Bacterial Biosynthesis of 1-Aminocyclopropane-1-Carboxylate (ACC) Deaminase and Indole-3-Acetic Acid (IAA) as Endophytic Preferential Selection Traits by Rice Plant Seedlings
Bacterial Biosynthesis of 1-Aminocyclopropane-1-Carboxylate (ACC) Deaminase and Indole-3-Acetic Acid (IAA) as Endophytic Preferential Selection Traits by Rice Plant Seedlings
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DOI：
10.1007/s00344-014-9415-3
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发表时间：
2014-09-01
影响因子：
4.8
通讯作者：
Mohammadi, Leila
中科院分区：
文献类型：
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作者：
Etesami, Hassan;Hosseini, Hossein Mirsyed;Mohammadi, Leila
在这项研究中，从伊朗田间种植的草木三叶草的根际和根瘤内分离出细菌。从与水稻轮作的三叶草根际(120个分离物)、内根(57个分离物)和根瘤(23个分离物)中分离到200个分离物。对这些菌株的几丁质酶、果胶酶、纤维素酶、铁载体、水杨酸、氰化氢、吲哚乙酸(IAA)、1-氨基环丙烷-1-羧酸(ACC)脱氨酶的产生、磷酸盐的溶解、对各种水稻病原菌的抑菌活性、N-2固定以及在水稻幼苗上的定殖性进行了评价和比较(内生菌株与根际细菌)。结果表明，内生菌株和根际菌株在植物生长促进(PGP)性状的数量和能力上存在差异。内生菌株产生IAA、ACC脱氨酶和铁载体的比例高于根际菌株。因此，三叶草可以形成自己的相关微生物群落，并作为内生菌群落和具有不同(PGP)特性的根际分离物的过滤器。我们还研究了最有希望的内生和根际菌株对水稻幼苗的PGP效应。IAA和ACC脱氨酶的产量、根定植的大小和植物的生长(根的伸长)与铁载体的产量和磷酸盐的溶解之间存在显著的相关性。根据它们促进水稻生长和定植水稻根的能力，确定了最好的细菌分离物(一个内生分离物和一个根际分离物)。根据16S rDNA序列分析，内生菌株CEN7和根际菌株CEN8分别与恶臭假单胞菌和荧光假单胞菌亲缘关系较近。在持续淹水条件下，水稻幼苗的内生和根际能力可能需要PGP性状的产生(如IAA、ACC脱氨酶等)。研究还表明，具有与三叶草相关的有效生长促进特性的各种根际细菌的存在可能被用于田间条件下的可持续作物管理。
In this study, bacteria were isolated from the rhizosphere and inside the roots and nodules of berseem clover plants grown in the field in Iran. Two hundred isolates were obtained from the rhizosphere (120 isolates), interior roots (57 isolates), and nodules (23 isolates) of clover plants grown in rotation with rice plants. Production of chitinase, pectinase, cellulase, siderophore, salicylic acid, hydrogen cyanide, indole acetic acid (IAA), 1-aminocyclopropane-1-carboxylate (ACC) deaminase, solubilization of phosphate, antifungal activity against various rice plant pathogen fungi, N-2 fixation, and colonization assay on rice seedlings by these strains was evaluated and compared (endophytic isolates vs. rhizosphere bacteria). The results showed both the number and the ability of plant growth-promoting (PGP) traits were different between endophytic and rhizosphere isolates. A higher percentage of endophytic isolates were positive for production of IAA, ACC deaminase, and siderophore than rhizosphere isolates. Therefore, it is suggested that clover plant may shape its own associated microbial community and act as filters for endophyte communities, and rhizosphere isolates with different (PGP) traits. We also studied the PGP effect of the most promising endophytic and rhizosphere isolates on rice seedlings. A significant relationship among IAA and ACC deaminase production, the size of root colonization, and plant growth (root elongation) in comparison with siderophore production and phosphate solubilization for the isolates was observed. The best bacterial isolates (one endophytic isolate and one rhizosphere isolate), based on their ability to promote rice growth and colonize rice roots, were identified. Based on 16S rDNA sequence analysis, the endophytic isolate CEN7 and the rhizosphere isolate CEN8 were closely related to Pseudomonas putida and Pseudomonas fluorescens, respectively. It seems that PGP trait production (such as IAA, ACC deaminase) may be required for endophytic and rhizosphere competence as compared to other PGP traits in rice seedlings under constant flooded conditions. The study also shows that the presence of diverse rhizobacteria with effective growth-promoting traits associated with clover plants may be used for sustainable crop management under field conditions.