Tom Warkentin

Screening techniques and sources of resistance to rusts and mildews in grain legumes

SummaryIn this paper we review the existence of sources of resistance and the various available screening methods for resistance in grain legumes against the airborne pathogens powdery mildews, downy mildews and rusts. Available resistance against these pathogens is not abundant and is particularly in risk of erosion owing to the constant generation and introduction of new races of the pathogen. A continuous search for more resistance sources is therefore a priority in legume breeding and special emphasis should be paid to selection of resistance mechanisms that are likely to be durable and to implementation of strategies to prolong the durability of existing resistance.

Genetic analyses and conservation of QTL for ascochyta blight resistance in chickpea (Cicer arietinum L.)

Ascochyta blight (AB) caused by Ascochyta rabiei (teleomorph, Didymella rabiei) Pass. Lab. is an important fungal disease of chickpea worldwide. Only moderate sources of resistance are available within the cultivated species and we hypothesized that the available sources may carry different genes for resistance, which could be pyramided to improve field resistance to AB. Four divergent moderately resistant cultivars CDC Frontier, CDC Luna, CDC Corinne, and Amit were each crossed to a highly susceptible germplasm ICCV 96029. Parents, F1 and F2 generations were evaluated under controlled conditions for their reactions to AB. A total of 144 simple sequence repeat (SSR) markers were first mapped to eight linkage groups (LG) for the CDC Frontierxa0×xa0ICCV 96029 population. Then based on the evidence from this population, 76, 61, and 42 SSR markers were systematically chosen and mapped in CDC Luna, CDC Corinne, and Amit populations, respectively. Frequency distributions of the AB rating in the F2 generation varied among the four populations. Composite interval mapping revealed five QTLs (QTL1–5), one on each of LG 2, 3, 4, 6, and 8, respectively, distributed across different sources, controlling resistance to AB. CDC Frontier contained QTL2, 3, and 4 that simultaneously accounted for 56% of phenotypic variations. CDC Luna contained QTL 1 and 3. CDC Corinne contained QTL 3 and 5, while only QTL 2 was identified in Amit. Altogether these QTL explained 48, 38, and 14% of the estimated phenotypic variations in CDC Luna, CDC Corinne, and Amit populations, respectively. The results suggested that these QTLs could be combined into a single genotype to enhance field resistance to AB.

Doubled-haploid production in chickpea (Cicer arietinum L.): role of stress treatments.

This is the first report on the production of double-haploid chickpea embryos and regenerated plants through anther culture using Canadian cultivar CDC Xena (kabuli) and Australian cultivar Sonali (desi). Maximum anther induction rates were 69% for Sonali and 63% for CDC Xena. Under optimal conditions, embryo formation occurred within 15–20xa0days of culture initiation with 2.3 embryos produced per anther for CDC Xena and 2.0 embryos per anther for Sonali. For anther induction, the following stress treatments were used: (1) flower clusters were treated at 4°C for 4xa0days, (2) anthers were subjected to electric shock treatment of three exponentially decaying pulses of 50–400xa0V with 25xa0μF capacitance and 25xa0Ω resistance, (3) anthers were centrifuged at 168–1,509g for 2–15xa0min, and finally (4) anthers were cultured for 4xa0days in high-osmotic pressure (563xa0mmol) liquid medium. Anthers were then transferred to a solid embryo development medium and, 15–20xa0days later, embryo development was observed concomitant with a small amount of callus growth of 0.1–3xa0mm. Anther-derived embryos were regenerated on plant regeneration medium. Electroporation treatment of anthers enhanced root formation, which is often a major hurdle in legume regeneration protocols. Cytological studies using DAPI staining showed a wide range of ploidy levels from haploid to tetraploid in 10–30-day-old calli. Flow cytometric analysis of calli, embryos and regenerated plants showed haploid profiles and/or spontaneous doubling of the chromosomes during early regeneration stages.

Breeding Annual Grain Legumes for Sustainable Agriculture: New Methods to Approach Complex Traits and Target New Cultivar Ideotypes

Although yield and total biomass produced by annual legumes remain major objectives for breeders, other issues such as environment-friendly, resource use efficiency including symbiotic performance, resilient production in the context of climate change, adaptation to sustainable cropping systems (reducing leaching, greenhouse gas emissions and pesticide residues), adaptation to diverse uses (seeds for feed, food, non-food, forage or green manure) and finally new ecological services such as pollinator protection, imply the need for definition of new ideotypes and development of innovative genotypes to enhance their commercialization. Taken as a whole, this means more complex and integrated objectives for breeders. Several illustrations will be given of breeding such complex traits for different annual legume species. Genetic diversity for root development and for the ability to establish efficient symbioses with rhizobia and mycorrhiza can contribute to better resource management (N, P, water). Shoot architectures and phenologies can contribute to yield and biotic constraint protection (parasitic weeds, diseases or insects) reducing pesticide use. Variable maturity periods and tolerance to biotic and abiotic stresses are key features for the introduction of annual legumes to low input cropping systems and for enlarging cultivated area. Adaptation to intercropping requires adapted genotypes. Improved health and nutritional value for humans are key objectives for developing new markets. Modifying product composition often requires the development of specific cultivars and sometimes the need to break negative genetic correlations with yield. A holistic approach in legume breeding is important for defining objectives with farmers, processors and consumers. The cultivar structures are likely to be more complex, combining genotypes, plant species and associated symbionts. New tools to build and evaluate them are important if legumes are to deliver their exciting potential in terms of agricultural productivity and sustainability as well as for feed and food.

Fast track genetic improvement of ascochyta blight resistance and double podding in chickpea by marker-assisted backcrossing

Ascochyta blight (AB) caused by the fungus Ascochyta rabiei Pass. Lab. is one of the major diseases of chickpea worldwide and a constraint to production in western Canada. The use of varieties with high levels of resistance is considered the most economical solution for long-term ascochyta blight management in chickpea. QTL for resistance to ascochyta blight have been identified in chickpea. The availability of molecular markers associated with QTL for ascochyta blight resistant and double podding provides an opportunity to apply marker-assisted backcrossing to introgress the traits into adapted chickpea cultivars. In the present study, molecular markers that were linked to the QTL for ascochyta blight resistance and the double podding trait, and those unlinked to the resistance were used in foreground and background selection, respectively, in backcrosses between moderately resistant donors (CDC Frontier and CDC 425-14) and the adapted varieties (CDC Xena, CDC Leader and FLIP98-135C). The strategy included two backcrosses and selection for two QTL for ascochyta blight resistance and a locus associated with double podding. The fixation of the elite genetic background was monitored with 16–22 SSR markers to accelerate restoration of the genetic background at each backcross. By the BC2F1 generation, plants with improved ascochyta blight resistance and double podding were identified. The selected plants possessed the majority of elite parental type SSR alleles on all fragments analyzed except the segment of LG 4, LG 6 and LG 8 that possessed the target QTL. The results showed that the adapted variety could be efficiently converted into a variety with improved resistance in two backcross generations.

Effect of genotype and environment on the concentrations of starch and protein in, and the physicochemical properties of starch from, field pea and fababean.

BACKGROUNDnThe effects of genotype and environment and their interaction on the concentrations of starch and protein in, and the amylose content and thermal and pasting properties of starch from, pea and fababean are not well known.nnnRESULTSnDifferences due to genotype were observed in the concentrations of starch and protein in pea and fababean, in the onset temperature (To) and peak temperature (Tp) of gelatinization of fababean starch, and in the pasting, trough, cooling and final viscosities of pea starch and fababean starch. Significant two-way interactions (location × genotype) were observed for the concentration of starch in fababean and the amylose content, To, endothermic enthalpy of gelatinization (ΔH) and trough viscosity of fababean starch. Significant three-way interactions (location × year × genotype) were observed for the concentration of starch in pea and the pasting, trough, cooling and final viscosities of pea starch.nnnCONCLUSIONnDifferences observed in the concentrations of starch and protein in pea and fababean were sufficient to be of practical significance to end-users, but the relatively small differences in amylose content and physicochemical properties of starch from pea and fababean were not.

Plant growth regulators improve in vitro flowering and rapid generation advancement in lentil and faba bean

Rapid generation technology (RGT) involves applying plant growth regulators to accelerate in vitro flowering and the use of immature seed to shorten the time required to produce the next generation of plants. The effect of different concentrations of flurprimidol and combinations of one cytokinin and two auxins on in vitro flowering was evaluated using two lentil (Lens culinaris Medik.) and two faba bean (Vicia faba L.) cultivars. Adding flurprimidol to the medium reduced the internode length of plants, and plant height was decreased to approximately 10xa0cm in both species. The optimal concentration of flurprimidol depended on the species and the light intensity. The combination of 0.3xa0μM flurprimidol, 5.7xa0μM indole-3-acetic acid, and 2.3xa0μM zeatin resulted in 100% of faba bean plants flowering and 90% setting seed. The combination of 0.9xa0μM flurprimidol, 0.05xa0μM 4-chloroindole-3-acetic acid, and with a perlite growth substrate resulted in 90% of lentil plants flowering and over 80% with seed set. However, faba bean showed better response with agar as the substrate. Under optimized conditions, a single generation cycle was achieved in 54xa0d for faba bean and 45xa0d for lentil. RGT could produce seven and eight generations per year for faba bean and lentil, respectively. For the single seed descent breeding method for self-pollinated plants, a seed of each plant in each generation is advanced three times per year until near-homozygosity, thus requiring more than 2xa0yr. The RGT method produces about double the number of generations per year and therefore has potential for significant acceleration of pulse crop breeding programs.

Genotypic abundance of carotenoids and polyphenolics in the hull of field pea (Pisum sativum L.)

BACKGROUNDnConsumption of pulse crops, including field pea, is considered effective for a healthy diet. Hulls (seed coats) play an important role for protection of the cotyledon and embryo, but also as mediating positive effects on health outcomes. The biochemical attributes of field pea hulls were thus assessed to determine the occurrence of specific phytochemicals and their genotypic variability.nnnRESULTSnSequestered bioproducts in mature hulls predominantly consisted of trans-lutein and chlorophylls a and b. Trace amounts of other carotenoid and pheophytin metabolites were identified. In developing hulls, violaxanthin, neoxanthin, lutein, zeaxanthin, chlorophylls a and b and β-carotene were detected. Genotypic differences in the accumulation of lutein and chlorophylls a and b were observed over years and locations. Polyphenolics and hydroxybenzoic acids were detected in the dun and maple field pea types-the only genotypes to have pigmented hulls. Unextractable patches of condensed tannin influenced the visual uniformity of the maple and dun genotypes, CDC Rocket and CDC Dundurn.nnnCONCLUSIONSnWithin the yellow and green market classes, carotenoid and chlorophyll accumulation was consistent. Green cotyledon varieties sequestered higher concentrations of lutein than the yellow cotyledon varieties. Maple and dun types were more variable, reflective of different selection criteria. The occurrence of flavonoid-related compounds was correlated only with pigmented seed coat genotypes. The dietary potential of the chlorophylls and carotenoids that accumulated in the hulls split from the green and yellow field pea types is discussed as a value-added prospect in food supplements.

CDC Tucker and CDC Leroy forage pea cultivars

CDC Tucker and CDC Leroy are forage pea (Pisum sativum L.) cultivars released in 2006 and 2008, respectively, by the Crop Development Centre, University of Saskatchewan, for distribution to Select seed growers in Saskatchewan and Alberta through the Variety Release Program of the Saskatchewan Pulse Growers. Both cultivars have a semileafless leaf type, high biomass production, good biomass quality, good seed yield, and resistance to powdery mildew (caused by Erysiphe pisi Syd.). Both cultivars have superior lodging resistance to the check cultivars Trapper and 40-10, but with slightly greater seed weight. CDC Tucker and CDC Leroy had similar lodging resistance and grain yield compared with the field pea check cultivar CDC Minuet.Key words: Pea, Pisum sativum L., cultivar description

CDC Orion kabuli chickpea

Taran, B., Bandara, M., Warkentin, T., Banniza, S. and Vandenberg, A. 2011. CDC Orion kabuli chickpea. Can. J. Plant Sci. 91: 355-356. CDC Orion, a kabuli chickpea (Cicer arietinum L.) cultivar, was released in 2010 by the Crop Development Centre, University of Saskatchewan for distribution to Select seed growers in western Canada through the Variety Release Program of the Saskatchewan Pulse Growers. CDC Orion has a pinnate leaf type, fair resistance to ascochyta blight (Ascochyta rabiei Pass. Lab.), late maturity, large seed size and high yield potential in the Brown and Dark Brown soil zones of the Canadian prairies.