ABSTRACT
Commercial sugarcane hybrids are derivatives from Saccharum officinarum and Saccharum spontaneum hybrids containing the full complement of S. officinarum and a few S. spontaneum chromosomes and recombinants with favorable agronomic characters from both the species. The combination of the two sub-genomes in varying proportions in addition to the recombinants presents a challenge in the study of gene expression and regulation in the hybrid. We now report the transcriptome analysis of the two progenitor species and a modern commercial sugarcane hybrid through long read sequencing technology. Transcripts were profiled in the two progenitor species S. officinarum (Black Cheribon), and S. spontaneum (Coimbatore accession) and a recent high yielding, high sugar variety Co 11015. The composition and contribution of the progenitors to a hybrid with respect to sugar, biomass, and disease resistance were established. Sugar related transcripts originated from S. officinarum while several stress and senescence related transcripts were from S. spontaneum in the hybrid. The hybrid had a higher number of transcripts related to sugar transporters, invertases, transcription factors, trehalose, UDP sugars, and cellulose than the two progenitor species. Both S. officinarum and the hybrid had an abundance of novel genes like sugar phosphate translocator, while S. spontaneum had just one. In general, the hybrid shared a larger number of transcripts with S. officinarum than with S. spontaneum, reflecting the genomic contribution, while the progenitors shared very few transcripts between them. The common isoforms among the three genotypes and unique isoforms specific to each genotype indicate that there is a high scope for improvement of the modern hybrids by utilizing novel gene isoforms from the progenitor species.
ABSTRACT
Sugarcane-derived biomass is a promising source of renewable energy to meet the growing demands for biofuel. Currently, modern sugarcane cultivars are unable to provide enough biomass due to their narrow genetic base and susceptibility to abiotic and biotic stresses. We have evaluated total of 23 hybrids derived from diverse genetic backgrounds of different Saccharum spp. and allied genera, one inbred and compared with commercial checks. Intergeneric hybrids (IGHs) KGS 99-100 and GU 04-432, produced significantly higher biomass (43.37 t ha-1 and 35.24 t ha-1, respectively) than commercial sugarcane have genes derived from Erianthus arundinaceus. Interspecific hybrids (ISHs) GU 07-3704 and 99-489, also produced significantly higher amounts of biomass (37.24 t ha-1 and 33.25 t ha-1, respectively) than commercial checks have genes from S. officinarum and S. spontaneum backgrounds. ISHs recorded significantly higher biomass yield, number of stalks and total dry matter percentage whereas, IGH group recorded significantly higher fibre percent. Furthermore, the clones resistant to red rot and sugarcane borers were identified. The estimated energy value for seven hybrid clones was found to be very high. Cluster analysis of genetic traits revealed two major clusters in traits improving biomass. Our study has revealed that the genetic diversity present in these hybrids could be used for improving biomass production and tolerance to abiotic and biotic stresses in cultivated sugarcanes.
