World Coffee Research has released the results of a study involving coffee researchers and collaborators from 15 countries at 23 sites into the responses of different Arabica varieties to coffee leaf rust (CLR).
CLR is caused by the fungus Hemileia vastatrix and can cause defoliation, reduced bean quality, and yield losses ranging from 35 per cent to more than 75 per cent. It is present in almost all coffee-growing regions.
The new study was published in Frontiers in Plant Science, with World Coffee Research Scientific Director Dr Tania Humphrey labelling it the most extensive evaluation of Arabica coffee varieties under diverse environmental conditions to date.
“No single country or institution can solve the complex challenges facing coffee on its own. This trial shows the power of global collaboration – by pooling data, expertise, and resources across continents, we’re able to generate insights no single program alone could uncover,” says Dr Humphrey.
“It’s a model not just for coffee, but for how agricultural science must evolve to meet the demands of a changing world.”
The International Multilocation Variety Trial (IMLVT) was established by World Coffee Research and partner institutions in 2015 and placed 31 Arabica coffee varieties from 11 breeding programs worldwide into 29 research plots in 18 countries.
For the CLR study, a subset of data from the global trial network was analysed based on data availability and quality. Data from 23 of the 29 original sites in 15 of 18 network countries was used, and performance of 29 of the 31 varieties was analysed.
The trial sites captured a range of climate conditions, from hot and dry sites in Zambia to cooler, wetter sites in Indonesia.
“The enormous global collaboration behind this study allowed the identification of varieties and their genetic backgrounds that perform well under local conditions, across macro-environments, and globally,” says WCR Research Scientist for Plant Breeding & Genomics Dr Jorge C. Berny Mier y Teran.
“Although further research is needed to understand the genetic basis of the resistance and its interaction with the environment, our results allow breeding programs to narrow down on useful variation and inform breeding strategies.”
No varieties in the study were found to be fully immune to CLR, but some showed high resistance across multiple sites.
It was found Parainema, Kartila 1, and IPR107 offered a promising balance of high resistance to CLR and stable performance across environments, while other varietals like EC16 and Catigua MG2 showed very high resistance in some sites, but did not show stable performance across all sites.
Varieties with pure Arabica backgrounds generally showed higher susceptibility, while those with interspecific introgressions, such as Timor hybrid derivatives, showed greater resistance.
CENFROCAFE, a Peruvian cooperative representing 2800 coffee-growing families, hosted one of the global network sites. Agricultural Manager Albertino Meza Ojedas says it is important to effectively pass on this knowledge to farmers to improve their futures in the industry.
“Understanding rust can be complex for farmers. By identifying which varieties really work against rust in real-world conditions, this research gives farmers better tools to sustain their crops, their incomes, their dignified life, and their future,” says Ojedas.
“It’s an honour to participate in this global study that brings together scientists from around the world to solve a shared problem.”
Full results from the study can be found here.
