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烟草内生拮抗细菌的筛选鉴定及其对黑胫病的防效与促生作用

Screening and identification of endophytic antagonistic bacteria from tobacco and their control effect and growth-promoting effect on black shank disease

  • 摘要: 为筛选对烟草疫霉(Phytophthora nicotianae)兼具拮抗与促生作用的烟草内生细菌,从洛阳地区健康烟株中分离内生细菌。通过平板对峙法、菌丝生长速率法及Salkowski比色法,筛选对烟草疫霉菌丝抑制率大于50%且吲哚乙酸(IAA)产量较高的菌株;结合形态学、生理生化特征及基于16S rDNA与gyrB基因的系统发育分析,对优选菌株进行鉴定;通过盆栽与田间试验评价目标菌株对烟草黑胫病的防效及促生效果。结果表明,从1 217株内生细菌中鉴定出7株菌株,包括贝莱斯芽孢杆菌(Bacillus velezensis,菌株8XY2、5ZJ1–10和7XY25)、枯草芽孢杆菌(Bacillus subtilis,菌株5ZJ23和8ZJ7)、短小芽孢杆菌(Bacillus pumilis,菌株6SJ11)及叶状微杆菌(Microbacterium foliorum,菌株5SY32)。其中,菌株6SJ11与7XY25的发酵滤液对烟草疫霉的抑菌率分别为70.56%和68.39%,IAA产量分别为10.48 mg·L–1和11.12 mg·L–1。盆栽试验显示,菌株6SJ11与7XY25对烟草黑胫病的预防效果分别为42.09%和40.52%,防治效果分别为40.39%和46.46%;田间试验中,菌株6SJ11与7XY25在旺长期的防治效果分别达67.48%和63.24%。综上,菌株6SJ11与7XY25在有效防控烟草黑胫病的同时,还能促进烟株不同发育时期的生长。

     

    Abstract: To screen endophytic bacteria from tobacco plants (Nicotiana tabacum) that have both antagonistic and growth-promoting effects against Phytophthora nicotianae, endophytic bacteria were isolated from healthy tobacco plants in Luoyang. Through the plate confrontation method, mycelial growth rate method and Salkowski colorimetric method, strains with mycelial inhibition rates of P. nicotianae greater than 50% and high indole-3-acetic acid (IAA) production were selected. The selected strains were identified based on morphological, physiological and biochemical characteristics and phylogenetic analysis of 16S rDNA and gyrB genes. The control efficacy and growth-promoting effects of the target strains on tobacco black shank disease were evaluated through pot and field experiments. The results showed that seven strains were identified from 1,217 endophytic bacteria, including Bacillus velezensis (strains 8XY2, 5ZJ1-10 and 7XY25), Bacillus subtilis (strains 5ZJ23 and 8ZJ7), Bacillus pumilis (strain 6SJ11) and Microbacterium foliorum (strain 5SY32). Among them, the mycelial inhibition rates of the fermentation filtrates of strains 6SJ11 and 7XY25 against P. nicotianae were 70.56% and 68.39%, respectively, and the IAA production was 10.48 mg·L–1 and 11.12 mg·L–1, respectively. The pot experiment showed that the preventive effects of strains 6SJ11 and 7XY25 on tobacco black shank disease were 42.09% and 40.52%, respectively, and the control effects were 40.39% and 46.46%, respectively. In the field experiment, the control effects of strains 6SJ11 and 7XY25 in the vigorous growth stage reached 67.48% and 63.24%, respectively. In conclusion, strains 6SJ11 and 7XY25 can effectively control tobacco black shank disease and promote the growth of tobacco plants at different growth stages.

     

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