Digitaria insularis (L.) Fedde (sourgrass) is a perennial monocotyledon weed easily found in soybean fields in Brazil. The emergence of herbicide-resistant sourgrass biotypes is common, making it difficult to control (Gonçalves Netto et al. 2021). In March 2019, yellow elongated necrotic spots were detected on sourgrass leaves, touching full mature soybean plants with anthracnose symptoms in a commercial soybean field in Brazil (23°07’34.4"S, 47°19’39.4"W), with around 200 sourgrass plants ha− 1 and 20% incidence of soybean anthracnose. Symptomatic leaf tissues of sourgrass were randomly sampled, disinfected (70% ethanol for 30 s, 1% sodium hypochlorite for 2 min) and incubated in a moist chamber at 25 °C with photophase of 12 h. After three days, a single-spore isolate (LFNDI01) was obtained from acervuli containing falcate conidia (20.24 to 26.67 × 3.33 to 4.76 μm, n = 30). Total DNA was extracted and β-tubulin (TUB2), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), histone H3 (HIS3), and the internal transcribed spacer (ITS) regions were amplified, sequenced and deposited in GenBank (accession numbers OP597269, OP597268, OP597270 and OP531846). The isolate LFNDI01 clustered with Colletotrichum truncatum (Schwein.) Andrus and Moore epitype (CBS 151.35) with the Bayesian Posterior Probability (BPP) of 1.00. Pathogenicity tests were performed with 30 days-old sourgrass plants sprayed with a conidial suspension of the LFNDI01 isolate (105 conidia mL− 1) or mock inoculated with sterile distilled water, and incubated at 25 °C for 7 days, when typical anthracnose symptoms were observed. Mock inoculated plants remained asymptomatic. C. truncatum was successfully reisolated from sourgrass leaves. Since C. truncatum is the main species associated with symptomatic soybean plants with anthracnose (Boufleur et al. 2021), this report indicates that sourgrass may play a role in the soybean anthracnose epidemiology as a primary inoculum source. To the best of our knowledge, this is the first report of C. truncatum causing anthracnose on sourgrass.
Tikami, I., Baroncelli, R., Ciampi-Guillardi, M., Martins, T.V., Boufleur, T.R., Massola, N.S. (2023). First report of anthracnose caused by Colletotrichum truncatum on Digitaria insularis in Brazil. JOURNAL OF PLANT PATHOLOGY, 106(1), 1-3 [10.1007/s42161-023-01457-3].
First report of anthracnose caused by Colletotrichum truncatum on Digitaria insularis in Brazil
Baroncelli, RSecondo
;
2023
Abstract
Digitaria insularis (L.) Fedde (sourgrass) is a perennial monocotyledon weed easily found in soybean fields in Brazil. The emergence of herbicide-resistant sourgrass biotypes is common, making it difficult to control (Gonçalves Netto et al. 2021). In March 2019, yellow elongated necrotic spots were detected on sourgrass leaves, touching full mature soybean plants with anthracnose symptoms in a commercial soybean field in Brazil (23°07’34.4"S, 47°19’39.4"W), with around 200 sourgrass plants ha− 1 and 20% incidence of soybean anthracnose. Symptomatic leaf tissues of sourgrass were randomly sampled, disinfected (70% ethanol for 30 s, 1% sodium hypochlorite for 2 min) and incubated in a moist chamber at 25 °C with photophase of 12 h. After three days, a single-spore isolate (LFNDI01) was obtained from acervuli containing falcate conidia (20.24 to 26.67 × 3.33 to 4.76 μm, n = 30). Total DNA was extracted and β-tubulin (TUB2), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), histone H3 (HIS3), and the internal transcribed spacer (ITS) regions were amplified, sequenced and deposited in GenBank (accession numbers OP597269, OP597268, OP597270 and OP531846). The isolate LFNDI01 clustered with Colletotrichum truncatum (Schwein.) Andrus and Moore epitype (CBS 151.35) with the Bayesian Posterior Probability (BPP) of 1.00. Pathogenicity tests were performed with 30 days-old sourgrass plants sprayed with a conidial suspension of the LFNDI01 isolate (105 conidia mL− 1) or mock inoculated with sterile distilled water, and incubated at 25 °C for 7 days, when typical anthracnose symptoms were observed. Mock inoculated plants remained asymptomatic. C. truncatum was successfully reisolated from sourgrass leaves. Since C. truncatum is the main species associated with symptomatic soybean plants with anthracnose (Boufleur et al. 2021), this report indicates that sourgrass may play a role in the soybean anthracnose epidemiology as a primary inoculum source. To the best of our knowledge, this is the first report of C. truncatum causing anthracnose on sourgrass.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
