Plant Sciences
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Item Fire severity and plant productivity recovery in a mixed grass prairie wildfire driven by extreme winds(International Journal of Wildland Fire, 2024-10) Grover, Sera A; Vera-Velez, Roy; Guo, Xulin; Lamb, EricBackground Wildfire on rangelands in the mixed grassland can severely disrupt livestock operations. Understanding how fire severity impacts post-fire production recovery is important for grazing management. Aims We examined how topography and other environmental factors influence wildfire severity, or the consumption of biomass and exposure of soil, under extreme (>120 km h−1) wind conditions in native mixed grass prairie in western Canada. We also examined how variation in fire severity impacts grassland production recovery. Methods Fire severity and production recovery were measured using the bare soil index (BSI) and normalised difference vegetation index (NDVI). Impacts of topography, wind exposure, and site capability on fire severity and production recovery were assessed using generalised additive models. Key results Fire severity varied as a function of slope, wind exposure and fuel load. Severity peaked at NDVI between 0 and 0.4, values associated with high litter content and minimal green vegetation. Interactions between slope and aspect with respect to dominant wind direction generated very high fire severity on slopes greater than 15° that faced into the wind. Production recovery increased moderately with higher fire severity and recovery was generally higher on sites with lower potential productivity. Implications Post-fire production recovery was rapid; fire severity and site capability had only modest impacts on recovery rates demonstrating the resilience of grassland ecosystems to even severe wildfire.Item Novel hydrothermal modification to alter functionality and reduce glycemic response of pea starch(Carbohydrate Polymers, 2024-10) Cheng, Fan; Sun, Gexiao; Xuehong, Li; Warkentin, Thomas; Ai, YongfengDespite being an effective and clean-label method, heat-moisture treatment (HMT) is not commonly used for starch modification in industry due to the difficulty of scale-up. This study aimed to develop a novel method of using extrusion combined with high-temperature drying (EHTD) as an alternative to HMT for starch modifica- tion. Pea starch was subjected to extrusion at 37.5 % moisture level and with a low-temperature profile (≤ 65 ◦C), followed by immediate heating at 130 ◦C for 1 h. EHTD significantly damaged the granules, altered the X- ray diffraction pattern, and reduced the relative crystallinity of pea starch. Overall, EHTD-modified pea starch exhibited increased gelatinization temperatures and decreased gelatinization enthalpy change, lowered pasting viscosity and gel hardness, as well as enhanced enzymatic resistance than the native pea starch. More impor- tantly, in a human feeding trial (n = 20 healthy participants) to monitor plasma glucose response over a period of 2 h after consuming water-boiled sample (35 g starch, dry basis), EHTD-modified pea starch exhibited 22 % reduction (p < 0.01) in plasma glucose incremental area under the curve as compared to the native counterpart. The results indicated that EHTD could be a new simple and clean-label method to produce functional and low- glycemic starch ingredients.Item Effects of rosemary extract addition on starch bioavailability and antioxidant properties of extruded pet foods(Animal Feed Science and Technology, 2024-07) Ren, Yikai; Bokshowan, Elise; Warkentin, Thomas; Weber, Lynn; Ai, YongfengThis study aimed to investigate the effects of rosemary extract (RE) addition on the starch digestion and antioxidant properties of extruded pet foods. Pet foods were extruded using rice, round pea (RP), and wrinkled pea (WP) flours as the sole starch sources with RE incorporated at levels of 0 (control), 1.0, 10.0, and 30.0 g/kg (RE0, RE1, RE10, and RE30, respectively). High-amylose WP pet food exhibited lower damaged/gelatinized starch content compared with rice and RP pet foods. The total phenolic contents and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability of the pet foods notably increased after the addition of RE, showing a clear upward trend as the incorporation level was elevated. RE10 (except for rice) and RE30 significantly decreased the starch digestibility of pet foods according to in vitro testing, with the greatest reduction observed for the high-amylose WP sample. Although RE1 did not significantly impact the overall in vitro and in vivo starch digestibility, the treatment consistently postponed the peak times of postprandial blood glucose responses to all the three extruded diets in beagles. The results indicated that RE effectively enhanced the antioxidant properties of extruded pet foods and slowed starch digestion rates.Item Important roles of coarse particles in pasting and gelling performance of different pulse flours under high-temperature heating(Food Chemistry, 2024-02) Lee, Dong-Jin; Cheng, Fan; Li, Dongxing; Ding, Ke; Carlin, Janelle; Moore, Emily; Ai, YongfengDehulled pea, lentil, and faba bean grains were milled into flours with 0.5- to 2.5-mm sieves. As the particle size decreased, damaged-starch contents of the flours from the same pulse crop increased. At a holding temperature of 95 ◦C in RVA, peak and final viscosities and gelling ability of the flours generally increased as the particle size decreased. When the holding temperature increased from 95 to 140 ◦C, pasting viscosities of pea and lentil flours and gel hardness of lentil flours gradually decreased. In contrast, pasting viscosities and gel hardness of faba bean flours reached the highest values at 120 ◦C. The comparison of the pulse flours varying in particle size across the three market classes revealed that coarse particles comprising agglomerated starch, protein, and dietary fiber (i. e., particles of the second peak in the bimodal particle-size distribution curves) showed significant correlations with certain important functional properties of pulse flours.Item What do Lygus like? Looking for potential trap crops to reduce faba bean damage(Springer, 2024-10-05) Aguiar‑Cordero, Teresa; Prager, SeanGrain legumes, such as faba bean (Vicia faba L.), are crucial for protein supply and soil fertility enhancement through nitrogen fixation. However, faba bean cultivation is challenged by Lygus plant bugs (Hemiptera: Miridae), which cause significant crop damage and seed quality loss. This study aimed to evaluate Lygus preferences between faba bean and alternative crops to develop effective management strategies. We conducted choice bioassay experiments under laboratory conditions and field plot experiments. Laboratory results indicated sex-based host preferences, with males favoring faba beans and females preferring canola. Field studies showed that faba beans adjacent to canola had higher Lygus abundance and damage compared to those next to peas, flax, and safflower. Safflower and sunflower demonstrated potential as trap crops to reduce Lygus damage to faba beans. Our findings provide insights into Lygus behavior and suggest that a combination of trap cropping, and targeted insecticide use could mitigate the impact of Lygus infestations on faba bean cultivation.Item Development of Aster Yellows on Crop and Noncrop Species from the Canadian Prairies(The American Phytopathological Society, 2023-04-03) Romero, Berenice; Dumonceaux, Tim; Olivier, Chrystel; Wist, Tyler; Prager, SeanAster yellows phytoplasmas (AYp) are a group of obligate parasites that infect a wide range of plant species, including crops such as canola and cereals and noncrops such as dandelion and wild mustard. In the Canadian Prairies, these microorganisms are mainly transmitted by a migratory species of leafhopper (Macrosteles quadrilineatus Forbes). Although a low incidence of the disease associated with this pathogen has been reported for most years in canola fields, several outbreaks have been documented in this region. A selection of crop and noncrop species commonly found in the Canadian Prairies and Arabidopsis thaliana were used to assess the suitability of these plant species as hosts for AYp (16SrI-B). Symptom expression and phytoplasma levels were examined at different time points following exposure to infective insects.A. thaliana,barley,and canola were susceptible to infection with AYp,yet symptoms differed among these plant species. A. thaliana and canola exhibited symptoms of infection as early as 2 weeks following exposure to infected insects,whereas symptoms in barley were observed at 5 weeks. A lower incidence rate was observed in wheat, and levels of AYp in phytoplasma-infected wheat plants were low.Dandelion and sowthistle tested negative for the presence of AYp at all time points, suggesting that these are unsuitable hosts for these microorganisms. Moreover, we observed a partial disassociation between the plant species that were suitable hosts for AYp and those that had been characterized as more suitable or suitable hosts for aster leafhopper oviposition and nymphal development in previous studies.Item Do options matter? Settling behavior, stylet sheath counts, and oviposition of Aster leafhoppers (Hemiptera: Cicadellidae) in two-choice bioassays(Oxford University Press, 2022-04-22) Romero, Berenice; Olivier, Chrystel; Wist, Tyler; Prager, SeanPolyphagous insects are characterized by a broad diet comprising plant species from different taxonomic groups. Within these insects, migratory species are of particular interest, given that they encounter unpredictable environments, with abrupt spatial and temporal changes in plant availability and density. Aster leafhoppers (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) arrive in the Canadian Prairies in spring and early summer and are the main vector of a prokaryotic plant pathogen known as Aster Yellows Phytoplasma (AYp). Host choice selection behaviour of Aster leafhoppers was evaluated through two-choice bioassays, using domesticated and wild plants species commonly found in the Canadian Prairies. Leaf tissues from these plants were collected and stained to quantify the number of stylet sheaths and eggs. To assess possible effects due to insect infection, two-choice bioassays were repeated using leafhoppers infected with AYp and a subset of plant species. When two domesticated or wild plant species were presented together, similar numbers of uninfected Aster leafhoppers were observed on both plant species in most combinations. In domesticated-wild plant bioassays, uninfected Aster leafhoppers preferred to settle on the domesticated species. There was little to no association between settling preferences and stylet sheath and egg counts. These findings provide a better understanding of AY epidemiology and suggest that after domesticated species germination, leafhoppers could move from nearby wild plants into the preferred cereals to settle on them, influencing the risk of AYp infection in some of these species.Item Oviposition behavior and development of Aster l eafhoppers ( Cicadellidae) on selected host plants from the Canadian Prairies(Entomological Society of America, 2020-09-12) Romero, Berenice; Olivier, Chrystel; Wist, Tyler; Prager, SeanSome plant pathogens are capable of manipulating their insect vectors and plant hosts in a way that disease transmission is enhanced. Aster leafhopper (Macrosteles quadrilineatus Forbes) (Hemiptera: Cicadellidae) is the main vector of Aster Yellows Phytoplasma (Candidatus Phytoplasma asteris) in the Canadian Prairies, which causes Aster Yellows (AY) disease in over 300 plant species including cereals and oilseeds. However, little is known about the host range of Aster leafhoppers or their host-choice selection behavior in this geographical region. Several crop and non-crop species commonly found in the Canadian Prairies were evaluated as food and reproductive hosts for Aster leafhoppers through no-choice bioassays. To study possible effects of pathogen infection, AY-uninfected and AY-infected insects were used. Cereals and some non-crops like fleabane were suitable reproductive hosts for Aster leafhoppers, with numbers of offspring observed in treatments using both AY-uninfected and AY-infected insects, suggesting an egg-laying preference on these plant species. Development was similar across the different plant species, except for canola and sowthistle, where growth indexes were lower. Sex-ratios of Aster leafhopper adults did not differ among the plant species or with respect to AY infection. Potential fecundity differed across plant species and was affected by the infection status of the insect. These findings have implications for AY epidemiology and suggest that while cereals can be suitable host plants for Aster leafhopper oviposition and development, some non-crop species could act as alternate hosts for leafhoppers that migrate into the Canadian Prairies before emergence of cereal and canola crops.Item Characterization of Aphanomyces euteiches pathotypes infecting peas in Western Canada(American Phytopathological Society, 2021) Sivachandra Kumar, Nimllash T; Caudillo-Ruiz, Kiela B; Chatterton, Syama; Banniza, SabineAphanomyces root rot, caused by the soil-borne oomycete Aphanomyces euteiches Drechs., has developed into a serious disease in the pea and lentil-producing areas of the Great Plains of North America. Based on six pea differentials previously used to differentiate 11 pathotypes in France, pathotypes were identified among field isolates from Saskatchewan (14) and Alberta (18). Four isolates from the USA and standard isolates for pathotypes I and III designated in the French study were also included. Each isolate was tested twice in replicated experiments by inoculating French pea differentials Baccara, Capella, MN 313, 902131, 552 and PI 80693, along with the Canadian susceptible pea cultivar CDC Meadow and partially resistant USDA line PI 660736 under controlled conditions. Pea plants grown in vermiculite were inoculated 10 days after seeding by pipetting 5 mL of a suspension containing 1 x 103 zoospores mL-1 to the base of each plant. Root discoloration was scored 10 days post-inoculation using a 0-5 scale. Testing revealed that 38 of the isolates, including standard pathotype I isolate RB84 belonged to pathotype I, 4 isolates including standard pathotype III isolate Ae109 were pathotype III, and USA isolate Ae16-01 was a pathotype II isolate. An alfalfa isolate from Quebec was avirulent on all pea genotypes. These findings indicate that pathotype type I is predominant on the Canadian prairies.