Predominance of the serpentine route in monoterpenoid indole alkaloid pathway of Catharanthus roseus

Abstract

Single runs of RP-HPLC procedure were used for simultaneous and organ-wise quantification of the terpenoid indole alkaloids (TIAs) serpentine, ajmalicine, vindoline, catharanthine, vincristine and vinblastine in whole adult plants of Catharanthus roseus, sampled from 81 accessions and F2 generation of a cross. The average total TIA content was 159 mg distributed among stem, root, leaf and inflorescence organs in 13:8:3:1 proportion. The root and stem barks, leaf-petiole and corolla petals were several fold TIA-richer than root and stem woods, leaf–lamina and rest of flower organs, respectively. TIAs were undetectable in seed but present in the seedling. Quantitatively, serpentine (+ ajmalicine), serpentine and catharanthine, vindoline, serpentine, catharanthine and vinblastine (+ vincristine) were the principal TIAs detected in stem, root, leaf and inflorescence organs, respectively. Significant amounts of vinblastine, vindoline and catharanthine were found present in the non-chlorophyllous corolla petals. Correlation studies showed that contents of catharanthine and serpentine in roots, catharanthine, vindoline and vinblastine in leaves, serpentine in roots and stems and stems and leaves were interdependent. Serpentine could be involved in suppressing the accumulation of other TIAs in leaves. The observed inter- and intra- organ contents of end-products from serpentine, catharanthine and vindoline TIA branch pathways and correlations between them showed predominance of the serpentine branch.