Genetic Improvement of Sorghum for Non-Grain Energy Uses
Grain, Forage & Bioenergy Research
Project Number: 5440-21220-032-00
Start Date: Feb 06, 2013
End Date: Feb 05, 2018
The long-term objectives of this project are to develop improved sorghum (Sorghum bicolor) germplasm (Figure 2) for biofuels production by 1) determining genetic, biochemical, and physiological mechanisms controlling traits beneficial to bioenergy conversion technologies (saccharification & fermentation, pyrolysis and combustion), 2) develop and release improved germplasm with these modified traits, and 3) determine the impact of fungal pathogens on sorghum with these modified traits. Over the next five years, the following specific objectives will be addressed:
Objective 1: Determine and manipulate the genetic, biochemical and physiological mechanisms controlling the biological pathways involved in non-grain energy sorghum germplasm.
Sub-objective 1.A: Determine the effects of six newly identified brown midrib (bmr) mutants on lignin synthesis and the monolignol biosynthetic pathway.
Sub-objective 1.B: Develop transgenic lines over-expressing genes in monolignol biosynthesis to determine their impact on lignin content and composition.
Sub-objective 1.C: Identify strategies for increasing the sugar content of sweet sorghum juice and improving its biomass composition for thermal conversion.
Objective 2: Determine the impact of fungal pathogens on non-grain energy sorghum germplasm, and determine mechanisms of resistance to sorghum pathogens.
Sub-objective 2.A: Determine the response of sorghum with modified lignin biosynthesis pathways to stalk pathogens.
Sub-objective 2.B: Determine whether modifications in the lignin biosynthetic pathway affect growth of the pathogen Colletotrichum sublineolum within sorghum leaves.
Sub-objective 2.C: Identify sweet sorghum parental lines with resistance to stalk pathogens.
Objective 3: Develop and evaluate germplasm to improve sorghum for non-grain energy uses.
Sub-objective 3.A: Determine the effects of brown midrib (low lignin) mutations alone or in combination on bioenergy conversion via saccharification and fermentation.
Sub-objective 3.B: Develop sorghum lines with novel lignin composition and determine the effects on bioenergy conversion.
Sub-objective 3.C: Develop sweet sorghum germplasm incorporating bmr6 and bmr12 to reduce lignin and determine the effects of these alleles on end-use quality.
The overall objective of this project is to improve sorghum (Sorghum biocolor) as an energy crop with the focus on the biomass or non-grain components of the plant. The project will conduct basic studies on the genetic, biochemical, and physiological mechanisms affecting the composition of sorghum biomass and its conversion to liquid fuels. The focus will be on decreasing or increasing lignin content and/or modifying its composition and on increasing sugar content and yield for juice extraction. Low lignin is desirable for the saccharification and fermentation conversion process while high lignin concentration is desirable for conversion via pyrolysis. The impacts of fungal pathogens on sorghum with compositionally modified biomass will be determined. Germplasm with desirable genes affecting the conversion of sorghum biomass to energy will be developed, fully characterized, and released and deposited in Germplasm Resources Information Network (GRIN) for use by public and private sector plant breeders for developing improved hybrids and cultivars. The project consists of three integrated components: germplasm development, molecular biology, and plant pathology (Figure 1). Molecular and conventional methodologies will be utilized, and the project scale will range from field-level to gene-level. The project also has extensive formal and informal collaborations enhancing our ability to conduct this research. Anticipated products include improved sorghum germplasm for the sorghum seed industry with enhanced energy traits and biotic stress tolerance, and tools to assess the biological pathways that impact bioenergy traits and fungal pathogen responses of sorghum.