arborea Roxb (melina) en el Trópico Húmedo Ecuatoriano

Article resulting from a research project financed by

the State Technical University of Quevedo

Edison Hidalgo Solano Notes

rlopez@uteq.edu.ec; https://orcid.org/0000-0001-8527-

María Estefanía Morán Vásquez

Forestry Engineer, Forestry Engineering Career,

Universidad Técnica Estatal de Quevedo, Quevedo-

Paola Eunice Díaz Navarrete,

ABSTRACT

conditions of Ecuador, a quality that has stimulated the establishment of intensive plantations

for commercial purposes. A disease with characteristics of vascular wilt and stem rot is killing

thousands of trees in the country. Ceratocystis fimbriata is listed as the causative agent of the

disease, However, the complex symptoms and the frequent isolation of Fusarium spp. from

diseased trees, make us suspect that this phytopathogen is involved in the pathogenesis of

melina. Koch's Postulates were applied at the greenhouse level, and for the effect, 5

treatments based on the inoculation of 17 G. arborea plants of 4-month-old per treatment

were plated. T1 = Fusarium sp.1, T2 = Fusarium sp.2, T3 = Fusarium sp.3, T4 = Fusarium sp.4,

Keywords: Apparent volume of necrosis, Koch's postulates, pathogenesis.

RESUMEN

condiciones edafoclimáticas del Ecuador, cualidad que ha estimulado el establecimiento de

plantaciones intensivas con fines comerciales. Una enfermedad con características de

marchitez vascular y pudrición del fuste está matando miles de árboles en el país. Ceratocystis

sintomatología y el frecuente aislamiento de Fusarium spp. desde árboles enfermos, hacen

sospechar que este fitopatógeno está implicado en la patogénesis de melina. Se aplicaron los

leves de enfermedad, sin embargo no murieron. Estos resultados se consideran como línea

base, e indicaría la implicación de Fusarium spp. en la enfermedad de melina, pero no son

concluyentes.

Palabras clave: Patogénesis, postulados de Koch, volumen aparente de necrosis.

considered a timber tree valued in the international industry for the production of paper pulp,

and also has excellent characteristics for the manufacture of furniture and tertiary products

(paper and beams) (Moya, 2004). According to MAGAP (2016) since the introduction of G.

significant planted area, where until 2015 there were 11458 hectares, representing 21.9% of

the 52395 ha, planted with other economically important forest species (teak, balsa, pine,

others) registered in the country.

According to Saltos-Sampedro (2019), in the last five years, a complex and aggressive disease

is affecting commercial melina plantations in THE, manifesting itself with a premature and

gradual detriment of vigor in the trees, accompanied by discoloration of the leaf system

the ascomycete fungus Ceratocystis fimbriata was the cause of the disease. However, periodic

visits to THE plantations show diseased trees with a different symptomatology to the one

previously described by Macías-Moncayo, (2019), leading to the suspicion that two diseases

are occurring at the same time in G. arborea forests and probably caused by different

phytopathogens.

This distinctive disease manifests itself with the rotting of the stem, and the consequent death

of the standing trees. This rotting generates circular, oval or elongated areas in the bark,

acquiring a cracked aspect of dark brown to black color, with a canker typology, whose

necrotic area can cover the circumference of the tree. The symptomatology begins with

wilting of the leaves and subsequent drying, until they finally fall to the forest floor. Reports

strains of Fusarium spp. previously isolated from diseased melina trees, we sought to

determine whether this phytopathogen was capable of causing disease in seedlings according

to Koch's postulates, and generating symptomatology similar to that observed in the field.

MATERIALS AND METHODS

Location of experimental site. The present study was conducted in the laboratory of

Environmental and Plant Microbiology of the Universidad Técnica Estatal de Quevedo (UTEQ),

where the collection of Fusarium spp. strains, collected from diseased melina trees, is located.

Activation of Fusarium spp. strains were reactivated in Petri dishes containing 10 mL of

potato, dextrose, agar (PDA) culture medium plus 0.2 mL of an antibiotic mixture (50 µg/mL

the bark and xylem of the plant. Inside the wound, a colony segment (0.5 cm disk) of the

was inside the plant, the wound was covered with parafilm tape. The control plants were

inoculated under the same conditions as above, with the difference that instead of inoculating

the pathogen, a segment of agar-agar (innocuous) was applied inside the wound and the

wound was closed with parafilm tape (Massimo et al., 2015).

The plants were watered periodically according to their needs. The experiment was

established for 155 days (5 months and 4 days), during which time the pertinent observations

were made on the health status of each of the inoculated plants, with the purpose of

detecting the appearance of symptoms related to stem rot associated with the inoculated

consisting of five treatments: T1 = melina plants inoculated with Fusarium sp.1, T2 = melina

plants inoculated with Fusarium sp.2, T3 = melina plants inoculated with Fusarium sp.3, T4 =

melina plants inoculated with Fusarium sp.4, T5 = uninoculated melina plants (control). For

each treatment, 17 melina plants were used (replicates).

analyzed under the analysis of variance scheme (ANOVA) with a significance level of 95% (P <

Subsequently, the LSD (least significant difference) test was applied, with a significance level

of 95% (P < 0.05). The SAS 9.0 statistical package for Windows was used for this purpose.

RESULTS

of necrosis caused by phytopathogenic fungi inoculated in melina plants, where significant

statistical differences (F=6.48; P=0.000) were detected between the lengths of necrosis

generated by the fungi. The treatments Fusarium sp.1, Fusarium sp.2, Fusarium sp.4,

produced the greatest necrosis lengths, with 10.95 cm; 12.91 cm; 9.71 cm, respectively, being

length of necrosis with 9.08 cm, being statistically superior to the other treatments. While the

phytopathogens endemic to the complex ecological zones where most melina plantations are

The values of apparent necrosis volume and total necrosis length generated by Fusarium spp.

on inoculated plants resemble those reported by Macias-Moncayo (2019) when he inoculated

a strain of Fusarium sp. on melina seedlings at greenhouse level and incubated them for 45

days.

The symptoms detected in seedlings inoculated with Fusarium sp.1 and Fusarium sp.2, begin

with a slight chlorosis of the foliar system. However, with the passing of the days the plants

did not die. Dissection (longitudinal and transverse cut) allowed us to observe areas of

necrosis in the vascular tissues of the inoculated plants. This symptomatological description

is quite similar to that detected in young and adult melina trees at field level (Saltos-

Sampedro, 2019).

Plants inoculated with Fusarium sp.1 and Fusarium sp.2 caused the highest apparent volumes

of necrosis, and generated mild disease symptoms, but did not die. These results are

considered as a baseline, and would indicate the involvement of Fusarium spp. in melina

disease, but are not conclusive.

REFERENCES

Barros-Bastidas, C., & Turpo, O. (2020). La formación en investigación y su incidencia en la

Belezaca-Pinargote, C.; Solano-Apuntes, E.; López-Tobar, R.; Baque-Mite, R.; Ávila-Loor, A.;

Gamboa Romero, M. A., Barros Morales, R. L., & Barros Bastidas, C. (2016). La agresividad

MAGAP (Ministerio de Agricultura, Ganadería, Acuacultura y Pesca). 2016. Programa de

McKinney, L.V.; Nielsen, L.R., Collinge, D.B.; Thomsem, I.M., Hansen, J.K. & E.D. Kjaer. 2014.

Massimo, N.C.; Nandi Devan, M.M.; Arendt, K.R. et al. 2015. Fungal endophytes in

Moya, R.; Araya, L. & B. Vilchez. 2008. Variation in the pith parameter of Gmelina

Salas-Rodríguez, A.; Murillo-Gamboa, O.; Murillo-Cruz, R.; Ávila-Arias, C. & X. Mata-Granados.