Comparative de novo transcriptome analysis identifies salinity stress responsive genes and metabolic pathways in sugarcane and its wild relative Erianthus arundinaceus [Retzius] Jeswiet

Erianthus arundinaceus [Retzius] Jeswiet, a wild relative of sugarcane has a high biomass production potential and a reservoir of many genes for superior agronomic traits and tolerance to biotic and abiotic stresses. A comparative physiological, anatomical and root transcriptome analysis were carried out to identify the salt-responsive genes and metabolic pathways associated with salt-tolerant E. arundinaceus genotype IND99-907 and salinity-sensitive sugarcane genotype Co 97010. IND99-907 recorded growth of young leaves, higher proline content, higher relative water content, intact root anatomical structures and lower Na(+)/K(+), Ca(2+)/K(+) and Mg(2+)/K(+) ratio as compared to the sugarcane genotype Co 97010. We have generated four de novo transcriptome assemblies between stressed and control root samples of IND99-907 and Co 97010. A total of 649 and 501 differentially expressed genes (FDR<0.01) were identified from the stressed and control libraries of IND99-907 and Co 97010 respectively. Genes and pathways related to early stress-responsive signal transduction, hormone signalling, cytoskeleton organization, cellular membrane stabilization, plasma membrane-bound calcium and proton transport, sodium extrusion, secondary metabolite biosynthesis, cellular transporters related to plasma membrane-bound trafficking, nucleobase transporter, clathrin-mediated endocytosis were highly enriched in IND99-907. Whereas in Co 97010, genes related to late stress-responsive signal transduction, electron transport system, senescence, protein degradation and programmed cell death, transport-related genes associated with cellular respiration and mitochondrial respiratory chain, vesicular trafficking, nitrate transporter and fewer secondary metabolite biosynthetic genes were highly enriched. A total of 27 pathways, 24 biological processes, three molecular functions and one cellular component were significantly enriched (FDR≤ 0.05) in IND99-907 as compared to 20 pathways, two biological processes without any significant molecular function and cellular components in Co 97010, indicates the unique and distinct expression pattern of genes and metabolic pathways in both genotypes. The genomic resources developed from this study is useful for sugarcane crop improvement through development of genic SSR markers and genetic engineering approaches.