Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/12/2015
Publication Date: 8/15/2015
Citation: Dowd, P.F., Berhow, M.A., Sattler, S.E. 2015. Reduction of lignin levels in mutant sorghum lines developed for saccharification leads to increased production of insecticidal compounds in stalk pith. National Meeting of the American Chemical Society. AGRO 75. Meeting Abstract.
Technical Abstract: Production of material for biomass that can be converted to energy sources such as ethanol is impeded by the presence of lignin that limits saccharafication. Lines of crops such as sorghum have been developed with reduced levels of lignin that have promise for use in bioenergy production due to enhanced rates of sacccharification. Two of mutant lines developed, that have bmr6 (disrupted cinnamyl alcohol dehydrogenase) and bmr12 (disrupted caffeic acid O-methyl transferase), have been converted into lines near isogenic with normal lignin line BTx623. Laboratory and field trials have so far indicated no consistent increases in insect or disease susceptibility in the low lignin lines, and often increased insect resistance. The most resistant tissue to caterpillars is the pith, which in some cases has killed nearly 50% of first instar corn earworms, while only about 6% of those feeding on normal lignin pith died. Initial chemical analysis after acid hydrolysis indicated increased levels of some phenolic acids obtained by acid hydrolysis, some of which caused reduced insect growth when incorporated into diet made from sorghum leaves. HPLC and accurate mass spectrometry indicated an increase in the levels of ferullated sugars including di-feruloyl-sucrose and feruloyl-glucose. Large scale separation and purification of pith extracts from the most resistant bmr6 line simple fractionation by reverse-phase flash chromatography resulted in a fraction that was greatly enriched in the feruloyl-sugars which was also shown to have the most impact on insects in controlled feeding studies.