Instituto de Genética Ewald A. Favret-CICVyA-INTA, Castelar, Buenos Aires, Argentina.
PLoS One. 2013 May 13;8(5):e63666. doi: 10.1371/journal.pone.0063666. Print 2013.
Nitrogen is the second most critical factor for crop production after water. In this study, the beneficial rhizobacterium Pseudomonas protegens Pf-5 was genetically modified to fix nitrogen using the genes encoding the nitrogenase of Pseudomonas stutzeri A1501 via the X940 cosmid. Pf-5 X940 was able to grow in L medium without nitrogen, displayed high nitrogenase activity and released significant quantities of ammonium to the medium. Pf-5 X940 also showed constitutive expression and enzymatic activity of nitrogenase in ammonium medium or in nitrogen-free medium, suggesting a constitutive nitrogen fixation. Similar to Pseudomonas protegens Pf-5, Pseudomonas putida, Pseudomonas veronii and Pseudomonas taetrolens but not Pseudomonas balearica and Pseudomonas stutzeri transformed with cosmid X940 showed constitutive nitrogenase activity and high ammonium production, suggesting that this phenotype depends on the genome context and that this technology to obtain nitrogen-fixing bacteria is not restricted to Pf-5. Interestingly, inoculation of Arabidopsis, alfalfa, tall fescue and maize with Pf-5 X940 increased the ammonium concentration in soil and plant productivity under nitrogen-deficient conditions. In conclusion, these results open the way to the production of effective recombinant inoculants for nitrogen fixation on a wide range of crops.
氮是仅次于水的作物生产的第二大关键因素。在这项研究中，通过 X940 科斯质粒，利用编码假单胞菌 A1501 固氮酶的基因，对具有固氮能力的根际有益细菌恶臭假单胞菌 Pf-5 进行了遗传改造。Pf-5 X940 能够在不含氮的 L 培养基中生长，表现出高固氮酶活性，并向培养基中释放大量铵。Pf-5 X940 还在铵培养基或无氮培养基中表现出固氮酶的组成型表达和酶活性，表明其具有组成型固氮能力。类似于恶臭假单胞菌 Pf-5，转染了 cosmid X940 的假单胞菌 putida、veronii 和 taetrolens 以及 balearica 和 stutzeri 都表现出组成型固氮酶活性和高铵产量，这表明这种表型取决于基因组背景，并且这种获得固氮细菌的技术不仅限于 Pf-5。有趣的是，Pf-5 X940 接种拟南芥、紫花苜蓿、高羊茅和玉米后，在氮缺乏条件下增加了土壤和植物中的铵浓度和生产力。总之，这些结果为生产广泛应用于各种作物的有效固氮重组菌接种剂开辟了道路。
