Increases in the longevity of desiccation-phase developing rice seeds: response to high temperature drying depends on harvest moisture content

• Background and Aims Earlier studies have suggested that the drying conditions routinely used by genebanks may not be optimal for subsequent seed longevity. The aim of this study was to compare the effect of hot-air drying with low temperature drying on subsequent seed longevity for 20 diverse rice accessions and to consider how factors related to seed production history might influence the results. • Methods Seeds were produced according to normal regeneration procedures at IRRI. They were harvested at different times (harvest date and days after anthesis (DAA), once for each accession) and dried either in a drying room (DR; 15% RH, 15°C), or in a flat-bed heated-air batch dryer (BD; 45°C, 8 h d-1) for up to 6 daily cycles followed by drying in the DR. Relative longevity was assessed by storage at 10.9% moisture content (m.c.) and 45°C. • Key Results Initial drying in the BD resulted in significantly greater longevity compared with the DR for 14 accessions (seed lots): the period of time for viability to fall to 50% for seeds dried in the BD as a percentage of that for seeds dried throughout in the DR varied between 1.3 and 372.2% for these 14 accessions. The seed lots that responded the most were harvested earlier in the season and at higher moisture content. Drying in the BD did not reduce subsequent longevity compared with DR drying for any of the remaining accessions. • Conclusions Seeds harvested at a m.c. where, according to the moisture desorption isotherm, they could still be metabolically active (>16.2%), may be in the first stage of the post-mass maturity, desiccation phase of seed development and able to increase longevity in response to hot-air drying. The genebank standards regarding seed drying for rice and, perhaps, for other tropical species should be reconsidered

Whose Power to Control? Some Reflections on Seed Systems and Food Security in a Changing World

Four key words are essential in understanding the changing global food system: power, control, risks and benefits. The interplay between state and private actors vying to influence the direction of change, and use whatever tools for control they can, is at the heart of the contention for the future control of food. It is one shaped by history and influenced by a changing geopolitics. This interplay has led to the creation of a range of global rules affecting food, agriculture and biodiversity in which those on ‘intellectual property’ or IP are central. These rules come from a system dominated by the interests of the biggest players. Also important are the changing understandings and nature of food security and the pathways to innovation in agri?food systems that are most likely to lead to a just, healthy and sustainable future for all. Developments in food and farming are central to this and are the context in which the political economy of cereal seed systems in Africa is grounded

Phenological growth stages of pepino (Solanum muricatum) according to the BBCH scale

[EN] The pepino (Soianum muricatum) is a solanaceous vegetatively propagated fruit crop of Andean origin. We provide a detailed description of phenological stages because it is of interest for pepino crop management and research. Given the increasing prominence of this crop, and the fact that it morphologically and developmentally variable, and different from other major solanaceous crops, we have developed a pepino specific BBCH (Biologische Bundesanstalt, Bundessortenamt, CHemische Industrie) numerical scale. Nine principal stages are described for germination/rooting, leaf development, formation of side shoots, main shoot elongation, inflorescence emergence, flowering, development of fruit, ripening of fruit and seed, and senescence. Secondary stages (two-digit scale) have been identified for all principal stages. Complementary descriptions using mesostages (three-digit scale) have been developed for leaf development, formation of side shoots, inflorescence emergence, and flowering phenological stages. A description of all phenological stages combined with illustrations is provided. The utility of the BBCH scale has been validated by comparing several traits of agronomic interest at specific developmental stages in a collection of pepino local varieties, modern cultivars and wild relatives. The BBCH scale developed provides uniform criteria for the description, identification and selection of phenological stages of the pepino and will facilitate the management, breeding and conservation of genetic resources of this crop. (C) 2014 Elsevier B.V. All rights reserved.Herraiz García, FJ.; Vilanova Navarro, S.; Plazas Ávila, MDLO.; Gramazio, P.; Andújar, I.; Rodríguez Burruezo, A.; Fita, A.... (2015). Phenological growth stages of pepino (Solanum muricatum) according to the BBCH scale. Scientia Horticulturae. 183:1-7. doi:10.1016/j.scienta.2014.12.008S1718

Foundation characteristics of edible Musa triploids revealed from allelic distribution of SSR markers

Background and Aims The production of triploid banana and plantain (Musa spp.) cultivars with improved characteristics (e.g. greater disease resistance or higher yield), while still preserving the main features of current popular cultivars (e.g. taste and cooking quality), remains a major challenge for Musa breeders. In this regard, breeders require a sound knowledge of the lineage of the current sterile triploid cultivars, to select diploid parents that are able to transmit desirable traits, together with a breeding strategy ensuring final triploidization and sterility. Highly polymorphic single sequence repeats (SSRs) are valuable markers for investigating phylogenetic relationships. Methods Here, the allelic distribution of each of 22 SSR loci across 561 Musa accessions is analysed. Key Results and ConclusionsWe determine the closest diploid progenitors of the triploid 'Cavendish' and 'Gros Michel' subgroups, valuable information for breeding programmes. Nevertheless, in establishing the likely monoclonal origin of the main edible triploid banana subgroups (i.e. 'Cavendish', 'Plantain' and 'Mutika- Lujugira'), we postulated that the huge phenotypic diversity observed within these subgroups did not result from gamete recombination, but rather from epigenetic regulations. This emphasizes the need to investigate the regulatory mechanisms of genome expression on a unique model in the plant kingdom. We also propose experimental standards to compare additional and independent genotyping data for reference. (Résumé d'auteur

Variation of morphological descriptors for the evaluation of tomato germplasm and their stability across different growing conditions

[EN] Germplasm and breeding materials are usually characterized using morphological and agronomic descriptors, which should have a high heritability. Despite the widespread use of tomato (Solanum lycopersicum) standardized descriptors, little information exists on environmental effects on descriptor values and their heritability. We have evaluated 12 tomato accessions from seven cultivar groups in three different environments (open-field conventional, open-field organic, and greenhouse) and characterized them with 36 descriptors. A wide range of variation was found for most descriptors, demonstrating their utility for describing tomato materials and their diversity and relationships. The analysis of descriptors variation reveals that while for some descriptors with a simple genetic control the accession effect accounts for 100% of the variation, for others like yield per plant only 10.83% of the variation observed is due to the accession effect. Although significant differences were found among environments for most descriptors, including a much higher yield in the open-field conventional environment than in the two others, the environmental effect was low for most traits. However, the genotype×environment effect generally had an important contribution to the structure of variation for many descriptors, and for three traits it had the highest contribution to the percentage of the sum of squares. As a result of the variation structure, the heritability values are high (> 0.7) for only 10 descriptors, while for five is low (< 0.3). Principal components analysis (PCA) reveals that projections in the PCA graph of a same accession grown in different environments plot together in the same area of the PCA graph. Although cultivar groups are generally clearly separated in the PCA graph, accessions from the same cultivar group in some cases are intermixed. These results have important implications for detecting tomato duplicates and establishing core collections, as well as for analyzing germplasm and breeding results, when using data sets containing data of accessions grown in different environments.This work has been partially funded by the TRADITOM (Traditional tomato varieties and cultural practices: a case for agricultural diversification with impacto n food security and health of European population) and G2P-SOL (Linking genetic resources, genomes and phenotypes of Solanaceous crops) projects. These projects have received funding from the European Union's Horizon 2020 research and innovation programme under grant agreements No 634561 (TRADITOM) and No 677379 (G2P-SOL). Authors are grateful to Mr. Jonatan Cerdan for his technical help.Figás-Moreno, MDR.; Prohens Tomás, J.; Casanova-Calancha, C.; Fernández De Córdova Martínez, PJ.; Soler Aleixandre, S. (2018). Variation of morphological descriptors for the evaluation of tomato germplasm and their stability across different growing conditions. Scientia Horticulturae. 238:107-115. https://doi.org/10.1016/j.scienta.2018.04.039S10711523

Seed development and maturation in early spring-flowering Galanthus nivalis and Narcissus pseudonarcissus continues post-shedding with little evidence of maturation in planta

Background and Aims: Seeds of the moist temperate woodland species Galanthus nivalis and Narcissus pseudonarcissus, dispersed during spring or early summer, germinated poorly in laboratory tests. Seed development and maturation were studied to better understand the progression from developmental to germinable mode in order to improve seed collection and germination practices in these and similar species. Methods: Phenology, seed mass, moisture content, and ability to germinate and tolerate desiccation were monitored during seed development until shedding. Embryo elongation within seeds was investigated during seed development and at several temperature regimes after shedding. Key Results: Seeds were shed at high moisture content (> 59%) with little evidence that dry mass accumulation or embryo elongation were complete. Ability to germinate developed prior to the ability of some seeds to tolerate enforced desiccation. Germination was sporadic and slow. Embryo elongation occurred post-shedding in moist environments, most rapidly at 20C in G. nivalis and 15C in N. pseudonarcissus. The greatest germination also occurred in these regimes, 78 and 48%, respectively, after 700 d. Conclusions: Seeds of G. nivalis and N. pseudonarcissus seeds were comparatively immature at shedding and substantial embryo elongation occurred post-shedding. Seeds showed limited desiccation tolerance at dispersal

Phenotypic and genetic diversity of Spanish tomato landraces

[EN] The structure of Spanish landraces of tomato (Solanum lycopersicum L) has been analyzed. This diversity has been evaluated using agro-morphological characteristics (43 descriptors), quality parameters (solid soluble contents and individual sugars and organic acids) and DNA markers (amplified fragment length polymorphisms, AFLP). A wide range of variation was found for all traits but in the DNA marker level. Certain common characteristics could be identified in populations of the same landrace in several of the dimensions analyzed, but generally, an overlap of the spectrum of variation of different landraces was found. The results indicate that in each landrace the populations are strongly selected using very basic morphological characteristics such as fruit shape, colour or ribbing, while other traits vary depending on each farmer preferences. Seed mixing and pollen contamination might introduce variation which would be purged by farmers at the morphological level, but would be maintained in quality and yield traits. Despite the introduction of spurious variation it would be still possible to identify certain relations between quality attributes and the morphological traits defining specific landraces. The existence of a wide level of variation in plant yield and quality profiles enables the development of selection programmes targeted to provide farmers with materials with economically viable yield and excellent organoleptic quality. The results also highlight the necessity to stress the efforts in morpho-agronomical and quality characterization over molecular characterization in the ex situ management of these resources, as well as not to underestimate the importance of intra-varietal variability. (C) 2013 Elsevier B.V. All rights reserved.This research was funded by the Generalitat Valenciana with the research projects GV-CAPA00-19 and GV/2007/003.Cebolla Cornejo, J.; Rosello Ripolles, S.; Nuez Viñals, F. (2013). Phenotypic and genetic diversity of Spanish tomato landraces. Scientia Horticulturae. 162:150-164. https://doi.org/10.1016/j.scienta.2013.07.044S15016416

Multifunctional crop trait ontology for breeders' data: field book, annotation, data discovery and semantic enrichment of the literature

The ‘Crop Ontology’ database we describe provides a controlled vocabulary for several economically important crops. It facilitates data integration and discovery from global databases and digital literature. This allows researchers to exploit comparative phenotypic and genotypic information of crops to elucidate functional aspects of traits

Medium-term seed storage of 50 genera of forage legumes and evidence-based genebank monitoring intervals

Genebanks maintaining seeds for long-term genetic resources conservation monitor seed lots to detect early loss in viability. Monitoring is costly and depletes valuable seed. Three decades of genebank seed germination test results of diverse forage species from 50 legume genera in the International Livestock Research Institute’s medium-term store (circa 8° C with 5 % moisture content) were analysed to determine whether advice on seed monitoring intervals could be derived. Cumulative normal distributions were fitted by probit analysis for each seed lot and compared within each genus. Six patterns of within-genus variation were identified: no detectable trend in germination test results during storage (4 genera); detectable trends, but variable (positive to negative) amongst lots (5); consistent slope of loss in viability amongst lots (17); consistent slope of increase in ability to germinate amongst lots (21); common loss in viability amongst lots (2); common increase in ability to germinate amongst lots (1). Seed lot monitoring intervals for the medium-term store were derived for each of 19 genera with consistent loss in viability across seed lots: three genera provided comparatively rapid deterioration, five met the general expectations for a medium-term store (2-10 years’ maintenance of high viability), whilst 11 provided much better survival. Moreover, 26 further genera provided no evidence as yet of seed deterioration; of these, 22 improved in ability to germinate during storage indicating confounding of hardseededness with viability in germination tests

Asymmetrical local adaptation of maize landraces along an altitudinal gradient

Crop landraces are managed populations that evolve in response to gene flow and selection. Cross-pollination among fields, seed sharing by farmers, and selection by management and environmental conditions play roles in shaping crop characteristics. We used common gardens to explore the local adaptation of maize (Zea mays ssp. mays) landrace populations from Chiapas, Mexico to altitude. We sowed seeds of 21 populations from three altitudinal ranges in two common gardens and measured two characteristics that estimate fitness: likelihood of producing good quality seed and the total mass of good quality seed per plant. The probability of lowland plants producing good quality seed was invariably high regardless of garden, while highland landraces were especially sensitive to altitude. Their likelihood of producing good seed quadrupled in the highland site. The mass of good quality seed showed a different pattern, with lowland landraces producing 25% less seed mass than the other types at high elevations. Combining these two measures of fitness revealed that the highland landraces were clearly adapted to highland sites, while lowland and midland landraces appear more adapted to the midland site. We discuss this asymmetry in local adaptation in light of climate change and in situ conservation of crop genetic resources