To clarify the adaptability of bacterial pathogen Pectobacterium parvum to its vector insect Drosophila melanogaster, flies were recolonized with P. parvum via artificial feeding, and the colonization and survival capabilities of P. parvum and its closely related species in D. melanogaster were compared using quantitative real-time PCR. The results showed that within seven days after feeding D. melanogaster with bacteria-containing glucose solution, the colonization capability of P. parvum in D. melanogaster was comparable to that of P. brasiliense, with a relative bacterial load reaching 8.00, and evidently higher than those of P. parmentieri, P. polaris and P. polonicum. Additionally, P. parvum could achieve efficient vertical transmission via D. melanogaster eggs, with a transmission efficiency significantly higher than that of other closely related species. The relative bacterial load in second-generation larvae reached 8.44, far higher than that of other Pectobacterium species. Furthermore, P. parvum significantly suppressed the expression of key genes in the host Imd immune pathway, including PGRP-LE and Relish, whereas P. polaris significantly induced the expression of these immune genes. These results indicate that P. parvum exhibits significantly stronger adaptation to D. melanogaster than its closely related species, which is closely associated with its strong in vivo colonization capacity, efficient egg-mediated vertical transmission, and significant suppression of key genes in the host Imd immune pathway.
| 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 |