Analysis of tomato agronomic traits using generation mean

Information on inheritance of agronomic traits and lack of tomato (Solanum lycopersicum L.) a robust breeding programme in Kenya, has led to dependency on imported tomato varieties. The objective of this study was to assess the inheritance of growth attributes of tomato lines in Kenya and identify cross family with great potential for further breeding. Six generations; namely P1, P2, F1, F2, BC1P1 and BC1P2‚ were developed from five parental lines. A split-plot design with crosses as main plots and generations as subplots was used in two sites (Kabete Field Station and Mwea Research Station), located in Kenya. Cross Roma VF x AVTO1424 and Roma VF x AVTO1314 were the earliest (33 days) to reach 50% flowering; while BC1P2‚ of Roma VF (38 days) was the latest to flower. Mwea Station had plants with the tallest plants, with a mean height of 62 cm at 50% flowering, compared to Kabete Station with a mean height of 48 cm. A significant increase (>10%) in plant height was registered in F1 generations compared to parental lines. Plant height at maturity across the environments ranged from 82 cm for shorter parent, Roma VF, to 120 cm for taller offspring BC1P1. Significant genotype x environment interactions were observed in Roma VF x AVTO1314 and Roma VF x AVTO1429 for days to 50% flowering, plant height, and number of trusses per plant. The importance of gene effects for agronomic trait inheritance was in additive and dominance-additive portions, which implied that traits were inherited

Yield stability in small red inter-racial common bean lines in Kenya

Agronomic performance of new common bean ( Phaseolus vulgaris L.) varieties may vary considerably in diverse agro-ecological zones, due to genotype-environment (G x E) interactions. A multi-site evaluation is, therefore, crucial in elite lines selection as it considers simultaneously both yield and stability of performance, making selection of genotypes more precise and refined. This study aimed at assessing the agronomic performance and yield stability of 24 F1.7 small red bean lines, selected for multiple disease resistance, using molecular markers from 16 inter-racial bean populations. The study lines were evaluated in low, medium and high altitude agro-ecological conditions in Kenya. G x E effects for grain yield were highly significant (P<0.001), implying that the agronomic potential of the small red bean lines varied with agro-ecological zones. Tigoni, the high altitude (2130 m above sea level) test site had the highest grain yield (3,809 kg ha-1). There were no significant differences between medium altitude (1820 masl) Kabete (1,100 kg ha-1) and low altitude (1150 masl) Mwea (1,025 kg ha-1) sites. Number of pods per plant was strongly positively correlated with seed yield (r=0.85***), and could be adopted by breeders as an indirect selection method for grain yield. The G x E interaction on grain yield was high (14.4%), implying that most of genotypes should be selected and recommended to specific environments. The high yielding line, KMA13-25-09 (3,385 kg ha-1), was the least stable across sites. Disease severity score for target diseases was low to intermediate regardless of the genotypes and sites.Les performances agronomiques des nouvelles vari\ue9t\ue9s de haricot commun ( Phaseolus vulgaris L.) peuvent varier consid\ue9rablement dans diverses zones agro-\ue9cologiques, en raison des interactions g\ue9notype-environnement (G x E). Une \ue9valuation multi-site est donc cruciale pour la s\ue9lection des lign\ue9es d\u2019\ue9lite, car elle prend en compte simultan\ue9ment le rendement et la stabilit\ue9 des performances, rendant la s\ue9lection des g\ue9notypes plus pr\ue9cise et affin\ue9e. Cette \ue9tude visait \ue0 \ue9valuer les performances agronomiques et la stabilit\ue9 au rendement de 24 lign\ue9es de haricots rouges F1.7, s\ue9lectionn\ue9es pour leur r\ue9sistance \ue0 de multiples maladies, \ue0 l\u2019aide de marqueurs mol\ue9culaires provenant de 16 populations de haricots interraciaux. Les lign\ue9es \ue9tudi\ue9es ont \ue9t\ue9 \ue9valu\ue9es dans des conditions agro-\ue9cologiques d\u2019altitude basse, moyenne et haute au Kenya. Les effets de G x E sur le rendement en grain \ue9taient tr\ue8s significatifs (P <0,001), ce qui impliquait que le potentiel agronomique des petites lign\ue9es de haricots rouges variait selon les zones agro-\ue9cologiques. Tigoni, le site d\u2019essai \ue0 haute altitude (2130 m au dessus du niveau de la mer), a eu le rendement grainier le plus \ue9lev\ue9 (3 809 kg ha-1). Il n\u2019y avait pas de diff\ue9rences significatives entre les sites de moyenne altitude (1820 m au dessus du niveau de la mer) de Kabete (1 100 kg ha-1) et de basse altitude (1150 m au dessus du niveau de la mer) Mwea (1 025 kg d\u2019ha-1). Le nombre de gousses par plante \ue9tait fortement corr\ue9l\ue9 positivement au rendement en graines (r = 0,85 ***) et pourrait \ueatre adopt\ue9 par les selectionneurs comme m\ue9thode de s\ue9lection indirecte pour le rendement en grains. L\u2019interaction G x E sur le rendement en grain \ue9tait \ue9lev\ue9e (14,4%), ce qui implique que la plupart des g\ue9notypes devraient \ueatre s\ue9lectionn\ue9s et recommand\ue9s pour des environnements sp\ue9cifiques. La lign\ue9e \ue0 haut rendement, KMA13-25-09 (3 385 kg ha-1), \ue9tait la moins stable sur tous les sites. Le score de gravit\ue9 de la maladie pour les maladies vis\ue9es \ue9tait faible \ue0 interm\ue9diaire, quels que soient les g\ue9notypes et les sites

Resistance and inheritance of common bacterial blight in yellow bean

Common bean ( Phaseolus vulgaris L.) is the most important food legume among the pulses. It is a cheap source of protein, especially in Sub-Saharan Africa. However, bean production is constrained by bacterial diseases, of which common bacterial blight ( Xanthomonas axonopodis p.v. phaseoli ) is prevalent in Africa. The objective of this study was to transfer resistance to common bacterial blight and determine its inheritance in yellow beans. Sources of resistance were CIAT lines, Wilk 2 and VAX 6, which were crossed with susceptible Lusaka yellow and Pembla. The parents, F1, F2 and backcross progenies were inoculated with X. axonopodis and the resulting blight severity determined. Quantitative traits, including days to flowering, number of pods, and seed yield were also determined. The F1 and backcrosses to the resistant parents were all resistant, while the F2 and backcrosses to the susceptible parents segregated in 3:1 and 1:1 ratios, respectively. Additive genetic effects were observed in quantitative traits like days to flowering, plant height, days to maturity and yield. Therefore, resistance to common bacterial blight is controlled by a single dominant gene. The resistant parents Wilk 2 and VAX 6 could be used to improve bean varieties that are susceptible to common bacterial blight.Le haricot commun ( Phaseolus vulgaris L.) est une nourriture la plus importante parmi les l\ue9gumineuses. C\u2019est une source moins ch\ue8re de prot\ue9ines, sp\ue9cialement en Afrique sub-Saharienne. Cependant, la production du haricot est handicap\ue9e par des maladies bact\ue9riennes, parmi lesquelles le fl\ue9trissement bact\ue9rien courant ( Xanthomonas axonopodis p.v. phaseoli ) qui est le plus prevalent en Afrique. L\u2019objectif de cette \ue9tude \ue9tait de transf\ue9rer la r\ue9sistance au fl\ue9trissement bact\ue9rien et de d\ue9terminer son h\ue9r\ue9dit\ue9 dans les haricots jaunes. Les sources de r\ue9sistance \ue9taient lign\ue9es CIAT, Wilk 2 et VAX 6, qui \ue9taient crois\ue9es avec le susceptible Lusaka jaune et Pembla. Les parents F1, F2 et les prog\ue9nies de croisement en retour \ue9taient inocul\ue9es avec X. axonopodis et le degr\ue9 de s\ue9v\ue9rit\ue9 du fl\ue9trissement d\ue9termin\ue9. Des traits quantitatifs, incluant les jours \ue0 la floraison, le nombre de gousses et le rendement en grains \ue9taient aussi d\ue9termin\ue9s. Les F1 et les produits de croisements en retour des parents r\ue9sistants \ue9taient tous r\ue9sistants, alors que les F2 et les produits de croisements en retour des parents susceptibles \ue9taient s\ue9gr\ue9gu\ue9s dans les rapports 3:1 et 1:1, respectivement. Des effects g\ue9n\ue9tiques additifs \ue9taient observ\ue9s dans les traits quantitatifs tels que les jours \ue0 la floraison, la hauteur des plants, les jours \ue0 la maturit\ue9 et le rendement. Ainsi, la r\ue9sistance au fl\ue9trissement bact\ue9rien est controll\ue9 par un seul g\ue8ne dominant. Les parents r\ue9sistants Wilk 2 et VAX 6 pourraient \ueatre utilis\ue9s pour am\ue9liorer les vari\ue9t\ue9s de haricot susceptibles au fl\ue9trissement bact\ue9rien commun

Validation of effectiveness marker-assisted gamete selection for multiple disease resistance in common bean

Plant breeding is the most cost-effective, practical and environmentally friendly strategy for reducing losses associated with bean diseases, especially in low-input agricultural systems because no additional investment is required from farmers. However, incorporating resistance to one pathogen may not result in a significant change because several diseases co-infection beans at the farm level. Consequently, breeding varieties with multiple disease resistance is a more appropriate, reliable and sustainable approach. In such context, gamete selection is the more appropriate breeding method because it allows simultaneous selection for multiple traits; though as originally proposed and validated, it is largely based on phenotypic evaluation for agronomic traits, which leads to delay in variety development and strong dependence on erratic weather conditions. The objective of this study was to validate 26 F1.8 elite bean lines selected for resistance to angular leaf spot (ALS), anthracnose, root rots, common bacterial blight (CBB) and bean common mosaic virus (BCMV), from inter-racial and inter-gene pool populations developed using molecular markers on the gamete selection method in early generations. Pathogens were isolated from diseased plants collected from various locations in central Kenya, multiplied on appropriate media and used to inoculate the test lines in a greenhouse at Kabete Field Station, University of Nairobi. Data on disease incidence and severity were collected at 14, 21, 28th days after inoculation, using the 1-9 CIAT scale; except for the root rot experiments for which data were recorded once at 21st day after seedling emergence. Results showed that five of the 26 elite lines possessed multiple resistance to five pathogens, eight to four pathogens, nine to three pathogens, three to two pathogens and one was resistant to one pathogen. This implied that markers, used in early generations, were effective in the identification and transfer of resistance genes to susceptible commercial varieties. However, there were no significant correlations in the reaction of tested genotypes to pathogens in this study, except between BCMV and ALS (r=0.3942*). This suggests that resistance genes are in different chromosomes and are assorted independently. The presence of genotypes with multiple disease resistance among test elite lines, confirms the effectiveness of inter-racial crosses and marker-assisted gamete selection to concurrently improve the resistance to common bean major diseases in Eastern Africa.L\u2019am\ue9lioration g\ue9n\ue9tique des plantes est la strat\ue9gie la moins co\ufbteuse, la plus pratique et la plus respectueuse de l\u2019environnement dans la r\ue9duction des pertes associ\ue9es aux maladies du haricot, en particulier dans les syst\ue8mes agricoles \ue0 faible usage d\u2019intrants. Ceci car aucun investissement suppl\ue9mentaire n\u2019est requis de la part des agriculteurs. Cependant, l\u2019incorporation de la r\ue9sistance \ue0 un agent pathog\ue8ne ne pourrait entra\ueener de changement significatif, car plusieurs maladies attaquent simultan\ue9ment le haricot. Par cons\ue9quent, le d\ue9veloppement de vari\ue9t\ue9s pr\ue9sentant une r\ue9sistance multiple aux maladies constitue une approche plus appropri\ue9e, fiable et durable. Dans ce contexte, la s\ue9lection des gam\ue8tes est la m\ue9thode d\u2019am\ue9lioration g\ue9n\ue9tique la plus appropri\ue9e car elle permet la s\ue9lection simultan\ue9e de plusieurs caract\ue8res\ua0; bien que, telle que propos\ue9e et valid\ue9e \ue0 l\u2019origine, elle repose en grande partie sur une \ue9valuation ph\ue9notypique des caract\ue8res agronomiques. Ceci retarde ainsi le d\ue9veloppement de la vari\ue9t\ue9 et entra\ueene une forte d\ue9pendance \ue0 des conditions m\ue9t\ue9orologiques, souvent irr\ue9guli\ue8res. L\u2019objectif de cette \ue9tude \ue9tait de valider la huiti\ue8me g\ue9n\ue9ration (F1.8) de 26 lign\ue9es \ue9lites de haricot s\ue9lectionn\ue9es pour leur r\ue9sistance \ue0 la maladie des taches angulaires, \ue0 l\u2019anthracnose, \ue0 la fonte des semis, \ue0 la bact\ue9riose commune du haricot et \ue0 la mosa\uefque commune du haricot. Ces lign\ue9es viennent des populations interraciales et inter-g\ue9niques de haricot, d\ue9velopp\ue9es en utilisant des marqueurs mol\ue9culaires sur la m\ue9thode de s\ue9lection des gam\ue8tes dans leurs premi\ue8res g\ue9n\ue9rations. Des agents phytopathog\ue8nes ont \ue9t\ue9 isol\ue9s \ue0 partir de plantes malades recueillies \ue0 divers endroits dans la partie centrale du Kenya, multipli\ue9s sur des milieux de culture appropri\ue9s et utilis\ue9s par la suite pour inoculer les lign\ue9es test\ue9es sous une serre, dans le champ exp\ue9rimental de l\u2019Universit\ue9 de Nairobi situ\ue9 \ue0 Kabete. Les donn\ue9es sur l\u2019incidence et la s\ue9v\ue9rit\ue9 des maladies ont \ue9t\ue9 enregistr\ue9es aux 14, 21 et 28\ue8me jours apr\ue8s l\u2019inoculation, \ue0 l\u2019aide de l\u2019\ue9chelle de CIAT allant de 1\ue0 9; \ue0 l\u2019exception des exp\ue9riences sur les fontes de semis pour lesquelles les donn\ue9es \ue9taient enregistr\ue9es une seule fois, au 21\ue8me jour apr\ue8s la lev\ue9e des plantules. Les r\ue9sultats ont montr\ue9 que cinq des 26 lign\ue9es \ue9lites pr\ue9sentaient une r\ue9sistance multiple \ue0 cinq agents pathog\ue8nes, huit \ue0 quatre agents pathog\ue8nes, neuf \ue0 trois agents pathog\ue8nes, trois \ue0 deux agents pathog\ue8nes et une \ue9tait r\ue9sistante \ue0 un agent pathog\ue8ne. Cela d\ue9montrait que les marqueurs mol\ue9culaires, utilis\ue9s dans les premi\ue8res g\ue9n\ue9rations, \ue9taient efficaces dans l\u2019identification et le transfert de g\ue8nes de r\ue9sistance \ue0 des vari\ue9t\ue9s commerciales sensibles. Cependant, il n\u2019y avait pas de corr\ue9lations significatives dans la r\ue9action des g\ue9notypes aux agents pathog\ue8nes, sauf entre la mosa\uefque commune du haricot et la maladie des taches angulaires (r = 0,3942*). Ceci sugg\ue8re que les g\ue8nes de r\ue9sistance sont dans diff\ue9rents chromosomes et assortis ind\ue9pendamment. La pr\ue9sence de g\ue9notypes, pr\ue9sentant une r\ue9sistance multiple aux maladies parmi les lign\ue9es \ue9lites test\ue9es, confirme l\u2019efficacit\ue9 des croisements interraciaux et de la m\ue9thode de s\ue9lection de gam\ue8tes assist\ue9e par marqueurs dans l\u2019am\ue9lioration simultan\ue9e de la r\ue9sistance aux principales maladies du haricot commun en Afrique de l\u2019Est

Inheritance of resistance to angular leaf spot in yellow beans

Angular leaf spot ( Phaeoisariopsis griseola (Sacc) is an important disease of common bean ( Phaseolus vulgaris L.) in most parts of Africa, causing yield losses of 40-80%. This study was carried out to determine the inheritance of resistance to angular leaf spot in yellow beans. Biparental crosses were done between susceptible yellow bean genotypes and angular leaf spot resistant parents to generate F1, F2 and backcrosses. Resistance was evaluated in a screen house and field after inoculation with Phaeoisariopsis griseola. The F1 were resistant, indicating that resistance was dominant. There was no significant deviation from the expected 3:1 ratio for resistant to susceptible in the F2 population, confirming that resistance to angular leaf spot was both monogenic and dominant. The backcross to Lusaka Yellow showed a 1:1 segregation ratio, while the backcrosses to Mexico 54 were all resistant. Pembela was susceptible to angular leaf spot, while the F1 were resistant. The ratio of 3:1 represents resistant : susceptible F2 populations. All backcrosses to Mexico 54 were resistant, confirming that resistance to angular leaf spot in Mexico 54 is controlled by a single dominant gene. The results of the study showed that resistance to angular leaf spot in yellow beans is governed by a single dominant gene. This can be used to improve the local landraces by incorporating angular leaf spot resistance and high yield traits.La t\ue2che agulaire des feuilles ( Phaeoisariopsis griseola (Sacc) est une maladie importante du haricot commun ( Phaseolus vulgaris L.) dans la plus part de regions africaines, causant des pertes de rendement d\u2019environ 4080%. Cette \ue9tude \ue9tait conduite pour d\ue9terminer l\u2019acquisition de la r\ue9sistance des haricots jaunes \ue0 la maladie de t\ue2che angulaire. Les croisements biparentaux \ue9taient effectu\ue9s entre les g\ue9notypes du haricot jaune susceptible et les parents r\ue9sistants \ue0 la g\ue9n\ue9ration F1, F2 ainsi que de croisements r\ue9currents. La r\ue9sistance \ue9tait \ue9valu\ue9e en serre et au champ apr\ue8s inoculation avec Phaeoisariopsis griseola. Les F1 \ue9taient r\ue9sistantes, indicant que la r\ue9sistance \ue9tait dominante. Il n\u2019avait aucune d\ue9viation significative du rapport attendu 3:1 pour la r\ue9sistance, au susceptible dans les populations F2, confirmant que la r\ue9sistance \ue0 la t\ue2che angulaire de feuilles \ue9tait monog\ue9nique et dominant. Les produits du croisement en retour de Lusaka Yellow a montr\ue9 un rapport de s\ue9gr\ue9gation 1:1, pendant que ceux de Mexico 54 \ue9taient tous r\ue9sistants. Pempela \ue9tait susceptible \ue0 la t\ue2che angulaire, alors que les F1 \ue9taient r\ue9sistantes. Les prog\ue9nies F2 s\ue9gr\ue9g\ue9es en un rapport 3:1 pour r\ue9sistant au susceptible et le backcross (croisement en retour) au Pempela avait donn\ue9 un rapport 1:1 pour r\ue9sistant au susceptible. Tous les produits du croisement en retour du Mexico 54 \ue9taient r\ue9sistants, confirmant que la r\ue9sistance \ue0 la t\ue2che angulaire des feuilles dans Mexico 54 est controll\ue9e par un seul g\ue8ne dominant. Les r\ue9sultats de cette \ue9tude ont montr\ue9 que la r\ue9sistance \ue0 la t\ue2che angulaire dans les haricots jaunes est gouvern\ue9e par un seul g\ue8ne dominant. Ceci peut \ueatre utilis\ue9 pour am\ue9liorer les vari\ue9t\ue9s locales indig\ue8nes par incorporation de la r\ue9sistance \ue0 la t\ue2che angulaire des feuilles et les traits \ue0 rendement \ue9lev\ue9

HETEROSIS AND COMBINING ABILITY FOR RELATED TRAITS IN TOMATO

Tomato ( Solanum lycopersicum L.) yields have continued to plummet in Kenya due to biotic stresses and reliance on low yielding varieties. This study aimed at determining heterosis and combining ability for fruit yield and yield components among tomato genotypes and select F1 hybrids combining high fruit yield and other market demanded traits under Kenyan conditions. Ten parental genotypes and their 45 F1 hybrids were studied using 10 710 half diallel mating design, excluding the reciprocals and the self\u2019s. The experiment was set up in Kiambu and Kirinyaga Counties in Kenya. Out of 45 F1 hybrids evaluated, 89% had reduced (negative heterosis) days to 50% flowering and 11% days to maturity, compared to their better parents. Higher heterosis (-9%) was recorded on days to flowering in AVTO1429 x Cal J VF) and -5% for maturity in Roma VF x AVTO1314. All the F1 hybrids had positive heterosis for number of trusses per plant and fruit yield. F1 hybrid AVTO1429 x AVTO1314 had the highest positive heterosis of 114.39% for fruit weight per plant yield. The results showed high significant difference among the ten genotypes for general and specific combining ability effects (male x female) for all the traits evaluated. There was additive and non-additive gene action for the traits, which are important aspects in developing a tomato breeding programme.Les rendements de la tomate (Solanum lycopersicum L.) ont continu\ue9 de chuter au Kenya en raison des stress biotiques et de la d\ue9pendance aux vari\ue9t\ue9s qui donnent le faible rendement. Cette \ue9tude visait \ue0 d\ue9terminer l\u2019h\ue9t\ue9rosis et \ue0 combiner la capacit\ue9 de rendement en fruits et les composants de rendement parmi les g\ue9notypes de tomates et s\ue9lectionner des hybrides F1 combinant un rendement \ue9lev\ue9 en fruits et d\u2019autres caract\ue9ristiques demand\ue9es par le march\ue9 dans les conditions kenyanes. Dix g\ue9notypes parentaux et leurs 45 hybrides F1 ont \ue9t\ue9 \ue9tudi\ue9s \ue0 l\u2019aide d\u2019un plan d\u2019accouplement 10 7 10 demi-diall\ue8le, \ue0 l\u2019exclusion de la s\ue9lection r\ue9currente r\ue9ciproque et autof\ue9condation. L\u2019exp\ue9rience a \ue9t\ue9 mise en place dans les comt\ue9s de Kiambu et Kirinyaga au Kenya. Les 89\ua0% de 45 hybrides F1 \ue9valu\ue9s avaient des jours r\ue9duits (h\ue9t\ue9rosis n\ue9gatif) \ue0 50\ua0% de floraison et 11\ua0% de jours jusqu\u2019\ue0 maturit\ue9, par rapport \ue0 leurs meilleurs parents. Une h\ue9t\ue9rosis plus \ue9lev\ue9e (-9 %) a \ue9t\ue9 enregistr\ue9e sur les jours pr\ue9c\ue9dant la floraison chez AVTO1429 x Cal J VF) et -5 % pour la maturit\ue9 chez Roma VF x AVTO1314. Tous les hybrides F1 avaient une h\ue9t\ue9rosis positive pour le nombre de grappes par plante et le rendement en fruits. L\u2019hybride F1 AVTO1429 x AVTO1314 pr\ue9sentait l\u2019h\ue9t\ue9rosis positive la plus \ue9lev\ue9e de 114,39 % pour le rendement en poids de fruit par plante. Les r\ue9sultats ont montr\ue9 une diff\ue9rence significative \ue9lev\ue9e entre les dix g\ue9notypes pour les effets de capacit\ue9 de combinaison g\ue9n\ue9raux et sp\ue9cifiques (m\ue2le x femelle) pour tous les traits \ue9valu\ue9s. Il y avait une action g\ue9nique additive et non additive pour les traits qui sont des aspects importants dans le d\ue9veloppement d\u2019un programme de s\ue9lection de tomates

Reaction of selected common bean genotypes to physiological races of Phaeoisariopsis griseola occurring in Kenya

The wide pathogenic variability occurring in Phaeoisariopsis griseola , the causal agent of angular leaf spot of common bean ( Phaseolus vulgaris L.), dictates that new sources of resistance be continuously identified. This study was undertaken to determine the reaction of selected bean genotypes to different races of P. griseola in order to identify potential sources of resistance to angular leaf spot. Selected bean genotypes from Eastern and Central Africa Bean Research Network (ECABREN) and National Dryland Farming Research Centre (NDFRC), Katumani in Kenya were separately inoculated with forty-four races of P. griseola and evaluated for disease development under greenhouse conditions. The genotypes included small- and large-seeded types. None of the genotypes was resistant to all the races, indicating a high complexity of the pathogen population. Thirteen genotypes were resistant (disease score 1 to 3) or moderately resistant (score 4 to 6) to at least 40 of the races. Small-seeded bean genotypes ECAB 0754 and ECAB 0617 were resistant or moderately resistant to all races except Mesoamerican race 33-39 and Afro-Andean race 58-18, respectively. Genotype ECAB 0754 exhibited the highest level of resistance, with an average disease severity of 1.1%. All the resistant or moderately resistant genotypes were of the small-seeded bean types which are commercially less popular. The commonly grown large-seeded genotypes were generally susceptible. Among the bean genotypes evaluated, the small-seeded pintos and browns/yellows possessed high levels of resistance. The results of this study indicate that different bean genotypes have varying levels of resistance to angular leaf spot that can be pyramided into appropriate background to provide durable resistance.Une large variabilit\ue9 pathog\ue9nique du Phaeoisariopsis griseola , l\u2019agent causal de la t\ue2che angulaire de feuilles du haricot commun ( Phaseolus vulgaris L.), sugg\ue8re qu\u2019il y\u2019ait une identification continue de nouvelles sources de r\ue9sistance. Cette \ue9tude \ue9tait entreprise pour d\ue9terminer la r\ue9action des g\ue9notypes de haricot s\ue9lectionn\ue9s aux diff\ue9rentes races de P. griseola afin d\u2019identifier de sources potentielles de r\ue9sistance \ue0 la maladie de t\ue2che angulaire de la feuille. Les g\ue9notypes de haricot fournis par l\u2019Eastern and Central Africa Bean Research Network (ECABREN) et le National Dryland Farming Research Centre (NDFRC), Katumani au Kenya \ue9taient s\ue9par\ue9ment inocul\ue9s avec quarante-quatre races de P. griseola pour l\u2019\ue9valuation en serre du d\ue9veloppement de maladies. Les g\ue9notypes comprenaient de petits et gros grains de semences. Aucune des g\ue9notypes n\u2019\ue9tait r\ue9sistant \ue0 toutes les races de maladies, indicant ainsi une complexit\ue9 \ue9lev\ue9e de la population des pathog\ue8nes. Treize g\ue9notypes \ue9taient r\ue9sistants (\ue9chelle de cotation: 1 \ue0 3) ou mod\ue9r\ue9ment r\ue9sistants (\ue9chelle de cotation: 4 \ue0 6) sur au moins quarante de toutes les races. Les g\ue9notypes de haricot \ue0 petits grains ECAB 0754 et ECAB 0617 \ue9taient r\ue9sistants ou mod\ue9r\ue9ment r\ue9sistants \ue0 toutes les races \ue0 l\u2019exception de Mesoamerican race 33-39 et Afro-Andean race 58-18, respectivement. Le G\ue9notype ECAB 0754 avait manifest\ue9 un niveau \ue9lev\ue9 de r\ue9sistance, avec un taux moyen de s\ue9verit\ue9 de 1.1%. Tous les g\ue9notypes r\ue9sistants ou mod\ue9r\ue9ment r\ue9sistants \ue9taient de ceux \ue0 petits grains commercialement moins populaires. Les g\ue9notypes \ue0 gros grains commun\ue9ment cultiv\ue9s \ue9taient g\ue9n\ue9ralement susceptibles. Parmi les g\ue9notypes \ue9valu\ue9s, ceux \ue0 petits grains "pintos" et bruns/jaunes \ue9taient dot\ue9s des niveaux \ue9lev\ue9s de r\ue9sistance. Les r\ue9sultats de cette \ue9tude montrent que diff\ue9rents g\ue9notypes de haricot poss\ue8dent de niveaux diff\ue9rents de r\ue9sistance \ue0 la maladie de t\ue2che angulaire de la feuille pouvant \ueatre combin\ue9s par pyramidage pour d\ue9velopper une vari\ue9t\ue9 de haricot \ue0 r\ue9sistance durable