Molecular Markers and Descriptor’s Suitable for Quantitative Trait Loci and Genome Mapping in Catharanthus roseus

Abstract

AbstractMost investigated perennial herb Catharanthus roseus is the only natural source for durable bioactive compounds vinblastine (VBL) and vincristine (VCR) as anticancer drugs. The VBL and VCR are the two main dimeric downstream products of the branched terpenoid indole alkaloids (TIAs) pathway. The in-planta high TIA production and storage abilities are essential for reducing the production cost and high availability of VBL and VCR. A large number of publications has been already made in the dissection of TIA pathway including various transcription factors, regulatory enzymes and genes. The derivation of Catharanthus roseus genotypes for high in-planta yields of pharmaceutical alkaloids is being carried out either by overexpression or underexpression of regulatory genes, steps/routes of the TIAs pathway. Selection of elite genotypes has been done through mutation, molecular breeding and transgenic approaches. The molecular mapping of quantitative trait loci (QTL) associated with different levels of individual metabolites (mQTL) combined with the mapping of morphological traits linked with TIAs are essential tools to investigate the genetic basis of variation/covariation in metabolites and plant phenology in C. roseus population. It is shown that the development of large number of molecular markers, genetics related to TIA pathway and molecular breeding approaches necessitates pyramidation of quantitative traits that contribute toward high alkaloid yield. The saturated genetic linkage map construction on molecular markers along with alkaloid yield-related QTLs in relation to DNA is a prerequisite for tracking QTLs. By the use of molecular DNA markers, observations recorded on a genetic resource collection, the quantitative and morphological traits and accessions possessing their contrasting manifestations have been already identified in C. roseus. The life cycle features and morphological descriptors of C. roseus are referred here in this chapter which render it favorable for speedy development of the desired QTL map. The knowledge generated through the scaffolded genome sequence of C. roseus it is possible now to understand the genes and their functions by integrating multidimensional informations. The genome sequence data is essential to map all possible QTLs related to the trait of interest which can be further analyzed to identify the superior alleles for TIAs’ synthesis in plant/organ by targeted genetic engineering approaches.KeywordsTIA pathwayDNA markersGenetic linkage mapQuantitative trait locusMarker-assisted selectionGenetic background