Detection and diagnosis of viruses infecting African and American
oil palms (Elaeis guineensis and E. oleifera)
1Francisco J. Morales, 1Iván Lozano, 1Mauricio Castaño, 1José Arroyave, 2Eduardo Peña, 1Cristian Olaya and 1Ana K. Martínez
1Virology Research Unit, International Center for tropical Agriculture(CIAT); 2Corporacion Colombiana de Investigación Agropecuaria (CORPOICA)
1 2
Abstract: African oil palm is one of the most important crops in the Tropics, as an essential oil in the diet of West Africans, as an industrial ingredient in many
Abstract: African oil palm is one of the most important crops in the Tropics, as an essential oil in the diet of West Africans, as an industrial ingredient in many
commercial products (e.g. soaps, cosmetics), and as aapromising bio-fuel. In Latin America, Colombia, Ecuador, Costa Rica and Brazil are the main producers of this
commercial products (e.g. soaps, cosmetics), and as promising bio-fuel. In Latin America, Colombia, Ecuador, Costa Rica and Brazil are the main producers of this
commodity. However, this crop is affected by viral diseases that either kill or force the destruction of young infected palms at the nursery stage. The Virology
commodity. However, this crop is affected by viral diseases that either kill or force the destruction of young infected palms at the nursery stage. The Virology
Research Unit of CIAT has characterized the only two viruses known in the world, responsible for the viral diseases known as ‘ringspot’ and ‘chlorotic mottle’. The
Research Unit of CIAT has characterized the only two viruses known in the world, responsible for the viral diseases known as ‘ringspot’ and ‘chlorotic mottle’. The
molecular characterization of these viruses, and particularly the African oil palm ringspot virus, has allowed the development and implementation of highly sensitive
molecular characterization of these viruses, and particularly the African oil palm ringspot virus, has allowed the development and implementation of highly sensitive
techniques for the detection and identification of these viruses in symptomless and symptomatic nursery and plantation oil palms. The RT-PCR and ELISA techniques
techniques for the detection and identification of these viruses in symptomless and symptomatic nursery and plantation oil palms. The RT-PCR and ELISA techniques
are currently available to detect these viruses in infected planting material, thus, avoiding the loss of young African and American oil palms in the plantation.
are currently available to detect these viruses in infected planting material, thus, avoiding the loss of young African and American oil palms in the plantation.
Introduction Plant virus detection
The African oil palm (Elaeis guineensis) is an economically The RT-PCR assay was tested using virus-infected oil palm tissue
important agricultural commodity that provides 30% of all the from the municipality of Tumaco, Nariño, in south-western
vegetable oils consumed in the world. The largest growers of African Colombia. A total of 99 ringspot-affected young African oil palms
oil palm are Malaysia and Indonesia, but West Africa, the center of assayed by RT-PCR, yielded the expected 875 bp fragment amplified
origin of this plant species, is the second most important African oil by the AOPRV primers (fig. 2b). Selected fragments obtained from
palm-producing region, and has the highest per capita consumption these RT-PCR tests produced true sequences corresponding to
of this vegetable oil in the world. AOPRV ORF1. Three hybrid (guineensis X oleifera) oil palms
assayed by RT-PCR in this investigation also yielded the expected
Latin America is also an important producer of African oil palm 875 bp bands, demonstrating their susceptibility to AOPRV. On the
and, to a lesser extent, of its native American oil palm (E. oleifera), contrary, none of the PC-affected young palms or the healthy control
used predominantly for crop improvement purposes. The renewed assayed, produced any visible PCR products (Fig. 2c). The presence
interest in alternative fuel sources, has led to a significant increase in of the potyvirus in mosaic-affected palms from Ecuador and
the area planted to African oil palm in tropical America. Colombia was readily detected by the ELISA tests (fig. 3b).
In Latin America, Colombia is the largest producer of African oil
palm (170,000 Has), followed by Ecuador (130,000 Has), Brazil
(56,000 Has) and Costa Rica (52,000 Has). Peru used to be an
important palm oil producer, but the ringspot disease caused the loss
of thousands of oil palms after its emergence in 1969.
B
C
A
Fig 2. a: ‘ringspot’ agent causal (AOPRV); b: AOPRV detection; c: ‘ringspot’ disease
(mancha anular) is different to ‘But rot’ (pudrición de cogollo)
A B
A B C
Fig. 3. a and b: ‘chlorotic ring’ agent causal; c. ‘chlorotic ring’ detection.
Conclusions
The molecular characterization of AOPRV made possible the
implementation of a reliable virus detection assay in both African
C D and hybrid progenies of African X American oil palms infected by
Fig 1. a: In 1985, the ‘ringspot’ disease was observed in the municipality of Tumaco, Nariño, Colombia;
AOPRV under natural conditions. A sensitive virus detection assay
b:‘ringspot’ symtomatology; c and d: ‘chlorotic ring’ symtomatology. in the nursery stage prevents the transplant of young infected palms
in the definitive plantation, where they usually express the lethal
symptoms induced by AOPRV.
The ringspot disease of oil palm is considered a major phytosanitary
It has been demonstrated here that the causal agent of the African
problem of this vegetable oil crop in southwestern Colombia, where
and American oil palm ringspot disease is a virus that belongs to the
it still kills thousands of young palms every year(fig. 1b).
family Flexiviridae, but it has not yet been assigned to a particular
Investigations conducted since 2000 at the International Center for
genus by the International Committee on the Nomenclature of
Tropical Agriculture (CIAT) in Palmira, Colombia, consistently
Viruses.
show the presence of a filamentous virus (AOPRV) ca. 800 nm in
It would be important to investigate the epidemiology of AOPRV,
length associated with ringspot-affected palms in the municipality of
considering its fairly rapid dissemination in the affected regions of
Tumaco, Nariño, Colombia(fig. 1a and 2a). The RNA of the African
Peru, Ecuador and Colombia, and its socioeconomic importance.
oil palm ringspot virus was totally cloned and sequenced, making
Although the possibility of mechanical transmission by contaminated
possible the implementation of the highly specific and sensitive RT-
tools, mainly machetes, cannot be ruled out in the case of AOPRV,
PCR technique to detect and identify the virus in young nursery
the possible existence of a slow-moving but persistent vector, such as
palms before they are transplanted in the field.
mites (vectors of allexi- and trichoviruses) or mealybugs/scales
(vectors of vitiviruses), is currently under investigation in our
A second viral disease of African oil palm, ‘chlorotic ring’(fig. 1c and
laboratory. The potyvirus is transmitted by various aphid species
1d) was first observed in 1996, in north-western Ecuador and south-
that feed in wild and cultivated grasses
western Colombia. This disease is not lethal, but growers eliminate
mosaic-affected palms at the nursery stage. The disease is caused by
a different filamentous virus ca. 750 nm in length, belonging to the REFERENCES
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spectrum monoclonal antibody. of a Potyvirus Infecting African Oil Palm in South America. J. Phytopathology 150, 297-301.