Abstract

Transposon-based functional genomics approach offers a great potential to characterize genes in plants.  This approach is specifically important for the large genome cereals where genetic transformation is not a routine. The system developed in barley relies on two parts of the maize Ac/Ds system, introduced into separate plants via particle bombardment into the cultivar Golden Promise. Using this system, single-copy Ds insertion lines (TNPs) have been generated in barley to identify genes and their function. Barley is a key ingredient in malting and brewing industry; therefore, gene discovery in relation to malting quality has an industrial perspective. We employed transposon- and synteny-based approaches to dissect an important malting quality chromosome region, QTL2. A Ds transposon insertion from TNP- 29 was previously mapped in the vicinity of QTL2. Reactivations of Ds transposon from this TNP line lead to identification of genes harboring in this QTL2 region. Identification of unique flanking sequences, using high-efficiency thermal asymmetric interlaced PCR and inverse PCR confirmed Ds insertion in genes potentially associated with malting quality such as ß-GAL1, ß-amylase-like gene. Alternatively, comparative genomic approach detected 22 candidate genes; one gene, TLP8 shows differential gene expression using qPCR, among malting and non-malting barley varieties. Biochemical analysis like binding assay and ELISA further confirms these findings. Integrated effort of saturation mutagenesis with Ds transposons and comparative genomics approach led us a better understanding of malting quality traits and candidate genes that display quantitative variation. We are currently developing similar resources in oat for functional genomic studies.