Reaction of Sorghum Lines Genetically Modified for Reduced Lignin Content to Infection by Fusarium and Alternaria spp.

Abstract

Two genes conferring the brown midrib (bmr) trait had been backcrossed into six elite sorghum lines, resulting in reduced lignin in the bmr lines when compared with the wild-type parent. Seed and leaf tissue from field-grown plants, planted at two locations, were screened for Alternaria spp. and Fusarium spp. on semi-selective media. The results suggest that bmr lines do not have increased susceptibility to colonization by Alternaria spp. However, significantly fewer colonies of Fusarium spp., including Fusarium moniliforme, were recovered from seed of reduced lignin lines from two genetic backgrounds. That the bmr trait in some genetic backgrounds might enable increased resistance to colonization by F. moniliforme was further supported by greenhouse experiments in which peduncles of developing heads were inoculated with F. moniliforme. Mean lesion measurements on bmr lines were significantly lower than those resulting from inoculations on wild-type lines. Analysis of near-isogenic lines revealed that mean lesion lengths on bmr lines were significantly less than those produced on their wild-type counterparts in four of the six genetic backgrounds. These results suggest that reduced lignin lines exhibit, in some cases, increased resistance to Fusarium spp., including F. moniliforme.

Soil and root populations of fluorescent Pseudomonas spp. associated with seedlings and field-grown plants are affected by sorghum genotype

“…Alternaria spp. are also commonly isolated from sorghum grain (Funnell and Pedersen 2006). Fusarium stalk rots can cause lodging and reduce yield (Tesso et al 2005) while grain infections by Alternaria spp.…”

“…In previous studies, Alternaria spp. were recovered at a much reduced rate, or not all from, from grain or leaf samples plated onto PCNB medium as compared with DCPA (Funnell and Pedersen 2006). Dichloran and antibiotics were purchased from Sigma-Aldrich (St. Louis).…”

“…Five to twenty fungal isolates were chosen at random from each set of DCPA and PCNB media plates from time points 3 and 4 at both locations during 2004 and all time-points at both locations during 2005. Isolates were transferred to one-half-strength PDA and identified morphologically as previously described (Funnell and Pedersen 2006). Fungi similar to Alternaria spp.…”

Mycorrhizal and Rhizobial Colonization of Genetically Modified and Conventional Soybeans

“…However, this speculation should be confirmed experimentally, since the genomic position of transgenic epsps resulting from a specific transformation event may affect the types of pleiotropies that occur, or effects on synthesis of phenolic compounds may be species specific. In addition, other genetic modifications also target production of phenolic compounds in crops, including those targeting lignin production in alfalfa, sorghum (Sorghum bicolor), and tobacco (Nicotiana tabacum) (6,15,22). However, we cannot extrapolate our data to genetic modifications that target other biochemical mechanisms in plants.…”

Opportunities and roadblocks in utilizing forages and small grains for liquid fuels

“…Although reduction in ligniWcation of plant tissues is widely held to reduce general Wtness [75], perturbations of the lignin biosynthetic pathway may unexpectedly aVect plant responses to pathogens in a positive fashion [32]. These results suggest that impaired lignin synthesis in sorghum may lead to an accumulation of other classes of compounds from phenylpropanoid metabolism, which directly inhibit the growth of sorghum pathogens.…”