No abstract

While the genetic control of wheat processing characteristics such as dough rheology is well understood, limited information is available concerning the genetic control of baking parameters, particularly sponge and dough (S&D) baking. In this study, a quantitative trait loci (QTL) analysis was performed using a population of doubled haploid lines derived from a cross between Australian cultivars Kukri x Janz grown at sites across different Australian wheat production zones (Queensland in 2001 and 2002 and Southern and Northern New South Wales in 2003) in order to examine the genetic control of protein content, protein expression, dough rheology and sponge and dough baking performance. The study highlighted the inconsistent genetic control of protein content across the test sites, with only two loci (3A and 7A) showing QTL at three of the five sites. Dough rheology QTL were highly consistent across the 5 sites, with major effects associated with the Glu-B1 and Glu-D1 loci. The Glu-D1 5 + 10 allele had consistent effects on S&D properties across sites; however, there was no evidence for a positive effect of the high dough strength Glu-B1-al allele at Glu-B1. A second locus on 5D had positive effects on S&D baking at three of five sites. This study demonstrated that dough rheology measurements were poor predictors of S&D quality. In the absence of robust predictive tests, high heritability values for S&D demonstrate that direct selection is the current best option for achieving genetic gain in this product category.

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Using large-scale field surveys across 12 estuaries in two provinces in Atlantic Canada, we analyzed changes in phytoplankton and benthic macroalgal communities as well as the canopy structure of eelgrass beds and quantified their carbon and nitrogen storage with increasing eutrophication. As eutrophication increased, phytoplankton biomass increased on average 1.8 times and phaeopigments doubled. Among macroalgae, the epiphytic Ulothrix speciosa increased 40 times in New Brunswick, and benthic Ulva lactuca 670 times in Prince Edward Island covering 61% of the bottom. Eelgrass showed a significant increase in leaf length and declines in shoot density and aboveground and belowground biomass, consistent with increased shading by opportunistic algae. As eelgrass biomass declined, so did the carbon storage capacity of the habitat. Nitrogen storage only declined in belowground eelgrass beds due to increasing tissue nitrogen content above ground with eutrophication. Despite province-and species-specific responses of primary producers to nutrient loading, principal component analysis revealed an overall shift from perennial eelgrass to opportunistic macroalgae and phytoplankton with eutrophication at the regional scale, indicating generalized eutrophication effects on primary producer assemblages.

No abstract

The Puccinia striiformis f. sp. tritici (Pst) pathotype, 134 E16A?, detected in 2002 in Australia, produced relatively lower and higher adult plant stripe rust responses, respectively, on cultivars Kukri and Janz in comparison to the pre-2002 Pst pathotype 110 E143A?. Molecular mapping of adult plant stripe rust response variation among 180 Kukri/Janz-derived doubled haploid lines over 4 years, two each with Pst pathotypes 110 E143A? and 134 E16A?, was performed. QYr.sun-7B and QYr.sun-7D were consistently contributed by Kukri and Janz, respectively. QYr.sun-7D corresponded to the genomic location of Yr18 and QYr.sun-7B remains to be formally named. QYr.sun-1B, QYr.sun-5B, and QYr.sun-6B were detected during more than one season irrespective of the Pst pathotypes used, whereas QYr.sun-3B was identified only during the 2003 crop season. QYr.sun-1A contributed by Janz, and QYr.sun-2A from Kukri, were detected only against Pst pathotypes 110 E143A? and 134 E16A?, respectively. The DH lines showing better resistance than the either parent carried combinations of 4 to 6 QTL. These lines are currently being used as stripe rust resistance donors in wheat breeding programs.

Marine vegetated habitats provide essential functions and services to ocean ecosystems and human well-being. It is unclear, however, how different habitat types compare. Using large-scale field surveys, we compared the canopy and community structure between eelgrass and rockweed beds in Atlantic Canada and assessed their nitrogen retention, carbon storage, and habitat services. We then used binary network models of predator-prey interactions to determine food-web structure and its robustness to species loss. Despite disparate 3-dimensional canopy structure, both habitats significantly enhanced overall abundance and diversity of associated flora and fauna, including several commercially important species. Significant differences occurred in the species assemblages within and between habitats and were attributed to different settlement opportunities, food availability, predation risk, and maneuverability. While eelgrass plants had higher nitrogen content, rockweed canopies maintained 8-fold greater biomass and, thus, 14-fold greater nitrogen and 8-fold greater carbon retention per unit area. Both rockweed and eelgrass food webs showed similarities to other temperate and tropical seagrass webs, yet their robustness to the loss of most connected species including primary producers was among the lowest; underscoring their vulnerability to disturbances affecting the functionally dominant primary producers. The present study demonstrates that marine vegetation provides important habitat, nitrogen, and carbon storage services, yet the extent of these services depends on the foundation species and its architecture. Changes in canopy structure will therefore have profound effects on associated food webs and ecosystem services. Thus, as increasing human pressures on coastal ecosystems threaten the continued supply of essential functions and services, the protection of marine vegetated habitats should be a management priority.

Seagrass beds provide important habitat for a wide range of marine species but are threatened by multiple human impacts in coastal waters. Although seagrass communities have been well-studied in the field, a quantification of their food-web structure and functioning, and how these change across space and human impacts has been lacking. Motivated by extensive field surveys and literature information, we analyzed the structural features of food webs associated with Zostera marina across 16 study sites in 3 provinces in Atlantic Canada. Our goals were to (i) quantify differences in food-web structure across local and regional scales and human impacts, (ii) assess the robustness of seagrass webs to simulated species loss, and (iii) compare food-web structure in temperate Atlantic seagrass beds with those of other aquatic ecosystems. We constructed individual food webs for each study site and cumulative webs for each province and the entire region based on presence/absence of species, and calculated 16 structural properties for each web. Our results indicate that food-web structure was similar among low impact sites across regions. With increasing human impacts associated with eutrophication, however, food-web structure show evidence of degradation as indicated by fewer trophic groups, lower maximum trophic level of the highest top predator, fewer trophic links connecting top to basal species, higher fractions of herbivores and intermediate consumers, and higher number of prey per species. These structural changes translate into functional changes with impacted sites being less robust to simulated species loss. Temperate Atlantic seagrass webs are similar to a tropical seagrass web, yet differed from other aquatic webs, suggesting consistent food-web characteristics across seagrass ecosystems in different regions. Our study illustrates that food-web structure and functioning of seagrass habitats change with human impacts and that the spatial scale of food-web analysis is critical for determining results.