Response of wheat constitutively expressing monolignol biosynthesis genes to fusarium head blight

Authors: Funnell-Harris, Deanna; DURAY, ZACHARY - University Of Illinois; Sattler, Scott; WEGULO, STEPHEN - University Of Nebraska; DILL-MACKY, RUTH - University Of Minnesota; Tatineni, Satyanarayana - Ts

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/8/2019
Publication Date: 12/8/2019
Citation: Funnell-Harris, D.L., Duray, Z., Sattler, S.E., Wegulo, S.N., Dill-Macky, R., Tatineni, S. 2019. Response of wheat constitutively expressing monolignol biosynthesis genes to fusarium head blight. In: Canty, S., A. Hoffstetter, B. Wiermer and R. Dill-Macky (Eds.), Proceedings of the 2019 National Fusarium Head Blight Forum (p. 48). East Lansing, MI/Lexington, KY: U.S. Wheat & Barley Scab Initiative.

Interpretive Summary:

Technical Abstract: The overall goal of this research is to utilize wheat lines constitutively expressing sorghum genes involved in the monolignol biosynthesis pathway, to identify unique sources of resistance to Fusarium head blight (FHB). Toward this goal, we have identified lines with enhanced resistance. We transformed the spring wheat cultivar CB037 to constitutively express one of four sorghum genes: one encoding for the transcription factor, SbMyb60, involved in regulation of genes in sorghum monolignol biosynthesis, and the monolignol biosynthetic enzymes coumaroyl shikimate 3-hydroxylase (SbC3H), caffeoyl coenzyme A 3-O-methyl transferase (SbCCoAOMT) and 4-coumarate:CoA ligase (SbBmr2). The transgenic lines were assessed for responses to the FHB pathogen, Fusarium graminearum, in greenhouse and field trials. For both greenhouse and field artificial inoculations, lines constitutively expressing SbC3H or SbCCoAOMT exhibited increased resistance to FHB. Lead events (two to four) were grown in a greenhouse and inoculated with F. graminearum by spray inoculation, to test for Type I resistance to FHB infection, and single-floret inoculation, to test for Type II resistance to pathogen spread. Area under the disease progress curve (AUDPC) was assessed for each, then grain was allowed to mature and the proportion of Fusarium damaged kernels (FDK) was determined. For spray inoculations, the AUDPC for one lead event constitutively expressing SbC3H (C3H_885) was significantly less than that for the moderately-susceptible parental genotype, CB037, although FDK was not significantly different. For all other constitutive expression lines, AUDPC and FDK were not significantly different from those of CB037 except for one SbBmr2 line in which FDK was higher. For single-floret inoculations, lines C3H_885 and CCoAOMT_894_A (constitutively expressing SbCCoAOMT) had an AUDPC significantly less than that for CB037. FDK for C3H_885 was again similar to that of CB037 while FDK for CCoAOMT_894_A was not significantly differently from that of the moderately-resistant check Sumai 3. In general, SbBmr2 and SbMyb60 constitutive expression lines were susceptible to FHB in greenhouse assays. Field spray inoculations also were performed (UMore Park, Rosemount, MN) during the 2018 season and FHB Incidence and Index (severity), proportion of FDK and DON levels were determined. All lines had similar levels of FHB Incidence with C3H_885 having the lowest. The constitutive expression lines C3H_885 and CCoAOMT_894 (from a different event than CCoAOMT_894_A) had FHB Indices not significantly different from that of Sumai 3. A line with constitutive expression of the SbMyb60 transcription factor, Myb_860, had significantly reduced proportion of FDK as compared with CB037. The DON level of C3H_885 was significantly reduced as compared with that of CB037. All other overexpression lines had FHB Indices, FDK or DON levels similar or even significantly greater than those of CB037. Because constitutive expression of SbC3H or SbCCoAOMT resulted in wheat lines with increased resistance in both greenhouse and field assessments, these lines provide valuable materials for future research to identify genes and pathways with altered activities in response to FHB associated with the observed increased resistance.