Pattern of diversity for morphological and alkaloid yield related traits among the periwinkle Catharanthus roseus accessions collected from in and around Indian subcontinent

Thirty two accessions of periwinkle Catharanthus roseus collected from different semitemperate to tropical geographical areas of Indian subcontinent, Madagascar, Singapore and Malaysia were characterized under field conditions for 53 growth, development, morphogenesis and alkaloid yield related characters over a few seasons at Lucknow, India. Large differences were observed among the accessions for each of the characters examined. The differences among the accessions ranged 3, 80 and 15 fold for the alkaloid yield related traits – leaf dry matter yield and leaf vincristine and vinblastine concentration, respectively. Strong correlations were observed between leaf area and leaf yield with leaf alkaloid, root and root alkaloid yields, contents of dimeric alkaloid in leaves with yields of respective alkaloids, leaf number and root alkaloid content with leaf vinblastine yield and leaf vinblastine content with leaf vincristine and vinblastine yields. Multi-variate analyses allowed classification of the accessions into 5 to 7 morphologically and presumably genetically distinct groups. Generally, the accessions coming from tropical agro-climates tended to get separated from those having origins in subtropical to semi-temperate environments. Three clusters were observed to bear complementary characters for possibly cross-parenting high alkaloid yielding transgressive segregants. One of the accessions of C. roseus in which the leaf vincristine content was 5 fold and vinblastine content one and a half fold of the respective all accession means appeared suitable for the domesticated cultivation. It was proposed that accumulation of high amounts of total alkaloids and one or more dimeric alkaloids in leaves of certain accessions may be a reflection of reproductive fitness achieved under the biotic and abiotic stresses imposed on their parent populations, sometime in their evolutionary pathway.