ADG2 is a DNA sequence mapped to a resistance (R) gene-rich region at the distal end of chromosome XI in potato (Solanum tuberosum subsp. andigena). The gene, in which ADG2 represents the predicted nucleotide-binding domain (NBS), was cloned and characterized. The coding region of the gene (designated as Y-1) is 6,187 bp long and structurally similar to gene N that confers hypersensitive resistance to Tobacco mosaic virus in Nicotiana spp. Both belong to the TIR-NBS-LRR class of genes and show 57% identity at the amino acid sequence level. The introns of Y-1 were spliced as predicted from the sequence. Y-1 cosegregated with Ry(adg), a gene for extreme resistance to Potato virus Y (PVY) on chromosome XI, as tested in a potato-mapping population and with independent potato cultivars. Leaves of the transgenic potato plants expressing Y-1 under the control of Cauliflower mosaic virus 35S promoter developed necrotic lesions upon infection with PVY, but no significant resistance was observed, and plants were systemically infected with PVY.

Ubiquitin belongs to a multigene family. In Drosophila two members of this family have been previously described. We report here the organization and expression of a third member, the DUb52 gene, isolated by screening a Drosophila melanogaster genomic library. This gene encodes an ubiquitin monomer fused to a 52-amino acid extension protein. There are no introns interrupting the coding sequence. Recently, it has been described that this extension encodes a ribosomal protein in Saccharomyces, Dictyostelium, and Arabidopsis. The present results show that the 5′ regulatory region of DUb52 shares common features with the ribosomal protein genes of Drosophila, Xenopus and mouse, including GC- and pyrimidine-rich regions. Moreover, sequences similar to the consensus Ribo-box in Neurospora crassa have been identified. Furthermore, a sequence has been found that is similar to the binding site for the TFIIIA distal element factor from Xenopus laevis. The DUb52 gene is transcribed to a 0.9 kb mRNA that is expressed constitutively throughout development and is particularly abundant in ovaries. In addition, the DUb52 gene has been found to be preferentially transcribed in exponentially growing Drosophila cells.

In the fruitfly Drosophila, as in all eukaryotes examined so far, some ubiquitin-coding sequences appear fused to unrelated open reading frames. Two of these fusion genes have been previously described (the homologues of UBI1-UBI2 and UBI4 in yeast), and we report here the organization and expression of a third one, the DUb80 gene (the homologue of UBI3 in yeast). This gene encodes a ubiquitin monomer fused to an 80-amino-acid extension which is homologous with the ribosomal protein encoded by the UB13 gene. The 5' regulatory region of DUb80 shares common features with another ubiquitin fusion gene, DUb52, and with the ribosomal protein genes of Drosophila, Xenopus and mouse. We also find helix-loop-helix protein-binding sequences (E-boxes). The DUb80 gene is transcribed to a 0.9 kb mRNA which is particularly abundant under conditions of high protein synthesis, such as in ovaries and exponentially growing cells.

Potato is the most important crop in Peru and late blight is the main disease affecting the crop. However, new varieties that are resistant to late blight often lack other traits that farmers and consumers prefer. Using participatory varietal selection, this study seeks to identify clones with high potential to become varieties with resistance to late blight but also feature a high marketable tuber yield and other preferred agronomic traits. During 2016–2017, 36 clones previously selected for high levels of resistance to late blight from population B developed by the International Potato Center, and three varieties used as controls (INIA 302 Amarilis moderately resistant, INIA303 Canchan and Yungay susceptible to late blight), were evaluated in five Peruvian locations. At harvest, five clones were selected based on (i) evaluations made by farmers through Participatory Varietal Selection, (ii) analysis of mixed models and Best Linear Unbiased Predictors for tuber yield, (iii) low glycoalkaloid content in tubers, and (iv) good organoleptic quality. These clones were evaluated again during 2017–2018 in four locations. Resistance to late blight and good marketable tuber yields were identified as the most important criteria for the selection of a new potato variety. The clones CIP308488.92, CIP308495.227 and CIP308478.59 were selected as promising clones having resistance to late blight and tuber yield superior to the local varieties, INIA-303 Canchan, Yungay, as well as good organoleptic quality and low glycoalkaloid content. These clones can be suggested for variety release in similar agroecological environments.

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