Robin Agnès, Mazurier Sylvie, Mougel Christophe, Vansuyt Gérard, Corberand Thérèse, Meyer Jean-Marie, Lemanceau Philippe
INRA, Université de Bourgogne, UMR1229 Microbiologie du Sol et de l'Environnement, CMSE, 17 rue Sully, BV 86510, F-21034 Dijon cedex, France.
Environ Microbiol. 2007 Jul;9(7):1724-37. doi: 10.1111/j.1462-2920.2007.01290.x.
A transgenic tobacco overexpressing ferritin (P6) was recently shown to accumulate more iron than the wild type (WT), leading to a reduced availability of iron in the rhizosphere and shifts in the pseudomonad community. The impact of the transgenic line on the community of fluorescent pseudomonads was assessed. The diversity of 635 isolates from rhizosphere soils, rhizoplane + root tissues, and root tissues of WT and P6, and that of 98 isolates from uncultivated soil was characterized. Their ability to grow under iron stress conditions was assessed by identifying their minimal inhibitory concentrations of 8-hydroxyquinoline for each isolate, pyoverdine diversity by isoelectrofocusing and genotypic diversity by random amplified polymorphism DNA. The antagonistic activity of representative isolates and of some purified pyoverdines against a plant pathogen (Pythium aphanidermatum Op4) was tested in vitro. In overall, isolates taken from P6 tobacco showed a greater ability to grow in iron stress conditions than WT isolates. The antagonism by some of the representative isolates was only expressed under iron stress conditions promoting siderophore synthesis and their pyoverdines appeared to have a specific structure as assessed by mass spectrometry. For other isolates, antagonism was still expressed in the presence of iron, suggesting the involvement of metabolites other than siderophores. Altogether, these data indicate that the transgenic tobacco that over-accumulates iron selected fluorescent pseudomonads, less susceptible to iron depletion and more antagonistic to the tested plant pathogen than those selected by the tobacco WT.
最近有研究表明，过量表达铁蛋白的转基因烟草（P6）比野生型（WT）积累了更多的铁，导致根际中铁的有效性降低以及假单胞菌群落发生变化。评估了转基因株系对荧光假单胞菌群落的影响。对从WT和P6的根际土壤、根表+根组织以及根组织中分离得到的635株菌株，以及从未耕种土壤中分离得到的98株菌株的多样性进行了表征。通过确定每种菌株对8-羟基喹啉的最低抑菌浓度来评估它们在铁胁迫条件下的生长能力，通过等电聚焦分析铁载体多样性，通过随机扩增多态性DNA分析基因型多样性。在体外测试了代表性菌株和一些纯化铁载体对植物病原菌（瓜果腐霉Op4）的拮抗活性。总体而言，从P6烟草中分离得到的菌株在铁胁迫条件下比WT分离株具有更强的生长能力。一些代表性菌株的拮抗作用仅在促进铁载体合成的铁胁迫条件下表现出来，并且通过质谱分析，它们的铁载体似乎具有特定的结构。对于其他菌株，在有铁的情况下仍表现出拮抗作用，这表明除铁载体外还有其他代谢产物参与其中。总之，这些数据表明，过量积累铁的转基因烟草选择了荧光假单胞菌，这些假单胞菌比烟草WT选择的假单胞菌更不易受到铁耗竭的影响，并且对测试的植物病原菌更具拮抗作用。
