GCRF-BBR: Developing a hybrid bean collection to advance climate-ready bean breeding

Common bean (Phaseolus vulgaris L.) is the most important food legume in the human diet, providing protein, micronutrients and complex carbohydrates for >300 million people in the tropics. Climate change scenarios predict that heat/drought and pests and diseases will be major pressures on bean production in the future.

As with most major crops, and because of its domestication history, cultivated common bean lacks genetic diversity. Wild relatives can be used to introduce this diversity for key traits of interest, and in some cases have already been used successfully to provide novel sources of resistance to pests and diseases in beans. This is by no means an easy process, as producing the next generation of plants from these "wide crosses" is difficult, making it hard for breeding programs to make use of the opportunities offered by these wild plants. However, wide crosses occur naturally where farmers grow cultivated beans adjacent to wild populations, as happens across the natural range of beans from Mexico to Argentina.

A number of these naturally occurring cultivated-wild hybrids populations have already been collected from sites throughout Central and South America and are stored in the CIAT genebank. We will characterise plants from twenty hybrid populations for priority breeding traits linked to climate change e.g. pest and disease resistance, and heat and drought tolerance. We will explore their genomes and provide all of this information to the bean breeding and research communities in an accessible way, to help users select the most suitable plants for their purpose. We will hold workshops and demonstrations to make sure that breeders and researchers are aware of this resource and understand how best to make use of it.

By reducing the barriers to inclusion of wild plants into bean breeding programmes, we will help breeders to produce better beans in a shorter time, which will have a positive impact on global food security.

We will develop a detailed resource for a set of domesticated/wild hybrids of common bean (Phaseolus vulgaris L.) and its sister taxa of the same section of the genus, namely P. albescens, P. coccineus, P. costaricensis and P. dumosus which are conserved within CIAT's ex situ collection. We will genotype 200 individuals from across 20 populations collected where farmers grow cultivated beans adjacent to wild populations, revealing their genetic diversity and exploring the distribution of introgressions to search for patterns of selection. We will also phenotype these materials for priority breeding traits linked to climate-change predictions (resistance to diseases such as anthracnose, web blight and white mold; stomatal count and root angle for heat/drought) and characterise these materials for morpho-agronomic traits of interest and breeding traits such as crossability and adaptability.

All data will be made available via CIAT's Germinate instance currently under development for the Genetic Resources Program's web portal. We will also hold workshops to demonstrate the materials in the field and the data and software available.

Common bean (Phaseolus vulgaris L.) is the most important food legume in the human diet, providing protein, micronutrients and complex carbohydrates for >300 million people in the tropics. Breeding priorities linked to climate change are focused on heat and drought tolerance, and resistance to pest and disease pressures. Breeding climate-ready bean varieties would help increase yield and improve the welfare of communities dependent on this essential crop.

The direct beneficiaries from this project will be bean (pre)breeders and researchers, as they will have access to a detailed germplasm collection of naturally occurring cultivated/wild hybrids including sister taxa. This collection will be characterised to provide important information for breeders and researchers including detailed characterisation data focused on relevant traits such as morphology, crossability, environmental adaptation, stomatal count, root traits and resistance to a selection of important fungal diseases. These data will help breeders to determine which materials to include into their programmes. Researchers and breeders will also have access to genotypic information for these materials which will promote exploration of novel alleles in regions of interest and development of new markers. Breeders will be able to take advantage of improved materials for their breeding programmes, and improved varieties will benefit farmers and consumers through a more predictable supply.

Indirect beneficiaries include researchers in other crops, as this approach may serve as an exemplar for other species and their wild relatives. This data will also benefit researchers interested in exploring introgression patterns and mechanisms of speciation.

In the long term, common bean-growing regions will benefit as they face fewer losses associated with pests/diseases and heat/drought, in particular in Latin America and Africa. Increased yield of beans will improve food security and public health in the face of climate change. Reduced dependency on pesticides will also provide environmental benefits.

This programme will generate new opportunities for collaborative work between NIAB and CIAT. The proposed work will directly impact the local UK community with the generation of new jobs in the fields of pathology and computational biology. This collaboration will contribute to reinforce the UK's leadership in bioinformatics and genomics, translating this expertise into the breeding of an important pulse crop and having a positive impact on the global economy.