Abstract
Sugarcane is a hybrid of Saccharum officinarum and Saccharum spontaneum, with minor contributions from other species in Saccharum and other genera. Understanding the molecular basis of cell wall metabolism in sugarcane may allow for rational changes in fiber quality and content when designing new energy crops. This work describes a comparative expression profiling of sugarcane ancestral genotypes: S. officinarum, S. spontaneum and S. robustum and a commercial hybrid: RB867515, linking gene expression to phenotypes to identify genes for sugarcane improvement. Oligoarray experiments of leaves, immature and intermediate internodes, detected 12,621 sense and 995 antisense transcripts. Amino acid metabolism was particularly evident among pathways showing natural antisense transcripts expression. For all tissues sampled, expression analysis revealed 831, 674 and 648 differentially expressed genes in S. officinarum, S. robustum and S. spontaneum, respectively, using RB867515 as reference. Expression of sugar transporters might explain sucrose differences among genotypes, but an unexpected differential expression of histones were also identified between high and low Brix° genotypes. Lignin biosynthetic genes and bioenergetics-related genes were up-regulated in the high lignin genotype, suggesting that these genes are important for S. spontaneum to allocate carbon to lignin, while S. officinarum allocates it to sucrose storage. Co-expression network analysis identified 18 transcription factors possibly related to cell wall biosynthesis while in silico analysis detected cis-elements involved in cell wall biosynthesis in their promoters. Our results provide information to elucidate regulatory networks underlying traits of interest that will allow the improvement of sugarcane for biofuel and chemicals production.Electronic supplementary materialThe online version of this article (doi:10.1007/s11103-016-0434-2) contains supplementary material, which is available to authorized users.
Highlights
Sugarcane is a C4 grass from the Saccharinae subtribe (Poacea family) that has the capacity to accumulate high levels of sucrose in its stems
We focused our analysis on the identification of cell wall-related genes in an attempt to advance the understanding of the particularities of cell wall biosynthesis and regulation in sugarcane, producing knowledge to contribute to the development of strategies to increase cane biomass yields and to design an energy cane that is better suited for industrial needs
S. spontaneum clearly differed from the other genotypes, as it had lower culm diameter, water content in the culm, photosynthetic rate, transpiration, sugar contents in intermediate and mature internodes, and had increased water use efficiency and lignin content in intermediate and mature internodes (Table 1)
Summary
Sugarcane is a C4 grass from the Saccharinae subtribe (Poacea family) that has the capacity to accumulate high levels of sucrose in its stems. Plant Mol Biol (2016) 91:15–35 derived from S. officinarum (70–80 %), while a smaller portion of the composition is attributed to S. spontaneum (10–20 %) and to recombinant chromosomes from these two species (*10 %) (D’Hont 2005; D’Hont et al 1996, 2008). These two main ancestral species show distinct phenotypes that were important in the breeding of the current varieties: S. officinarum is a sweet cane with thick, juicy and low-fiber culms, whereas S. spontaneum typically exhibits a low sugar content, thin and fibrous culms, more tillers per plant, and higher stress tolerance (Paterson et al 2013). The possibility of using biomass for bioenergy production, and the recent interest in bioenergy-dedicated crops, has led to increasing interest in the production of a cane that generates the maximum amount of primary energy per hectare, referred to as energy cane, which typically exhibits a lower sugar content, but higher biomass yield and higher fiber content (Leal et al 2013)
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