First report of angular leaf spot in Acmella oleracea caused by the foliar nematode Aphelenchoides pseudobesseyi

• Published in: Journal of plant diseases and protection (2006) Vol. 131; no. 5; pp. 1707 - 1720
• Main Authors: Silva, Marcela de Freitas, Faccioli, Felipe Castro, Honório, Amanda Pereira, Fonseca, Andressa Rodrigues, Boari, Alessandra de Jesus, de Oliveira, Cláudio Marcelo Gonçalves, Buonicontro, Dalila Sêni
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-10-2024
• Subjects: Biomedical and Life Sciences; Life Sciences; Original Article; Plant Pathology; Plant Physiology; Plant Sciences; Pathogenicity; Jambu; Etiology; Plant-parasitic nematodes; Integrative taxonomy
• ISSN: 1861-3829; 1861-3837
• DOI: 10.1007/s41348-024-00982-2

Jambu plants (
Acmella oleracea
) exhibiting necrotic angular leaf spots were collected in Belém—Pará, Brazil. Suspected to be a disease caused by nematodes, the jambu leaves were processed and the presence of nematodes from
Aphelenchoides
genus was observed using a light microscope. These nematodes were reared on
Fusarium
sp. and subsequently morphologically and molecularly characterized to species level.
Aphelenchoides
sp. associated with jambu exhibited morphological and morphometric characteristics similar to those within the
A. besseyi
complex (
A. besseyi
sensu stricto,
A. oryzae
and
A. pseudobesseyi
). Still, these characteristics were insufficient to confirm the identity of this population. However, the Bayesian inference analysis, utilizing the expansion segment of the large subunit (D2-D3 LSU) of nuclear ribosomal DNA, yielded results with a high posterior probability, indicating that the
Aphelenchoides
sp. associated with jambu belongs to the
A. pseudobesseyi
species. Under controlled conditions, the reproduction of the nematode in the leaf tissues (RF > 1) was observed, resulting in disease symptoms. The highest reproductive rate of
A. pseudobesseyi
(RF = 2.6) was observed from inoculation with 100 nematodes per leaf (500 nematodes per plant). Based on Seinhorst analysis, the tolerance limit in jambu plants infected with
A. pseudobesseyi
was 250 nematodes. It is concluded that
A. pseudobesseyi
is the etiological agent of the jambu angular leaf spot. For future evaluation of jambu resistance on
A. pseudobesseyi
, an inoculate maximum of 100 nematodes per leaf is recommended.