Response of Fusarium thapsinum to Sorghum brown midrib Lines and to Phenolic Metabolites

Abstract

Sorghum lines were bred for reduced lignin for cellulosic bioenergy uses, through the incorporation of brown midrib (bmr)6 or -12 into two backgrounds (RTx430 and Wheatland) as either single or double-mutant lines. When these lines were assessed for resistance to Fusarium thapsinum stalk rot, a cause of lodging, they were as resistant to F. thapsinum as the near-isogenic wild type. Peduncles of newly identified bmr lines from an ethyl-methanesulfonate-mutagenized population, inoculated with F. thapsinum, were as resistant as the wild-type line, BTx623. One bmr line (1107) had significantly smaller mean lesion lengths than BTx623, suggesting that a mutation is associated with reduced susceptibility. Growing F. thapsinum on medium with ferulic, vanillic, sinapic, syringic, and caffeic acids (phenolic compounds derived from the lignin pathway and elevated in different bmr lines) indicated that F. thapsinum was tolerant to these compounds. When eight other sorghum fungi were tested for response to the presence of these compounds, ferulic acid inhibited these fungi. Most of the phenolics inhibited F. verticillioides and F. proliferatum. Accumulation of phenolic metabolites in bmr plants may inhibit growth of some sorghum pathogens, while other factors such as aromatic phytoalexins or salicylic acid may be involved in resistance to F. thapsinum.

Alkaloids and phenolics biosynthesis increases mango resistance to infection by Ceratocystis fimbriata

“…According to Funnell-Harris et al (2014), one possible effect of changes in phenolics composition in the plant is due to their direct effect on inhibiting pathogens growth. The authors provided in vitro evidence that ferulic acid inhibited several fungi, which could explain the increase of sorghum lines resistance to some diseases (Funnell-Harris et al 2014).…”

“…According to Funnell-Harris et al (2014), one possible effect of changes in phenolics composition in the plant is due to their direct effect on inhibiting pathogens growth. The authors provided in vitro evidence that ferulic acid inhibited several fungi, which could explain the increase of sorghum lines resistance to some diseases (Funnell-Harris et al 2014). Blodgett and Stanosz (1997) observed that different concentrations of phenolic compounds and monoterpenes of red pine inhibited in vitro the spore germination and mycelial growth of Sphaeropsis sapinea.…”

“…The alkaloids (theobromine and 7-methylxanthine) and phenolic compounds (caffeic acid, p-coumaric acid, gallic acid, protocatechuic acid, catechin and epicatechin) were dissolved in methanol:water solution (80:20, v/v) at the concentrations of 10, 20 and 30 mg•mL −1 according to Adrian et al (1997), Funnell-Harris et al (2014) and Mace et al (1985). Petri dishes (9 cm diameter) were filled with 20 mL of PDA and a hole (7 mm diameter) was made in the center of each dish (Rodrigues et al 2004).…”

“…Two PDA plugs (7 mm diameter), obtained from the margin of an actively growing colony of C. fimbriata, were placed approximately 1.5 cm from the center of each hole (Rodrigues et al 2004). Plates were transferred to an incubator (25 °C; 12 h light/12 h dark) and the fungal colony diameter was measured once at the same time of the day on multiple days (every 24 h) according to Blodgett and Stanosz (1997) and Funnell-Harris et al (2014). Radial fungal growth rate (mm/day) was obtained by measuring fungal growth in each dish using an electronic digital caliper and was stopped when two fungal colonies reached confluence in the control treatment (Rodrigues et al 2004).…”

Dedicated Herbaceous Biomass Feedstock Genetics and Development

“…However, there is evidence that in some cases plants with modified lignin may have greater resistance [97]. One cause of greater disease resistance may be due to the increased amount of ferulic acid compounds in the mutants [32]. Leaves from mature bmr plants were more resistant to corn earworm (Helicoverpa zea (Boddie)) and fall armyworm, both common insect pests, than those of the normal lignin lines, possibly due to increased vanillic acid [28].…”