37 research outputs found
Imbalanced Lignin Biosynthesis Promotes the Sexual Reproduction of Homothallic Oomycete Pathogens
Lignin is incorporated into plant cell walls to maintain plant architecture and to ensure long-distance water transport. Lignin composition affects the industrial value of plant material for forage, wood and paper production, and biofuel technologies. Industrial demands have resulted in an increase in the use of genetic engineering to modify lignified plant cell wall composition. However, the interaction of the resulting plants with the environment must be analyzed carefully to ensure that there are no undesirable side effects of lignin modification. We show here that Arabidopsis thaliana mutants with impaired 5-hydroxyguaiacyl O-methyltransferase (known as caffeate O-methyltransferase; COMT) function were more susceptible to various bacterial and fungal pathogens. Unexpectedly, asexual sporulation of the downy mildew pathogen, Hyaloperonospora arabidopsidis, was impaired on these mutants. Enhanced resistance to downy mildew was not correlated with increased plant defense responses in comt1 mutants but coincided with a higher frequency of oomycete sexual reproduction within mutant tissues. Comt1 mutants but not wild-type Arabidopsis accumulated soluble 2-O-5-hydroxyferuloyl-l-malate. The compound weakened mycelium vigor and promoted sexual oomycete reproduction when applied to a homothallic oomycete in vitro. These findings suggested that the accumulation of 2-O-5-hydroxyferuloyl-l-malate accounted for the observed comt1 mutant phenotypes during the interaction with H. arabidopsidis. Taken together, our study shows that an artificial downregulation of COMT can drastically alter the interaction of a plant with the biotic environment
Evaluating Ascorbate Oxidase as a Plant Defense Against Leaf-Chewing Insects Using Transgenic Poplar
Reduced lignin content and altered lignin composition in the warm season forage grass Paspalum dilatatum by down-regulation of a Cinnamoyl CoA Reductase Gene
Understanding lignin biosynthesis in poplar through genetic engineering
International audienc
Downregulation of cinnamoyl-coenzyme a reductase in poplar: multiple-level phenotyping reveals effects on cell wall polymer metabolism and structure
International audienc
Ectomycorrhizal Colonization and Diversity in Relation to Tree Biomass and Nutrition in a Plantation of Transgenic Poplars with Modified Lignin Biosynthesis
Wood from biomass plantations with fast growing tree species such as poplars can be used as an alternative feedstock for
production of biofuels. To facilitate utilization of lignocellulose for saccharification, transgenic poplars with modified or
reduced lignin contents may be useful. However, the potential impact of poplars modified in the lignification pathway on
ectomycorrhizal (EM) fungi, which play important roles for plant nutrition, is not known. The goal of this study was to
investigate EM colonization and community composition in relation to biomass and nutrient status in wildtype (WT, Populus
tremula6Populus alba) and transgenic poplar lines with suppressed activities of cinnamyl alcohol dehydrogenase, caffeate/
5-hydroxyferulate O-methyltransferase, and cinnamoyl-CoA reductase in a biomass plantation. In different one-year-old
poplar lines EM colonization varied from 58% to 86%, but the EM community composition of WT and transgenic poplars
were indistinguishable. After two years, the colonization rate of all lines was increased to about 100%, but separation of EM
communities between distinct transgenic poplar genotypes was observed. The differentiation of the EM assemblages was
similar to that found between different genotypes of commercial clones of Populus6euramericana. The transgenic poplars
exhibited significant growth and nutrient element differences in wood, with generally higher nutrient accumulation in
stems of genotypes with lower than in those with higher biomass. A general linear mixed model simulated biomass of oneyear-
old poplar stems with high accuracy (adjusted R2 = 97%) by two factors: EM colonization and inverse wood N
concentration. These results imply a link between N allocation and EM colonization, which may be crucial for wood
production in the establishment phase of poplar biomass plantations. Our data further support that multiple poplar
genotypes regardless whether generated by transgenic approaches or conventional breeding increase the variation in EM
community composition in biomass plantations.Open-Access-Publikationsfonds 2013peerReviewe