Bioinformatic and morphological characterization of Catharanthus roseus mutants

Abstract

Catharanthus roseus, a member of the Apocynaceae family, has been studied extensively for its valuable chemotherapeutic monoterpenoid indole alkaloids (MIAs). Ethyl methanesuphonate (EMS) mutagenesis is a screening tool that has been used to look for altered MIA profiles in hope of discovering mutations of crucial MIA biosynthetic genes. Without a high-throughput mutation detection screen for C. roseus sequencing data, a range of techniques must be used to discover the EMS-induced changes within the plant. Bioinformatic and morphological analysis revealed the likely alterations leading to unique MIA profiles in two C. roseus EMS mutants: the high-ajmalicine accumulating line M2-0754 and the low-MIA accumulating line M2-1582. Expression of geissoschizine synthase (GS) was downregulated almost seven-fold in the leaves of M2-0754, leading to the accumulation of an alternate pathway MIA from the labile intermediate. The low-MIA profile and increased auxin sensitivity of M2-1582 is likely due to the expression of a dysfunctional auxin influx transport protein homologue.