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目的研究小麦PGPR(植物根际促生菌)菌株的个体生态学及其在小麦根圈的定植动态。方法采用三亲本杂交法将发光酶基因luxAB转入具有固氮能力的小麦根际促生菌AzotobacterN2106菌株中,获得标记菌株N2106-L,将标记菌株接种到灭菌和非灭菌的黄褐土、红壤和黄潮土中研究其存活状况,采用根盒试验追踪标记菌株在小麦根圈的定植动态。结果标记菌株N2106-L具有发光活性和对km、str、tet三种抗生素的抗性,且具有较好的遗传稳定性。N2106-L在灭菌土壤中的数量稍高于非灭菌土壤;在3种土壤中的数量依次为:黄褐土>黄潮土>红壤。N2106-L在小麦根表定植密度大于根际定植密度;在小麦根际,小麦播种10 d时标记菌株在0~2 cm深度根际土壤定植达到最大值(2.17±0.25)×106CFU/g土,20 d时在2~4 cm深度的根际土壤中达到最高定植水平(3.92±0.47)×105CFU/g土;在小麦根表,标记菌株在小麦播种10 d时在所有深度的根段均达到最高定植水平,0~2 cm根段定植密度为(3.60±0.60)×106CFU/g鲜根,12 cm以下根段达到(2.78±0.56)×104CFU/g鲜根。结论标记菌株随着根的伸长不断向根尖方向扩散,且较为稳定地在小麦根圈定植,研究结果为小麦PGPR菌株的应用提供了可靠实验数据。
Objective To study the individual ecology of wheat PGPR (plant rhizosphere growth promoting bacteria) strain and its colonization in wheat root circle. Methods The luxAB gene was transferred into Azotobacter NO2106, a nitrogen-fixing rhizosphere rhizobacteria strain, by the method of three parents to obtain marker strain N2106-L. The marker strains were inoculated into sterile and non-sterile yellow cinnamon soil. The red-soil and yellow-brown soil were studied for their survival status. Root-box test was used to trace the colonization of the labeled strain in the wheat root circle. Results The marker strain N2106-L had the activity of luminescence and resistance to three antibiotics such as km, str and tet, and had good genetic stability. The amount of N2106-L in the sterilized soil was slightly higher than that in the non-sterile soil. The order of the amount of N2106-L was yellow-brown soil> yellow-brown soil> red soil. The density of N2106-L was higher than that of rhizosphere in the root surface of wheat. In the rhizosphere of wheat, the maximum of rhizosphere soil was reached at the depth of 0-2 cm (2.17 ± 0.25) × 106CFU / g soil At 20 d, the highest colonization level (3.92 ± 0.47) × 105 CFU / g was reached in the rhizosphere soil at the depth of 2 ~ 4 cm. At the root surface of wheat, The highest rooting density was reached at the root of 0 ~ 2 cm (3.60 ± 0.60) × 106CFU / g fresh roots, while the roots under 12 cm reached (2.78 ± 0.56) × 104CFU / g fresh roots. CONCLUSION: The marker strains spread to the apical direction with the elongation of root, and colonized more stably in wheat rhizosphere. The results provided reliable experimental data for the application of wheat PGPR strains.