Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4), the causal agent of Fusarium wilt of banana (FWB), is currently the major threat to the banana industry worldwide (Dita et al. 2018). Restricted to South Asia for more than 20 years, Foc TR4 has spread in the last years to the Middle East, Mozambique, and Colombia (García-Bastidas et al. 2019; https://pestdisplace.org/embed/news/map/disease/11). The incursion of Foc TR4 in Colombia increased awareness and prevention efforts across Latin American and the Caribbean (LAC). However, new Foc TR4 outbreaks in LAC countries were considered a matter of time. In April 2021, banana (Musa spp., Cavendish, AAA) plants (30% of incidence) showing typical symptoms of FWB, such as leave yellowing, wilting and vascular discoloration were observed in one farm (about 1 ha) located in Querecotillo, Peru (4°43’54.84”S 80°33’45.00”W). Mycological analyses of samples (pseudostem strands) collected from 10 symptomatic plants were performed as described by Dita et al. (2010). These analyses revealed a continuous presence of fungal colonies identified as Fusarium oxysporum species complex. Molecular diagnostics targeting two different genome regions (Dita et al 2010; Li et al. 2013) identified nine of these isolates as Foc TR4. These results were further confirmed by qPCR analyses using the commercial Clear Detections TR4 kit. The genome of four single-spore isolates (PerS1, PerS2, PerS3 and PerS4) was sequenced using the Illumina platform (MiSeq Kit, 2x151 bp Paired-End). The strain PerS4 was also sequenced using Oxford Nanopore (FLOW-MIN111; R10.3 chemistry) as described by Lopez-Alvarez et al., (2020). The generated draft assembly yielded 533 contigs for a size of 47 Mbp (BioProject: PRJNA755905), which is comparable with sizes of previously reported Foc TR4 strains (Asai et al. 2019; García-Bastidas et al. 2019; Maymon et al. 2020; Warmington et al. 2019; Zheng et al. 2018). The sequence assembly showed high contiguity (94.9%) and high similarity (95.48%) with the high-quality genome sequence of the Foc TR4 isolate ‘UK0001’ (Warmington et al. 2019). Further analyses to identify the presence/absence of full sequences for the putative effector genes (Secreted In Xylem - SIX) and their allelic copies, also revealed that the SIX genes profile of the strains isolated from Querecotillo matched with previously reported Foc TR4 isolates (Czislowski et al. 2017). Pathogenicity tests with three isolates and water controls were performed as described by Dita et al. (2010), using five Cavendish plantlets per treatment. Four weeks after the inoculation typical external and internal symptoms of FWB were observed only in the inoculated plants. Fungal isolates recovered from inoculated plants tested positive for Foc TR4 when analyzed with PCR diagnostics as mentioned above. No fungal isolates were recovered from water-control plants which did not show any symptoms. Altogether, our results confirm the first incursion of Foc TR4 in Peru. Currently, Foc TR4 has the phytosanitary status of a present pest with restricted distribution in Peru and it is under official control of the National Plant Protection Organization – SENASA. Reinforced prevention and quarantine measures, disease monitoring and capacity building to detect, contain and manage eventual new outbreaks of Foc TR4 are strongly encouraged across LAC banana producing countries, especially for those bordering Peru with larger banana plantations, such as Ecuador and Brazil.

Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is the causal agent of Fusarium wilt, a major threat to the banana industry worldwide. Here, we report the genome of a Foc TR4 strain from Peru, sequenced using a combination of Illumina and Oxford Nanopore Technologies.

Keywords: Beauveria bassiana -Eurysacca melanocampta -quitin colloidal -laminarinThe aim of this investigation was to study the growth of Beauveria bassiana, grown in liquid media supplemented with minimum media with more artificial substrate (glucose, laminarin o colloidal chitin) and with minimum media with more natural substrate from E. melanocampta or Peronospora farinosa, for which we evaluated the number of spores and biomass. For this was used the CCB-LE 262 strain of B. bassiana, which was inoculated in different culture media and for which growth was evaluated after 24 h, 96 h and 216 h. Our results indicate that the highest number of spores was obtained in the artificial culture medium supplemented with laminarin 6 -1 (ML), with spores 67.80 x 10 ·mL , whereas the best natural media was that supplemented with 6 -1powder of E. melanocampta (M ), with 18.53 x 10 mL spores. The highest biomass was

ResumenEl hongo Beauveria bassiana Vuill. es muy conocido por su capacidad entomopatógena, pero también existe referencias de ser un hongo antagonista, una de las posibles formas de su antagonismo es la antibiosis debido a la presencia de enzimas hidrolíticas en su genoma. Las principales enzimas expresadas contra fitopatógenos son las β-1,3-glucanasas, ya que la pared celular de los fitopatógenos como hongos y oomycetes está constituida en su mayoría por polímeros de β-1,3-glucanos. Se evaluó por qPCR la expresión de dos genes, el gen exo-beta-1,3-glucanasa [XM_008597142.1] y el gen de glucósido hidrolasa familia 55 [XP_008597332.1] de B. bassiana en los días 0, 4 y 7, frente a medios líquidos con distintas fuentes de carbono, laminarina 0,1%, pulverizado de F. oxysporum 0,1% y pulverizado de hojas infestadas con P. variabilis 0,1%. Entre los genes analizados se encontró el ratio más alto en los medios con F. oxysporum para el gen glucósido hidrolasa familia 55 (GH55), los medios con P. variabilis no tuvieron una expresión significativa. Nosotros postulamos que el aumento de la expresión del gen glucósido hidrolasa familia 55 (GH55), en el día 4, en medios con F. oxysporum podría ser importante en el metabolismo de B. bassiana frente a este sustratos.

Expresión de genes quitinasas de ResumenEl hongo filamentoso Beauveria bassiana es el agente de control biológico más utilizado en la actualidad, ya que es muy conocido por su actividad entomopatógena y por su referencia como hongo antagonista. El modo de infección de B. bassiana es a través de la degradación de la quitina presente en la cutícula del insecto o pared celular de hongos patógenos cuyo mecanismo de acción involucra la actividad de las enzimas y los genes de quitinasas. La expresión de dos genes de quitinasas; el gen de la familia 18.4 (XM_008603039.1) y el gen CHIT1 (EU828354.1) de B. bassiana, se han evaluado mediante RT-qPCR a partir de RNA extraídos a los 0, 4 y 7 días, de cultivos líquidos inducidos con diferentes fuentes de carbono: quitina coloidal 1,8%, laminarina 0,1%, pulverizado de F. oxysporum 0,1% y pulverizado de hojas infectadas con P. variabilis 0,1%. La expresión relativa frente a genes referenciales de actinina y tubulina muestran que en el día 7 la expresión del gen CHIT1 incrementó en 1,87 ± 0,35 veces en los medios con F. oxysporum, mientras que el gen quitinasa de la familia 18.4 presentó mejor expresión en los medios con P. variabilis siendo su incremento de 5,88 ± 1,35 veces. Este incremento de la expresión de los genes quitinasa de la familia 18.4 (XM_008603039.1) y CHIT1 (EU828354.1) de B. bassiana sugiere que estas enzimas tienen una expresión diferencial en el desarrollo y tipo de cultivo.Palabras claves: Quitinasa, Beauveria bassiana, Peronospora variabilis, Fusarium oxysporum, RT-qPCR. AbstractThe Beauveria bassiana filamentous fungus is the most biological control agent frequently used today due to its entomopathogenic activity and antagonist fungi capacity. B. bassiana infects the insects through the degradation of the chitin present in the cuticle, also; affects the cell wall of pathogenic fungi. This mechanism involves enzymatic activities and activation of Chitinase genes. Gene expression of the family 18.4 (XM_008603039.1) and CHIT1 (EU828354.1) of B. bassiana, were evaluated, by RT-qPCR at 0, 4 and 7 days. The assay consists of four media with different carbon sources: colloidal chitin 1.8%, laminarin 0.1%, pulverized of F. oxysporum 0.1% and pulverized leaves infected with P. variabilis 0.1%. Relative expression using actinin and tubulin as referential genes, showed that CHIT1 gene expression increased 1.87 ± 0.35 times on day 7 in the medium with F. oxysporum, while chitinase gene 18.4 family presented the best expression in the medium with P. variabilis increasing 5.88 ± 1.35 times on day 7. This increase in the expression of 18.4 family chitinase genes (XM_008603039.1) and CHIT1 (EU828354.1) of B. bassiana suggests that these enzymes have differential expression in the developing and type of culture.