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of Phytopathology

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Diversity and taxonomy of Fusarium solani isolated of wilted Agave tequilana var. azul plants

By Viviana Montaño Becerrra, Norma Alejandra Mancilla Margalli, Cristina Chávez Sánchez, Martin Eduardo Avila Miranda*

* Corresponding Author. Email: martin.am@tlajomulco.tecnm.mx / Institution: Instituto Tecnológico de Tlajomulco

Accepted: 16/September/2024 – Published: 25/October/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2310-5

Abstract Background/Objective. The objective of this work was to identify 24 strains of F. solani isolated from agave with wilt, with respect to the new phylogenetic species; determine their molecular similarity to F. solani f. spp.; determine their genetic diversity and their pathogenic capacity in agave, bean and corn.

Materials and Methods. Sequences of the ITS1-5.8S-ITS2 fragment of 24 agave isolates and those of F. solani f. spp., were compared with GenBank and FUSAROID-ID. Amplified 18S rRNA sequences were aligned with sequences reported of F. solani f. spp. phaseoli and batatas, defining the presence of introns. Genetic diversity was determined with the DNA RepPCR marker. Representative strains were tested against agave, bean and maize seedlings, evaluating their pathogenicity as root rot severity.

Results. Isolates morphologically identified as F. solani, GenBank placed them as F. solani or included in the FSSC, three strains were identified as Xenoacremonium sp. FUSAROID-ID defined that the sequences of F. solani were highly similar to those of Neocosmospora martii, N. pseudoradicicola, N. solani and N. falciformis. The ITS1-5.8S-ITS2 sequences and absence of introns in its SSU indicated that none is F. solani f. sp. phaseoli. Isolates obtained from agave were pathogenic to A. tequilana and a criollo corn cv, but not to Fusarium-resistant corn. No agave isolates were pathogenic to beans.

Conclusions. Four phylogenetic species of FSSC cause root rot in agave; F. solani isolates from agave did not affect Fusarium-resistant corn. It is safe to intercrop beans in agave.

Keywords: Neocosmospora, Rep-PCR, f. sp. phaseoli.

Figure 1. Appearance of plants from which the <em>Fusarium solani</em> strains were isolated A) <em>Agave tequilana</em> var. azul plant, with symptoms of agave wilt. B) Typical reddish necrotic tissue in the crown and the base of the stem.
Figure 1. Appearance of plants from which the Fusarium solani strains were isolated A) Agave tequilana var. azul plant, with symptoms of agave wilt. B) Typical reddish necrotic tissue in the crown and the base of the stem.
Figure 2. Microphotograph of the main morphological characteristics used to identify <em>Fusarium solani</em> isolations obtained from necrotic tissue in the crown or base of the stem of <em>Agave tequilana</em> var. azul plant. A). Long conidiophores with only one microconidium. B) <em>Fusarium</em> macroconidia.
Figure 2. Microphotograph of the main morphological characteristics used to identify Fusarium solani isolations obtained from necrotic tissue in the crown or base of the stem of Agave tequilana var. azul plant. A). Long conidiophores with only one microconidium. B) Fusarium macroconidia.
Figure 3. Appearance of fungal cultures after five days of growing in PDA at 28 °C. A) FsDr strain, identified molecularly as <em>Xenoacremonium</em> sp.and B) <em>Fusarium solani</em> FsP strain. C) Microphotograph of mycelium and conidiophore of the FsDr strain without macroconidia
Figure 3. Appearance of fungal cultures after five days of growing in PDA at 28 °C. A) FsDr strain, identified molecularly as Xenoacremonium sp.and B) Fusarium solani FsP strain. C) Microphotograph of mycelium and conidiophore of the FsDr strain without macroconidia