Coffea arabica is native of Ethiopia, where the major genetic diversity of the species is found. Historians believe that coffee seeds were first taken from the coffee forests of Southwestern Ethiopia to Yemen, where it was cultivated as a crop.
A landrace is a domesticated, locally adapted, traditional variety of a species of animal or plant that has developed over time, through adaptation to its natural and cultural environment of agriculture and pastoralism, and due to isolation from other populations of the species.
In coffee, most landrace varieties originate from the forests of Ethiopia, where C. arabica evolved, through a process of human-led domestication. They are generally associated with very high cup quality and lower yields.
Bourbon and Typica Group
A small number of coffee trees taken out of Yemen beginning in the late 17th century form the basis of most worldwide arabica coffee production today, what we now call the “Bourbon and Typica genetic groups” (so-called because of the names of the famous Bourbon and Typica varieties which are the progenitors of this group). From Yemen, seeds were taken to India and then from India to the Indonesian island of Java by the Dutch, which gave rise to the “Typica” lineage (also called Arabigo or Indio). Typica plants were taken to conservatories in Europe and then spread across the American continent along colonial trade routes during the 18th century. Seeds were also introduced from Yemen to the island of Bourbon, which gave rise to the “Bourbon” lineage. The first Bourbon plants reached the American continent through Brazil after 1850. Both Typica and Bourbon plants were introduced to Africa in the 19th century through various routes. For a detailed history of how varieties in the Bourbon and Typica genetic group came to dominate global coffee production, see History of Bourbon and Typica.
These varieties are associated with standard or high cup quality, but are susceptible to the major coffee diseases. Today, coffee production in Latin America is still based to a large extent on cultivars developed from Typica and Bourbon varieties, contributing to a significant genetic bottleneck for C. arabica. It Brazil, which accounts for 40% of world production, 97.55% of coffee cultivars are derived from Typica and Bourbon.
Introgressed varieties are those that possess some genetic traits from another species—mainly, C. canephora (Robusta), but also sometimes C. liberica. (“Introgressed” means “brought over.”) In the 1920s, a C. arabica and a C. canephora plant on the island of East Timor sexually reproduced to create a new coffee now known as the Timor Hybrid. This Arabica variety contains Robusta genetic material that allowed the plant to resist coffee leaf rust. Coffee experts realized the value of this disease resistance and began using the Timor Hybrid in experiments to create new varieties that could resist leaf rust. They selected many different lines of Timor Hybrid, and then crossed them with other varieties, most commonly the high-yielding dwarf Arabica varieties Caturra and Villa Sarchi. These crosses (Timor Hybrid x Caturra, and Timor Hybrid x Villa Sarchi) led to the creation of the two main groups of introgressed Arabica varieties: Catimors and Sarchimors. It’s important to note that, contrary to common belief, neither Catimors nor Sarchimors are themselves distinct varieties. Instead, they are groups of many different distinct varieties with similar parentage. Other introgressed varieties, like Batian, were creating from complex multiple crosses involving the Timor Hybrid; RAB C15 is the only introgressed variety in this catalog that was not created using the Timor Hybrid—it originates from a controlled cross made by Indian breeders between C. canephora and the Arabica Kent variety. Many introgressed varieties are covered in this catalog. These varieties have traditionally been associated with lower cup quality than others, but they have been essential for coffee farmers for whom coffee leaf rust and coffee berry disease are a major threat.
A note about coffee leaf rust resistance
Coffee leaf rust is one of the most important threats to coffee production globally. Coffee rust is a disease caused by the fungus Hemileia vastatrix that causes defoliation and may result in severe crop losses.
The emergence in the late 20th century of introgressed arabica varieties that were resistant to coffee leaf rust provided key protection against crop loss for many coffee producers for nearly three decades. Starting in the early 21st century, coffee experts in Central America began to notice that some historically rust-resistant varieties were being infected by rust, notably, Lempira in Honduras and Costa Rica 95 in Costa Rica. Because most of the available introgressed varieties obtained their rust resistance via a shared parent (the Timor Hybrid), it is believed by most experts that most existing rust-resistant varieties will no longer be resistant in the near-to-medium term.
Data in the catalog about specific varieties rust resistance status is based on validated reports by scientific entities. Unfortunately, because the coffee sector is still in the very early phases of building a good global system for rust research, tracking rust outbreaks, and following the breakdown of resistance, it is not always easy to validate when a variety is being affected by rust. In addition, the impact of rust on a specific variety can be different in different geographies, and depending on the race of rust (something that is not easy to identify currently). The challenge is made greater because many farmers don’t know for certain what varieties they have; in such cases, reports of rust impacting a historically resistant variety have to be carefully checked to ensure that the plants being affected are indeed the supposed variety.
Even so, significant anecdotal evidence supports the conclusion that the breakdown of rust resistance is accelerating in many parts of the world, and World Coffee Research is working closely with research bodies in various countries to understand the impact.
World Coffee Research will update the resistance status of a variety in the following circumstances:
- The breeder of the variety has issued an official statement announcing the breakdown of resistance
- World Coffee Research has validated the appearance of rust on a historically resistant variety using DNA fingerprinting and consultation with the breeder (if there is one), and local experts.
Confirmation of the breakdown of resistance in one country does not necessarily mean that resistance is broken in all countries. Consequently, information will be provided about where resistance breakdowns have been confirmed.
Hybrids generally are offspring resulting from the crossing of two genetically distinct individuals. For the purposes of this catalog, “hybrids” refers to F1 hybrids, a new group of varieties created by crossing genetically distinct Arabica parents and using the first-generation offspring. Many of these relatively new varieties were created to combine the best characteristics of the two parents, including high cup quality, high yield, and disease resistance. F1 hybrids are notable because they tend to have significantly higher production than non-hybrids.
An important note about F1 hybrids
Seeds taken from F1 hybrid plants will not have the same characteristics as the parent plants. This is called “segregation” (see figure below). It means that the child plant will not look or behave the same as the parent, with potential losses of yield, disease resistance, quality, or other agronomic performance traits. The variety should only be reproduced through clonal propagation. It is therefore important for farmers to know that F1 hybrids seedlings should be purchased from trusted nurseries.