First Report of Cophinforma tumefaciens Pathogenic to the Invasive Tree Neltuma juliflora in Brazil
Year: 2025
Type: article
Abstract: Neltuma juliflora is a medium-sized, fast-growing species with strong nitrogen-fixing capacity and high tolerance to semi-arid and arid conditions (Gebrehiwot and Steger 2024). Native to the Americas, it was introduced to northeastern Brazil in 1942 to enhance drought resilience and restore degraded areas (Damasceno et al. 2020). Its rapid spread in non-native environments has led to its classification as an invasive species that threatens local biodiversity (Lima 2005). Today, it is regarded as one of the world's most aggressive invasive plants. In September 2023, pods of N. juliflora (Fabaceae) with dark superficial lesions and internal rot were observed in Petrolândia, Pernambuco, Brazil (Figure 1). Ten plants were examined, and four showed pod rot symptoms. Tissue fragments from lesion margins were surface-disinfected, plated on potato dextrose agar (PDA) and incubated at 28°C. Emerging colonies were transferred to water agar for hyphal-tip isolation and maintained on PDA. Colonies were olive green to dark grey on the obverse and olive green to black on the reverse (Figure 2). Conidia were hyaline, aseptate, ellipsoid to obovoid, measuring 17.4–30.2 × 6.5–10 µm (average 24.3 × 7.4 µm; n = 50) (Figure 3). Three isolates were identified as Cophinforma spp. and deposited in the Coleção de Fitopatógenos da Universidade Federal de Alagoas (COUFAL) as COUFAL0602, COUFAL0603, and COUFAL0604. Genomic DNA was extracted from seven-day-old cultures following the CTAB protocol (Doyle and Doyle 1987). ITS, tef1-α, and tub2 loci were amplified for multilocus analysis using standard primers. Sequences were deposited in GenBank (ITS: Accession Nos. PV544873–PV544875; tef1-α: PV553489–PV553491; tub2: PV553492–PV553494). Bayesian inference based on the concatenated dataset placed all isolates within Cophinforma tumefaciens, with a posterior probability of 1.00 (Figure 4). Although molecular and phylogenetic data generally enable reliable species delimitation in Cophinforma, the absence of tef1-α sequences for the type species C. mamane limits robust comparisons (Phillips et al. 2013). Pathogenicity was confirmed through assays on mature pods and healthy 90-day-old seedlings of N. juliflora. For pod inoculation, mycelial plugs were taken from 7-day-old PDA cultures; for seedlings, colonised parboiled rice grains served as inoculum. Inoculated pods and seedlings were kept in a humid chamber at 28°C for 2 days. Pods developed dark surface lesions and dry internal rot four days post inoculation (dpi) (Figure 5). Seedlings also showed symptoms from four dpi, including cankers on woody tissues (Figure 5), followed by resinous exudation and branch dieback seven dpi. Controls remained symptomless. Fungi reisolated from symptomatic tissues matched the original isolates, fulfilling Koch's postulates. C. tumefaciens is globally distributed and recorded on various hosts. In Brazil, it has been reported to cause stem rot and dieback in cashew (Cardoso et al. 2019). To our knowledge, this is the first report of rot symptoms caused by C. tumefaciens on N. juliflora worldwide.
Source: New Disease Reports
DOI: 10.1002/ndr2.70088
Authors: K. R. S. França, M. M. M. Ferro, G. J,T Souza, M. V. S. Silva, F. M. Feijó, J. F. Lima, A. M. F. Silva, I. P. Assunção, G. S. A. Lima
Institution: Universidade Federal de Alagoas
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: diamond
OpenAlex ID: W4417449397