Peer review

Guar is a legume of industrial importance due to the presence of gum (galactomannan) in its seed endosperm. The mannose (M)/galactose (G) ratio in the galactomannan molecule is critical in deciding the physico-chemical properties of guar gum. We report down regulation of galactomannan galactosyltransferase (GMGT) which links G residues to the M backbone in the galactomannan molecule. The RNAi cassette containing the sense-antisense sequence for gmgt was delivered into guar variety RGC-936 using Agrobacterium tumefaciens-mediated gene transfer. Maximum number of putative transformed shoots regenerated from the cotyledonary node explants cultured in vitro on Murashige and Skoog (MS) medium containing 1.5 mg/L indole-3-acetic acid (IAA), 4.0 mg/L butyric acid (BA) and 1.0 mg/L gibberellic acid (GA3). In vitro regenerated shoots were rooted on half-strength MS medium containing 4% sucrose and 2 mg/L indole-3-butyric acid (IBA). The quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) analysis showed reduced levels of GMGT expression in the seed endosperm of 35 days after flowering (DAF) stage pods. The present findings are expected to be beneficial in taking up gene characterization and agronomic traits improvement studies in guar.

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