Molecular and biochemical characterization of a potato collection with contrasting tuber carotenoid content.

After wheat and rice, potato is the third most important staple food worldwide. A collection of ten tetraploid (Solanum tuberosum) and diploid (S. phureja and S. chacoense) genotypes with contrasting carotenoid content was subjected to molecular characterization with respect to candidate carotenoid loci and metabolic profiling using LC-HRMS. Irrespective of ploidy and taxonomy, tubers of these genotypes fell into three groups: yellow-fleshed, characterized by high levels of epoxy-xanthophylls and xanthophyll esters and by the presence of at least one copy of a dominant allele of the ß-Carotene Hydroxylase 2 (CHY2) gene; white-fleshed, characterized by low carotenoid levels and by the presence of recessive chy2 alleles; and orange-fleshed, characterized by high levels of zeaxanthin but low levels of xanthophyll esters, and homozygosity for a Zeaxanthin Epoxidase (ZEP) recessive allele. Novel CHY2 and ZEP alleles were identified in the collection. Multivariate analysis identified several groups of co-regulated non-polar compounds, and resulted in the grouping of the genotypes according to flesh color, suggesting that extensive cross-talk exists between the carotenoid pathway and other metabolite pathways in tubers. Postharvest traits like tuber dormancy and weight loss during storage showed little correlation with tuber carotenoid content, with the exception of zeaxanthin and its esters. Other tuber metabolites, such as glucose, monogalactosyldiacyglycerol (a glycolipid), or suberin precursors, showed instead significant correlations with both traits.

Early transcriptional changes in Beta vulgaris in response to low temperature.

MAIN CONCLUSION: Major metabolic pathways and genes affected by low-temperature treatment were identified and a thorough picture of the early transcriptional changes in sugar beet plantlets upon cold stress was given. Sugar beet (Beta vulgaris L.) is an important source of sugar and bioethanol production in temperate areas worldwide. In these areas, plantlet survival and sucrose yield of mature plants can be seriously limited by low temperatures, especially when plantlets are exposed to freezing temperatures (below 0 °C) at the early developmental stages. This frequently occurs when the crop is sown in early spring or even in autumn (autumn sowing) to escape drought at maturity and pathogen outbreaks. The knowledge of molecular responses induced in plantlets early upon exposure to low temperature is necessary to understand mechanisms that allow the plant to survive and to identify reactions that can influence other late-appearing traits. In this work, a wide study of sugar beet transcriptome modulation after a short exposure to a cold stress, mimicking what is experienced in vivo by young plantlets when temperature drops in the early spring nights, was carried out by high-throughput sequencing of leaves and root RNAs (RNA-Seq). A significant picture of the earliest events of temperature sensing was achieved for the first time for sugar beet: the retrieval of a great amount of transcription factors and the intensity of modulation of a large number of genes involved in several metabolic pathways suggest a fast and deep rearrangement of sugar beet plantlets metabolism as early response to cold stress, with both similarities and specificities between the two organs.

NMR-based metabolomics for organic farming traceability of early potatoes.

(1)H HRMAS-NMR spectroscopy was successfully used to determine the metabolic profiles of 78 tubers obtained from three early genotypes grown under organic and conventional management. The variation in total hydrogen, carbon, and nitrogen contents was also assessed. A PLS-DA multivariate statistical analysis provided good discrimination among the varieties and cropping systems (100% unknown samples placed in a cross-validation blind test), suggesting that this method is a powerful and rapid tool for tracing organic potatoes. As a result of the farming system, the nitrogen content decreased by 11-14% in organic tubers, whereas GABA and lysine accumulated in the organic tubers of all clones. Clear variations in primary metabolites are discussed to provide a better understanding of the metabolic pathway modifications resulting from agronomical practices.

Rituximab induces different but overlapping sets of genes in human B-lymphoma cell lines.

The therapeutic unconjugated anti-CD20 Mab rituximab is used for the treatment of B-non-Hodgkin's lymphomas. We have studied the direct biological effects, signalling and gene expression profiles induced by rituximab in two human B-lymphoma cell lines, DHL4 and BJAB, using microarray, quantitative PCR and gel shift analysis. Rituximab alone inhibited thymidine uptake and induced homotypic adhesion in DHL4 only, but not BJAB. Analysis of Affymetrix microchips carrying probes for about 10,000 human cDNAs, allowed us to identify 16 genes in DHL4 and 12 in BJAB induced by rituximab at 4 h. Eleven and seven of these genes were specific for DHL4 and BJAB, respectively; whereas the remaining five were up-regulated in both cell lines. Mean induction ranged from 2- to 16-fold. Real time PCR analysis allowed us to confirm up-regulation of all genes identified, except one in BJAB. Time course of induction of eight genes was studied, showing peak induction in most cases at 4 h. The up-regulation of 5/5 genes was also observed with the F(ab')(2) fragment of rituximab. Analysis of three further B-cell lymphoma lines showed that gene induction is not restricted to BJAB and DHL4. Finally, we show that rituximab alone can induce AP1 activation in both cell lines and provide evidence that the ERK1/2 pathway is involved in the rituximab-mediated up-regulation of gene expression. These data demonstrate that rituximab alone has direct signalling capacity in different B-lymphoma lines, inducing distinct but overlapping sets of genes which may play a role in the biological and/or therapeutic effect of the antibody.