The relationships within Drosophila melanogaster species group are controversial from morphology, chromosomes and DNA sequences. This study utilises a molecular approach aimed at uncovering the phylogenetic relationships among 33 taxa representing 8 subgroups of D. melanogaster species groups. Mitocondrial ND4L-ND4 was sequenced in the all 8 subgroups covering a wide geographic area. MP and Bayesian analysis produced an identical tree topology with relatively strong support in most nodes. It reveals that the melanogaster species group clustered in three main lineages：1）montium subgroup; 2） ananassae subgroup; 3） Oriental subgroups （ melanogaster, ficsphila, eugracilis, elegans, syzukii and takahashii）. The montium subgroup branched off first, followed by the ananassae subgroup. In the third lineage, melanogaster is the most divergent subgroup followed by ficsphila, eugracilis, elegans in that order. The suzukii and takahashii sister subgroups are the last to branch off.
为挖掘对烟草镰刀菌根腐病具有较强拮抗作用的生防菌株,绿色防治烟草镰刀菌根腐病,本研究利用平板对峙法分离筛选出一株对尖孢镰刀菌具有高效拮抗活性的菌株TH0008,抑菌率为86.3%,通过形态学、生理生化特征以及16S rRNA序列分析鉴定该菌株为高地芽胞杆菌(Bacillus altitudinis)。该菌株发酵上清液中含有几丁质酶和纤维素酶,可溶解病原菌的细胞壁;同时烟苗中PPO、POD和PAL防御酶活性升高,说明菌株TH0008能诱导烟草产生抗性。盆栽试验也发现菌株TH0008对镰刀菌根腐病的防控优于商品化的农药甲霜·锰锌可湿性粉剂,相对防效达到84.9%,表明高地芽胞杆菌TH0008在绿色防治烟草根腐病中具有较大的应用潜力。To identify biocontrol strains with strong antagonistic effects against Fusarium root rot disease in tobacco and promote environmentally friendly management of this disease, a bacterial strain TH0008 was isolated using the dual-culture method and exhibited high antagonistic activity against Fusarium oxysporum with an inhibition rate of 86.3%. The strain was identified as Bacillus altitudinis based on morphological, physiological, biochemical characteristics, and 16S rRNA gene sequence analysis. The fermentation supernatant of TH0008 contained chitinase and cellulase, which can degrade the cell walls of pathogens, and it significantly induced the activity of defense enzymes PPO, POD, and PAL in tobacco seedlings. Pot experiments further demonstrated that strain TH0008 provided superior control of Fusarium root rot disease compared to the commercial fungicide Metalaxyl-Mancozeb wettable powder, achieving a relative control efficacy of 84.9%. These findings suggest that Bacillus altitudinis TH0008 has significant potential for sustainable biological control of tobacco root rot disease.
