Project Number: 3072-21000-008-14-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Feb 1, 2011
End Date: Jan 31, 2017
1. To develop transgenic lines overexpressing phenylpropanoid biosynthetic enzymes. 2. To determine the effects of modifications to lignin biosynthesis through bmr loci or transgenic overexpression on phloem-feeding and chewing insects of sorghum. 3. To determine the effects these lignin modifications have on fungi causing foliar or stalk diseases in sorghum. 4. To determine the alternations in metabolitic profiles of relevant lines with significantly increased resistance to either insects or fungi. 5. To determine the changes in global gene expression profiles of relevant lines with significantly increased resistance to either insects or fungi.
Altering lignin content and composition are targets to improve lignocellulosic biomass for bioenergy conversion processes, the affects of these alterations on plant-biotic interactions are unknown. We hypothesize that specific modification to the lignin biosynthetic pathway will alter the defense responses of host plants to insects and/or fungal pathogens. Our aim is to gain insight on the underlying causes that contribute to the altered defense responses. The sorghum genotypes we will use for the proposed experiments will carry three bmr mutants, which reduce lignin content and alter lignin composition. To increase phenolic compounds and lignin, we will utilize transgenic approaches whereby transgenic sorghum events will be generated that harbor cassettes for the over-expressing of PAL, C3H and CRR, three key enzymes monolignol biosynthesis along with a transcription factor strategy through expression of MYB68, a known regulator of lignin biosynthesis. These transgenic events should increase flux through the phenylpropanoid pathway thereby increasing phenolic subunits available for lignin biosynthesis. However, we are cognizant that these transgenic events may display altered phenylpropanoid metabolism and phenolic profiles, without a concomitant lignin content change. We will use the RTx430 background for these experiments, for which we currently have near-isogenic lines for bmr6 and bmr12.