A bridge for food crops
The Crop Trust’s Pre-breeding Project links genebanks and breeding programs to develop greater diversity in crop plants.
The World Vegetable Center invited partners from the Crop Trust’s Eggplant and Carrot Pre-breeding Project teams to meet and discuss their progress at WorldVeg headquarters from 2-5 July 2018.
Through pre-breeding, researchers strive to identify desirable traits and genes of interest in wild relatives of cultivated crops, and make crosses to ensure the traits and genes are incorporated into intermediate breeding lines. Those lines then can be used by plant breeders to improve crops for the benefit of farmers and consumers.
Project participants from Bangladesh, Côte d’Ivoire, Sri Lanka, Spain, USA and Taiwan, and representatives from seed companies in France and Thailand reviewed their pre-breeding activities to expand the number and availability of traits, particularly for adaptation to climate change.
“Many crop wild relatives never participated in the domestication process,” said Dr. Jaime Prohens from the Universitat Politècnica de València and leader for Spain’s eggplant pre-breeding activities. “They are the sources for adaptation to climate change and other challenges we face in agriculture.”
The Crop Trust—the global organization that operates the Svalbard Seed Vault and conserves crop diversity to protect global food security—currently sponsors 19 pre-breeding projects, including eggplant and carrot.
Linking genebanks and breeding
All the food crops we produce were developed by selection and breeding for specific characteristics. Maybe farmers wanted a taller cornstalk for easier harvesting, or consumers preferred a rounder, firmer eggplant. In securing those qualities, however, other important properties such as drought tolerance or resistance to a particular pest were “lost” or bred out of many cultivated crops, narrowing their genetic makeup.
Wild relatives of cultivated crops carry important genes: for heat tolerance, resistance to disease, high levels of specific nutrients, color, taste, shape—even traits we may not yet be aware of.
The trick is getting that vast genetic diversity into the hands of plant breeders.
“Genebanks and breeding programs collaborate in pre-breeding,” said Dr. Mohamed Rakha, WorldVeg vegetable breeder. “Each brings something important to the table.”
Genebanks hold many different variations of crop traits farmers still use. They also conserve traits farmers no longer require, traits never previously used by farmers, or traits that have not yet been discovered.
“New diseases are likely to occur as climates change,” said Dr. Philipp Simon, leader of the Carrot Team from the United States Department of Agriculture and the University of Wisconsin – Madison. “And crop wild relatives may have the traits for resistance.”
But this diverse pool of genetic material may never be used in breeding programs to improve crops. There are several reasons why: Some accessions have narrow environmental niches or are unsuitable for agronomic needs. Adequate quantities of seed may not available in a timely manner. And without accurate documentation and descriptions of an accession’s characteristics for breeders to consult, the value of a genebank collection to breeders is greatly diminished.
Working with accessions directly from a genebank can be challenging for breeders. Pre-breeding efforts to do the early work of trait selection, providing breeders with better and more diverse materials to develop crop improvements.
“Pre-breeding is the essential step in increasing the diversity of specific cultivated material,” said Benjamin Kilian, plant genetic resource scientist at the Crop Trust. “It contributes to the resilience of our production systems by ensuring cultivated crops can adapt to dynamic climatic conditions and changes in the range and intensity of common pests and diseases, or even new pests and diseases.”
Story and photos: Maureen Mecozzi
Experimenting with eggplant
On 4 July, the Crop Trust Eggplant and Carrot teams visited an extraordinary eggplant farmer, Mr. Zhang Wen-jun, in Pu-xin, central Taiwan.
Mr. Zhang is the second of three generations producing this valuable crop for local markets around Changhua and Taichung, and beyond to Taipei. Decades ago, when the senior Mr. Zhang began growing eggplant, he set out his seedlings in rows and didn’t prune the plants. The dense stands of leaves didn’t allow for good air circulation or let in enough sunlight—or produce good yields.
After experimenting with different staking and pruning methods, father and son developed a “V”-shaped support for their eggplant crop. Each plant—pruned to just one main stalk and two stems, with only one eggplant fruit per node—thrives in the light and airy structure.
Now Mr. Zhang #2 and his son harvest 500 kg of eggplant daily from the family’s three 1-hectare fields.
The family produces ‘Maji’, a local favorite with an elongated shape. The fruits can be 45 cm or longer. In summer, consumers want eggplant with dark purple skin, Mr. Zhang told the group. In winter, they prefer lighter purple skin. He plants twice a year, in March and November, regularly rotates the crop, and follows a three-time field flooding-and-drying regimen in October to help control diseases.