Fruit Anthracnose on Cavendish Bananas Caused by <i>Colletotrichum fructicola</i> in Guangxi, China
Bibliographic record
Abstract
Cavendish banana (Musa spp. AAA group) is one of the main fruit crops worldwide. It is widely planted in Guangdong, Hainan, Guangxi, Fujian and Yunnan provinces in southern China. In November 2020, banana fruits with anthracnose symptoms were collected from Dayu Town (N 23.17°, E 109.80°), Guigang City, and Chengjun Town (N 22.60°, E 110.00°), Yulin City, Guangxi Province, China, where the disease was found on about 70% of the banana plants, and on individual fruit, up to 10% of the surface was covered with symptoms. The symptoms initially began with rust-colored spots on the surface of the immature fruit, which gradually became sunken and cracked as the disease progressed. Small tissues (5×5 mm) from the pericarp at the junction of disease and health were surface-disinfected in 75% ethanol for 10 s, 2% sodium hypochlorite (NaClO) for 1 min, and washed three times in sterile water. Tissue pieces were placed on potato dextrose ager (PDA) and incubated at 25°C. Fifty-nine morphologically similar colonies were obtained after 5 days of incubation, with 100% isolation frequency. Of 59 isolates, GG1-3 isolated from Guigang City and YL4-2 isolated from Yulin City were selected as representative strains for intensive study. Mycelia were off-white for both isolates and conidia obtained from PDA were cylindrical, unicellular, hyaline and obtuse ends, with sizes of 11.5 ± 1.8×3.9 ± 0.8 µm (n=60) and 11.5 ± 1.6×4.1 ± 0.6 µm (n=60) for GG1-3 and YL4-2, respectively (Prihastuti et al. 2009). Genomic DNA was extracted from 7-day-old aerial mycelia using a DNAsecure Plant Kit (Tiangen Biotech, China). The internal transcribed spacer (ITS), the intergenic region of apn2 and MAT1-2-1 (ApMAT) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were amplified and sequenced (White et al. 1990; Silva et al.2012; Templeton et al. 1992). Sequences were deposited in GenBank (ITS, OR596961 to OR596962; GAPDH, OR661771 to OR661772; APMAT, OR661773 to OR661774) and showed 100% identities with the corresponding type strains sequences of C. fructicola. Phylogenetic tree was constructed with software raxmlGUI v.2.0.0 based on sequences of multiple loci (ITS, GAPDH and ApMAT) and Maximum Likelihood method. Phylogenetic analysis revealed that the two isolates and C. fructicola were clustered in the same clade, with 94% bootstrap support. According to morphology and phylogenetic analysis, the two isolates GG1-3 and YL4-2 were identified as C. fructicola. For pathogenicity tests, healthy fruits were surface sterilized with 75% ethanol followed by a wash with sterilized water. Five adjacent needle punctures in a 5-mm-diameter circle were made with a sterilized needle on healthy fruits, followed by inoculation with 20 μL of conidial suspension (106 spores/ml), and sterilized water was used as controls. All banana fruit were incubated in a humid chamber at 28°C. After 4 days, all inoculated fruits showed visible symptoms and had rust-colored spots on the margins, while control banana fruits remained symptomless. The fungus was isolated from the inoculated fruit and the isolates were found to match the morphological and molecular characteristics of the original isolates, confirming Koch's hypothesis. To our knowledge, this is the first report of fruit anthracnose on Cavendish bananas caused by C. fructicola in China. This study will provide valuable information for prevention and management of anthracnose on banana fruit.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".