Characterization of Proteins Homologous to Nucleotide Sugar Transporters in Arabidopsis thaliana

The nucleotide sugar transporters (NST) and the plastidic phosphate transporters (pPT) proteins share structural and functional similarities. They mediate the transport of phosphorylated and nucleotide-coupled metabolites through the membranes of plastids, Golgi apparatus and endoplasmic reticulum (ER). Recently, a great number of proteins homologous to the NST/pPT proteins have been identified in Arabidopsis and only a few of them have been characterized. The majority of these homologous proteins cluster in three subfamilies, namely the KV/A/G, KT and KD subfamilies. Two members of the KV/A/G subfamily, KVAG1 and KVAG2, have a putative plastidic targeting signal. This made them interesting candidates as putative providers of nucleotide sugars for the synthesis of specific plastid lipids. In this study, the intracellular localization and in planta expression of these proteins was analyzed. cDNA fusions to GFP revealed the localization of both proteins in the Golgi apparatus and not in plastids. Transport experiments using liposomes and the proteins heterologously expressed in yeast were performed; however no significant transport of nucleotide sugars was detected. Homozygous knock-out T-DNA lines, kvag1-1 and kvag2-1, presented general wild type phenotype and development, except for a small reduction in the phospholipid content in leaves. The transport of CDP-choline and CDP-ethanolamine, precursors of phospholipid biosynthesis, by KVAG2 was also evaluated; however the transport rates were not significantly higher than the controls. Additional evidence is presented for the Golgi localization of other members of the KV/A/G subfamily. T-DNA knock-out mutants for these genes were identified and they all showed a similar wild type phenotype

History and impact of a bean (Phaseolus spp., Leguminosae, Phaseoleae) collection

This work explains the reasons why a bean collection was established in 1973 at the International Center of Tropical Agriculture (CIAT) near Palmira in Colombia. It shows the impact of the collection on plant breeding and in agricultural development through the distribution of germplasm to the center’s bean breeding program, to successively find resistances to pests and diseases, adaptation to low phosphorus and drought, and more recently higher content of iron and zinc in seeds. The collection was also used to progress knowledge in biological sciences, as shown by a dozen of examples. A reason behind these successes was foresight and focus on diversity per se in the collection. The paper ends with a number of suggestions for the way ahead for the genetic resources conservation and management of these bean crops, and possible take-home lessons for curators in charge of other similar collections

Using phenomics to identify and integrate traits of interest for better-performing common beans: A validation study on an interspecific hybrid and its Acutifolii parents

Evaluations of interspecific hybrids are limited, as classical genebank accession descriptors are semi-subjective, have qualitative traits and show complications when evaluating intermediate accessions. However, descriptors can be quantified using recognized phenomic traits. This digitalization can identify phenomic traits which correspond to the percentage of parental descriptors remaining expressed/visible/measurable in the particular interspecific hybrid. In this study, a line of P. vulgaris, P. acutifolius and P. parvifolius accessions and their crosses were sown in the mesh house according to CIAT seed regeneration procedures