Abstract
BackgroundSugarcane, a tropical C4 perennial crop, is capable of producing 30–100 tons or more of biomass per hectare annually. The lignocellulosic residue remaining after sugar extraction is currently underutilized and can provide a significant source of biomass for the production of second-generation bioethanol.ResultsMYB31 and MYB42 were cloned from maize and expressed in sugarcane with and without the UTR sequences. The cloned sequences were 98 and 99 % identical to the published nucleotide sequences. The inclusion of the UTR sequences did not affect any of the parameters tested. There was little difference in plant height and the number of internodes of the MYB-overexpressing sugarcane plants when compared with controls. MYB transgene expression determined by qPCR exhibited continued expression in young and maturing internodes. MYB31 downregulated more genes within the lignin biosynthetic pathway than MYB42. MYB31 and MYB42 expression resulted in decreased lignin content in some lines. All MYB42 plants further analyzed showed significant increases in glucose release by enzymatic hydrolysis in 72 h, whereas only two MYB31 plants released more glucose than control plants. This correlated directly with a significant decrease in acid-insoluble lignin. Soluble sucrose content of the MYB42 transgenic plants did not vary compared to control plants.ConclusionsThis study demonstrates the use of MYB transcription factors to improve the production of bioethanol from sugarcane bagasse remaining after sugar extraction.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0559-1) contains supplementary material, which is available to authorized users.
Highlights
Sugarcane, a tropical C4 perennial crop, is capable of producing 30–100 tons or more of biomass per hectare annually
Alignment of cloned ZmMYB31 and ZmMYB42 sequences ZmMYB31 and ZmMYB42 were cloned from maize and transformed into sugarcane under the control of a maize ubiquitin promoter
MYB31ORF 7 was taller than controls and MYB42UTR 30 was shorter
Summary
A tropical C4 perennial crop, is capable of producing 30–100 tons or more of biomass per hectare annually. The lignocellulosic residue remaining after sugar extraction is currently underutilized and can provide a significant source of biomass for the production of second-generation bioethanol. Hybrids) is a C4 perennial crop grown in tropical and subtropical climates that is capable of producing large amounts of dry biomass per hectare annually [1]. Best known for accumulating and storing high concentrations of sucrose in its stem, and its use for sugar production, sugarcane produces abundant lignocellulosic residues that remain after sugar extraction. Pretreatment steps to Poovaiah et al Biotechnol Biofuels (2016) 9:143 remove lignin lead to the formation of compounds that inhibit saccharification and fermentation [5]
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