Identification and reproducibility of diagnostic DNA markers for tuber starch and yield optimization in a novel association mapping population of potato (Solanum tuberosum L.)

KEY MESSAGE: SNPs in candidate genesPain-1,InvCD141(invertases),SSIV(starch synthase),StCDF1(transcription factor),LapN(leucine aminopeptidase), and cytoplasm type are associated with potato tuber yield, starch content and/or starch yield. ABSTRACT: Tuber yield (TY), starch content (TSC), and starch yield (TSY) are complex characters of high importance for the potato crop in general and for industrial starch production in particular. DNA markers associated with superior alleles of genes that control the natural variation of TY, TSC, and TSY could increase precision and speed of breeding new cultivars optimized for potato starch production. Diagnostic DNA markers are identified by association mapping in populations of tetraploid potato varieties and advanced breeding clones. A novel association mapping population of 282 genotypes including varieties, breeding clones and Andean landraces was assembled and field evaluated in Northern Spain for TY, TSC, TSY, tuber number (TN) and tuber weight (TW). The landraces had lower mean values of TY, TW, TN, and TSY. The population was genotyped for 183 microsatellite alleles, 221 single nucleotide polymorphisms (SNPs) in fourteen candidate genes and eight known diagnostic markers for TSC and TSY. Association test statistics including kinship and population structure reproduced five known marker–trait associations of candidate genes and discovered new ones, particularly for tuber yield and starch yield. The inclusion of landraces increased the number of detected marker–trait associations. Integration of the present association mapping results with previous QTL linkage mapping studies for TY, TSC, TSY, TW, TN, and tuberization revealed some hot spots of QTL for these traits in the potato genome. The genomic positions of markers linked or associated with QTL for complex tuber traits suggest high multiplicity and genome wide distribution of the underlying genes. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00122-016-2665-7) contains supplementary material, which is available to authorized users

Conservación de cultivares de patata (Solanum tuberosum L.) mediante criopreservación

The shoot-tips of plants of 10 potato cultivars maintained by micropropagation were frozen (ultra rapid freezing) and cryopreserved in liquid nitrogen for three months. The survival rate of the thawed specimens exceeded 50%, and even reached 100% in the case of the cultivar Fénix. The average regeneration rate was between 2.5% and 22.0%, depending on the cultivar and the presence of extra plant hormones in the regeneration medium. Cytogenetic stability was confirmed by flow cytometry: no polyploid plants were found. The regenerated plants showed vegetative development characteristics of their respective cultivars.Se ha aplicado la criopreservación mediante el método de congelación ultrarrápida a 10 cultivares de patata mantenidos por micropropagación. Para ello se congelaron y conservaron en nitrógeno líquido meristemos apicales. La supervivencia tras la descongelación, transcurrido un periodo de tres meses, fue superior al 50% en todos los casos, alcanzando en algún cultivar, como Fenix, hasta el 100% de los meristemos congelados. Las tasas de regeneración se situaron entre el 2,5% y el 22,0%, dependiendo del cultivar empleado y el uso de fitohormonas en el medio MS sólido con agarosa. La estabilidad citogenética fue evaluada mediante citometría de flujo, no encontrando en ningún caso poliploides. Las plantas regeneradas mostraron un desarrollo vegetativo aparentemente idéntico a los cultivares originales

Comunicación corta. Introgresión de la resistencia a mildiu (Phytophthora infestans L.) en la patata cultivada a partir de especies Solanum silvestres tuberíferas

We have analyzed resistance to (Phytophthora infestans) in five progenies derived from crosses between wild tuberbearing potatoes (Solanum okadae, Solanum canacense, Solanum bukasovii, Solanum jamessii and Solanum raphanifolium) and cultivated diploid potato species (Solanum phureja, Solanum goniocalyx and a dihaploid of Solanum tuberosum). Different levels of resistance to P. infestans, from 11 to 81%, were found in leaves and tubers in the evaluated progenies. This variation indicates a variable number of major genes (R genes), minor genes and/or defeated R-genes, which have been transferred from the parental genotypes. Correlation analyses between leaf and tuber infection levels were low and not significant.Se ha analizado la resistencia a Phytophthora infestans en progenies derivadas de cruzamientos entre especies silvestres tuberíferas de Solanum okadae, Solanum canacense, Solanum bukasovii, Solanum jamessii y Solanum raphanifolium y especies cultivadas diploides de Solanum phureja, Solanum goniocalyx y un dihaploide de Solanum tuberosum. Se han encontrado diferentes niveles de resistencia, entre el 11 y el 81%, tanto en hojas como en tubérculos, en las cinco progenies evaluadas Esta variación indica un número variable de genes mayores (genes R), genes menores y/o genes R superados, los cuales han sido transferidos de los genotipos parentales. El análisis de correlación de los niveles de infección entre hoja y tubérculo fueron bajos y no significativos

Microsatellite variation in potato landraces from the island of La Palma

Nineteen microsatellite markers were used to fingerprint a set of 19 potato landraces from the island of La Palma (Canary Islands). These landraces represent relicts of early introductions from South America, although most are commonly cultivated by local farmers. The SSR primers detected 62 polymorphisms, 13 of which were present in all landraces. Several accession- and group-specific markers were detected. Jaccard similarity coefficients were estimated from the molecular data and UPGMA cluster analysis was performed. Some cultivars with related common names clustered together. In some cases, e.g., for the ‘Conejera’ landrace, the molecular patterns were discrepant with previous species assignments, suggesting the need for a more detailed morphological and comparative study of these accession

Modulation of LTCC Pathways by a Melusin Mimetic Increases Ventricular Contractility During LPS-Induced Cardiomyopathy

Aim: Sepsis-induced cardiomyopathy is commonplace and carries an increased risk of death. Melusin, a cardiac muscle-specific chaperone, exerts cardioprotective function under varied stressful conditions through activation of the AKT pathway. The objective of this study was to determine the role of melusin in the pathogenesis of lipopolysaccharide (LPS)-induced cardiac dysfunction and to explore its signaling pathway for the identification of putative therapeutic targets. Methods and results: Prospective, randomized, controlled experimental study in a research laboratory. Melusin overexpressing (MelOV) and wild-type (MelWT) mice were used. MelOV and MelWT mice were injected intraperitoneally with LPS. Cardiac function was assessed using trans-thoracic echocardiography. Myocardial expression of L-type calcium channel (LTCC), phospho-Akt and phospho-Gsk3-b were also measured. In separate experiments, wild-type mice were treated post-LPS challenge with the allosteric Akt inhibitor Arq092 and a mimetic peptide (R7W-MP) targeting the LTCC. The impact of these therapies on protein-protein interactions, cardiac function, and survival was assessed. MelOV mice had limited derangement in cardiac function after LPS challenge. Protection was associated with higher Akt and Gsk3-b phosphorylation and restored LTCC density. Pharmacological inhibition of Akt activity reversed melusin-dependent cardiac protection. Treatment with R7W-MP preserved cardiac function in wild-type mice after LPS challenge and significantly improved survival. Conclusions: This study identifies AKT / Melusin as a key pathway for preserving cardiac function following LPS challenge. The cell-permeable mimetic peptide (R7W-MP) represents a putative therapeutic for sepsis-induced cardiomyopathy