The Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.
J Exp Bot. 2013 Apr;64(6):1565-73. doi: 10.1093/jxb/ert031. Epub 2013 Feb 11.
Many plant-growth-promoting rhizobacteria (PGPR) associated with plant roots contain the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase and can metabolize ACC, the immediate precursor of the plant hormone ethylene, thereby decreasing plant ethylene production and increasing plant growth. However, relatively few studies have explicitly linked ethylene emission and/or action to growth promotion in these plant-microbe interactions. This study examined effects of the PGPR Variovorax paradoxus 5C-2 containing ACC deaminase on the growth and development of Arabidopsis thaliana using wild-type (WT) plants and several ethylene-related mutants (etr1-1, ein2-1, and eto1-1). Soil inoculation with V. paradoxus 5C-2 promoted growth (leaf area and shoot biomass) of WT plants and the ethylene-overproducing mutant eto1-1, and also enhanced floral initiation of WT plants by 2.5 days. However, these effects were not seen in ethylene-insensitive mutants (etr1-1 and ein2-1) even though bacterial colonization of the root system was similar. Furthermore, V. paradoxus 5C-2 decreased ACC concentrations of rosette leaves of WT plants by 59% and foliar ethylene emission of both WT plants and eto1-1 mutants by 42 and 37%, respectively. Taken together, these results demonstrate that a fully functional ethylene signal transduction pathway is required for V. paradoxus 5C-2 to stimulate leaf growth and flowering of A. thaliana.
许多与植物根系相关的植物生长促进根际细菌（PGPR）含有 1-氨基环丙烷-1-羧酸（ACC）脱氨酶，并可以代谢 ACC，即植物激素乙烯的直接前体，从而减少植物乙烯的产生并促进植物生长。然而，在这些植物-微生物相互作用中，明确将乙烯排放和/或作用与生长促进联系起来的研究相对较少。本研究使用野生型（WT）植物和几种乙烯相关突变体（etr1-1、ein2-1 和 eto1-1），研究了含有 ACC 脱氨酶的 PGPR Variovorax paradoxus 5C-2 对拟南芥生长和发育的影响。V. paradoxus 5C-2 土壤接种促进了 WT 植物和乙烯过量产生突变体 eto1-1 的生长（叶面积和地上生物量），并使 WT 植物的花启动提前了 2.5 天。然而，这些效应在乙烯不敏感突变体（etr1-1 和 ein2-1）中并未出现，尽管根系的细菌定殖相似。此外，V. paradoxus 5C-2 使 WT 植物的莲座叶 ACC 浓度降低了 59%，WT 植物和 eto1-1 突变体的叶片乙烯排放分别降低了 42%和 37%。综上所述，这些结果表明，V. paradoxus 5C-2 刺激拟南芥叶片生长和开花需要一个功能齐全的乙烯信号转导途径。
