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Phytate is the major storage form of phosphorus in crop seeds, but is not well digested by humans and non-ruminant animals. In addition, phytate chelates several essential micronutrients which are also excreted contributing to phosphorus pollution in the environment. This research was aimed at the biochemical and molecular characterization of two low phytate pea mutant lines, 1-150-81 and 1-2347-144 developed at the Crop Development Centre, University of Saskatchewan in collaboration with Dr. Victor Raboy, USDA, Idaho. Low phytic acid (lpa) crops are low in phytic acid and high in inorganic phosphorus (Pi). In Study I, two lpa pea genotypes, 1-150-81, 1-2347-144, and their progenitor CDC Bronco were evaluated in field trials for two years. The lpa genotypes did not significantly differ from CDC Bronco in all agronomic traits assessed except for lower seed weight and grain yield. The concentration of IP6 at 14 DAF was not significantly different among CDC Bronco, 1-150-81 and 1-2347-144. However, the concentrations of IP6 among CDC Bronco, 1-150-81 and 1-2347-144 started to differ significantly from 21 DAF onwards. The lpa genotypes 1-150-81 and 1-2347-144 showed 65% and 60% reduction in IP6, respectively, when compared to their progenitor CDC Bronco at 49 DAF. The Pi concentrations between the lpa genotypes were similar and significantly higher than CDC Bronco from 21 DAF to 49 DAF. At 49 DAF, 1-150-81 and 1-2347-144 were 72 and 84% higher in Pi, respectively, than CDC Bronco. The total P concentration was similar in lpa genotypes and CDC Bronco throughout the seed development. This study elucidated the rate and accumulation of phosphorus compounds in lpa genotypes. In Study II, aiming at understanding the genetic basis of the lpa mutation in pea lines 1-150-81 and 1-2347-144, a 1530 bp open reading frame of myo-inositol phosphate synthase gene (MIPS) was amplified from CDC Bronco and the lpa genotypes. Sequencing results showed no difference in coding sequence in MIPS between CDC Bronco and lpa genotypes. Transcript levels of both MIPS and myo-inositol tetrakisphosphate1-kinase (ITPK1) were relatively lower at 49 DAF than at 14 DAF for CDC Bronco and lpa lines. There was no difference in expression level of both MIPS and ITPK1 between CDC Bronco and the lpa genotypes at 49 DAF. The data demonstrated that mutation in MIPS was not responsible for lpa trait in pea. Study III was aimed at developing a single nucleotide polymorphism (SNP) based genetic linkage map and mapping genomic regions associated with phytic acid-phosphorus (PA-P) concentration using PR-15 recombinant inbred lines (RILs) derived from a cross between a low phytate (lpa) pea genotype, 1-2347-144 and normal phytate pea cultivar CDC Meadow. A total of 163 RILs were genotyped using 1536 SNP markers in an Illumina GoldenGate array. Three hundred and sixty seven polymorphic SNP markers, ordered into 7 linkage groups (LGs), generated a linkage map with a total length of 437.2 cM. The phytic acid locus was mapped on to LG5. A quantitative trait locus (QTL) for iron bioavailability was mapped on to the same location in LG5 as phytic acid concentration. Potential benefits arising out of this research include improved bioavailability of phosphorus, iron and zinc in foods and feeds, less phosphorus excretion and environmental pollution and a saving in feed costs.

The occurrence of D. weischeri Chizhov, Borisov & Subbotin, a newly described stem nematode species of creeping thistle (Cirsium arvense L.), and D. dipsaci (Kühn) Filipjev, a pest of garlic and quarantine parasitic species of many crops, has been reported in Canada. This research was conducted to determine if D. weischeri is a pest of agricultural crops, especially yellow pea (Pisum sativum L.) in the Canadian Prairies. Significant (P < 0.05) slight reproduction (1 < ratio of final to initial population < 2) of D. weischeri occurred on two (Agassiz and Golden) of five varieties of yellow pea examined. Other annual pulse and non-pulse crops, including common bean, chickpea, lentil, spring wheat, canola, and garlic were non-hosts for D. weischeri. Conversely, a range of reproduction responses to D. dipsaci was observed with all pulse crops being a host of the nematode. Ditylenchus weischeri was not a seed-borne parasite of yellow pea, unlike, D. dipsaci which was recovered from seed. Conversely, D. weischeri and not D. dipsaci was recovered from creeping thistle seeds. In callused carrot disks, with no addition of medium, an increase of 54 and 244 times the addition density of 80 nematodes was obtained for D. weischeri and D. dipsaci, respectively, after 90 days. Temperature had a significant influence on the development of D. weischeri and D. dipsaci in yellow pea. Development of D. weischeri did not proceed past adult stage at 17 and 22°C whereas a minimum generation time of 30 days was apparent at 27°C with the associated accumulated growing degree-days of 720 degree-days (above a base temperature of 3°C). The minimum generation time for D. dipsaci was 24, 18 and 22 days with 336, 342 and 528 degree-days at 17, 22 and 27°C, respectively. In field microplots, grain yield of yellow pea were not significantly affected by addition density of D. weischeri. At harvest, the total number of recovered nematodes per plant was not significantly different than the added at the start. The results of these studies confirm that D. weischeri is unlikely to be a pest of yellow pea for weather conditions of the Canadian Prairies. / October 2016

When in commercial practice seed peas (Pisum sativum) are harvested, the vines are cut and windrowed or bunched and allowed to cure for a week or longer, depending upon the moisture content of the crop and weather conditions. The sooner the crop can be threshed, the less is the chance of loss caused by rain and the often-necessary attendant operation of turning the windrow or bunch to facilitate drying. In general, growers wait until the vines, pods, and seeds are quite dry. To what extent this is necessary is not known.

Abstract Gibberellins (GAs) are a class of plant hormones that regulate many aspects of plant growth and development including seed germination, stem elongation and fruit development. To investigate the regulation of GA biosynthesis and the impact of altered GA levels on plant growth and development, transgenic pea (Pisum sativum L. cv. Carneval) plants were generated to overexpress PsGA3ox1 (codes for GA 3-hydroxylase which converts GA20 to bioactive GA1) under the control of the CaMV-35S promoter. Increased expression of the transgene PsGA3ox1 was correlated with altered plant phenotype including longer internodes, larger stipules and tendrils, and longer pods. Transgenic lines also showed upregulation of the GA catabolic genes PsGA2ox1 and/or PsGA2ox2, suggesting that GA1 substrate-induced feedback regulation also occurs to maintain GA homeostasis. Changes in endogenous GAs, quantified using an isotope dilution method, indicated that an increased flux in GA biosynthesis occurred in the expanding internodes, stipules and tendrils of the PsGA3ox1-overexpressor lines. Higher bioactive GA1 levels and growth were correlated with lower PsGA2ox1 transcript levels in elongating internodes, and oscillation of these parameters between adjacent elongating internodes in the PsGA3ox1-overexpression lines suggests that coordination of bioactive GA levels and growth occurs between adjacent internodes. During germination and early seedling growth, GA gene expression studies suggested that PsGA3ox1-overexpression increased the flux through to bioactive GA in the cotyledons, shoots and roots of pea seedlings, resulting in longer shoots but shorter roots. Auxins are a class of plant hormones involved in growth and differentiation of plants that can influence GA biosynthesis and action. The location and action of auxins is in part regulated by auxin carrier proteins. The expression patterns of the putative auxin efflux carrier genes PsPIN1 and PsPIN2 in elongating internodes were correlated with vascular re-patterning events in this tissue, and PsGA3ox1-overexpression appears to increase internode PsPIN1 and PsPIN2 transcript abundance and the formation of the vascular connections between the internode and the axillary buds. Overall, characterization of PsGA3ox1-overexpressor lines in pea demonstrated that bioactive GA levels are tightly regulated in pea tissues for the coordination of plant growth and development. / Plant Science

The use of herbicides in cropping systems is routine in western Canada as is the practice of rotating crops between cereals, oilseeds and pulse crops. Often, herbicides that are appropriate one year in the crop rotation are not compatible with the following crop. Additionally, certain herbicides are designed to target certain enzyme pathways that can interfere with amino acid synthesis. These pathways also exist in the microbial community, including Rhizobium species. Rhizobia have a unique symbiotic relationship with legumes. In return for a carbon source, rhizobia not only fix atmospheric dinitrogen (N2) for the plant, but also can increase soil N reserves for the following year. With herbicides targeting amino acid synthesis in both plants and microbes, there is a possibility that N2 fixation may be inhibited by the application of certain herbicides.<p> This project was designed to examine possible negative effects of herbicide application on N2 fixation in field pea (Pisum sativum L.) and chickpea (Cicer arietinum L.). The study included field, growth chamber and laboratory experiments in which the effects of pre- and post-emergent herbicides, as well as herbicide residues in soil were examined.<p> In the field experiments, some early season measurements suggested that herbicide application had a negative impact on various growth and N2 fixation parameters. However, as the season progressed, plants recovered from early herbicide damage and N2 fixation ultimately was relatively unaffected. Growth chamber experiments similarly revealed that N2 fixation was largely unaffected by herbicide application when the application rates were relatively low (i.e., at rates intended to simulate partial herbicide breakdown, and thus lower than the recommended field rate). Although, N2 fixation was suppressed where high rates of herbicide (i.e., greater than recommended field rate) were applied, the efficiency of the rhizobia to fix N2, (i.e., the amount of N2 fixed per unit nodule mass), was unaffected. This along with a laboratory experiment which monitored growth of rhizobia in vitro, confirmed that rhizobia were not directly affected by the herbicides used in this study and that overall N2 fixation was not inhibited directly by the application of these herbicides. It was concluded that any negative impact on N2 fixation caused by herbicides used in this study, was related to the impact of the herbicide on crop growth, and was not due to any direct effects of the herbicide on the rhizobia.

Pea populations derived from ten crosses were scored by coupling phase linked sequence characterized amplified region (SCAR) markers A001 and A002, and repulsion phase linked SCAR marker A004 for lodging resistance during the F2 generation. The objective of this project was to test the efficiency of implementation of these three SCAR markers in marker-assisted selection (MAS) for lodging resistance in pea breeding. Chi-square tests showed that A001 and A004 followed a two independent gene segregation model in all of the eight populations that segregated for these two markers. In the F3 field trial, the differences between mean lodging score of A001 (DNA band present) and a001 (DNA band absent) classes varied from -0.5 to -0.9 with an average of -0.6, based on a 1 to 9 lodging scale, across the eight populations surveyed. The differences between mean lodging score of a004 (DNA band absent) and A004 (DNA band present) classes varied from -0.4 to -1.1 with an average of -0.7, across the eight populations surveyed. In comparison, when the combination of two markers (A001; a004 vs. a001; A004) was used, lodging score differences varied from -0.7 to -1.5, with an average of -1.0 across the eight populations. T-test results showed that significant differences (P<0.05) in lodging score were observed between A001 and a001 classes in seven out of eight populations, and between A004 and a004 classes in six out of eight populations. Further T-tests showed that significant lodging differences were observed among the four classes of the A001 and A004 marker combination in seven out of eight populations assessed, including differences at P<0.01 level in six populations. The greater differences among marker combination classes than between individual marker classes showed that combining two markers was more effective than use of each marker alone in MAS. The marker combination explained (R2) 19-57% of lodging and 4-43% of plant height variation in the eight populations surveyed. The high temperature and potential nitrogen leaching in the summer of 2003, reduced plant growth and lodging. Under optimal growth conditions, differences in lodging between resistant and susceptible cultivars could have been greater. Five new markers generated by simple sequence repeat (SSR) primers SAD134, SAB81 and SAD141 were identified in the recombinant inbred line (RIL) population derived from MP1401 × Carneval. The markers generated from primers SAD134 and SAB81 explained 12% and 13% of lodging variation in the RILs, respectively. Primer SAD141 produced three markers which explained 19%, 11% and 25% of lodging variation in the RILs, respectively. Linkage analysis showed that none of the three markers derived from primer SAD141 were allelic. The combination of the three markers from primer SAD141 explained 28% of lodging variation. However, utilization of any of these new markers with A001 and A004 did not substantially increase the proportion of lodging variation being explained. Thus, the new markers have limited potential to improve the efficiency of MAS for lodging resistance in pea breeding.

The focus of this research was to develop a plant-based microcapsule for flax oil by complex coacervation. Complex coacervation involves the electrostatic attraction between two polymers of opposing charges. Specifically, the research aimed to: a) identify the ideal biopolymer and solvent conditions required for complex coacervation involving pea protein isolate (PPI) and gum Arabic (GA); b) understand the functional behaviour of PPI-GA complexes as food and biomaterial ingredients; and c) develop methodologies for encapsulating flax oil within PPI-polysaccharide capsules. Complex coacervation between PPI-GA was found to be optimized at a biopolymer weight mixing ratio of 2:1 in the absence of salt. The functional behaviours of the optimized biopolymer mixture were then investigated as a function of pH (4.30-2.40) within a region dominated by complex coacervation. Emulsion stability was found to be greater for PPI-GA mixture systems relative to PPI alone at pH values between 3.10 and 4.00; emulsions produced under one-step emulsification exhibited higher stability compared to those of two-step emulsification at all pH values. Foam expansion was independent of both biopolymer content and pH, whereas foam stability improved for the mixed system between pH 3.10 and 4.00. The solubility minimum was broadened relative to PPI at more acidic pH values. These findings suggested that the admixture of PPI and GA under complexing conditions could represent a new food and/or biomaterial ingredient, and has potential as an encapsulating agent. Two encapsulation processes were employed in this research: high speed mixing (two-step emulsification) and low speed mixing (one-step emulsification). Flax oil capsules formed using the gelatin-GA mixture (as control) under high speed mixing exhibited low moisture content, water activity and surface oil, and afforded adequate protection against oxidation relative to free oil over a 25 d storage period. The PPI-GA mixture failed to produce acceptable capsules using either high or low speed mixing. In contrast, PPI-alginate capsules were produced and exhibited similar chemical properties as gelatin-GA capsules, except with lower encapsulated flax oil content (30% vs. 50% w/w). However, oxidative stability may adversely affected by the low speed mixing condition during encapsulation.

Pea populations derived from ten crosses were scored by coupling phase linked sequence characterized amplified region (SCAR) markers A001 and A002, and repulsion phase linked SCAR marker A004 for lodging resistance during the F2 generation. The objective of this project was to test the efficiency of implementation of these three SCAR markers in marker-assisted selection (MAS) for lodging resistance in pea breeding. Chi-square tests showed that A001 and A004 followed a two independent gene segregation model in all of the eight populations that segregated for these two markers. In the F3 field trial, the differences between mean lodging score of A001 (DNA band present) and a001 (DNA band absent) classes varied from -0.5 to -0.9 with an average of -0.6, based on a 1 to 9 lodging scale, across the eight populations surveyed. The differences between mean lodging score of a004 (DNA band absent) and A004 (DNA band present) classes varied from -0.4 to -1.1 with an average of -0.7, across the eight populations surveyed. In comparison, when the combination of two markers (A001; a004 vs. a001; A004) was used, lodging score differences varied from -0.7 to -1.5, with an average of -1.0 across the eight populations. T-test results showed that significant differences (P<0.05) in lodging score were observed between A001 and a001 classes in seven out of eight populations, and between A004 and a004 classes in six out of eight populations. Further T-tests showed that significant lodging differences were observed among the four classes of the A001 and A004 marker combination in seven out of eight populations assessed, including differences at P<0.01 level in six populations. The greater differences among marker combination classes than between individual marker classes showed that combining two markers was more effective than use of each marker alone in MAS. The marker combination explained (R2) 19-57% of lodging and 4-43% of plant height variation in the eight populations surveyed. The high temperature and potential nitrogen leaching in the summer of 2003, reduced plant growth and lodging. Under optimal growth conditions, differences in lodging between resistant and susceptible cultivars could have been greater. Five new markers generated by simple sequence repeat (SSR) primers SAD134, SAB81 and SAD141 were identified in the recombinant inbred line (RIL) population derived from MP1401 × Carneval. The markers generated from primers SAD134 and SAB81 explained 12% and 13% of lodging variation in the RILs, respectively. Primer SAD141 produced three markers which explained 19%, 11% and 25% of lodging variation in the RILs, respectively. Linkage analysis showed that none of the three markers derived from primer SAD141 were allelic. The combination of the three markers from primer SAD141 explained 28% of lodging variation. However, utilization of any of these new markers with A001 and A004 did not substantially increase the proportion of lodging variation being explained. Thus, the new markers have limited potential to improve the efficiency of MAS for lodging resistance in pea breeding.

Nitrogen (N) contained in roots and rhizodeposits represents a significant input of crop residue-N into soil that is often unaccounted, despite its contribution to the total N budget and its influence on soil nutrient cycling. Utilizing 15N-labeling methodologies under controlled conditions, the goal of this research was to quantify the input of belowground N (BGN), including rhizodeposits and roots, to soil and to investigate the influence of BGN on soil N cycling processes from the major pulse and oilseed crop grown across the Canadian prairies—namely, field pea and canola, respectively. Using continuous 15N2 labeling, the input of fixed-N to rhizosphere soil from pea plants amounted to less than 2% of the total plant N assimilated via fixation. Nodulation and root 15N enrichment were positively related to rhizosphere 15N enrichment, suggesting that the relatively low input of fixed-N to soil was due to low N fixation in this system. Shoot 15N-labeling techniques enabled a higher 15N enrichment in roots; as a result, rhizodeposition was detected in the rhizosphere as well as the surrounding bulk soil. Rhizodeposition accounted for 7.6 and 67% of plant N and BGN, respectively, in mature pea. Temporal changes in the pattern of rhizodeposition were detected as evidenced by differing 15N enrichment in rhizosphere versus bulk soils. In comparison to pea, a higher proportion of BGN contributed to the total residue-derived N from canola. The higher quantity of N rhizodeposition by canola was related to greater root biomass. However, pea rhizodeposition contributed more to soil inorganic N pools; this was sustained over time, as a higher proportion of pea BGN contributed to the growth of a subsequent wheat crop. In addition, wheat uptake of residue-derived N was twice as much from belowground compared to straw residues. Whereas the abundance of denitrifying bacterial communities in the rhizosphere was uncoupled from rhizodeposition and denitrification enzyme activity (DEA), root-derived 15N correlated with DEA in pea and canola. This research highlights the importance of belowground inputs from differing crop species on N budgets and soil N cycling.