Annual Report - IHBT

CSIR-IHBT Annual Report 2010-11Metabolic engineering of vinca alkaloid pathwayA cDNA library was constructed from young leaves of Catharanthus roseus and sequenced. Analysesof sequence data revealed various genes of the secologanin and vindoline pathways (Table 2).Table 2 Various genes of the secologanin (S) and vindoline (V) pathwaysGene familyCyclaseGlycosyltransferasesCytochrome p450/MonooxygenaseGenes identified(S)(S)10-hydroxygeraniol oxidoreductase (S)Hydroxylasetabersonine 16-hydroxylase (V), geraniol 10-hydroxylase (S), desacetoxyvindoline4-hydroxylase (V)Hydratase (V) (18 sequences)N-methyltransferase 2,3-dihydro-3-hydroxytaberosonine-N-methyltransferase (V)Methyltransferaseloganic acid methyltransferase (S), 16-hydroxytabersonine-O-methyltransferase (V)Synthasesecologanin synthase (S)Otherstryptophan decarboxylase, strictosidine synthase, strictosidine beta-glucosidaseTotal number of transcripts in the library: 35,341; E-value cut off=1e -05In another study, the possibility of conversion of 16-methoxytabersonine into 16-methoxy-2, 3-dihydro-3-hydroxytabersonine was analysed using 18 hydratases obtained from the cDNA library(Table 3).Table 3 Transcriptome analyses of identified hydratasesHydratase scaffoldscaffold1524; scaffold6664; scaffold14267; C174768;C182064; C220804scaffold4881; scaffold7018; scaffold12057; C158946;C168920; C192928; C186618; C196402; C197736scaffold14527C218090C177082BlastX resultsAconitase protein (3-isopropylmalate dehydratase)Enoyl-CoA hydratase (Crotonase)Cyanate hydrataseNaphthoate synthaseCarbamoylputrescine amidase (Nitrilase)Putative microRNAs and their targets from horsegramIn a new activity, an EST based approach was used to identify novel miRNAs in horsegram. Atotal of 989 ESTs were subjected to CAP3 assembly to remove the redundancy. This resulted inan output of 72 contigs and 606 singletons as non-redundant datasets. The miRNAs were thenpredicted by using miRNA-finder. A total of eight potential miRNAs were predicted and named ashor-miR1 to hor-miR8. The target mRNAs for these miRNAs belong to zinc finger, chromosomecondensation, protein kinase, abscisic acid-responsive, calcineurin-like phosphoesterase, diseaseresistance and transcriptional factor family proteins. These targets appeared to be involved in plantgrowth and development, and environmental stress responses.17