For further information contact: ciat-bean@cgiar.org

[Improved Small-seeded Middle American Bean Germplasm]
[Improved Large-seeded Andean Bean Germplasm]
[Strategies Developed for Management of Diseases and Pests]
[Improved Cultivars and Management Practices Developed and Tested]

Output 1: Improved Small-seeded Middle American Bean Germplasm with Less Dependence on Inputs

Drought Tolerance

• Drought-tolerant lines selected at the CIAT Palmira Experiment Station were tested in an international trial and the tolerance of several was confirmed.
• More than 160 crosses and 7500 F₁-derived F₂ families were evaluated for drought, identifying at least 15 elite crosses and 260 elite families.
• The superior performance of two bred lines (A 801 and SEA 5) and two landraces (Carioca and G 21212) under drought was shown as being associated with resistance to soil-borne pathogens and with an ability to mobilize photosynthates to developing grains and to use acquired N and P more efficiently for grain production.
• Field evaluation of recombinant inbred lines for drought resistance led to the identification of several lines that were superior to their parents. This superior performance was associated with low seed P content and high content of total nonstructural carbohydrates in seeds.

Resistance to Al and Mg Toxicities

• Two bred lines (MAM 46 and MAR 1) and two landraces (Carioca and G 92) were shown as being superior in their resistance to Al. This superior performance was related to greater concentrations of Ca and Mg in shoot tissues.
• A reliable screening method, based on shoot growth and leaf expansion, was used to identify Calima and G 21212 as landraces resistant to toxic levels of manganese.

Tolerance to Low P Soil

• Four genotypes (G 21212, MAM 38, 'Negro Cotaxtla 91', and VAX 2,) were shown as being superior in their tolerance of low P supply in soil. G 21212 was particularly outstanding in its ability to use P and N for grain production.

Resistance to Viruses

• The selection of the bgm-1 gene was applied to about 7000 individual plants in a single season, more than doubling the capacity to screen for this gene.
• The highest levels ever recorded of resistance to bean golden yellow mosaic virus (BGYMV) were observed in 2000-2001.
• The proportion of materials resistant to bean common mosaic virus (BCMV) has increased in the Andean Region. This trend, however, seems associated with the cultivation of more medium- and small-seeded bean cultivars in the Region, compared with the proportion of large-seeded beans currently managed by PROFRIZA (The Andean Bean Network).

Resistance to Fungal Pathogens

• Lines developed for angular leaf spot (ALS) resistance from multiple sources maintained their resistance at two different sites with contrasting isolates.
• Greenhouse evaluation of potential sources of ALS resulted in the identification of 12 accessions and two bred lines (AND 277 and RWR 222) as highly resistant to race 63-63.
• Ascochyta resistance and, possibly, anthracnose resistance has been transferred into snap-bean breeding lines, which can serve as future parental material.
• Nine genotypes combining tolerance to low fertility stress and resistance to Macrophomina phaseolina and Sclerotium rolfsii. were identified.
• Accessions G 2494, G 4495, G 6981, G 13778, and G 20592 were shown as being highly resistant to both M. phaseolina and S. rolfsii.

Resistance to Insect Pests

• New sources were identified for resistance to Thrips palmi, Empoasca kraemeri, Zabrotes subfasciatus, and Acanthoscelides obtectus.
• New lines, incorporating insect resistance, were selected.
• Initiation of studies on mechanisms of resistance to Thrips palmi.
• Progress made in developing molecular markers for resistance to Apion godmani.

Breeding for High-iron Contents in Bean Lines

• The high iron trait found in a wild bean was successfully transferred to cultivated beans through two cycles of backcrossing.

Output 2: Improved Large-seeded Andean Bean Germplasm with Less Dependence on Inputs

Breeding for Multiple-disease Resistance

• Resistance to common bacterial blight (CBB) and ALS was incorporated into advanced Andean breeding lines and tested in inoculated yield trials.
• Marker-assisted selection (MAS) was applied to introgress bean golden mosaic virus (BGMV) resistance genes into advanced breeding lines with red-mottled seed type.
• Popping beans (ñuñas) were crossed with anthracnose and BCMV resistance sources to develop new bush-type and climbing varieties of ñuñas.
• Forty-nine interspecific lines, derived from simple and complex crosses of Phaseolus vulgaris with P. coccineus or P. polyanthus, were shown to have combined high levels of resistance to anthracnose and ALS.

Resistance to Empoasca Leafhoppers

• New crosses were made to incorporate resistance to Empoasca spp. into red mottled beans for the Caribbean and other regions.

Evaluating Bean Classes

• Preliminary germplasm and advanced breeding-line nurseries for climbing beans were tested at two sites to evaluate yield components.
• Cream-mottled advanced lines were developed from multiple crosses.

Breeding for High-iron Contents

• Beans with higher iron contents were bred from advanced and recurrent backcrosses with a wild accession and a high-iron mapping population parent (donor parents, respectively).

Output 3: Strategies Developed for Management of Diseases and Pests in Bean-based Cropping Systems

Coevolution of Host-plant and Pathogen

• Pathotype diversity in the fungus Colletotrichum lindemuthianum was shown not to be congruent with common bean gene pools, thus revealing a lack of coevolution between the pathogen and common bean gene pools.
• Pathotype and genetic diversity for C. lindemuthianum was shown to be highest in Middle America. The Mesoamerican population contained all alleles found in the Andean population and other alleles, suggesting that this pathogen originated and was disseminated from this region.
• Twelve species of the fungal genus Pythium were found in association with common bean, although not all are pathogenic.

Pathogen Variation

• Eight loci specific markers developed in 2001 were shown to differentiate between Phaeoisariopsis griseola groups, while revealing geographical structuring and according to host gene pool.
• The use of sequence information of ribosomal genes showed that P. griseola is taxonomically close to Mycosphaerella spp. (anamorph Cercospora spp.) and Cladosporium fulvum.

Genetic Resistance to Diseases

• Resistance to ALS in the bred line MAR 1 was shown to be conditioned by a single dominant gene.
• A marker that segregated with the resistance gene in MAR 1 was identified.
• Resistance to CBB is very stable in VAX 6, and the fuscans strain of Xanthomonas campestris pv. phaseoli is highly pathogenic.
• Both dominant and recessive genes were shown to condition resistance to ALS. G 5686 and G 10909 have two dominant epistatic genes, 'Don Timoteo' has one dominant gene, while 'Montcalm' and 'Amendoim' have two recessive genes.
• The sources of resistance to whitefly-transmitted geminiviruses selected so far have been effective in controlling at least four different geminivirus species known to attack beans in Latin America.
• Yields can increase by as much as 64 percent with the use of resistant varieties and by 56 percent with tolerant varieties.

Other Means of Controlling Diseases

• A potential biocontrol agent (the fungus Pythium oligandrum) was identified from samples collected from bean roots.
• Identifying the "sterility" ("amachamiento" in Spanish) virus in beans led to the implementation of effective management control practices directed at the chrysomelid vectors of the virus.

Managing Thrips and Whiteflies

• An action threshold for Thrips palmi was validated on snap beans.
• Levels of resistance to insecticides in whitefly (Trialeurodes vaporariorum) and T. palmi populations were identified.
• IPM components and management strategies were developed and successfully tested for combined populations of whiteflies and thrips on snap beans.

Output 4: Improved Cultivars and Management Practices developed and Tested in Partnership with our African Bean Project, NARS, and Regional Networks

Adapting Technologies to Stresses

• The Costa Rican national program has selected many lines with commercial grain and tolerance of low soil fertility.
• Preliminary testing of climbing beans in Haiti shows that they can be adapted to the environment but require higher soil fertility.
• Several partners, including national agricultural research systems (NARS) and the CIAT Hillsides Project, are increasingly taking up drought research in Central America.
• Partners are evaluating a set of 19 genotypes for response to ALS.
• Partners are evaluating a set of 49 genotypes for their adaptation to abiotic constraints such as drought, Al toxicity, and low nutrient supply.

Varietal Development

• The Bean Team Nursery (VEF, its Spanish acronym) was revived, and specific traits were evaluated for more than 300 breeding lines and germplasm entries with the participation of the entire team.
• BAT 304 ('Brunca') and 'Tío Canela' were identified as very promising cultivars in Haiti.
• CIAT provided advanced Andean red-mottled breeding lines to Caribbean regional trial nurseries.
• Twelve varieties, developed from CIAT materials, were released during 2000 and 2001 in four countries.
• Access to CIAT's Bean Virology facilities makes possible the advancement of bean breeding materials for sub-Saharan Africa.

Training

• CIAT bean project scientists actively participate in international conferences and meetings.
• Individual training was given to national scientists.
• National and international scientists and students received individual and group training.

Other Activities

• An important project on bean genomics was approved to facilitate collaboration with national partners and with the Agropolis (The International Complex for Research and Higher Education in Agriculture, Montpellier, France).
• Continuous support was given to the breeding programs of PROFRIJOL (Programa Cooperativo Regional de Frijol para Centroamérica, México y el Caribe), the Andean Zone, African networks, and individual country programs.
• CIAT scientists participated in the planning of activities for PROFRIJOL, the Andean Zone, and African networks.
• Seed was distributed to all collaborating partners.
• Joint collaboration and concept notes were prepared.
• The Web Page for Project IP-1 was adapted for the new CIAT Web site.