BackgroundThe objective of this research was to map quantitative trait loci (QTLs) of multiple traits of breeding importance in pea (Pisum sativum L.). Three recombinant inbred line (RIL) populations, PR-02 (Orb x CDC Striker), PR-07 (Carerra x CDC Striker) and PR-15 (1–2347-144 x CDC Meadow) were phenotyped for agronomic and seed quality traits under field conditions over multiple environments in Saskatchewan, Canada. The mapping populations were genotyped using genotyping-by-sequencing (GBS) method for simultaneous single nucleotide polymorphism (SNP) discovery and construction of high-density linkage maps.ResultsAfter filtering for read depth, segregation distortion, and missing values, 2234, 3389 and 3541 single nucleotide polymorphism (SNP) markers identified by GBS in PR-02, PR-07 and PR-15, respectively, were used for construction of genetic linkage maps. Genetic linkage groups were assigned by anchoring to SNP markers previously positioned on these linkage maps. PR-02, PR-07 and PR-15 genetic maps represented 527, 675 and 609 non-redundant loci, and cover map distances of 951.9, 1008.8 and 914.2 cM, respectively. Based on phenotyping of the three mapping populations in multiple environments, 375 QTLs were identified for important traits including days to flowering, days to maturity, lodging resistance, Mycosphaerella blight resistance, seed weight, grain yield, acid and neutral detergent fiber concentration, seed starch concentration, seed shape, seed dimpling, and concentration of seed iron, selenium and zinc. Of all the QTLs identified, the most significant in terms of explained percentage of maximum phenotypic variance (PVmax) and occurrence in multiple environments were the QTLs for days to flowering (PVmax = 47.9%), plant height (PVmax = 65.1%), lodging resistance (PVmax = 35.3%), grain yield (PVmax = 54.2%), seed iron concentration (PVmax = 27.4%), and seed zinc concentration (PVmax = 43.2%).ConclusionWe have identified highly significant and reproducible QTLs for several agronomic and seed quality traits of breeding importance in pea. The QTLs identified will be the basis for fine mapping candidate genes, while some of the markers linked to the highly significant QTLs are useful for immediate breeding applications.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1368-4) contains supplementary material, which is available to authorized users.

The majority of the total phosphorus in seeds is stored in the form of phytate, a mixed-cation sait of phytic acid. Phytate is not weii digested by humans and monogastric animais. Phosphorus excretion is one of the major poliutants of surface waters in many locations in the worid. important micronutrients such as iron and zinc bound to phytate are aiso excreted, potentiaiiy leading to micronutrient deficiencies. Low-phytate mutants have been developed in several crop species as one strategy to deal with the phytate probiem. The objective of this research was the deveiopment of low-phytate pea (Pisum sativum L.) using chemical mutagenesis of cultivar CDC Bronco, and the agronomic characterization of two resulting lines. In these lines, phytate phosphorus concentration was reduced by approximateiy 60%, with a compensating increase in inorganic phosphorus. The lowphytate lines were similar in agronomic performance to CDC Bronco, except for somewhat slower time to flowering and maturity, slightly lower seed weight, and slightly lower grain yield. Low-phytate field pea should have potential to improve phosphorus and micronutrient bioavailability in human and animal diets.

Increasing the carotenoid concentration of pulse crop seeds is part of a biofortification strategy. The objective of this research was to evaluate the concentration and distribution of carotenoids in the seeds of twelve pea (Pisum sativum L.) cultivars and eight chickpea (Cicer arietinum L.) cultivars grown at multiple locations during 2 yr in Saskatchewan, Canada using high performance liquid chromatography (HPLC) with a diode array detector. Lutein was the major carotenoid in both crops, with mean lutein concentration ranging from 7.2 µg g−1 to 17.6 µg g−1 and 6.3 µg g−1 to 11.0 µg g−1 in pea and chickpea, respectively. Violaxanthin, zeaxanthin, and β‐carotene were also present in both crops. Green cotyledon pea cultivars had approximately twice as many total carotenoids (16–21 µg g−1) than yellow cotyledon pea cultivars (7–12 µg g−1). Cultivar had a greater effect than environment on carotenoid concentration in both crops. Location effects were significant for violaxanthin, lutein, and total carotenoid concentration for pea and for violaxanthin and zeaxanthin in chickpea. Year effect was significant for all carotenoids in pea and significant for β‐carotene in chickpea. The cultivar × location interaction was significant for violaxanthin in pea and chickpea and for lutein in pea. Among the three seed tissues, carotenoid concentration was greatest in the cotyledon followed by the embryo axis and seed coat in both crops. The results of this investigation should be useful for improving nutritional quality in pulse crops.

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Field pea (Pisum sativum L.) seeds have high nutritional value but also contain phytate which can inhibit the absorption and utilization of nutrients. Phytate is the main storage form of phosphorus in the seeds but chelates Fe, Zn and some other micronutrients and is not well digested by monogastrics. Peas with pigmented seed coats contain polyphenols which also have anti-nutritional properties. To increase the nutritional value of field pea seeds, two low phytate lines (1-150-81 and 1-2347-144) containing higher inorganic phosphorus concentration (IN-P) and lower phytate-phosphorus concentration (PA-P) than the normal phytate varieties were developed from CDC Bronco in previous research. The objectives of this research were 1) to determine the effect of genotype and environment on iron bioavailability in a set of five pea varieties differing in phytate concentration and iron concentration using in vitro digestion/Caco-2 cell culture bioassay; 2) to determine the effect of seed coats on iron bioavailability by testing whole seeds compared to dehulled seeds in varieties differing in seed coat pigmentation using in vitro digestion/Caco-2 cell culture bioassay; 3) to determine the inheritance of iron bioavailability in field pea by evaluating recombinant inbred lines differing in phytate concentration using in vitro digestion/Caco-2 cell culture bioassay; 4) to determine the effects of pea with the low phytate trait on body weight and hemoglobin concentration of chickens. Iron concentration (FECON) did not differ significantly between normal and low phytate varieties. Iron bioavailability (FEBIO) of the two low-phytate lines was 1.4 to 1.9 times higher than that of the three normal phytate varieties, and growing environment also had a significant effect on FEBIO. Peas with pigmented seed coats contained 7 times lower FEBIO than peas with non-pigmented seed coat. The removal of the seed coat increased the FEBIO in peas with pigmented seed coat 5 to 6 times. From previous research on PR-15 recombinant inbred lines (RILs) which were developed from a cross between low phytate line 1-2347-144 and a normal phytate variety CDC Meadow, it was found that PA-P was controlled by a single gene. FEBIO, in this study, was also found to follow a bimodal frequency distribution, characteristic of single gene iii control, and it was highly correlated with PA-P in the PR-15 lines. In vivo studies were used to evaluate iron absorption of chickens fed with low and normal phytate pea diets. The diets containing the low-phytate pea lines had no significant effect on chicken body weight and hemoglobin level, compared with the diets containing normal phytate pea varieties. An unexpected high FECON was discovered in the diets that was traced to the ingredients of limestone and dicalcium-phosphate which likely affected the experimental results.iv

, H. 2006. Prediction of crude protein content in field peas using near infrared reflectance spectroscopy. Can. J. Plant Sci. 86: 157-159. A rapid, near-infrared spectroscopic method to predict the crude protein contents of 72 field pea lines grown in Saskatchewan, both whole seeds and ground samples, was established. Correlation coefficients between the laboratory and predicted values were 0.938 and 0.952 for whole seed and ground seed, respectively. Both methods developed are adequate to support our field pea breeding programme. Mots clés: Pois de grande culture, spectroscopie par réflectance dans le proche infrarouge, protéine brute Field pea (Pisum sativum L.) crops are utilized in both food and feed applications. In both cases, high protein content is desirable. Breeding programs produce thousands of lines a year, which are evaluated for agronomic and quality traits. Assessment of protein content by the Dumas combustion method is accurate but expensive, primarily due to the high initial cost of the equipment. A method for the rapid, inexpensive assessment of protein content would allow this trait to be more effectively evaluated in a breeding program.

Low phytic acid (lpa) crops are low in phytic acid and high in inorganic phosphorus (Pi). In this study, two lpa pea genotypes, 1-150-81, 1-2347-144, and their progenitor CDC Bronco were grown in field trials for two years. The lpa genotypes were lower in IP6 and higher in Pi when compared to CDC Bronco. The total P concentration was similar in lpa genotypes and CDC Bronco throughout the seed development. The action of myo-inositol phosphate synthase (MIPS) (EC 5.5.1.4) is the first and rate-limiting step in the phytic acid biosynthesis pathway. Aiming at understanding the genetic basis of the lpa mutation in the pea, a 1530 bp open reading frame of 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. Transcription levels of MIPS were relatively lower at 49 days after flowering (DAF) than at 14 DAF for CDC Bronco and lpa lines. This study elucidated the rate and accumulation of phosphorus compounds in lpa genotypes. The data also demonstrated that mutation in MIPS was not responsible for the lpa trait in these pea lines.