Morphological and molecular characterization of Fusarium spp pathogenic to pecan tree in Brazil

Abstract

ABSTRACT. The occurrence of Fusarium spp associated with pecan tree (Carya illinoinensis) diseases in Brazil has been observed in recent laboratory analyses in Rio Grande do Sul State. Thus, in this study, we i) obtained Fusarium isolates from plants with disease symptoms; ii) tested the pathogenicity of these Fusarium isolates to pecan; iii) characterized and grouped Fusarium isolates that were pathogenic to the pecan tree based on morphological characteristics; iv) identified Fusarium spp to the species complex level through TEF-1α sequencing; and v) compared the identification methods used in the study. Fifteen isolates collected from the inflorescences, roots, and Fusarium spp pathogenic to pecan tree seeds of symptomatic plants (leaf necrosis or root rot) were used for pathogenicity tests. Morphological characterization was conducted using only pathogenic isolates, for a total of 11 isolates, based on the mycelial growth rate, sporulation, colony pigmentation, and conidial length and width variables. Pathogenic isolates were grouped based on morphological characteristics, and molecular characterization was performed by sequencing TEF-1α genes. Pathogenic isolates belonging to the Fusarium chlamydosporum species complex, Fusarium graminearum species complex, Fusarium proliferatum, and Fusarium oxysporum were identified based on the TEF-1α region. Morphological characteristics were used to effectively differentiate isolates and group the isolates according to genetic similarity, particularly conidial width, which emerged as a key morphological descriptor in this study.

Morphological and molecular characterization of Cladosporium cladosporioides species complex causing pecan tree leaf spot

“…However, pathogens have recently been identified in pecan cultures, including Fusarium spp causing choke disease and leaf necrosis associated with root rot (Lazarotto et al, 2014a), and Pestalotiopsis spp responsible for leaf spot (Lazarotto et al, 2014b).…”

Morphological aspects and effect of carbon sources in the physiology of Fusarium oxysporum f. sp. passiflorae

“…oxysporum presents significant variations between isolates such as colony colour, colony size, dry mycelial weight (mg), size of microconidia, macroconidia and septations (Chougule and Andoji, 2016), colony coloration (Nath et al, 2017), mycelial types, presence of chlamydospores, apical and basal cells among other characteristics (Gupta et al, 2014;Hafizi et al, 2013;Lazarotto et al, 2014).…”

Development of a polymerase chain reaction-restriction fragment length polymorphism method for identification of the Fusarium genus using the transcription elongation factor-1α gene

“…The pathogenic isolates to the pecan tree were identified, based on the TEF-1α gene, as belonging to the F. chlamydosporum species complex, F. graminearum species complex, F. proliferatum, and F. oxysporum (16). A TEF-1α-RFLP technique was described for the identification of the three clades of F. oxysporum (17).…”