Department of Biology, University of Waterloo, Waterloo, ON, Canada.
J Appl Microbiol. 2012 Nov;113(5):1139-44. doi: 10.1111/j.1365-2672.2012.05409.x. Epub 2012 Aug 21.
The ability of 1-aminocyclopropane-1-carboxylate (ACC) deaminase-containing plant growth-promoting bacterial (PGPB) endophytes Pseudomonas fluorescens YsS6 and Pseudomonas migulae 8R6, their ACC deaminase minus mutants and the rhizospheric plant growth-promoting bacterium Pseudomonas putida UW4 to delay the senescence of mini carnation cut flowers was assessed.
Fresh cut flowers were incubated with either a bacterial cell suspension, the ethylene precursor ACC, the ethylene inhibitor l-α-(aminoethoxyvinyl)-glycine or 0·85% NaCl at room temperature for 11 days. Levels of flower senescence were recorded every other day. To verify the presence of endophytes inside the plant tissues, scanning electron microscopy was performed. Among all treatments, flowers treated with wild-type ACC deaminase-containing endophytic strains exhibited the most significant delay in flower senescence, while flowers treated with the ACC deaminase minus mutants senesced at a rate similar to the control. Flowers treated with Ps. putida UW4 senesced more rapidly than untreated control flowers.
The only difference between wild-type and mutant bacterial endophytes was ACC deaminase activity so that it may be concluded that this enzyme is directly responsible for the significant delay in flower senescence. Despite containing ACC deaminase activity, Ps. putida UW4 is not taken up by the cut flowers and therefore has no effect on prolonging their shelf life.
The world-wide cut flower industry currently uses expensive and potentially environmentally dangerous chemical inhibitors of ethylene to prolong the shelf life of cut flowers. The use of PGPB endophytes with ACC deaminase activity has the potential to replace the chemicals that are currently used by the cut flower industry.
评估含有 1-氨基环丙烷-1-羧酸（ACC）脱氨酶的植物促生细菌（PGPB）内生菌荧光假单胞菌 YsS6 和米根霉 8R6、其 ACC 脱氨酶缺失突变体和根际促生细菌恶臭假单胞菌 UW4 延迟迷你康乃馨切花衰老的能力。
将新鲜切花在室温下用细菌悬浮液、乙烯前体 ACC、乙烯抑制剂 l-α-（氨基乙氧基乙烯基）-甘氨酸或 0.85%NaCl 处理 11 天。每隔一天记录一次花朵衰老程度。为了验证内生菌在植物组织内的存在，进行了扫描电子显微镜观察。在所有处理中，用野生型 ACC 脱氨酶含内生菌株处理的花朵衰老速度最慢，而用 ACC 脱氨酶缺失突变体处理的花朵衰老速度与对照相似。用恶臭假单胞菌 UW4 处理的花朵比未处理的对照花朵衰老得更快。
野生型和突变型细菌内生菌之间的唯一区别是 ACC 脱氨酶活性，因此可以得出结论，该酶直接负责显著延缓花朵衰老。尽管恶臭假单胞菌 UW4 含有 ACC 脱氨酶活性，但它不会被切花吸收，因此对延长其货架寿命没有影响。
全球切花产业目前使用昂贵且潜在对环境有害的乙烯化学抑制剂来延长切花的货架寿命。使用具有 ACC 脱氨酶活性的 PGPB 内生菌有可能取代切花产业目前使用的化学物质。
