Anthracnose caused by Colletotrichum gloeosporioides occurs extensively during the post-harvest storage of papaya (Carica papaya L.), significantly affecting fruit quality and yield. In this study, the excellent antagonistic bacteria J-11 agaist C. gloeosporioides were screened from the rhizosphere soil of papaya, and the antagonistic characteristics and biological control ability were explored. The size of biocontrol bacterium J-11 was about 1.5 μm×3.3 μm (growing for 3 d), Gram-positive (G+), rod-shaped or oval, common single arrangement, and its morphological characteristics were consistent with Bacillus velezensis. The sequences of 16S rRNA, gyrA and gyrB genes of strain J-11 were 99.28%, 97.57% and 98.79% consistent with those of B. velezensis model strain OOT-47, respectively. Phylogenetic tree analysis showed that the tested strain J-11 and Bacillus velezensis LB4 were clustered into one branch. According to the results of morphological, molecular biological and physicochemical analysis, it was confirmed that the microbial antagonistic pathogen of papaya C. gloeosporioides in Zhanjiang area of Guangdong was B. velezensis. Strain J-11 demonstrated a broad-spectrum antifungal ability, inhibiting the growth of three pathogenic fungi of C. gloeosporioides, C. siamense and Botryosphaeria dothidea, with antagonism indices of 0.48, 0.41 and 0.40, respectively. The control testing showed that the inhibition rate of strain J-11 against the C. gloeosporioides on papaya leaves was 89.96%, and the inhibition rate of strain J-11 against the C. gloeosporioides on papaya fruits in vitro was 84.92%. Strain J-11 screened in this study has a certain control effect on papaya anthracnose, which could provide a theoretical basis for in-depth study of the antibacterial mechanism of plant biocontrol bacteria and will lay a foundation for its development and utilization.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |