**4. A genetic source of resistance to FY**

The causal agent of FY is still unknown, but a possible genetic solution for this problem exists. This genetic solution resides upon the fact that the American oil palm (*Elaeis oleifera* (Kunth) Cortés) and the interspecific hybrids between this species and the African oil palm are considered resistant to this disease [47].

The genus *Elaeis* (from the Greek *Elaion* that means oil) belongs to the class Liliopsida (Monocotyledones), order Arecales (Palmales), family Arecaceae (Palmae), subfamily Arecoideae, tribe Cocoseae (Cocoinaea) and, subtribe Elaeidinae [48, 49]. This genus consists of two species, *E. guineensis* and *E. oleifera*, with a pantropical distribution and two distinct diversity centers, Nigeria and South America, respectively [50–52]. The former is the African oil palm, the predominant species in commercial plantations Worldwide, and known in Brazil as "Dendê"; and the latter is the American oil palm, which originated from Central and South America, and is known as "Caiaué" [53].

The American oil palm is endemic to Equatorial America, with natural populations distributed from Central America to northern South America, including the countries of Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Honduras, Mexico, Nicaragua, Panama, Peru, Suriname, and Venezuela [1]. In Surinam, there are dense stands on poor, sandy soil, while in Colombia, it can grow in damp or even swampy situations near or on the banks of rivers [1].

The American oil palm also has a history of use as a source of vegetable oils and other products, but its most important value to the oil palm industry is its capacity to hybridize with the African oil palm [1]. The interest in the germplasm of this species is due to valuable characteristics for breeding programs of the African oil palm, such as slow growth, oil quality (mainly unsaturated oil) [54], and disease resistance, including FY [47].

These two species can sexually cross and generate fertile interspecific hybrids with intermediate characteristics to the two parental species [55]. Some interspecific hybrids between these species are already commercially available, and the Brazilian genetic group of *E. oleifera* is parental to most of them — Manicoré (BRS Manicoré from Embrapa, and [Mangenot × Manicoré] × La Mé from PalmElit SAS), Manaus (Amazon from ASD Costa Rica), and Coari (Coari × La Mé, Coari × Yangambi) [47].

Independent whether the origin of FY is biotic or abiotic, or a combination of both, once it is finally known, new studies will be necessary to confirm this genetic resistance and gain insights on possible strategies to transfer this resistance to the African oil palm more efficiently and effectively, besides the use of interspecific crosses followed by backcrosses.
