Assessment of Inoculation Methods of Thielaviopsis paradoxa (De Seynes) Höhn into Oil Palm Seedlings under Greenhouse Conditions.

Sandra Gaitán-Chaparro,Hernán Mauricio Romero,Edwin Navia-Rodríguez

doi:10.3390/jof7110910

Sandra Gaitán-Chaparro, Hernán Mauricio Romero + Show 1 more

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https://doi.org/10.3390/jof7110910

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Abstract

Oil palm (Elaeis guineensis Jacq. and Elaeis Oleifera Cortes) is one of the most important oil crops in the world. Colombia is the fourth-largest oil palm producer worldwide. However, oil palm diseases are a significant factor affecting yield. Thielaviopsis paradoxa (De Seynes) Höhn is a pathogen that affects young palm trees, causing spear rot. Four disease establishment methods were studied to replicate, in a controlled environment, the symptoms of the disease found in the field. Young palm trees were inoculated with a suspension of endoconidia using either local infiltration, drip, scissor cut, or direct contact with agar blocks bearing mycelia and conidia. The effects of the inoculation methods were studied in dose-method-disease severity experiments conducted in a greenhouse under controlled conditions. All four methods resulted in T. paradoxa infections and the development of symptoms of the disease. The disease severity was correlated with the method and dose of inoculation. In trials to test Koch’s postulates, T. paradoxa was isolated from areas of disease progression in the inoculated trees, but the teleomorph Ceratocystis paradoxa (Dade) Moreau was not observed. A photographic record of the infection process at different times post-infection was compiled. Given that establishing the disease through artificial inoculation is essential for assessing plant pathogenesis, this study determined that the local infiltration method (1 × 106 endoconidia mL−1) and a 3–7 day incubation period were critical for the development of symptoms as severe as those observed in natural infections in the field.

Highlights

The genus Elaeis belongs to the monocotyledonous family Arecaceae
The objective of this work was to assess four methods for the inoculation of oil palm with T. paradoxa under controlled conditions to set up a T. paradoxa-oil palm pathosystem that may be used in omics studies
Fungi 2021, 7, x FO(FRigPEuErRe R1E).VTIEhWe morphological characteristics coincide with the previous descriptions of Thielaviopsis paradoxa (De Seynes) Höhn [21]

Summary

Introduction

The genus Elaeis belongs to the monocotyledonous family Arecaceae. It comprises two taxonomically well-defined species, the African oil palm Elaeis guineensis and the American oil palm Elaeis oleifera. One of the pathogens of oil palm is Thielaviopsis paradoxa, the anamorph of Ceratocystis paradoxa, which belongs to the family Ceratocystidaceae [4] It is a pathogen with a broad host range, including economically important crops, such as sugarcane, date palm, banana, sorghum, cocoa, sweet potato, coconut, pineapple, corn, and other palm species [5,6,7]. Diseases caused by T. paradoxa have a high destructive potential for oil palm plantations They have been designated in many different ways in the literature (stem exudation, black burn, spear leaf rot, and bud rot) [4,5]. The fungus has been reported as the causal agent of bunch discoloration disorder in most date palm-producing countries, including Saudi Arabia [9,10,11], Iraq, Kuwait [12], Qatar [13], and Egypt [14]. Several studies have been conducted to control this pathogen with biological and chemical methods in different hosts [6,17,18]

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