The species of the genus Sansevieria (Agavaceae) are popularly known in Brazil as Saint Jorge swords. The family includes approximately 60 species of African origin, which are extremely rustic, adapting very well to the sun or shade and heat or cold (Lorenzi and Souza 2001). Several fungi, including those from the Botryosphaeriaceae family, have been reported to cause leaf disease in Sansevieria trifasciata worldwide (Farr and Rossman 2019). In Brazil, there are no reports of fungal diseases in Sansevieria spp.

In December 2018, plants of S. trifasciata var. Laurentii (De Wild.) showing symptoms of leaf blight were observed in the gardens of the Center for Agricultural Sciences of the UFPI, Teresina, Piauí, Brazil. Small fragments of colonized tissue were removed from the samples, disinfested in 70% ethanol for 1 min and 2% sodium hypochlorite for 2 min, then transferred to sterilized distilled water and dried on sterile paper. The isolates were cultivated in potato dextrose agar culture medium (PDA) and incubated at 26 ± 2 °C for 3 to 5 days under a 12-h photoperiod.

The preliminary identification of the fungal isolates was based on morphological characteristics. A mycelial plug 6 mm in diameter taken from a 7-day-old culture was transferred to a PDA. The color and morphology of the colony were evaluated. The isolates were cultured on 2% water agar (WA) overlaid with sterilized twigs of Pinus to induce pycnidia formation and sporulation. Measurements of 30 selected conidia were performed. Single-spore isolates were deposited in the culture Collection of Phytopathogenic Fungi at the Phytopathology Laboratory at the UFPI (accession numbers: COUFPI 239 and COUFPI 241).

To confirm their identification, the isolates were grown on PDA for 7 days at 26 °C under a 12 h photoperiod. The aerial mycelium was scraped off the colony surface, and DNA was extracted (Moller et al. 1992). The DNA concentration was estimated visually in a 1.0% agarose electrophoresis gel stained with ethidium bromide and visualized under UV light.

The internal transcribed spacer (ITS) region was amplified with the primers ITS1 and ITS4 (White et al. 1990), and transcription elongation factor 1-α (EF1-α) was amplified with the primers 728F (Carbone and Kohn 1999) and EF2R (O’Donnell et al. 1998). The PCR products were purified and sequenced by Macrogen Inc. (Seoul, South Korea). Additional sequences of Botryosphaeriaceae isolates were obtained from GenBank (Table 1). The obtained sequences were aligned using the multiple sequence alignment program MUSCLE® implemented in MEGA v. 8 software. The resulting alignment was deposited in TreeBASE under accession number ID25814. Bayesian inference analyses were performed using the Monte Carlo chain method. Mr. Modeltest 2.3 (Posada and Buckley 2004) was used to determine the evolutionary model of the nucleotides that best fit the data; the models used in the phylogenetic analyses were HKY for ITS and HKY + I for EF-1α.

Table 1 Isolates and DNA sequences data used in phylogenetic analysis
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Phylogenetic analysis was performed at the CIPRES web portal (Miller et al. 2010) using MrBayes version v. 3.2 (Ronquist et al. 2011). Markov chains were run simultaneously from random trees to 10,000,000 generations. Trees were sampled every 1000th generation for a total of 10,000 trees. The first 2500 trees were discarded as burn-in in each analysis. The sequences obtained in this study were deposited in GenBank (Table 1).

To confirm pathogenicity, isolates were cultured on PDA for 4 days at 26 °C under a 12-h photoperiod before inoculation onto 6-month-old plants of S. trifasciata var. Laurentii, Hahnii, Prain, and Sansevieria cylindrica. Plants were inoculated with sterile toothpicks, inserting fungal structures in the basal, middle and apical regions of the leaves. Plant inoculated with non-infected toothpicks were used as a negative control. After inoculation, the plants were maintained in a moist chamber constructed using plastic bags for 24 h. These bags were then removed, and the plants were kept in an environment with the temperature controlled at 26 ± 2 °C. Disease development was observed until 30 days after inoculation. The experiment was repeated twice, and five replicates of each variety/species were tested for each isolate.

The isolates were pathogenic to S. trifasciata var. Laurentii, Hahnii, Prain, and S. cylindrica. Leaf blight symptoms similar to the symptoms found in the field (Fig. 1a) were observed four days after inoculation, starting with dark lesions around the inoculation point (Fig. 1b). No symptoms were observed on the control plants. The isolates were consistently recovered from the inoculated plants.

Fig. 1
figure 1

Neoscytalidium dimidiatum pathogenic to Sansevieria trifasciata. (a) Necrosis symptoms observed in the field. (b) Symptomatic plant seven days after inoculation with the COUFPI 239 isolate. (c) Colony after four days of incubation in PDA medium at ± 26 °C under a 12 h photoperiod. (d–f) Different forms and pigmentation in chain arthroconidia

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Based on multigene phylogenetic analysis, the isolates were identified as Neoscytalidium dimidiatum. Isolates COUFPI 239 and COUFPI 241 were grouped with the reference isolate of N. dimidiatum (CBS 499.66) with high support (Bayesian posterior probability = 0.99) (Fig. 2).

Fig. 2
figure 2

Bayesian phylogenetic tree of ITS-5.8S rDNA and EF-1α sequences showing the phylogenetic relationships among species of Neoscytalidium based on the evolutionary models HKY for ITS and the HKY + I for EF-1α. Posterior probability values are indicated above the nodes. The isolates used in this study are highlighted in bold. The tree is rooted with Neofusicoccum mangiferae and Neofusicoccum vitifusiforme

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The isolate cultures presented a white color and cotonose mycelium, were denser at the center and border. After the third day, the colonies became light gray, and they later became dark gray (Fig. 1c), showing the reverse pattern of the same color. The hyphae were light brown and septate. The arthroconidia were diverse in morphology and coloration; 0–1 septum was observed, and most were ovoid and light brown (Fig. 1f). Arthroconids were arranged in chains (Fig. 1d, e). The arthroconids were 10.04 to 15.94 × 7.13 to 9.92 μm. Pycnidia were observed after 10 days of incubation.

Neocytalidium dimidiatum has been reported to cause leaf blight in S. trifasiata in Malaysia (Kee et al. 2017). In Brazil, N. dimidiatum has been reported to cause root rot in physic nut and cassava (Machado et al. 2012; Mello et al. 2018), black root rot in cassava (Machado et al. 2014), dieback in grapevine and mango (Correia et al. 2016; Marques et al. 2013). Our study provides the first report of leaf blight on Sansevieria trifasciata in Brazil caused by Neoscytalidium dimidiatum.