Parthiba Balasubramanian

Antioxidant and Anti-inflammatory Activities of Bean (Phaseolus vulgaris L.) Hulls

Hulls obtained by mechanical abrasive dehulling from four bean cultivars were extracted with two solvents, aqueous (70%) acetone and water, and the extracts evaluated for antioxidant and anti-inflammatory activities in relation to their phenolic contents. Total phenolic content and antioxidant activity of bean hulls, measured using oxygen radical absorbance capacity (ORAC) values, were 6-8-fold those of corresponding whole beans. Aqueous acetone (70%) extracted over twice the amount of total phenolics from hulls that exhibited significantly higher antioxidant and stronger inhibitory effect on both cyclooxygenases, COX-1 and COX-2, than water. Acetone extract of black bean hull exhibited strong COX-1 (IC(50) = 1.2 microg/mL) and COX-2 (IC(50) = 38 microg/mL) inhibitory effects, even outperforming aspirin. Bean hull water extracts were stronger inhibitors of lipoxygenase, 15-LOX, than corresponding acetone extracts. Anti-inflammatory activity of bean hulls was dependent on their phenolic content and antioxidant activity that were significantly affected by cultivar and extracting solvent.

Phytic acid, phytase, minerals, and antioxidant activity in Canadian dry bean ( Phaseolus vulgaris L.) cultivars.

Ten bean cultivars grown in southern Manitoba in 2006 were evaluated for variability in phytate, phenolic, and mineral contents, phytase activity, and antioxidant properties to elucidate the relationship of these components. Phytic acid content and phytase activity varied significantly among cultivars and market classes, ranging from 16.7 to 25.1 g/kg and from 224 to 361 phytase activity unit/kg of sample, respectively. The bean cultivars with total phenolic content ranging from 2.2 to 5.6 g of catechin equiv/kg of sample exhibited significant variation in antioxidant capacity [1.6-11.2 microM Trolox equiv (TE)/g of dry matter] and peroxyl radical scavenging activity (72-158 microM TE/g) using photochemiluminescence and fluorescence assays, respectively. Multivariate data analysis performed on 22 components analyzed in this study using principal component analysis and cluster methods demonstrate that differences in phytase, antioxidant activity, mineral contents, and bioavailability are much larger within market class than among bean cultivars.

Influence of growth habit, row spacing, and seed infection on bean anthracnose development

Bean anthracnose, caused by Colletotrichum lindemuthianum, has been responsible for severe seed yield and quality losses in many dry bean (Phaseolus vulgaris) producing regions of the world. A 2-year study conducted at two field locations in Manitoba examined the effect of differences in seed-borne infection level, row spacing, and growth habit on anthracnose development and any associated losses in seed yield and quality in four navy bean entries and two pinto bean entries. Row spacing had little or no effect on anthracnose severity, but the narrow row spacing (30 cm) always produced the highest yield. A seed-borne infection level of 10% resulted in a significant decrease in the percent seedling emergence of the navy bean entries but usually did not reduce the emergence of the pinto bean cultivars. Nevertheless, anthracnose ratings were most severe on the pinto bean cultivars early in the growing season. The results suggest that the larger seed size of the pinto bean cultivars might have resulted in the emergence of a higher percentage of infected seedlings, which would have caused the disease to rapidly spread in these cultivars. The effect of seed-borne anthracnose infection on the crop canopy and on the pods became evident late in the growing season and resulted in higher incidences of anthracnose seed discoloration. Growth habit did not consistently influence anthracnose severity, since the entries with the lowest disease ratings were a viny navy bean line and an indeterminate, upright navy bean line.

Differential accumulation of polyphenolics in black bean genotypes grown in four environments.

Environmental effects on polyphenolic composition of pigmented seed coat tissue were examined in four black bean genotypes, grown in four locations in Canada. Genotype was the most significant determinant in the phenotypic expression of flavonoid traits across four locations (p < 0.0001). The genotype x environment interaction was not significantly different for anthocyanin or extractable condensed tannin (syn. proanthocyanidin) but was significant for the bound anthocyanidin concentration (p < 0.05). One trace metabolite, (-)-epicatechin, was identified, but no flavonols were detected in the seed coats. Sequestration of anthocyanin in the seed coat was genotype-dependent and predominantly consisted of delphinidin with lesser amounts of petunidin and malvidin. Pigment sequestration in the two integument layers of the seed coat appeared to be mutually exclusive across all genotypes in terms of the pigment chemical character. Tissue-specific accumulation of extractable and bound anthocyanin in the outer integument was observed. The inner integument was devoid of anthocyanin, and the pigment consisted solely of condensed tannin inclusions. The occurrence of condensed tannin together with anthocyanin pigments, whether extractable or bound either by oxidation or by cross-linking, influenced the visual uniformity of seeds of bean cultivars. The co-occurrence of these compounds could have an effect on postharvest appearance during storage, on canning quality, and on the dietary effects of the putative functional food profile in the black bean market class.

Resurgence of bacterial wilt of common bean in North America

Bacterial wilt, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens (CFF), was a serious disease of common bean (Phaseolus vulgaris) in the United States in the early 1970s but was not reported for two decades after that time. Following this absence, the disease was reported again in the United States in North Dakota in 1995 and in Colorado, Nebraska, and Wyoming from 2004 to 2007. In addition to the three coloured variants (yellow, orange and purple) of CFF reported in the United States in 1970s, a new pink variant of the pathogen was discovered in Nebraska in 2008. In Canada, the disease was reported in central Canada (Ontario) in the 1950s. The yellow and orange variants were found in western Canada in 2002, and the purple variant was found in 2006. These recent reports indicate a resurgence of bacterial wilt of bean in North America. The discovery of new variants suggests that the pathogen may be evolving. This minireview examines the resurgence of bacterial wilt of bean in North America, as well as its world distribution, symptoms, host range, and recent research progress in identification and detection, epidemiology, impacts, and methods of control of this disease.

Bacterial wilt resistance in kidney beans

Bacterial wilt, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens, is a widespread problem of dry beans on the Canadian prairies and is listed as a quarantine disease by some countries. The development of resistant cultivars is one of the most effective methods for controlling bacterial wilt. Fourteen kidney bean cultivars were screened against the three variants (yellow, orange and purple) of C. flaccumfaciens pv. flaccumfaciens. High levels of resistance to the three variants were observed in the light red kidney bean cultivars AC Litekid, Chinook 2000 and Redkanner as well as the dark red kidney bean cultivars Cabernet and Red Hawk. These five resistant kidney bean cultivars should be useful sources of bacterial wilt resistance in dry bean breeding programs. Neither of the two white kidney bean cultivars tested consistently showed high levels of resistance to all of the color variants of the bacterial wilt pathogen. Key words: Phaseolus vulgaris, kidney bean, bacterial wilt, Curtobacterium fla...

Biological nitrogen fixation and nifH gene expression in dry beans (Phaseolus vulgaris L.)

Akter, Z., Pageni, B. B., Lupwayi, N. Z. and Balasubramanian, P. M. 2014. Biological nitrogen fixation andnifH gene expression in dry beans (Phaseolus vulgarisL.). Can. J. Plant Sci. 94: 203-212. Dry bean (Phaseolus vulgaris L.) is one of the least efficient nitrogen (N2) fixers among legumes (approximately 30 to 50 kg N ha-1). To identify efficient N2 fixers, 22 dry bean genotypes were screened for symbiotic N2-fixation in potted low-N soil in the greenhouse under four treatments: (1) uninoculated, (2) inoculated with commercial Rhizobium leguminosarum bv. phaseoli inoculant Nitrastik-D®, (3) inoculated with commercial Rhizobium inoculant Nodulator®, and (4) fertilizer N added. Expression of nitrogenase reductase (nifH) gene in selected uninoculated genotypes (nodulated by indigenous rhizobia) was quantified by reverse transcription polymerase chain reaction (RT-PCR) to know if expression of this gene was an indicator of N2-fixation. Nitrogen fixation potential varied among the genotypes and between the rhizobia inoculants. Genotypes differed in shoot (5.17 to 8.39 g plant-1) and root (1.71 to 6.44 g plant-1) dry weights, nodule number (0 to 155 nodules plant-1) and mass (0.055 to 0.250 mg plant-1), and N2-fixed (0 to 129 mg N plant-1). Genotypes GH-196, FR 266 and AC Redbond fixed the most N2 (60 to 112 mg N plant-1) with either rhizobial inoculant, and Viva fixed the highest amount (129 mg N plant-1) when inoculated with Nitrastik-D. In contrast, AC Black Diamond, Island, Winchester, AC Polaris, LEF 2RB and SEA 5 had low N2-fixing potential (3 to 23 mg N plant-1) in inoculated treatments. The qRT-PCR analysis indicated that nifH gene expression was 5 fold higher in GH-196 compared to the non-nodulating mutant R99, which further confirmed the high N2-fixation capacity of GH-196. After confirmation in the field, dry bean genotypes with improved N2-fixation potential identified in this study may be used as parents in breeding programs in the development of future cultivars. The nifH gene expression may be used as a rapid test to select dry beans with high N2-fixation potential.

Seedborne infection affects anthracnose development in two dry bean cultivars

Anthracnose, caused by the seedborne pathogen Colletotrichum lindemuthianum, is a serious disease of dry bean (Phaseolus vulgaris) that can severely reduce seed yield and quality. A 2 year field study examined how seedborne infection (0%, 1%, 2%, 5%, 10%, and 20%) affected seedling emergence, seedling infection, the buildup of anthracnose in the crop canopy, yield, seed mass, and seed discolouration in ‘Navigator’ navy bean and ‘AC Ole’ pinto bean. The incidence of seedling infection was significantly higher in ‘AC Ole’ than it was in ‘Navigator’ resulting in an early establishment of the disease on the pinto bean cultivar. There was a linear increase (P < 0.01) in anthracnose severity within the crop canopy and on the pods with higher rates of seedborne infection in both cultivars. Increases in seedborne infection rates also resulted in a significant decline (P < 0.01) in yield and seed mass. Comparisons of the 0% and the 20% seedborne treatments indicated that severe anthracnose development resulted in yield losses of 27% in ‘Navigator’ and 20% in ‘AC Ole’. These losses are comparable with the extent of yield reductions reported in a previous fungicidal study on anthracnose control in Manitoba. Key words: anthracnose, Colletotrichum lindemuthianum, dry beans, Phaseolus vulgaris, seed transmission. L’anthracnose, causée l’agent pathogène séminicole Colletotrichum lindemuthianum, est une maladie importante des haricots secs qui peut sérieusement en réduire les rendements et la qualité. Une étude sur le terrain, qui s’est échelonnée sur deux ans, a permis d’examiner comment l’infection séminicole (0 %, 1 %, 2 %, 5 %, 10 % et 20 %) influençait l’émergence et l’infection des semis, la prolifération de l’anthracnose sur le feuillage des plants ainsi que le rendement, le poids et la décoloration des semences chez le cultivar de petit haricot blanc ‘Navigator’ et chez celui de haricot pinto ‘AC Ole’. L’incidence de l’infection des semis chez le cultivar ‘AC Ole’ était significativement plus élevée que chez ‘Navigator’, ce qui provoquait la survenue hâtive de la maladie chez le haricot pinto. Il y avait une augmentation linéaire (P < 0,01) quant à la gravité de l’anthracnose sur le feuillage ainsi que sur les cosses affichant des taux plus élevés d’infection séminicole, et ce, chez les deux cultivars. Des augmentations des taux d’infection séminicole entraînent également une baisse significative (P < 0,01) des rendements et du poids des semences. Des comparaisons des traitements séminicoles (0 % et 20 %) ont indiqué que la prolifération massive de l’anthracnose provoquait des baisses de rendement de 27 % chez ‘Navigator’ et de 20 % chez ‘AC Ole’. Ces baisses sont comparables à celles rapportées dans une étude précédente effectuée sur les fongicides et ayant pour but la lutte contre l’anthracnose au Manitoba. Mots-clés : anthracnose, Colletotrichum lindemuthianum, haricots secs, Phaseolus vulgaris, transmission par semence.

Identification of bacterial pathogens and races of Pseudomonas syringae pv. phaseolicola from dry bean fields in Western Canada

Abstract Several bacterial diseases can significantly impact dry bean production in western Canada. The objectives of this study were to assess the incidence of multiple bacterial diseases on dry bean in southern Alberta and to determine the prevalent races causing halo blight (HB) in western Canadian dry bean fields. Field surveys combined with a pathogen isolation component were conducted in 2012–2014 to determine relative frequency of bacterial pathogens. Bacterial pathogens causing HB and brown spot were most commonly isolated from symptomatic tissues, whereas the pathogens causing common blight (CBB) and bacterial wilt were infrequently detected. In order to screen bean breeding lines for resistance to HB, the races of Pseudomonas syringae pv. phaseolicola (Pph) present in western Canada needed to be determined. A total of 114 Pph isolates were recovered from dry bean samples from Alberta, Saskatchewan and Manitoba in 2010–2013. Virulence testing of these isolates on the halo blight dry bean differential set indicated that only races 2 and 6 were present. These races were equally predominant in Manitoba, race 2 comprised 81% of Alberta isolates, and only race 2 occurred in Saskatchewan. Screening of select CBB-resistant breeding lines indicated that all were susceptible to a race 2 isolate of Pph. However, several commercial cultivars either currently grown, or recently registered for commercial production in Alberta, showed reduced susceptibility to HB. These results should be applicable to dry bean breeding programmes attempting to incorporate halo blight resistance into Canadian-adapted dry bean lines.

Island pinto bean

Island is a high-yielding, tall, partially upright pinto bean (Phaseolus vulgaris L.), with short vines and an average seed weight of 38.5 g 100 seeds-1. It was developed at the Agriculture and Agri-Food Canada (AAFC) Research Centre, Lethbridge, AB, in collaboration with the AAFC Research Station, Morden, MB. Island is well adapted to wide-row irrigated production of the Canadian prairies, with yields exceeding those of Othello, the check cultivar. Island is moderately susceptible, as is Othello, to race 73 of anthracnose [caused by Colletotrichum lindemuthianum (Sacc. & Magnus) Lams.-Scrib]; and is moderately resistant to white mould [caused by Sclerotinia sclerotiorum (Lib.) de Bary]. Key words: Pinto (bean), cultivar description, high yield