Two induced macro-mutants of periwinkle with enhanced contents of leaf and root alkaloids and their inheritance

Abstract Periwinkle ( Catharanthus roseus ), an important medicinal plant, is the source of highly valued anti-cancer and anti-hypertension alkaloids. Seeds of variety, ‘Dhawal’ were treated with ethyl methanesulfonate to induce mutants with increased contents of alkaloids. Two macro-mutants, ‘necrotic leaf’ and ‘nerium leaf’, were isolated from the M 2 generation. The ‘necrotic leaf’ mutant exhibited irregular light-green to yellowish-green and brownish lesions on seedling leaves up to about 5th leaf stage. Later, it resembled its parental variety. The ‘nerium leaf’ mutant had leaves distinctly different from its parental variety. Both the mutants, which were found to be true breeding in the M 3 generation, were advanced to the M 6 generation through manual selfing in the glasshouse and evaluated in comparison with their parental variety. Both mutants exhibited significantly higher contents of total leaf and root alkaloids and anti-cancer leaf alkaloids, vincristine and vinblastine than the parental variety. Their leaf and root yields were, however, significantly lower than their parental variety. Both the macro-mutant traits were inherited as monogenic recessive traits. Gene symbols nl and ne are proposed for recessive alleles responsible for the production of ‘necrotic leaf’ and ‘nerium leaf’ traits, respectively. The ‘necrotic leaf’ mutant appears to be the first lesion mimic mutant to be reported in any medicinal or aromatic plant.