Molecular cloning, characterization and transcriptional variability study of resistance gene candidates from wild Curcuma spp. for resistance against Pythium aphanidermatum.

TLDR: A PCR mediated approach has been made using degenerate primers designed on conserved region (P-loop and GLPL) of the NBS domain from R-genes that provides the source for cloning analogous sequences called resistance gene candidates (RGCs) from three wild turmeric plants resistant or susceptible to Pythium aphanidermatum.

Abstract: The genetic base of preferred turmeric (Curcuma longa L.) genotypes has eroded due to their continuous domestication through exclusive vegetative routes thus making them highly susceptible to various pests and pathogens. Molecular cloning of resistance related sequences from wild genotypes can result in efficient turmeric improvement by evolving more effective resistance specificities compared to cultigens. In this study, a PCR mediated approach has been made using degenerate primers designed on conserved region (P-loop and GLPL) of the NBS domain from R-genes that provides the source for cloning analogous sequences called resistance gene candidates (RGCs) from three wild turmeric- Curcuma aromatica, Curcuma angustifolia and Curcuma zedoaria. Twenty-one wild turmeric RGCs were isolated and grouped into four phenetic classes. A strong amino acid identity ranging from 41 to 53% together with presence of internal conserved motifs provided evidence that the isolated RGCs belong to the non-toll interleukin receptor (non-TIR) NBS-LRR R-gene sub-family. Southern hybridization showed a high copy representation of turmeric RGCs. Expression variability of wild turmeric RGCs was analyzed through reverse transcription PCR in root tissues of the three wild turmeric plants resistant or susceptible to Pythium aphanidermatum. Cap12 and Can12 showed a constitutive expression in both resistant and susceptible plants of Curcuma aromatica and Curcuma angustifolia respectively while Czp11 expression was realized only in Pythium aphanidermatum resistant lines of Curcuma zedoaria as well as Curcuma longa L. This result can pave way towards the identification and characterization of a potential Pythium aphanidermatum resistance gene in turmeric.