Genome-Wide Analysis of LIM Gene Family in Populus trichocarpa, Arabidopsis thaliana, and Oryza sativa

In Eukaryotes, LIM proteins act as developmental regulators in basic cellular processes such as regulating the transcription or organizing the cytoskeleton. The LIM domain protein family in plants has mainly been studied in sunflower and tobacco plants, where several of its members exhibit a specific pattern of expression in pollen. In this paper, we finely characterized in poplar six transcripts encoding these proteins. In Populus trichocarpa genome, the 12 LIM gene models identified all appear to be duplicated genes. In addition, we describe several new LIM domain proteins deduced from Arabidopsis and rice genomes, raising the number of LIM gene models to six for both species. Plant LIM genes have a core structure of four introns with highly conserved coding regions. We also identified new LIM domain proteins in several other species, and a phylogenetic analysis of plant LIM proteins reveals that they have undergone one or several duplication events during the evolution. We gathered several LIM protein members within new monophyletic groups. We propose to classify the plant LIM proteins into four groups: αLIM1, βLIM1, γLIM2, and δLIM2, subdivided according to their specificity to a taxonomic class and/or to their tissue-specific expression. Our investigation of the structure of the LIM domain proteins revealed that they contain many conserved motifs potentially involved in their function

Increased Resistance of Bt Aspens to Phratora vitellinae (Coleoptera) Leads to Increased Plant Growth under Experimental Conditions

One main aim with genetic modification (GM) of trees is to produce plants that are resistant to various types of pests. The effectiveness of GM-introduced toxins against specific pest species on trees has been shown in the laboratory. However, few attempts have been made to determine if the production of these toxins and reduced herbivory will translate into increased tree productivity. We established an experiment with two lines of potted aspens (Populus tremula×Populus tremuloides) which express Bt (Bacillus thuringiensis) toxins and the isogenic wildtype (Wt) in the lab. The goal was to explore how experimentally controlled levels of a targeted leaf beetle Phratora vitellinae (Coleoptera; Chrysomelidae) influenced leaf damage severity, leaf beetle performance and the growth of aspen. Four patterns emerged. Firstly, we found clear evidence that Bt toxins reduce leaf damage. The damage on the Bt lines was significantly lower than for the Wt line in high and low herbivory treatment, respectively. Secondly, Bt toxins had a significant negative effect on leaf beetle survival. Thirdly, the significant decrease in height of the Wt line with increasing herbivory and the relative increase in height of one of the Bt lines compared with the Wt line in the presence of herbivores suggest that this also might translate into increased biomass production of Bt trees. This realized benefit was context-dependent and is likely to be manifested only if herbivore pressure is sufficiently high. However, these herbivore induced patterns did not translate into significant affect on biomass, instead one Bt line overall produced less biomass than the Wt. Fourthly, compiled results suggest that the growth reduction in one Bt line as indicated here is likely due to events in the transformation process and that a hypothesized cost of producing Bt toxins is of subordinate significance

Comparison of the consequences on lignin content and structure of COMT and CAD downregulation in poplar and Arabidopsis thaliana

International audienceLignification, a major biological event in the plant kingdom, is still poorly understood due to the structural complexity and to the high variability of native lignins. Poplars underexpressing two enzymes of the monolignol biosynthetic pathway (caffeic acid/5 hydroxyferulic O-methyltransferase or cinnamyl alcohol dehydrogenase) or Arabidopsis thaliana knock-out T-DNA insertion mutants in the genes encoding these enzymes have been obtained and analysed for the quantity and quality of their lignins. COMT or CAD down-regulation induced in poplar, a woody plant, and in Arabidopsis, the annual crucifer model plant, show similar specific alterations in lignin structure due to the incorporation of unusual phenolics in the polymer. The specific structural traits of lignins, which account for higher (CAD deficiency) or lower (COMT deficiency) susceptibility to alkaline delignification processes have been delineated. Lignins of COMT depressed plants essentialy comprise guaiacyl (G) units together with substantial amounts of 5-hydroxyguaiacyl (5-OH-G) units. They display a markedly higher frequency of resistant interunit bonds including new structures (benzodioxanes) and a lower frequency of free phenolic lignin units. These changes make the lignin polymer less amenable ta alkaline delignification. Lignins of CAD deficient plants display a higher content of free phenolic groups, and incorporation of sinapaldehyde units, both associated with a greater solubility in dilute alkali at room temperature. The lignin characteristics of the CAD antisense poplars allow a reduction in the amount of alkali required for paper pulp making using the Kraft procedure

Differences in plant mass between the aspen lines.

<p>Mean leaf, stem and root mass (and ±SE) of plants from Wt, Bt17and Bt27 lines), pooled for all herbivore treatments, at the end of the experiment. Bars with different letters indicate significant differences among lines (<i>P</i><0.05).</p

Beetle survival and degree of leaf damage.

<p>The mean number of live <i>Phratora vitellinae</i> adults per plant and the degree of leaf damage on leaves from Wt, Bt17and Bt27 plants at the end of the trials in the high (initially 7 beetles plant) and low (initially 3 beetles per plant) herbivore density treatments. Bars with different letters indicate significant differences among lines (<i>P</i><0.05).</p

Changes in plant height and stem mass.

<p>Mean height and stem mass (and ±SE) of plants from Wt, Bt17and Bt27 lines at the end of the experiment. Bars with different letters indicate significant differences (<i>P</i><0.05) among lines within the same herbivory treatment and different numbers inside the bars denote significant differences within the same line but between treatments. Please note that the ANOVA analysis revealed no significant interaction between line and herbivory for stem mass. As a result, no pair-wise statistical comparisons were conducted for stem mass and the bars therefore lack letters.</p

Multi-site genetic modification of monolignol biosynthesis in alfalfa ( Medicago sativa

Article on multi-site genetic modification of monolignol biosynthesis in alfalfa (Medicago sativa) and the effects on lignin composition in specific cell types