by CIAT Comunicaciones | Aug 9, 2019

Figure: Using the genetic traits of a wild bean species, CIAT and the Crop Trust are breeding heat-tolerant common beans to benefit farmers in Latin America and Africa.

The challenge of a growing food demand in a changing climate has long driven the development of hardier bean varieties at the International Center for Tropical Agriculture (CIAT) based in Colombia. As part of a partnership with the Crop Trust-led Crop Wild Relatives Project (CWR), CIAT scientists are using conventional crop breeding techniques to transfer heat-tolerance traits from two wild types (accessions or samples) of tepary beans, or Phaseolus acutifolius, to commercial bean varieties, or Phaseolus vulgaris.

The effort will benefit smallholder farmers in Colombia, Honduras, and Mozambique, who will start evaluating the new pre-bred materials in early to mid-2020. The researchers will also identify molecular markers of the genes responsible for heat tolerance, which may generate critical knowledge for breeding staple crops for a hotter, drier, and more weather-uncertain world.

Common beans are vulnerable to higher temperatures and droughts. Future climate scenarios suggest certain bean-growing regions will be warmer, especially at night, which can severely impact yields. Globally, suitable areas for conventional bean varieties could decline 20–50 percent by 2050, according to the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS).

For beans to continue playing a major role in human diets, new varieties must adapt and thrive. Scientists believe crop wild relatives (CWR) are essential to meet this goal. Wild relatives have valuable genetic diversity that can be used to develop high-yielding crops that tolerate high temperatures, increased soil salinity, and harsher and more frequent pest and disease outbreaks.

The wealth of the genebank

Loss of wild landscapes has threatened the continued existence of many CWRs, which evolved over centuries and millennia to adapt to their particular climates. Fortunately, CIAT’s genebank has nearly 40,000 accessions (or samples) of beans, many of which are wild species. This rich collection is the starting point for plant breeders, farmers, and researchers around the world who are seeking climate-proofed bean varieties.

Scientists began this project by studying 300 bean types in the genebank, which yielded two wild tepary beans that have nighttime heat tolerance of 28°C and are native to Sonora, Mexico. “These wild beans grow in arid climates with very dry and high-temperature conditions,” said Gloria Mosquera, a CIAT scientist and project researcher.

Once they discovered the suitable accessions, breeders started teasing out the desired traits and introduced them into domesticated bean varieties.

“Working with wild, genetically distant relatives of cultivated beans is always challenging,” said Mosquera. But CIAT’s breeding program had already overcome some of the inherent challenges to crossing these bean species, and breeders harnessed intermediary hybrids with attractive features – such as yield and appearance – to accelerate the process of breeding the new varieties.

“If genes that provide heat tolerance are identified along with the molecular markers associated with them, breeding programs will be able to more easily transfer this tolerance to other bean varieties. This has the potential to shorten breeding cycles and save time and resources,” said Mosquera. “This could prove especially valuable to developing bean hybrids in other parts of Latin America and Africa that are expected to have hotter climates in the coming decades.”

Essential partners, global reach

The breeding programs at the Colombian Corporation for Agricultural Research (Agrosavia), Zamorano University (Honduras), and Mozambique’s Institute of Agricultural Research (IIAM) are project partners. These collaborators will receive the genetic material produced by CIAT to continue selecting potential bean varieties that can help farmers face heat-related challenges brought about by climate change. Research will also be done hand in hand with farmers, who are essential to determining if new materials meet the expectations of consumers.

“We want partners – and farmers – to make the most out of the material CIAT is transferring to them,” said Steve Beebe, the leader of the bean program at CIAT. “In the end, we hope to see the release of a variety that not only can survive higher temperatures, but also shows commercial appeal in terms of production and disease management, and, ultimately, improves the quality of life of smallholders.”

“The results of this project, including all selected advanced tepary-introgression lines, will be available to all breeding programs around the world,” said Benjamin Kilian, a senior scientist at the Crop Trust. “We are excited to be supporting CIAT scientists in their efforts to harness the use of wild relatives in helping adapt our agriculture to climate change.”

See https://blog.ciat.cgiar.org/heat-tolerant-wild-beans-tapped-to-breed-commercial-beans-for-hotter-climates/