Adaptation,diversity, and exploitation of global white lupin (Lupinus albus L.) landrace genetic resources

White lupin requires grain yield improvement to realize its potential as a high-protein grain crop. Some 121 entries representing 13 germplasm pools (11 landrace pools from European countries and from regions of North and East Africa, West Asia and Atlantic islands, and one winter-type and one spring-type variety pools) were evaluated in three major agroclimatic conditions, i.e., Mediterranean and subcontinental climate in Italy under autumn sowing and suboceanic climate in France under spring sowing, with the aim to assess: (i) the variation among and within germplasm pools for grain yield and 13 major morphophysiological traits; (ii) the impact of evaluation environments on entry characteristics; and (iii) the relation of wide- and specific-adaptation responses with morphophysiological traits. Indications on top-yielding genetic resources, entry morphophysiological traits and association of these traits with grain yield were largely environment-specific. Germplasm pools summarized a fairly high portion of genotypic and genotype × environment (GE) interaction variation, indicating their usefulness as a criterion for locating genetic resources with specific characteristics. Adaptive responses of germplasm pools and individual entries, modeled through Additive Main effects and Multiplicative Interaction analysis, highlighted the outstanding agronomic value for specific agroclimatic conditions of a few landrace germplasm pools in comparison with variety pools. Overall within-pool diversity for morphophysiological traits and adaptive response was largest in the landrace pools from Italy, Turkey, East Africa and West Asia. Only flowering time and individual seed weight exhibited high genetic correlations between environments for entry response, suggesting caution in inferring accession characteristics from evaluation data obtained in environments very different from those targeted by possible germplasm users. Optimal flowering time was early in the spring-sown environment, intermediate in the Mediterranean environment, and late (associated with winter survival) in the subcontinental-climate environment. Owing to the association of phenology with several other traits, germplasm ordination for adaptation pattern and for overall morphophysiological variation were very similar. Pod fertility emerged among the seed yield components because of its correlation with grain yield in each environment combined with fairly low GE interaction. Beside contributing to the ecogeographic classification of landrace germplasm, our results can support breeding programs of Europe and Mediterranean-climate regions in defining useful genetic resources, adaptation strategies and adaptive traits. Genetic resources from Madeira & Canaries (high-yielding across environments), Italy (featuring high adaptive and morphophysiological diversity) and a few other regions are of special interest for breeding in targeted definite agroclimatic conditions.     

Pasting properties of transgenic lines of a commercial bread wheat expressing combinations of HMW glutenin subunit genes

Seven transgenic lines of a commercial wheat (Triticum aestivum L.) cultivar expressing transgenic subunits 1Ax1, 1Dx5 and 1Dy10, alone or in combination have been developed. Pasting properties were determined in these transgenic lines using a Rapid Visco Analyser (RVA) in order to determine the possible impact of HMW-GS transgene expression on the starch properties. Expression of the HMW-GS transgenes increased the proportions of the corresponding 1Ax, 1Dx and 1Dy subunits affecting significantly the ratios of HMW-GS:LMW-GS and x-type:y-type HMW-GS. Starch granule size distribution varied significantly among all transgenic lines, with the Anza control and transgenic line T616 (expressing subunits 1Ax1 and 1Dy10) showing the highest and the lowest percentage of B granules, respectively. All transgenic lines increased the water-binding capacities (WBC) at 25 °C and 90 °C. Line T606 (expressing subunits 1Ax1 and 1Dx5) and line T590 (expressing subunit 1Dy10) showed the lowest and the highest values for peak viscosity, respectively. Notably, lines expressing only transgenic x-type subunits (T580, T581 and T606), with high ratios of x-type:y-type HMW-GS, had low peak viscosities, final viscosities and breakdown viscosities. Line T590 had the highest breakdown viscosity while lines T606 and T581 had the lowest.     

Sensitivities to DMI fungicides in populations of Podosphaera fusca in south central Spain

BACKGROUND: Cucurbit powdery mildew elicited by Podosphaera fusca (Fr.) U Braun & N Shishkoff limits crop production in Spain. Disease control is largely dependent on fungicides such as sterol demethylation inhibitors (DMIs). Fungicide resistance is an increasing problem in this pathogen. To overcome such risk, it is necessary to design rational control programmes based upon knowledge of field resistance. The aim of this study was to investigate the state of DMI sensitivity of Spanish P. fusca populations and provide tools for improved disease management. RESULTS: Using a leaf‐disc assay, sensitivity to fenarimol, myclobutanil and triadimenol of 50 isolates of P. fusca was analysed to determine discriminatory concentrations between sensitive and resistant isolates. As no clearly different groups of isolates could be identified, discriminatory concentrations were established on the basis of maximum fungicide field application rate, 100 mg L^?1 for the three fungicides tested. Subsequently, a survey of DMI resistance was carried out in different provinces located in the south central area of Spain during the cucurbit growing seasons in 2002, 2003 and 2004. Examination of a collection of 250 isolates revealed that 23% were resistant to fenarimol and 7% to triadimenol, the provinces of Almería, Badajoz and Murcia being the locations with the highest frequencies of resistance. By contrast, no resistance to myclobutanil was found. CONCLUSION: Results show that fenarimol and, to a lesser extent, triadimenol have become less efficient for controlling cucurbit powdery mildew in Spain. These are important observations that should lead to reconsideration of the current disease management programmes. Copyright © 2010 Society of Chemical Industry     

High prevalence of viruses in table grape from Spain detected by real-time RT-PCR

Table grapes from one of the most important growing area in Spain (Vinalopó, Alicante) protected by the Designation of Origin “Vinalopó bagged table grape”, were surveyed and analysed to determine the prevalence of the five viruses included in the Spanish certification program: Arabis mosaic virus (ArMV), Grapevine fanleaf virus (GFLV), Grapevine fleck virus (GFkV), Grapevine leafroll associated virus-1 (GLRaV-1) and Grapevine leafroll associated virus-3 (GLRaV-3). Ninety five sampling points were selected and the position of grapevine plants georeferenced. Samples were collected in two different vegetative periods and analyses were performed by ELISA and real-time RT-PCR. Purified RNA and immobilized viral targets from plant extracts on nylon membranes were used in parallel assays as templates for PCR assays. In order to analyse these five viral species by real-time RT-PCR, new specific primers and TaqMan probes were designed for detection of ArMV and GFkV. Real time RT-PCR from purified RNA was more sensitive than spot version and ELISA tests. The most prevalent virus was GFLV (95.8%) followed by GLRaV-3 (94.7%), GLRaV-1 (66.3%) and GFkV (65.3%). ArMV was not detected in any sample. The high level of viral infections and the presence of mixed infections suggest that initial infected plant material and uncontrolled traffic of propagation material have played an important role in the spread of viruses.     

Aluminium-induced effects on growth,morphogenesis and oxidative stress reactions in in vitro cultures of quince

The effects of Al³⁺ [supplied as Al₂(SO₄)₃·18H₂O] addition to culture media (pH 4.0) on growth, morphogenesis (in leaf explants), and oxidative stress reactions in in vitro cultures of ‘BA 29’ quince were investigated. Aluminium (Al 0.5 mM) strongly inhibited shoot growth in the proliferation and rooting phases (Al 2.2 mM), reduced shoot proliferation (Al 1.1 mM), and induced tissue browning. Superoxide dismutase (SOD) activity was increased in shoot cultures supplemented with 2 mM Al. Malondialdehyde (MDA) content of shoots was strongly increased by Al during proliferation (starting from Al 1.7 mM) and rooting (already at Al 1.1 mM), thus serving as a good ‘marker’ for Al toxicity. Even a low concentration of Al (0.5 mM) in the shoot induction medium was found to inhibit shoot regeneration. When standard (Al 0) shoot induction medium was used, leaf explant growth was only reduced by 2.2 mM Al in the subsequent growth phases. Following a preliminary selection for their growth on Al-enriched media, 82 potentially Al-tolerant quince somaclones were selected for further trials.     

Soil fertility and GIS raster models for tropical agroforestry planning in economically depressed and contaminated Caribbean areas (coffee and kidney bean plantations)

In the jaragua-bahoruco-enriquillo biosphere reserve, located on the southern border between the Dominican Republic and Haiti, there are depressed rural areas with soils with high content in Cadmium and other heavy metals which originate naturally in the geological substrate. Data from 80 soils and an inventory of 76 plantations (coffee and kidney bean were used) to design a GIS (geographic information systems) tool which integrated statistical multivariate methods, soil parameters including heavy metal content into models of land planning, agricultural development, forests and protection of the health of the area’s inhabitants and the natural environment. This GIS tool is based on raster models of an open source, which use combination and reclassification operations based on the maps, geostatistical methods (Kriging), statistical analyses external to the GIS, and cartography of limiting and excluding particular factors for crops (including heavy metal soil content). The GIS tool developed discriminates extreme situations in sustainable agroforestry planning in contaminated rural areas of the Caribbean, Central America and other tropical regions.     

Stand development patterns as a consequence of the mortality in Austrocedrus chilensis forests

The forests of Austrocedrus chilensis (D. Don) Pic. Sern. et Bizarri in Argentina suffer decline and mortality throughout their natural distribution known as ‘mal del ciprés’. While several aspects of this, to date, temporally unpredictable process of overstory tree mortality have been the focus of detailed studies, there has been little research on tree growth and stand dynamics in symptomatic forests nor stand development patterns and prediction of future stand structure. We studied 12 stands in northern Patagonia (Province of Río Negro) using stand reconstruction studies to examine the changes in stand structure over time as a consequence of overstory mortality and the implications of these structural changes on the establishment and growth of the residual overstory. Dendrochronological analyses were used to reconstruct stand establishment and structure over time, and to study past diameter growth patterns. Mortality in A. chilensis forests was variable in time among stands. As expected, overstory mortality led to the successful establishment of trees in the understory in all stands; however, the response of residual overstory trees was variable. Understory establishment was low in some stands and high in others depending on the density of the overstory. While overstory trees in almost all stands released after the onset of the mortality, the pattern was not distinctive, varying in time, number and magnitude. In some stands, growth releases occurred after single or multiple tree deaths suggesting a relationship between processes, while in others this was not the case. Even when the patterns of recruitment in the understory and the overstory response varied greatly among stands, when examined together, some general patterns emerged. This study is the first to intensively explore the dynamics of A. chilensis forests affected by ‘mal del ciprés’. Additionally, this study showed that arbitrarily categorizing disturbances as discrete or chronic masks the true process of release of growing space and the resulting stand dynamics.