Wild Cousins Boost Eggplant Breeding on Our Warming Planet
30 January 2022
The world’s farmers urgently need new crop varieties that are resilient to such results of climate change as droughts and outbreaks of new pests and diseases.
A team led by Jaime Prohens at the Universitat Politècnica de València in Spain set out to produce just such varieties through the Eggplant Pre-Breeding Project.
The team used wild relatives of eggplant—weedy cousins of the domesticated crop—to add new, useful traits to domesticated varieties so they can withstand a hotter, drier climate in Southeast Asia, sub-Saharan Africa and the Mediterranean Basin. The offspring of these crosses are now conserved in genebanks and available to eggplant breeders around the world.
The work was carried out as part of the Crop Wild Relatives Project, a global initiative supported by the Government of Norway and managed by the Crop Trust.
The Crop Trust spoke with Prohens about the project’s accomplishments, challenges and future.
What are you most proud of about this project?
We achieved what we set out to do, and more. Prior to this project, eggplant breeding had barely scratched the surface of the potential of crop wild relatives to develop new, resilient eggplants. But we need to adapt our agriculture to climate change to survive, so this work is incredibly important.
We grew a wide range of eggplant wild relatives under extreme conditions of heat and drought, and challenged them with pests and diseases to see which ones have the characteristics we’re looking for. I’m happy to say we found many that fit the bill.
In the end, we developed eggplants with the best characteristics of both the domesticated varieties and their wild cousins. Now, smallholder farmers growing eggplant in extreme drought can still feed their families. All this work gives breeders access to a completely unexplored new genepool.
What were some of the challenges you encountered?
Evaluating the plants under real farming conditions that mimic the stress caused by climate change was hard! How do you mimic high temperatures, drought stress and pest and disease pressure in a controlled but realistic way?
We grew the plants under very particular conditions, using mobile greenhouses to control precisely how much rainfall the plants received, and by planting in the dry season, when temperatures are higher and water availability is lower than during the wet season, when farmers usually plant this crop. These trials were conducted in Côte d’Ivoire and Sri Lanka to get a wider range of growing conditions.
What lessons did you learn?
One of the most important lessons is that when we crossed different species the amount of fruit produced—and hence the number of seeds—depended very much on the environmental conditions where the plants were growing.
This highlighted the value of a project like this one, with activities in several very different locations. It allowed us to produce more seeds of more hybrids than would have been possible if we were working at only one location. Some of the crosses we made had never been attempted before, which taught us a lot about the biology of the crop and its wild relatives.
How does all this benefit plant breeders and farmers?
This project provides the foundations for a revolution in eggplant breeding. We’ve made a huge amount of new eggplant diversity available and found plants with characteristics eggplant breeders need to produce tomorrow’s climate-resilient varieties. Drought tolerance and resistance to spider mites and to bacterial wilt are just some of the traits these plants have in their favor.
And, perhaps most importantly, this diversity is freely available through the Plant Treaty’s Standard Material Transfer Agreement, and the data from all evaluations and trials have been added to the publicly available Germinate eggplant database for easy access.
What surprised you?
The results exceeded all our expectations! We didn’t expect to be able to generate so many different eggplant crosses. We were even able to cross domesticated eggplants with a wild relative that diverged from their common ancestor almost 7 million years ago, an extraordinary feat because these plants are so distantly related. Imagine all the additional evolutionary history we now have access to. It’s amazing.
The Eggplant Pre-breeding Project, part of the Crop Trust’s Crop Wild Relatives Project, included partners from the Universitat Politècnica de València (Spain), Université Félix Houphouët-Boigny (Côte d’Ivoire), the University of Peradeniya (Sri Lanka) and the World Vegetable Center (Taiwan). Seven companies also collaborated on the project by testing the materials and evaluating their breeding potential for different traits.