseus cells (strain C20) under varying 2,4-D conditions (omission and feeding).
• Monitoring cell growth and alkaloid accumulation.
• Analyzing the reversibility of 2,4-D's inhibitory effects at different growth phases.
• Comparing alkaloid accumulation following feeding with loganic acid, secologanin, and loganin.

Main Results:

• Omission of 2,4-D during subculture enhanced alkaloid accumulation without affecting cell growth.
• 2,4-D primarily inhibited alkaloid accumulation during the growth phase, with partial reversibility observed during the stationary phase.
• The inhibitory effect of 2,4-D feeding weakened over the alkaloid accumulation period.
• Lower accumulation with loganic acid feeding compared to secologanin and loganin suggests loganic acid methylation is a potential 2,4-D target.

Conclusions:

• Alkaloid accumulation in Catharanthus roseus cells is more sensitive to 2,4-D than cell growth.
• 2,4-D likely acts on both upstream non-specific terpenoid pathways and downstream specific alkaloid pathways.
• Loganic acid methylation is a potential target for 2,4-D's regulatory action in alkaloid biosynthesis.