In collaboration with Drs. Susan Nchimbi and Paul Kusolwa, Sokoine University, single plant selections were completed from 35 PIC populations and a number of trials were evaluated in Arusha and Mbeya, Tanzania from 6/07 to 6/13/2015.

Single plant selections from 35 PIC populations were completed at Selian (Arusha; left photo) and at Uyole (Mbeya; right photo) Stations.

Evaluation of the ADP

A subset of 47 lines from the ADP population, that performed well in 2014, were evaluated at the Selian Station in Arusha for white mold; and in Mbeya for rust, angular leaf spot and vigor. This ADP subset was replicated three times. The average score for ALS was 5.7, and for rust and vigor were 3.9 and 3.0, respectively, in Mbeya. Tanzanian breeding lines were identified with potential for release.

Evaluation of the Durango Diversity Panel

Two hundred pinto, pink, small/medium red, and great northern lines and cultivars were evaluated in Arusha and Mbeya, for reaction to rust, white mold, angular leaf spot and adaptation. The full range of response was seen for each disease, from very susceptible to resistant, and good production potential was noted for some genotypes at both sites. Much of the germplasm in this panel was well adapted to both environments. Openness to seed types in Tanzania may create an opportunity for pinto and great northern market classes, while the small red class is already an acceptable market class.

 Single Plant Selection from PIC populations

Single plant selections from 35 PIC populations were completed at Selian (Arusha; left photo) and at Uyole (Mbeya; right photo) Stations. About 600 selections were completed. Plant rows of selections from 2014 from the PIC-005 population, Canada (ADP-0010) x CAL 143, and from the PIC-003 population, Kilombero (ADP-0004) x AND 277 population, showed no disease in Arusha and were evaluated for rust and angular leaf spot in Mbeya. These lines show promise for future release.

Through coordination by James Bokosi (Bunda College), 35 PIC populations were grown at three sites in Malawi:

1. Dedza District – (Bembeke Research Station) which is well known for heavy disease pressure and degraded, low fertility soils (low N, P and pH);
2. Bunda College Farm—which was fertilized but was experiencing drought conditions;
3. Bvumbwe—which exhibited the best growing conditions but suffered disease pressure.

The 35 populations were developed from crosses between ADP lines with superior performance across different countries and stress conditions and a list of them is available on the ARS-FtF website http://arsftfbean.uprm.edu/bean/?page_id=2

Plants were selected based on agronomic performance and tolerance to biotic and abiotic stresses in the field without regard to seed types. The F5 seed from each individual F4 plant will be planted as F5 plant rows in the off-season in order to obtain enough seed for thorough evaluation and selection among these fixed breeding lines during the next growing season in Malawi in 2016. It is expected after sorting based on seed shape and color that about 500 F5 lines will be selected.

Local common bean market classes present at a road-side stand in Malawi

Evaluation of the ADP

A subset of the ADP population consisting of 40 lines was evaluated at two locations: Bunda College Farm and at Bvumbwe Research Station. The African landraces Kiangwe, Kasukany, Kokola, and Kablanketi Ndefu stood out and a few lines from N. America performed well: Silver Cloud, VA19, and Pink Panther. Poor plant stand was observed for 30% of the plots and appeared to be due to a field effect not genotype. Good stand establishment for all of the ADP and PIC materials at Bvumbwe site indicated that the seed source from S. Africa had good germination quality. Drought was the prevailing stress at Bunda.

National Bean Trials

The Bunda National Bean Trials consisted of 16 entries which included 15 advanced lines and one common check Kalima (CAL 143). The lines were a mix of Andean and Middle American lines and a variety of seed types including black, small red, carioca, brown, sugar cranberry, large red and red mottled. The trials were planted at three research stations and three on-farm trials: Dedza District, Champhira, and Kukuluma. The Middle American materials outperformed the Andean lines at all sites, but a few Andean lines showed promise.

A simple cart was constructed from the design of White and Conley (2013) (https://www.crops.org/publications/cs/pdfs/53/4/1646) in Mayaguez, Puerto Rico for the Climate-Resilient Bean project. The original cart was designed at the USDA-ARS, U.S. Arid-Land Agricultural Research Center in Maricopa, Arizona. The design was modified to include a steering mechanism for the back tires in order to facilitate turning the cart in the field (photos below). The cart was designed to be able to cover two rows of common bean, while the distance between the tires can be adjusted for different row widths and for transport in the back of a standard pick-up truck.

The cart is being used for the collection of canopy temperature, plant height, leaf area, and GPS location data from field plots related to a Feed the Future Bean Innovation Lab for Climate-Resilient Beans (http://www.feedthefuture.gov/article/feed-future-innovation-labs). This research aims at identifying mechanisms associated with abiotic stress tolerance in common bean.

The design of the field data collection cart includes a bar for turning the wheels of two bicycles to facilitate movement through the field. Computer, GPS, sensors, and datalogger equipment are mounted on the cart for the collection of field data (as per White and Conley, 2013).

White, J. W. and Conley M. M. 2013. A flexible, low-cost cart for proximal sensing. Crop Science 53:1646-1649.

This study examined the nodulation characteristics of 400 lines from the Andean Diversity Panel (ADP). Inoculation with Rhizobium tropici strain CIAT 899 and Rhizobium etli CIAT 632 was carried out in a screenhouse using pasteurized sand in benches. Ten seeds per cultivar/line were sown from each line after surface disinfection with 10% bleach, followed by rinses with sterile water. The Rhizobium strains were grown individually in a Yeast Mannitol Broth Media.  Five days after sowing the seedlings, they were inoculated with 1 ml of 1 x 10⁹ rhizobia cells/ml. Rhizobia counts were conducted with a hematocytometer and the estimation of the viable rhizobia cells was carried out in Yeast Mannitol Agar using the drop plate method. The inoculation consisted of applying 1 ml of the Rhizobium broth culture of each strain separately onto the stem of each seedling. Cultivar Verano was included as a local check with each group of ten lines evaluated in sequential plantings. Nodulation was evaluated 12 days after inoculation by counting the nodules in the upper 3 cm of the roots and the location of the upper-most nodule (UMN) was measured in cm.  In the combined analysis for both Rhizobium strains, the results showed contrasting results in nodule numbers resulting from the inoculation with R. tropici and R. etli with 134 different ADP lines (Figure 1). Lines that formed the greatest number of nodules 12 days after inoculation in the upper 3 cm of the root are shown in contrast with ADP lines that had the lowest number of nodules (Figure 1).

Even though all 134 ADP lines nodulated with both strains, significant differences (P > 0.05) were found between Rhizobium tropici and Rhizobium etli in the number of nodules produced by each strain (Figure 2). The 134 ADP lines produced the highest number of nodules with Rhizobium etli. These findings are particularly important since reports indicate that Andean genotypes prefer R. etli over R. tropici. However, from the 134 ADP lines, ADP-390, 456 and 514 nodulated better with R. tropici than with R. etli. The outstanding lines for overall nodulation were ADP-186, 225, 302, 368, 390, 444, 456, 477 and 514.

Luseko Chilagane working with Ana Vargas at the ARS in Mayaguez, Puerto Rico.

Luseko Chilagane, PhD student in Dr. Susan Nchimbi’s program at Sokoine U. in Morogoro, Tanzania completed a workshop on biological nitrogen fixation at the U. of Puerto Rico in collaboration with Dr. Consuelo Estevez de Jensen and worked on collaborative research on Angular Leaf Spot (ALS) at the ARS in Mayaguez, Puerto Rico. ALS is a widespread disease in Southern and Eastern African common bean production zones, and a critical constraint to common bean production there and in Latin America. Luseko Chilagane and Luz Miryam Serrato, a PhD student at the U. of Puerto Rico researching ALS, worked on PCR amplification and sequencing of specific loci from ALS isolates collected in both Puerto Rico and Tanzania. This diversity analysis will yield important information regarding ALS variability and the corresponding response in common bean.

Arusha, Mbeya, and Morogoro, Tanzania (6/09-6/15/2014)

Cooperative nurseries were coordinated between the Sokoine University and the ARS-FtF project at three sites in Tanzania. The ADP population (192 lines) was evaluated in collaboration with Susan Nchimbi and Paul Kusolwa at the Selian Station in Arusha for Ascochyta blight and Rust; at the Uyole Station in Mbeya for Acochyta Blight and Rust; and at the Mafiga Station in Morogoro for Agronomic performance. The analysis of the data showed good correlation, 0.75 and 0.72 for Rust and Ascochyta, respectively, between Arusha and Mbeya. This is the first evaluation of the ADP where consistent Ascochyta Blight pressure was present from natural infection, allowing for the evaluation of this important disease. Interestingly, there was little correlation between rust in the ADP in Tanzania during this evaluation and rust data collected from the ADP in South Africa in 2014, indicating a difference in the rust complex between the two sites. This geographic variability in the rust pathogen and potentially other pathogens such as Angular leaf spot (ALS), highlights the importance of multi-site trials. No fertilizer was applied at these sites, while residual fertility was noted in the non-nodulating controls in Mbeya and Morogoro. The potential yield, vigor, and overall plant development was superior at the Mbeya, Uyole Station. The prevalent disease at all sites was Ascochyta blight and Rust, while ALS incidence was low.

Data collection in Mbeya, Tanzania

Ascochyta blight

Single Plant Selection from PIC populations

The two PIC (Phaseolus Improvement Cooperative) populations evaluated at the three sites in Tanzania represent the first collaborative selection of F4 plants from bulk populations as a part of the FtF project in Africa (information about these populations is on this website). The parents of these two populations were identified as superior lines from the ADP. The PIC-005 population, Canada (ADP-0010) x CAL 143 (ADP-526), showed superior disease resistance to the PIC-003 population, Kilombero (ADP-0004) x AND 277 (ADP-553), thus most selections were made in the former population at all three sites.

About 5-15 selections were made (using ribbons tied to main stem to identify plants, photos below) from each 8 row plot for disease resistance, yield potential, and agronomic performance. The selected lines showed superior disease resistance and agronomic performance as compared to most of the ADP lines evaluated at each site, and thus shows the potential for accelerated breeding progress using this approach.

ARS collaborators in Potchefstroom at Halo blight field trial (left). Dr. Deidre Fourie with halo blight trial in the greenhouse in Potchefstroom (right).

The 2014 ADP nursery, comprised of 410 entries and three replications, was planted under field conditions in Potchefstroom and Cedara, and in the greenhouse in Potchefstroom, by Dr. Deidre Fourie of the South African Agriculture Research Counil (ARC). The ADP nursery in Potchefstroom was inoculated with race 6 of the halo blight (HB) pathogen. HB is a serious disease of common bean in many countries of Eastern and Southern Africa. Race 6 is important because it overcomes all HB monogenic resistance ‘R’ genes. The HB disease in Potchefstroom in 2014 was consistently distributed throughout the entire field with many entries displaying high levels of HB severity (susceptibility) and some entries with resistance to HB. Thus, this was an excellent nursery for HB resistance screening. The most significant finding was the identification of 29 ADP entries with resistance to HB. Any ADP accession with resistance to HB at Potchefstroom is a potential new source of HB resistance to race 6.

These findings form a foundation of genotype response data that can be used for the development of Andean bean cultivars with resistance to HB in Africa and other locations worldwide. These findings also provide a base for additional studies of the HB disease. The ADP entries planted at Cedara exhibited a broad range of response to rust and angular leaf spot (ALS) diseases. Both diseases, that are widespread and economically important in Africa, occur naturally at Cedara. The reaction of known cultivars at Cedara indicated that 2014 was also an excellent year for rust and ALS resistance screening.

Dr. Fourie showing ADP collection in AFC cold storage unit in Potchefstroom (left). Collaborators discussing angular leaf spot ratings in Cedara (right).

A total of 89 ADP entries were identified as resistant to ALS and 84 ADP entries as resistant to rust. Moreover, a total of 42 entries were resistant to both diseases. Equally important, of the 84 entries with resistance to rust at Cedara in 2014, 29 entries were also resistant to rust at Cedara in 2013. It was interesting and important that the six Mesoamerican ALS differential cultivars were highly resistant to rust and ALS at Cedara in 2014. Conversely, all six Andean ALS differential cultivars were either susceptible to rust and ALS in 2014 or had at least intermediate levels of severity to both diseases.

These results, as observed at Cedara in previous years, suggest that Andean cultivars in South Africa and other countries of Eastern Africa, are much more likely to be susceptible to ALS and rust, while the Mesoamerican cultivars are more likely to be resistant to both diseases. These results also suggest that the isolates of the ALS and rust pathogens present in the field at Cedara co-evolved with bean primarily of Andean origin since they generally infect Andean bean cultivars, but not Mesoamerican beans. Similar results are likely to be observed for rust, angular leaf spot, and anthracnose in other countries of Eastern and Southern Africa, where Andean beans predominate.

The ADP cultivars with resistance to rust and ALS are important candidates for further rust evaluation to determine if they harbor new Andean disease resistance genes that can be used to broaden the genetic base of common bean for resistance to highly variable pathogens. Finally, one of the most important discoveries of the evaluation in Potchefstroom and Cedara is the identification of 15 cultivars with resistance to the three diseases, HB, ALS, and rust.

Dry beans (Phaseolus vulgaris L) are a nutrient dense, low cost food and therefore are an excellent value for consumers (Drewnowski and Rehm, 2013). In spite of this value, long cooking times limit bean consumption. This is true in developing countries where cooking fuel is sometimes scarce and in developed countries where consumers don’t have time to invest in cooking (Brouwer. et al. 1989). Understanding the genetic variability for cooking time in beans would help efficiently breed fast cooking bean varieties. The objective of this study was to evaluate the cooking time of a panel of Andean bean lines from diverse market classes and seed types important in major bean growing and consuming regions of Africa and the Americas.

Modified Mattson-type cooker (left). Technician measuring cooking times (right)

Materials and Methods: A subset of 250 bean lines of the Andean Diversity Panel (ADP) was grown in 2012 at the Montcalm Research Farm in Entrican, MI. Two replications were planted per entry in a randomized complete block design. The cooking time of each entry was then determined using a modified Mattson-type cooker (Mattson 1946) on 25 pre-soaked bean seeds in DI water for 12 hrs. Weight differences between raw and soaked seeds were measured to determine water uptake. The optimum cooking time was recorded as the time it takes for 80% of the plungers to pierce the seeds (Wang, 2005).

Figure1: Range in cooking time of 250 bean genotypes grouped by seed type. Numbers in parentheses represent how many of genotypes in each market class. The black line in each bar indicates the mean cooking time of the samples.

Results and Discussion: Cooking data was collected on 250 bean genotypes representing diverse Andean germplasm from eight major market classes. The cooking time ranged from 17 min to 90 min and the fastest and slowest cooking beans were both cranberry types (Figure 1). As a group, the white beans were the fastest cooking and also had the least amount of diversity for range of cooking time. This diversity analysis will be useful to identify parental materials, to understand the genetics control of cooking time, and to breed fast cooking beans in diverse Andean market classes.

References: Brouwer I. et al. 1989. Nutritional impacts of an increasing fuelwood shortage in rural households in developing countries. Progress Food Nutr. Sci13:349-361.

Drewnowski A, Rehm C. 2013 Vegetable Cost Metrics Show That Potatoes and Beans Provide Most Nutrients Per Penny. PLoS One 8(5): e63277.

Mattson S. 1946. The cookability of yellow peas. Acta Agric Scand 2: 185-191.

Wang, N. and Daun, J. K. 2005. Determination of cooking times of pulses using an automated Mattson cooker apparatus. J. Sci. Food Agric., 85:1631–1635.

With global climate change, abiotic stresses are receiving considerable attention by plant breeders as there is an immediate need for improving drought and heat tolerance in crops throughout the world. Dry bean is a major source of protein consumed by the poor and an important source of iron, folate, and other nutrients needed by the human body. Though significant contributions of improved germplasm have been identified, highly productive and abiotic/biotic stress tolerant common bean varieties are needed in Africa in order to increase production and thereby improve nutrition.

Diversity panels can provide a broad range of germplasm and aid in the exploitation of genes underlying complex traits, such as drought. In this study, the Andean diversity panel (ADP) was evaluated at the Agricultural Research Institute of Mozambique (IIAM) Sussendenga, Mozambique Station in a collaborative research effort with Dr. Magalhaes Miguel (IIAM).

Processing of common bean plants for shovelomics root trait data collection in Sussendenga, Mozambique

There is a high genotype by environment interaction for complex traits like drought tolerance and observing lines in different locations is of primary importance. In Sussendenga, Mozambique, root traits were characterized, including: basal root angle, basal whorl number, basal root number, number of adventitious roots, stem diameter, tap root diameter, and nodule and disease ratings were collected on 287 lines in two replications by Jennifer Trapp (USDA-ARS), Karen Cichy (USDA-ARS), and Jimmy Burridge (Pennsylvania State University). This data will be analyzed by association mapping using SNP data generated by Dr. Perry Cregan, USDA-ARS, using the BeanCAP SNP chip.

A subset from the 287 lines was grown in a field trial in Othello, WA to further characterize these lines under drought stress. A total of 31 lines were grown in both locations and combined for root trait analysis. Six of the 8 traits analyzed showed significant differences among lines and a correlation was computed between Sussendenga and Othello for those significant traits (Table 1). The high correlation for tap diameter, basal root whorl number, and stem diameter indicate potentially heritable traits that could be useful for plant breeders given further evidence for their association with additional desirable traits.

Table 1. Correlation values for root traits between Sussendenga, Mozambique and Othello, WA.

BROAD SPECTRUM RESISTANCE TO DRY BEAN RUST DISEASE DISCOVERED IN AFRICAN LANDRACE CULTIVARS

Dry edible bean production provides a banquet for fungal pathogens to feast upon. Small-holder subsistence farmers in poorer countries suffer the most from these uninvited guests, because they cannot afford fungicides or other technologies, such as disease resistance, to combat the pathogens. The major fungal diseases plaguing dry bean producers in Sub-Saharan Africa and worldwide are rust, angular leaf spot, anthracnose, and root rots. Our aim is to provide resource poor farmers with dry bean cultivars harboring resistance to one or more of the prevalent bean diseases that negatively affect their livelihoods.

One focus of our Feed the Future Grain Legumes Project has been to evaluate a large panel of accessions for resistance to the aforementioned diseases. The panel consists of old landraces and new cultivars representing the large seeded ‘Andean’ bean types produced around the world. Large-seeded beans are the preferred type in Africa. The greatest progress made thus far has been in the identification of broad spectrum resistance to rust in large seeded landrace cultivars that originate from Tanzania. These landraces, with confirmed resistance in field trials in Africa and the US, provide breeders with a valuable source of rust resistance for improving large-seeded African cultivars used by small-holder farmers. Another set of materials with broad spectrum resistance to rust was found within lines from the Ecuadorian National Program (INIAP), through work conducted in collaboration with the Feed the Future Legume Innovation Lab USAID project.

The identification of dry bean accessions with broad spectrum resistance to rust disease is an exciting discovery. Our project has already initiated crosses with these materials to transfer the resistance into other susceptible cultivars and dry bean market classes (yellow, red mottled, white, tan, etc.) for small-holder farmers in Sub-Saharan Africa.

Broad spectrum resistance to the devastating bean rust disease in Africa. Photograph A compares a Tanzanian landrace with broad spectrum resistance (left) to a susceptible accession (right). Notice the reduced biomass and vigor of the susceptible line. Photograph B shows typical rust symptoms, including necrotic leaf spots and fungal pustules, on susceptible dry bean leaves. Both images are from the Cedara Agricultural Research Station, Kwazulu Natal Province, South Africa. (Photo credits: Talo Pastor-Corrales, USDA-ARS Beltsville; 2013)