Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 21, 2009
Publication Date: August 11, 2011
Citation: Funnell-Harris, D.L., Pedersen, J.F., Sattler, S.E. 2011. Brown Midrib (Low Lignin) Sorghum Mutations Result in Restricted Growth of Fusarium and Alternaria spp. Meeting Abstract. Oral presentation to be given at Great Plains Sorghum Conference, Amarillo, TX, Aug. 11-12, 2009. Technical Abstract: To increase usability of sorghum for bioenergy and forages, two different brown midrib (bmr) genes, bmr6 and bmr12, were backcrossed into five elite backgrounds, resulting in reduced lignin near-isogenic genotypes. When compared with wild-type, field-grown grain from bmr6 and bmr12 plants had significantly reduced colonization by Fusarium spp. in the Gibberella fujikuroi species complex, a group that includes sorghum pathogens. Fusarium isolates were identified to species using sequence analysis of the translation elongation factor gene. Three of the most commonly identified species, members of G. fujikuroi, were the pathogens Fusarium thapsinum, Fusarium proliferatum and Fusarium verticillioides. Other commonly isolated species, Fusarium graminearum, Fusarium subglutinans (also a member of G. fujikuroi) and two genotypes in the Fusarium incarnatum/equiseti species complex (FIESC) likely colonize sorghum asymptomatically. Chi-square analysis showed that the ratios of Fusarium species colonizing bmr12 grain were significantly different from those of wild-type, indicating that bmr12 affects colonization by Fusarium spp. across genetic backgrounds. A member of FIESC, which was the second most commonly recovered Fusarium genotype from wild-type grain, was absent from bmr12 grain, while the pathogen F. proliferatum was recovered at a lower rate from bmr12 grain, as compared with wild-type. A triplicated bioassay was conducted in which peduncles were inoculated with sorghum fungi F. thapsinum, F. verticillioides, Fusarium armeniacum and Alternaria alternata, which were virulent on wild-type plants in most cases. Mean lesion lengths were significantly reduced on one or both bmr lines infected by F. thapsinum F. verticillioides, or A. alternata compared to lesions produced on near-isogenic wild-type plants. These data indicate that bmr6 and bmr12 affect colonization by Fusarium spp. and A. alternata.