Fernández-Llamosas Helga, Ibero Juan, Thijs Sofie, Imperato Valeria, Vangronsveld Jaco, Díaz Eduardo, Carmona Manuel
Microbial and Plant Biotechnology Department, Centro de Investigaciones Biológicas-CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain.
Department of Environmental Biology, Centre for Environmental Sciences, Hasselt University, 3590 Diepenbeek, Belgium.
Microorganisms. 2020 Sep 22;8(9):1453. doi: 10.3390/microorganisms8091453.
Environmental pollutants can generate stress in plants causing increased ethylene production that leads to the inhibition of plant growth. Ethylene production by the stressed plant may be lowered by Plant Growth-Promoting Bacteria (PGPB) that metabolizes the immediate precursor of ethylene 1-aminocyclopropane-1-carboxylate (ACC). Thus, engineering PGPB with ACC deaminase activity can be a promising alternative to mitigate the harmful effects of pollutants and thus enhance plant production. Here we show that the aromatics-degrading and metal-resistant sp. CIB behaves as a PGP-bacterium when colonizing rice as an endophyte, showing a 30% increment in plant weight compared to non-inoculated plants. The cloning and expression of an gene led to a recombinant strain, sp. CIB (pSEVA237acdS), possessing significant ACC deaminase activity (6716 nmol mg h), constituting the first PGPB of the Rhodocyclaceae family equipped with this PGP trait. The recombinant CIB strain acquired the ability to protect inoculated rice plants from the stress induced by cadmium (Cd) exposure and to increase the Cd concentration in rice seedlings. The observed decrease of the levels of reactive oxygen species levels in rice roots confirms such a protective effect. The broad-host-range pSEVA237acdS plasmid paves the way to engineer PGPB with ACC deaminase activity to improve the growth of plants that might face stress conditions.
环境污染物会给植物造成压力，导致乙烯产量增加，进而抑制植物生长。受胁迫植物产生的乙烯可被植物促生细菌（PGPB）降低，这类细菌可代谢乙烯的直接前体1-氨基环丙烷-1-羧酸（ACC）。因此，构建具有ACC脱氨酶活性的PGPB可能是减轻污染物有害影响从而提高植物产量的一种有前景的替代方法。在此我们表明，芳香族化合物降解且耐金属的某菌株CIB作为内生菌定殖于水稻时表现为一种PGP细菌，与未接种的植物相比，植物重量增加了30%。一个基因的克隆和表达产生了一株重组菌株，即某菌株CIB（pSEVA237acdS），其具有显著的ACC脱氨酶活性（6716 nmol mg h），成为红环菌科首个具备这种PGP特性的PGPB。重组CIB菌株获得了保护接种水稻植株免受镉（Cd）暴露诱导的胁迫以及提高水稻幼苗中Cd浓度的能力。在水稻根中观察到的活性氧水平的降低证实了这种保护作用。广宿主范围的pSEVA237acdS质粒为构建具有ACC脱氨酶活性的PGPB以促进可能面临胁迫条件的植物生长铺平了道路。
