Abstract
Lignocellulosic biomass can be a significant source of renewable clean energy with continued improvement in biomass yield and bioconversion strategies. In higher plants, the leaf blade is the central energy convertor where solar energy and CO2 are assimilated to make the building blocks for biomass production. Here we report that introducing the leaf blade development regulator STENOFOLIA (STF), a WOX family transcription factor, into the biofuel crop switchgrass, significantly improves both biomass yield and sugar release. We found that STF overexpressing switchgrass plants produced approximately 2-fold more dry biomass and release approximately 1.8-fold more solubilized sugars without pretreatment compared to controls. The biomass increase was attributed mainly to increased leaf width and stem thickness, which was also consistent in STF transgenic rice and Brachypodium, and appeared to be caused by enhanced cell proliferation. STF directly binds to multiple regions in the promoters of some cytokinin oxidase/dehydrogenase (CKX) genes and represses their expression in all three transgenic grasses. This repression was accompanied by a significant increase in active cytokinin content in transgenic rice leaves, suggesting that the increase in biomass productivity and sugar release could at least in part be associated with improved cytokinin levels caused by repression of cytokinin degrading enzymes. Our study provides a new tool for improving biomass feedstock yield in bioenergy crops, and uncovers a novel mechanistic insight in the function of STF, which may also apply to other repressive WOX genes that are master regulators of several key plant developmental programs.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Biofuels
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Biomass
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Brachypodium / genetics
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Brachypodium / metabolism
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Carbohydrate Metabolism
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Cell Proliferation
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Chromatin Immunoprecipitation
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Crops, Agricultural / genetics
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Crops, Agricultural / metabolism
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Cytokinins / genetics*
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Cytokinins / metabolism
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DNA, Plant / genetics
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Gene Expression Regulation, Plant
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Green Fluorescent Proteins / metabolism
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Homeostasis
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Medicago truncatula / genetics*
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Oligonucleotide Array Sequence Analysis
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Oryza / genetics
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Oryza / metabolism
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Oxidoreductases / genetics
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Panicum / genetics*
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Panicum / metabolism
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Phenotype
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Plant Leaves / metabolism
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Plant Proteins / genetics*
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Plant Proteins / metabolism
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Plants, Genetically Modified / genetics
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Plants, Genetically Modified / metabolism
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Transcription Factors / genetics*
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Transcription Factors / metabolism
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Transgenes
Substances
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Biofuels
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Cytokinins
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DNA, Plant
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Plant Proteins
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Transcription Factors
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Green Fluorescent Proteins
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Oxidoreductases
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cytokinin oxidase
Grants and funding
This work was supported by: Ministry of Science and Technology of the People’s Republic of China (2015CB150103, 2016YFD0101001, and 2014CB138701) to HL and TL, National Natural Science Foundation of China (31470381) to HL, Chinese Academy of Agricultural Sciences to HL and LN, Samuel Roberts Noble Foundation to ZYW, the National Science Foundation (NSF) grant IOS-1354422 to MT; and the National Institute of Food and Agriculture, U.S. Department of Agriculture, under the Agricultural Experiment Station to MT. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.