GGE biplot analysis of yield stability for Andean dry bean accessions grown under different abiotic stress regimes in Tanzania

Large seeded Andean dry beans ( Phaseolus vulgaris L.) are most preferred in Africa. However, low soil fertility and increasing drought stress conditions due to climate change are among the challenges faced by farmers in this region. The purpose of this study was to identify Andean genotypes with yield stability and to identify the best environments for selection of this trait. GGE-Biplot analysis was used to examine 183 Andean bean genotypes in Tanzania. Results indicated significant environment (E), genotype (G) and genotype x environment (GE) effects for seed yield. The environment explained 46%, genotype 20%, and GE 34% of the total (G + E + GE) variation. Two principal components explained 41.21% (PC1) and 26.35% (PC2) of GGE sum of squares. The Andean genotypes, ADP-102 (Jessica)- purple mottle, large seed, bush plant habit,\ua0released by Selian Agriculture Research Institution (ARI) in Tanzania; ADP-220 (G5625)- red, large seed, vine plant habit, from Central America; ADP-276 (G13654) - brown, medium seed, vine, from Mexico; and ADP-648 (\u2018Red Kloud\u2019) large red kidney, with bush plant habit, were stable across environments and can be recommended for general adaptation across environments. An individual location for selection for yield stability was not identified, thus justifying the continued need for multiple test sites.Les haricots secs andins \ue0 grosses graines ( Phaseolus vulgaris L.) sont les plus pr\ue9f\ue9r\ue9s en Afrique. Cependant, la faible fertilit\ue9 du sol et le stress croissant de la s\ue9cheresse caus\ue9 par le changement climatique font partie des d\ue9fis auxquels sont confront\ue9s les agriculteurs de cette r\ue9gion. L\u2018objectif de cette \ue9tude \ue9tait d\u2019identifier les g\ue9notypes andins avec une stabilit\ue9 de rendement et d\u2019identifier les meilleurs environnements pour la s\ue9lection de ce trait. L\u2019analyse GGE-Biplot a \ue9t\ue9 utilis\ue9e pour examiner 183 g\ue9notypes de haricot andin en Tanzanie. Les r\ue9sultats ont montr\ue9 des effets significatifs sur l\u2019environnement (E), le g\ue9notype (G) et le g\ue9notype x environnement (GE) sur le rendement en grain. L\u2019environnement expliquait 46%, le g\ue9notype 20% et l\u2019EG 34% de la variation totale (G + E + GE). Deux composantes principales expliquent 41,21% (PC1) et 26,35% (PC2) de la somme des carr\ue9s GGE. Les g\ue9notypes andins, ADP-102 (Jessica) - marron violet, grosse graine, habitude de plante de brousse, publi\ue9s par l\u2019Institut de recherche sur l\u2019agriculture Selian (ARI) en Tanzanie; ADP-220 (G5625) - Rouge, grosse graine, habitude de plante de la vigne, d\u2019Am\ue9rique centrale; ADP-276 (G13654) - brun, graine moyenne, vigne, en provenance du Mexique; et le grand rein rouge ADP-648 (\uabRed Kloud\ubb), avec l\u2018 habitude des plantes de brousse, \ue9taient stables dans tous les environnements et pouvaient \ueatre recommand\ue9s pour une adaptation g\ue9n\ue9rale dans tous les environnements. Un emplacement individuel pour la s\ue9lection de la stabilit\ue9 du rendement n\u2019a pas \ue9t\ue9 identifi\ue9, ce qui justifie le besoin de la continuite de test multiples des sites

Selective Phenotyping Traits Related to Multiple Stress and Drought Response in Dry Bean

Abiotic stress tolerance in dry bean (Phaseolus vulgaris L.) is complex. Increased population sizes are contributing to finding QTL conditioning stress response but phenotyping has not kept pace with high throughput genotyping for such studies. Our objectives were to determine effectiveness of 20 most tolerant and 20 most susceptible lines representing phenotypic extremes from a RIL population (‘Buster’ x \u27Roza’ [BR]) to facilitate examination of 19 traits for relevance to stress response and to validate existing QTL conditioning stress response. Using phenotypic extremes tested across multiple trials, eight of the 19 traits were clearly associated with drought stress. Pod wall ratio (PW), plant biomass by weight or a visual rating, and greenness index (NDVI) were most associated with seed yield (SY) under stress followed by phenology traits. The phenotypic extreme lines were also useful for validating QTL previously identified in the whole RIL population conditioning SY, seed weight (SW) and days to flower (DF), harvest maturity (HM), and seed fill (DSF). New QTL were identified for biomass, PW, and NDVI which co-segregated with major QTL for seed yield SY1.1BR and SY2.1BR. The preliminary finding of NDVI 1.1BR supports aerial imaging in larger genetic populations geared toward QTL analysis of stress response. In summary, phenotypic extremes helped sort through traits relevant to stress response in the Buster x Roza RIL population and verified the effect of two major QTL in response to terminal drought

Seventy-five years of breeding dry bean of the western USA

A periodic comparison of cultivars is essential to assess selection gains, determine deficiencies, define objectives, and set breeding priorities. Our objective was to assess the progress, or lack thereof, achieved in improving yield, plant type, maturity, and resistance to major bacterial, fungal, and viral diseases of dry bean of the western USA from 1918 to 1998. Twenty-five great northern, pink, pinto, and red cultivars were evaluated for seed yield at three locations in Idaho and for anthracnose, Bean common mosaic virus, Bean common mosaic necrosis virus, common and halo bacterial blights, Fusarium and Rhizoctonia root rots, Fusarium wilt, and white mold in Colorado, Idaho, and Washington between 1999 and 2006. Yield ranged between 2904 kg ha-1 for pinto 'UI 111' to 3921 kg ha- 1 for 'Bill Z', which represents a 35% gain in 54 yr. Yield gain in great northern was 587 kg ha-1 , pink 136 kg ha-1 , and red 687 kg ha- 1 . Stability indices ranged from 0.57 for 'Kodiak' to 1.86 for 'UI 3'. Maturity ranged from 90 d for 'UI 320' to 97 d for 'Frontier'. Seed weight ranged from 28 g for 'Viva' to 41 g for UI 320. An acceptable degree of resistance to Rhizoctonia root rot was achieved in most cultivars. All cultivars were susceptible to anthracnose, common bacterial blight, and white mold, and all except 'Chase' to halo blight. Only 'Matterhorn', 'Weihing', and Kodiak combined an upright Type II growth habit with resistance to BCMV and rust. An integrated breeding strategy should be explored for simultaneous improvement of multiple traits in future cultivars

The role of molecular markers in breeding for qualitative and quantitative traits of common bean

Improving selection efficiency through indirect selection is an attractive alternative to plant breeders working to improve qualitative and quantitative traits of common bean (Phaseolus vulgaris L). For the successful application of indirect selection, tight linkages must be developed between simple selectable genetic markers and an economically important gene or quantitative trait loci (QTL) controlling a complex trait. Although indirect selection for qualitative traits appears most promising, direct selection for major gene traits may in certain cases be easier, faster and more cost effective. However, indirect selection of race-specific disease resistance genes offers breeders a viable alternative to ensure that favorable gene combinations are present in new cultivars. Simplifying the selection of complex traits using QTL analysis with linked markers would permit selection in the absence of the pathogen or in locations where trait expression is variable. Combining different mechanisms for resistance is only possible using markers when the phenotypic expression is similar after disease inoculation. Random amplified polymorphic DNA (RAPD) markers tightly linked to individual race-specific resistance genes forms the basis for effective indirect selection for durable genetic resistance. Over 30 RAPD markers linked to 17 major genes which condition resistance to four pathogens of common bean nave been found. In addition, markers associated with QTL conditioning resistance to the three diseases (bean golden mosaic virus, common bacterial blight and web blight) of major importance in the tropics have been identified. These tightly linked RAPD markers have potential to facilitate the efficient selection of complex traits and pyramiding of epistemic resistance genes against different pathogens of common bean. Limitations to marker-assisted selection and the value of genetic mapping and QTL analysis in improving the efficiency of bean breeding programs are discussed.Mejorar la eficiencia de selección de caracteres cualitativos y cuantitativos del frijol común (Phaseolus vulgaris L.) a través de la selección indirecta es una opción atractiva para los mejoradores. Para la aplicación exitosa de la selección indirecta, debe desarrollarse los ligamentos estrechos entre los marcadores genéticos simples seleccionables y un gen económicamente importante o un locus de caracter cuantitativo (QTL). Aunque la selección indirecta de caracteres cualitativos parece ser más prometedora, la selección directa de caracteres cualitativos en algunos casos puede ser más fácil, más rápida y más barata. Sin embargo, la selección indirecta de genes de resistencia específica a las razas de un patógeno variable ofrecen a los mejoradores una alternative viable para asegurar que las combinaciones favorables de genes esten presentes en los nuevos cultivares. Simplificando la selección de caracteres complejos usando marcadores ligados a QTL permitirá la selección en ausencia del patógeno o en localidades donde la expresión del caracter de expresión es variable. La combinación de diferentes mecanismos de resistencia es sólo posible usando marcadores cuando la expresión fenotípica es similar a la obtenida después de la inoculación con el patógeno. Los marcadores RAPDs (Random amplified polymorphic DNA) estrechamente ligados a genes individuales de resistencia a razas especificas de un patógeno, forman la base para la selección indirecta y efectiva de una resistencia genética durable. Más de 30 marcadores RAPD ligados a 17 genes principales que controlan la resistencia a cuatro patógenos de frijol común han sido identificados. Además, marcadores asociados con QTL que controlan la resistencia a tres enfermedades (virus de mosaico dorado, bacteriosis común y mustia hilachosa) de gran importancia en los trópicos también han sido identificados. Estos marcadores RAPD estrechamente ligados, pueden ser utilizados en la selección eficiente de caracteres complejos y en la acumulación (piramidar) de genes de resistencia epistática contra diferentes patógenos del frijol común. Las limitaciones de selección con marcadores moleculares, el valor del mapeo genético y del análisis de QTL para mejorar la eficiencia de selección en frijol son discutidos

Registration of Common Bacterial Blight Resistant Pinto Bean Germplasm Line ABCP-8

Pinto bean (Phaseolus vulgaris L.) germplasm line ABCP-8 (Reg. no. GP-237, PI 635118) was developed by the University of Nebraska Agricultural Research Division in cooperation with USDA-ARS and released in 2004. This line was bred specifically for enhanced resistnace to common bacterial blight [caused by Xanthomonas campestris pv. phaseoli (Smith) Dye]. Pinto and other dry bean market classes (dark red kidney, great northern, navy, etc.) grown in the U.S.A. east of the continental divide are often attacked by common bacterial blight, a seed-transmitted disease that causes up to 40% yield loss in susceptible cultivars as well as reduction of seed quality through discoloration of infected seed. Development of cultivars with genetic resistance combined from different sources is the most cost effective method to control common bacterial blight

Seventy-five years of breeding dry bean of the western USA

A periodic comparison of cultivars is essential to assess selection gains, determine deficiencies, define objectives, and set breeding priorities. Our objective was to assess the progress, or lack thereof, achieved in improving yield, plant type, maturity, and resistance to major bacterial, fungal, and viral diseases of dry bean of the western USA from 1918 to 1998. Twenty-five great northern, pink, pinto, and red cultivars were evaluated for seed yield at three locations in Idaho and for anthracnose, Bean common mosaic virus, Bean common mosaic necrosis virus, common and halo bacterial blights, Fusarium and Rhizoctonia root rots, Fusarium wilt, and white mold in Colorado, Idaho, and Washington between 1999 and 2006. Yield ranged between 2904 kg ha-1 for pinto 'UI 111' to 3921 kg ha- 1 for 'Bill Z', which represents a 35% gain in 54 yr. Yield gain in great northern was 587 kg ha-1 , pink 136 kg ha-1 , and red 687 kg ha- 1 . Stability indices ranged from 0.57 for 'Kodiak' to 1.86 for 'UI 3'. Maturity ranged from 90 d for 'UI 320' to 97 d for 'Frontier'. Seed weight ranged from 28 g for 'Viva' to 41 g for UI 320. An acceptable degree of resistance to Rhizoctonia root rot was achieved in most cultivars. All cultivars were susceptible to anthracnose, common bacterial blight, and white mold, and all except 'Chase' to halo blight. Only 'Matterhorn', 'Weihing', and Kodiak combined an upright Type II growth habit with resistance to BCMV and rust. An integrated breeding strategy should be explored for simultaneous improvement of multiple traits in future cultivars

Sequence‐Based Introgression Mapping Identifies Candidate White Mold Tolerance Genes in Common Bean

Core Ideas Sequenced‐based introgression mapping rapidly maps QTL to a physical location A highly polymorphic candidate gene associated with apoptosis maps in the WM7.1 QTL A highly polymorphic gene associated with effector recognition maps in the WM8.3 QTL White mold, caused by the necrotrophic fungus Sclerotinia sclerotiorum (Lib.) de Bary, is a major disease of common bean (Phaseolus vulgaris L.). WM7.1 and WM8.3 are two quantitative trait loci (QTL) with major effects on tolerance to the pathogen. Advanced backcross populations segregating individually for either of the two QTL, and a recombinant inbred (RI) population segregating for both QTL were used to fine map and confirm the genetic location of the QTL. The QTL intervals were physically mapped using the reference common bean genome sequence, and the physical intervals for each QTL were further confirmed by sequence‐based introgression mapping. Using whole‐genome sequence data from susceptible and tolerant DNA pools, introgressed regions were identified as those with significantly higher numbers of single‐nucleotide polymorphisms (SNPs) relative to the whole genome. By combining the QTL and SNP data, WM7.1 was located to a 660‐kb region that contained 41 gene models on the proximal end of chromosome Pv07, while the WM8.3 introgression was narrowed to a 1.36‐Mb region containing 70 gene models. The most polymorphic candidate gene in the WM7.1 region encodes a BEACH‐domain protein associated with apoptosis. Within the WM8.3 interval, a receptor‐like protein with the potential to recognize pathogen effectors was the most polymorphic gene. The use of gene and sequence‐based mapping identified two candidate genes whose putative functions are consistent with the current model of Sclerotinia pathogenicity