Integrative analyses of genetic variation in enzyme activities of primary carbohydrate metabolism reveal distinct modes of regulation in Arabidopsis thaliana

Multiparallel QTL analysis of 15 Arabidopsis primary carbohydrate metabolism enzymes reveals that traits affecting primary metabolism are often correlated

Meiotic crossover reduction by virus-induced gene silencing enables the efficient generation of chromosome substitution lines and reverse breeding in Arabidopsis thaliana.

Plant breeding applications exploiting meiotic mutant phenotypes (like the increase or decrease of crossover (CO) recombination) have been proposed over the last years. As recessive meiotic mutations in breeding lines may affect fertility or have other pleiotropic effects, transient silencing techniques may be preferred. Reverse breeding is a breeding technique that would benefit from the transient downregulation of CO formation. The technique is essentially the opposite of plant hybridization: a method to extract parental lines from a hybrid. The method can also be used to efficiently generate chromosome substitution lines (CSLs). For successful reverse breeding, the two homologous chromosome sets of a heterozygous plant must be divided over two haploid complements, which can be achieved by the suppression of meiotic CO recombination and the subsequent production of doubled haploid plants. Here we show the feasibility of transiently reducing CO formation using virus-induced gene silencing (VIGS) by targeting the meiotic gene MSH5 in a wild-type heterozygote of Arabidopsis thaliana. The application of VIGS (rather than using lengthy stable transformation) generates transgene-free offspring with the desired genetic composition: we obtained parental lines from a wild-type heterozygous F1 in two generations. In addition, we obtained 20 (of the 32 possible) CSLs in one experiment. Our results demonstrate that meiosis can be modulated at will in A. thaliana to generate CSLs and parental lines rapidly for hybrid breeding. Furthermore, we illustrate how the modification of meiosis using VIGS can open routes to develop efficient plant breeding strategies

The role of natural variation in dissecting genetic regulation of primary metabolism

Primary carbohydrate metabolism plays an essential role in the growth and development of plants. Despite the fact that most of the intermediary steps in the metabolic pathways involved are known, knowledge about the genetic regulation of this complex biochemical network is limited. We have recently shown that exploring natural variation is an efficient approach to reveal genetic regulation at various stages along the path from genotype to phenotype.1 In this study genetic analyses were performed at the levels of gene expression, activity of a subset of enzymes involved in carbohydrate metabolism and abundance of the metabolites involved in the reactions catalyzed by these enzymes. Although a strong correlation was observed between the different entities analyzed, specific regulation of individual components could also be observed at different levels. These results show that the genetic regulation of plant carbohydrate metabolism is highly complex which advocates the application of multi-disciplinary approaches to disentangle the various interacting regulatory modes

EpiRILsand parentsQTL-mapping_rawLCMScdfs

EpiRILs and parents QTL-mapping raw LCMS dat

Genotypic and tissue-specific variation of Populus nigra transcriptome profiles in response to drought.

Climate change is one of the most important challenges for mankind in the far and near future. In this regard, sustainable production of woody crops on marginal land with low water availability is a major challenge to tackle. This dataset is part of an experiment, in which we exposed three genetically differentiated genotypes of Populus nigra originating from contrasting natural habitats to gradually increasing moderate drought. RNA sequencing was performed on fine roots, developing xylem and leaves of those three genotypes under control and moderate drought conditions in order to get a comprehensive dataset on the transcriptional changes at the whole plant level under water limiting conditions. This dataset has already provided insight in the transcriptional control of saccharification potential of the three Populus genotypes under drought conditions and we suggest that our data will be valuable for further in-depth analysis regarding candidate gene identification or, on a bigger scale, for meta-transcriptome analysis

Biomass traits and candidate genes for bioenergy revealed through association genetics in coppiced European Populus nigra (L.).

BackgroundSecond generation (2G) bioenergy from lignocellulosic feedstocks has the potential to develop as a sustainable source of renewable energy; however, significant hurdles still remain for large-scale commercialisation. Populus is considered as a promising 2G feedstock and understanding the genetic basis of biomass yield and feedstock quality are a research priority in this model tree species.ResultsWe report the first coppiced biomass study for 714 members of a wide population of European black poplar (Populus nigra L.), a native European tree, selected from 20 river populations ranging in latitude and longitude between 40.5 and 52.1°N and 1.0 and 16.4°E, respectively. When grown at a single site in southern UK, significant Site of Origin (SO) effects were seen for 14 of the 15 directly measured or derived traits including biomass yield, leaf area and stomatal index. There was significant correlation (p < 0.001) between biomass yield traits over 3 years of harvest which identified leaf size and cell production as strong predictors of biomass yield. A 12 K Illumina genotyping array (constructed from 10,331 SNPs in 14 QTL regions and 4648 genes) highlighted significant population genetic structure with pairwise FST showing strong differentiation (p < 0.001) between the Spanish and Italian subpopulations. Robust associations reaching genome-wide significance are reported for main stem height and cell number per leaf; two traits tightly linked to biomass yield. These genotyping and phenotypic data were also used to show the presence of significant isolation by distance (IBD) and isolation by adaption (IBA) within this population.ConclusionsThe three associations identified reaching genome-wide significance at p < 0.05 include a transcription factor; a putative stress response gene and a gene of unknown function. None of them have been previously linked to bioenergy yield; were shown to be differentially expressed in a panel of three selected genotypes from the collection and represent exciting, novel candidates for further study in a bioenergy tree native to Europe and Euro-Asia. A further 26 markers (22 genes) were found to reach putative significance and are also of interest for biomass yield, leaf area, epidermal cell expansion and stomatal patterning. This research on European P. nigra provides an important foundation for the development of commercial native trees for bioenergy and for advanced, molecular breeding in these species