Rethinking pulse crop production in the era of Aphanomyces root rot

Non-Peer Reviewe

Characterization of Aphanomyces euteiches pathotypes infecting peas in Western Canada

Saskatchewan Pulse GrowersPeer ReviewedAphanomyces 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

Mechanisms of biological control of Fusarium root and stem rot of greenhouse cucumber by Gliocladium catenulatum

Gliocladium catenulatum strain J1446 (formulated as Prestop WP, Verdera Oy) is a biological control agent of Fusarium root and stem rot caused by Fusarium oxysporum f. sp. radicis-cucumerinum on greenhouse cucumber plants. The mechanisms involved in biocontrol efficacy are currently unknown. Following transformation of G. catenulatum with the ß-glucuronidase (uidA) gene, blue-stained mycelia could be seen growing on the surface and within epidermal and cortical cells of roots, stems and shoots 3 weeks after treatment. Application of G. catenulatum preceding inoculation with Fusarium significantly reduced pathogen populations on roots compared to plants inoculated with Fusarium alone, while densities of the biocontrol agent increased in the presence of the pathogen. Factors influencing root population levels included nutrient solution pH, temperature and growing media type, while cucumber cultivar, root wounding and addition of nutrients did not appear to significantly affect colonization. In culture, G. catenulatum produced chitinase and ß-1,3-glucanase enzymes on chitin or laminarin as a sole carbon source, respectively, and caused localized degradation of Fusarium hyphae. Cucumber root extracts from G. catenulatum-colonized plants had significantly higher levels of glucanase at 7 days post-application compared to untreated controls. Reverse-transcription polymerase chain reaction using primers designed to amplify a ß-1,3-glucanase gene confirmed G. catenulatum glucanase expression on roots. In a split-root system, G. catenulatum applied to one-half of the roots prior to inoculation with Fusarium on the other half did not significantly reduce disease compared to plants treated with Fusarium only. There was no detectable increase in chitinase, peroxidase or polyphenol oxidase enzyme activity in roots and leaves following treatment with G. catenulatum. Competitive colonization of the rhizosphere by G. catenulatum, which is facilitated by its mycoparasitic ability, are the primary mechanisms by which pathogen development and disease incidence is reduced

AAC Expedition pinto dry bean

AAC Expedition is a high yielding pinto dry bean (Phaseolus vulgaris L.) cultivar with a semi-upright, indeterminate bush (Type IIb) growth habit, large seed size, low percentage of hard seed and bright seed coat colour. Improved seed quality traits especially bright seed coat colour and low percentage of hard seeds after soaking, and high yield potential of AAC Expedition will make it a preferred pinto bean cultivar for commercial production. AAC Expedition developed by Agriculture and Agri-Food Canada (AAFC) Research and Development Centre, Lethbridge, AB, is well suited for commercial production under irrigation in Alberta and Saskatchewan.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

AAC Y073 yellow dry bean

AAC Y073 is a high yielding yellow dry bean (Phaseolus vulgaris L.) cultivar with a partially upright, determinate bush (Type I) growth habit, early maturity, and large seeds with a bright yellow seed coat. Large, bright yellow seeds of AAC Y073 is an improvement over the current check cultivar CDC Sol. AAC Y073 was developed at the Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB, and is well suited for commercial production under irrigation in Alberta and Saskatchewan.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

AAC Y012 and AAC Y015 yellow dry bean

AAC Y012 and AAC Y015 are high yielding, early maturing yellow dry bean (Phaseolus vulgaris L.) cultivars with a determinate bush growth habit (Type I), improved seed coat colour and partial field resistance to white mould. AAC Y012 and AAC Y015 were developed at the Agriculture and Agri-Food Canada (AAFC) Research and Development Centre, Lethbridge, AB. AAC Y012 and AAC Y015 are suitable for irrigated wide row production in Alberta and Saskatchewan.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

AAC Cranford cranberry dry bean

AAC Cranford is an early maturing cranberry dry bean (Phaseolus vulgaris L.) cultivar with high yield, an upright determinate bush (Type I) growth habit and large seed size. Currently, dry bean cultivars in the cranberry bean market class are only commercially grown in Manitoba and Ontario primarily due to their late maturity. Therefore, AAC Cranford with its early maturity and high yield potential will enable growers to commercially produce cranberry bean in Alberta and Saskatchewan.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Interactions of Root-Feeding Insects with Fungal and Oomycete Plant Pathogens

Soilborne fungal and oomycete pathogens are the causal agents of several important plant diseases. Infection frequently co-occurs with herbivory by root-feeding insects, facilitating tripartite interactions that modify plant performance and mortality. In an agricultural context, interactions between pathogens, herbivores, and plants can have important consequences for yield protection. However, belowground interactions are inherently difficult to observe and are often overlooked. Here, we review the impact of direct and indirect interactions between root-associated insects, fungi, and oomycetes on the development of plant disease. We explore the relationship between insect feeding injury and pathogen infection, as well as the role of insects as vectors of fungal and oomycete pathogens. Synergistic interactions between insects and phytopathogens may be important in weed suppression, and we highlight several promising candidates for biocontrol. Bridging the gap between entomological and pathological research is a critical step in understanding how interactions between insects and microorganisms modify the community structure of the rhizosphere, and how this impacts plant functioning. Furthermore, the identification of belowground interactions is required to develop effective pest monitoring and management strategies

TECHNIQUES FOR SCREENING CERCOSPORA LEAF SPOT RESISTANT FENUGREEK GENOTYPES

Cercospora leaf spot (CLS) caused by Cercospora traversiana is an important phyto-pathological problem of fenugreek (Trigonella foenum graecum L), a multiuse legume crop. Field screenings for resistant plants, although accurate and effective, demand significant time and a sizable workforce to accomplish the goal. Also, weather conditions in the field may not always be favourable for uniform disease spread which eventually may lead to failure of the overall experiment. Whole plant assays (WPA) and detached leaf assays (DLA) with artificial inoculation not only help in scaling up the number of plants screened but also reduce the space, time and the amount of inoculum needed for the experiment. The results from our two experiments indicate that both WPA and DLA methods can be used reliably to differentiate the resistant and susceptible genotypes of fenugreek. In addition, the correlation coefficient (r = 0.875, pThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author