• Yield losses caused by late blight (Phytophthora infestans (Mont.) de Bary) in potato crops in Ireland

      Dowley, L.J.; Grant, Jim; Griffin, D. (Teagasc, Oak Park, Carlow, Ireland, 2008)
      Field experiments, using foliage blight susceptible cultivars, were conducted at Oak Park, Carlow from 1983 to 2007 to determine the loss in potato production caused by crop infection with Phytophthora infestans. In each of the 25 years an untreated control was compared with protectant and with systemic fungicide programmes to determine the effect of late blight on the defoliation percentage at the end of the season, the area under the disease progress curve, marketable tuber yield, total tuber yield and yield of blighted tubers. The earliest date of first recorded late blight was 22 June and the latest was 15 September, but in 15 of the 25 years, blight was first recorded between 17 July and 13 August. Disease reached epidemic proportions in all but 4 of the years. Yields varied considerably among years. The mean loss in total yield from not using a fungicide was 10.1 t/ha. Differences in yield were significant across the 25 seasons. No overall increase in aggressiveness of the pathogen could be detected over the 25-year period.
    • Yield of temperate forage grassland species is either largely resistant or resilient to experimental summer drought

      Hofer, Daniel; Suter, Matthias; Haughey, Eamon; Finn, John A.; Hoekstra, Nyncke J.; Buchman, Nina; Luscher, Andreas (Wiley, 2016-06-17)
      1.Due to climate change, an increasing frequency and severity of drought events are expected to impair grassland productivity, particularly of intensively managed temperate grasslands. 2.To assess drought impacts, a common field experiment to manipulate precipitation was set up at three sites (two Swiss and one Irish) using monocultures and mixtures with two and four key forage species. Species differed in their functional traits: a shallow-rooted non-legume (Lolium perenne L.), a deep-rooted non-legume (Cichorium intybus L.), a shallow-rooted legume (Trifolium repens L.) and a deep-rooted legume (Trifolium pratense L.). A 9-week summer drought was simulated, and soil water status, above-ground biomass yield and plant nitrogen (N) limitation were compared to a rainfed control. 3.Based on soil water measurements, the drought induced severe stress at both Swiss sites and extreme stress at the Irish site. Under severe stress, the legumes were more drought resistant and showed an average change in above-ground biomass (CAB, compared to rainfed control) of only −8% and −24% (for the two Swiss sites), while the non-legumes had an average CAB of −51% and −68%. The lower resistance of non-legumes coincided with an apparent limitation of plant N, which further increased under drought. Under extreme drought (Irish site), growth nearly ceased with an average CAB of −85%. 4.During a 6-week post-drought period with adequate water supply (Swiss sites), formerly drought-stressed species were highly resilient and either attained (legumes) or clearly outperformed (non-legumes) the yield level of the rainfed controls. This outperformance coincided with post-drought reductions in N limitation in formerly drought-stressed species. As a result, aggregated over the drought and the post-drought periods, a negative drought impact was found only for the shallow-rooted L. perenne at one of the severely stressed sites. 5.Significant overyielding by multispecies mixtures was evident under rainfed control conditions (+38% across all three sites, P < 0·05) and was equally apparent under severe drought (+50%, P < 0·05). This overyielding was greatest in mixtures with approximately equal species proportions and was sufficiently large that drought-stressed mixtures at least attained the same yield as the average of the rainfed monocultures. Under extreme drought, growth almost ceased in monocultures and mixtures. 6.Synthesis and applications. Yields of selected species of intensively managed temperate grasslands are either resistant to a single severe drought or are highly resilient as soon as soil moisture levels recover after the drought event. However, these forage species seem unable to cope with an extreme drought event. Combining species in mixtures can compensate for yield reductions caused by severe drought and it offers a practical management tool to adapt forage production to climate change.
    • β-lactoglobulin as a molecular carrier of linoleate: characterisation and effects on intestinal epithelial cells in vitro

      Le Maux, Solene; Giblin, Linda; Croguennec, Thomas; Bouhallab, Said; Brodkorb, Andre (American Chemical Society, 2012-08-27)
      The dairy protein β-lactoglobulin (βlg) is known to bind hydrophobic ligands such as fatty acids. In the present work, we investigated the biological activity in vitro of linoleate once complexed to bovine βlg. Binding of linoleate (C18:2) to bovine βlg was achieved by heating at 60 °C for 30 min at pH 7.4, resulting in a linoleate/βlg molar binding stoichiometry of 1.1, 2.1, and 3.4. Two types of binding sites were determined by ITC titrations. Binding of linoleate induced the formation of covalent dimers and trimers of βlg. The LD50 on Caco-2 cells after 24 h was 58 μM linoleate. However, cell viability was unaffected when 200 μM linoleate was presented to the Caco-2 cells as part of the βlg complex. The Caco-2 cells did not increase mRNA transcript levels of long chain fatty acid transport genes, FATP4 and FABPpm, or increase levels of the cAMP signal, in response to the presence of 50 μM linoleate alone or as part of the βlg complex. Therefore, it is proposed that βlg can act as a molecular carrier and alter the bioaccessibility of linoleate/linoleic acid.
    • β-Lactoglobulin-linoleate complexes: In vitro digestion and the role of protein in fatty acids uptake

      Le Maux, Solene; Brodkorb, Andre; Croguennec, Thomas; Hennessy, Alan A; Bouhallab, Said; Giblin, Linda (Elsevier Inc and American Dairy Science Association, 2013-07)
      The dairy protein β-lactoglobulin (BLG) is known to bind fatty acids such as the salt of the essential longchain fatty acid linoleic acid (cis,cis-9,12-octadecadienoic acid, n-6, 18:2). The aim of the current study was to investigate how bovine BLG-linoleate complexes, of various stoichiometry, affect the enzymatic digestion of BLG and the intracellular transport of linoleate into enterocyte-like monolayers. Duodenal and gastric digestions of the complexes indicated that BLG was hydrolyzed more rapidly when complexed with linoleate. Digested as well as undigested BLG-linoleate complexes reduced intracellular linoleate transport as compared with free linoleate. To investigate whether enteroendocrine cells perceive linoleate differently when part of a complex, the ability of linoleate to increase production or secretion of the enteroendocrine satiety hormone, cholecystokinin, was measured. Cholecystokinin mRNA levels were different when linoleate was presented to the cells alone or as part of a protein complex. In conclusion, understanding interactions between linoleate and BLG could help to formulate foods with targeted fatty acid bioaccessibility and, therefore, aid in the development of food matrices with optimal bioactive efficacy
    • β-Lactoglobulin: A Whey Protein Fraction with Enhanced Functionality

      Mehra, Raj; Raggett, Elaine; O'Kennedy, Brendan; Kelly, Philip M.; Rawle, Donal (Teagasc, 2001-08-01)
      Infant formula manufacturers are progressively moving towards the development of the next generation of infant milk formula based on the inclusion of α-lactalbumin-enriched ingredients in order to further ‘humanise’ baby milk, as well as to reduce the allergenicity associated with the presence of β-lactoglobulin ( β-lg). Since α-lactalbumin represents one of the two major whey protein fractions in bovine milk, the viability of new fractionation processes currently under development will depend inter alia on the functional value that will attach to the remaining fraction, namely β-lg. Since this protein fraction influences whey protein functionality for the most part, it is to be expected that its availability in an enriched form should lead to further enhancement of its key functional properties, and stimulate further market opportunities. It is therefore imperative that attention is given to the processes and functionality of β-lg produced by different processing approaches. Hence, the overall objective of the project was: - To source and/or produce sufficient quantities of β-lg-enriched ingredients obtained through whey protein fractionation using different technologies, and to evaluate their functionality in model and food systems. - To investigate the influence of thermal treatments and ionic environment on the molecular structure of purified β-lg in order to understand their effect on protein functionality (gelation). - To improve the water-holding capacity of β-lg-enriched fraction so that it could compete more favourably with carbohydrate hydrocolloids in food applications. Downstream processing of β-lg was manipulated to influence the composition, and hence the functional properties of β-lg-enriched fractions. * β-Lg-enriched fractions had enhanced functional properties compared to WPC 75 and WPI. * β-Lg-enriched fraction has clear advantages over conventional whey protein products (WPC, WPI), in that it can be tailor-made to have specific functional properties desired in particular food products. * Water-binding properties of β-lg-enriched fraction could be improved by multi-stage heating.