Starmaya—the future of coffee?

In coffee as in other crops, F1 hybrids have the potential to combine traits that matter most to farmers—higher yields and disease resistance—with the trait that matters most to consumers—taste, a combination that has been difficult to attain in the past. But F1 hybrids are limited by a key constraint: Currently, they can only be produced by technically sophisticated nurseries, of which there are only a handful in the world. Therefore, although these varieties are “best in class,” almost no farmers have access to them. Starmaya may change that.

Limited availability of hybrids for farmers

Until now, the only way to efficiently reproduce F1 hybrids for farmers has been through clonal propagation, which must be done in laboratories. But there are few labs that produce coffee hybrids commercially in the world, and the cost can be double that of plants reproduced by seed. None of the existing labs produces more than 1 million seedlings per year.

Coffee is typically sold to farmers as seed. In crops like corn, F1 hybrid seeds are created through manual controlled pollination. This is not economically feasible in coffee due to the biology of the plant. In order to produce F1 hybrid seeds in coffee, you need a workaround. Researchers have identified that workaround—the inability of one parent to produce pollen (called male sterility). It led to the creation of Starmaya—the first F1 hybrid Arabica plant able to be propagated by seed.

Starmaya represents a major breakthrough in coffee breeding that suggests the main constraint on the widespread production of F1 hybrids for farmers around the world may soon fall away.

Advancing global research

World Coffee Research, whose global research agenda includes boosting the use of new technologies that benefit the coffee sector, will incorporate Starmaya into some of its research and trial programs. So far, Starmaya is the only F1 hybrid from seed. But researchers are actively looking for more varieties exhibiting male sterility that could be used in breeding.

The current landscape for coffee hybrids

Still, there are a small handful of F1 hybrid varieties in coffee, but because of the constraints on propagation, they are not widely available for farmers. The most prevalent is Centroamericano, a rust resistant, high yielding cross between Sarchimor T5296 and wild accession Rume Sudan with cupping scores that can exceed those of Caturra, the standard in the region. It was released in 2001 for farmers in Central America. It is estimated that it is planted on roughly 1000 hectares in the region. In breeding evaluations, it showed production increases of 22–47% over the parent varieties. Cupping scores ranged from 75-87 vs. 74-79 for Caturra (SCAA evaluation), and bean size is also superior to Caturra (ranged from 69-85 for Centroamerica vs 56-85% for Caturra).

The potential to scale up the use of hybrids in coffee through seed propagation made by possible by male-sterility is huge. A one-hectare seed garden for coffee is capable of producing enough seed for over 200 hectares of coffee. Currently, a coffee clonal propagation lab can produce only enough seedlings for 15 hectares of coffee. Seed gardens are substantially less expensive to build and maintain, and do not require the technical expertise that clonal propagation labs do. While it might in the future be possible to establish dozens or hundreds of hybrid seed gardens in the world, it’s unlikely that so many cloning labs would be created.

The increased size and vigor of hybrids between plant varieties and species had been known for centuries. But perhaps the most famous case of hybrids changing agricultural fates is that of maize, or corn. Since the advent of maize hybrids, which are substantially higher yielding that non-hybrids, maize production in the Unites States has increased six-fold over the last 60 years. It’s estimated that about half that gain is due to the genetic progress created by the introduction of hybrids.

World Coffee Research believes that hybrids hold great promise to advance the coffee industry through genetic progress. But for that progress to be realized, it must become both easier and cheaper to get hybrids into the hands of coffee farmers around the world. The creation of Starmaya is a signal that the future may be close at hand. There are also risks for smallholders of using F1 hybrids, especially of those farmers are used to saving their own seed (F1 seed should never be saved).

The science behind F1 hybrids through seed

As early as 1998, coffee breeders recognized that it would be theoretically possible to propagate F1 hybrids via seed if one of the parent plants were sterile. If you place two different fertile coffee varieties—your desired hybrid Mother and Father varieties—together in a typical field of coffee, the offspring would be all over the place. Some offspring would be the result of Mother to Mother crossing (resulting in offspring that look like the Mother), some Father to Father (offspring like the Father), and only some would be Mother to Father (offspring hybrids of the two). This is obviously an inefficient way to produce hybrid seed.

However, if one of the varieties in the field is sterile (meaning it does not produce pollen), then any offspring (e.g., coffee cherries, the product of sexual reproduction of the Mother and Father) that appear on male sterile plants must be hybrids between Mother x Father. Wind or pollinators would carry the pollen from the pollen-producing variety onto the sterile variety, and the resulting cherries would necessarily be hybrids. The challenge was to find a naturally male sterile plant that could be a suitable breeding parent.

In 2001, researchers from CIRAD collaborating in a public-private coffee breeding project with ECOM, noticed a male-sterile Arabica plant at the CATIE germplasm bank for coffee in Costa Rica. Breeders crossed it with Marsellesa, a newer-generation rust-resistant variety (Timor Hybrid 832/2 x Villa Sarchi CIFC 971/10). After observing good performance in field trials in Nicaragua, ECOM decided to release the variety, calling it Starmaya.