Enrique Ritter

Selection of housekeeping genes for qRT-PCR analysis in potato tubers under cold stress

Quantitative real-time polymerase chain reaction (qRT-PCR) is currently the most sensitive method used for quantitative gene expression studies. However, minimal variation in the amount of material and presence of inhibitors affecting enzyme efficiency can lead to significant quantification errors. Accurate data normalization is vital using reference genes as internal controls. Many so-called housekeeping genes or reference genes with assumed stable expression can exhibit either up- or downregulation depending on the developmental stage or other environmental conditions. We have evaluated six reference genes (actin, APRT, 18S rRNA, ef1α, β-tubulin and ribosomal protein L2) for qRT-PCR profiling experiments in potato tuber tissues of five varieties during cold storage at different temperatures and treatment periods. Genes were ranked according to their expression stability by BestKeeper, geNorm and NormFinder software tools in the same order. This means that any of them can be used for this purpose. The results indicated that ef1α and APRT were the most stably expressed genes in the potato tuber tissues under different cold storage regimes. We therefore recommend use of this pair of genes as internal controls for gene expression studies under the described conditions.

Genetic relationships among local potato cultivars from Spain using SSR markers

Microsatellite markers (SSR) were used to fingerprint a total of 105 local potato cultivars from Spain. A set of 41 cultivars from Tenerife Island, 19 from the island of La Palma, and 45 local varieties from peninsular Spain were analysed. Some of these varieties represent relicts of the early introductions originating from South America and have been characterised previously morphologically and ecophysiologically. We observed within our materials a total of 76 SSR alleles. Only seven of them were present in all varieties. Several accession and group specific alleles were detected. Similarity coefficients were computed from the molecular data and cluster analyses were performed. The obtained dendrogram was generally in good agreement with previous classifications of the accessions as Solanum tuberosum L. subsp. andigena (Juz. et Bukasov) Hawkes S. tuberosum L. subsp. tuberosum and S. chaucha Juz. et Bukasov genotypes. Also cultivar groups with identical or related common names showed the same SSR patterns or clustered closely together. In addition we performed Principal Coordinate Analysis with the set of genotypes. Results of both analysis methods were generally in good agreement, but also some smaller differences were detected in the associations of groups and genotypes. According to the molecular patterns for some accessions misleading or confounded names were evident, and in some cases the molecular patterns showed also discrepancies with previous species assignments, suggesting the need for a more detailed comparative study of these accessions.

First genetic linkage map of Taraxacum koksaghyz Rodin based on AFLP, SSR, COS and EST-SSR markers.

Taraxacum koksaghyz Rodin (TKS) has been studied in many occasions as a possible alternative source for natural rubber production of good quality and for inulin production. Some tire companies are already testing TKS tire prototypes. There are also many investigations on the production of bio-fuels from inulin and inulin applications for health improvement and in the food industry. A limited amount of genomic resources exist for TKS and particularly no genetic linkage map is available in this species. We have constructed the first TKS genetic linkage map based on AFLP, COS, SSR and EST-SSR markers. The integrated linkage map with eight linkage groups (LG), representing the eight chromosomes of Russian dandelion, has 185 individual AFLP markers from parent 1, 188 individual AFLP markers from parent 2, 75 common AFLP markers and 6 COS, 1 SSR and 63 EST-SSR loci. Blasting the EST-SSR sequences against known sequences from lettuce allowed a partial alignment of our TKS map with a lettuce map. Blast searches against plant gene databases revealed some homologies with useful genes for downstream applications in the future.

Utilization of SSR and cDNA markers for screening known QTLs for late blight (Phytophthora infestans) resistance in potato

All published QTLs and genes for Phytophthora resistance were projected onto the bins of a high-density reference map of potato. Further, a transcriptome map containing around 700 cDNA-AFLP (TDF) markers was anchored to this map. We have analysed cDNA markers which are co-located with these resistance QTLs by cloning, sequencing and by performing homology searches in public sequence databases. Several interesting homologies were detected with typical resistance and stress response genes. On the other hand, we have screened all known QTL locations on the 12 potato chromosomes via linked SSR markers for the presence of a selectable QTL for Phytophthora resistance in four genetic backgrounds. Progenies descended from different Solanum wild species as resistance sources. Leaf and tuber resistances were analysed. In all case studies, several selectable QTLs were detected which descended from either parent. Tuber and leaf QTLs varied from progeny to progeny and between leaves and tubers. In none of the progenies were resistance levels of leaf and tuber blight correlated.

New Sources of Resistance to Potato Pathogens in old Varieties of the Canary Islands

In the Canary Islands, a number of old Andean potato introductions have been maintained by farmers and are cultivated there since the sixteenth century. Genetic resistance is an inexpensive way to control the main pests and diseases of potato and avoids the use of phytochemicals or other costly protective measures. In this study, we have analysed eight Solanum tuberosum subsp. andigena and S. tuberosum subsp. tuberosum accessions, representing old potato varieties from Tenerife Island, for their resistance levels to Phytophthora infestans, Globodera rostochiensis, Globodera pallida and Pectobacterium atrosepticum. New resistance sources against P. infestans in leaves and P. atrosepticum were found, as well as partial resistance to both nematode species. The results suggest the potential exploitation of the cultivar Venezolana Negra in breeding programmes in order to improve pest and disease resistance of potato.

The Spirit Project: Strengthening the Capacities for Fostering Innovation Along Potato Value Chains in East Africa

Abstract The project SPIRIT was conducted in Tanzania, Rwanda, Uganda and Kenya from 2012 to 2016 with the aim of increasing the contribution of agricultural science, technology and innovation to social development in East Africa. The project involved literature research, on-site visits and meetings with farmers, research institutions and stakeholders, information compilation, database establishment and a project webpage. A strategy with three main objectives and associated actions was implemented. The first objective focused on the improvement of scientific and technological knowledge of East African research organizations. For this, state-of the-art research on innovative technologies and practices for enhanced product quality was assessed; a web-based knowledge-sharing platform was created; the “East Africa Potato Research and Knowledge Exchange Forum” was constituted and six meetings with visits were realized. The second objective focused on private and civil society actors and governmental services and aimed at reinforcing their capacities for generating and adopting innovative technologies and practices. Sixteen innovation sessions were conducted. Guidelines for enhancing product quality along the potato value chain in East Africa were elaborated and disseminated. The third objective targeted governmental bodies with competences in policy-making for promoting changes in policies. Proposals for policymakers were developed and transferred to relevant authorities.