Introduction of the phzH gene of Pseudomonas chlororaphis PCL1391 extends the range of biocontrol ability of phenazine-1-carboxylic acid-producing Pseudomonas spp. strains
Introduction of the phzH gene of Pseudomonas chlororaphis PCL1391 extends the range of biocontrol ability of phenazine-1-carboxylic acid-producing Pseudomonas spp. strains
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DOI：
10.1094/mpmi.2001.14.8.1006
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发表时间：
2001-08-01
影响因子：
3.5
通讯作者：
Bloemberg, GV
中科院分区：
文献类型：
--
作者：
Chin-A-Woeng, TFC;Thomas-Oates, JE;Bloemberg, GV
绿蚜假单胞菌PCL1391防治番茄尖孢镰刀菌引起的番茄根腐病和脚腐病。番茄根腐病菌的生防活性是由吩嗪-L-甲酰胺(Pcn)的产生介导的，而产生吩嗪-L-羧酸(Pcn)的生防菌P、荧光菌2-79和金色P菌30-84不能控制该病，为了确定酰胺基在生防中的作用，对PCL1391菌株的PCN生物合成基因进行了鉴定和鉴定。在phzA的下游通过phzG，发现了一种新的吩嗪生物合成基因phzH，它是PCN的L-羧酰胺基团存在所必需的，因为PCL1391的phzH突变株积累了PCA，所推导的PhzH蛋白与属于II类谷氨酰胺转移酶的天冬酰胺合成酶具有同源性，表明PCA转化为PCN是通过PhzH催化的转氨酶反应进行的。PhzH的突变导致生防活性丧失，说明多氯联苯的L-羧胺基团对番茄根腐病和根腐病的防治起关键作用。通过在反式中补充phzH基因，恢复了突变体的PCN生产和生防活性。此外，将tac启动子控制下的phzH转移到生防菌P，荧光菌2-79和生防菌P，aureofaciens 30-84，可以使这些菌株产生PCN，而不是PCA，并抑制番茄根腐病和脚腐病。因此，我们第一次证明了，引入单一基因可以有效地扩大细菌菌株的生防能力范围。
Pseudomonas chlororaphis PCL1391 controls tomato foot and root rot caused by Fusarium oxysporum f.sp. radicis-lycopersici, Its biocontrol activity is mediated by the production of phenazine-l-carboxamide (PCN), In contrast, the take-all biocontrol strains P, fluorescens 2-79 and P, aureofaciens 30-84, which produce phenazine-l-carboxylic acid (PCA), do not control this disease, To determine the role of the amide group in biocontrol, the PCN biosynthetic genes of strain PCL1391 were identified and characterized. Downstream of phzA through phzG, the novel phenazine biosynthetic gene phzH was identified and shown to be required for the presence of the l-carboxamide group of PCN because a phzH mutant of strain PCL1391 accumulated PCA, The deduced PhzH protein shows homology with asparagine synthetases that belong to the class II glutamine amidotransferases, indicating that the conversion of PCA to PCN occurs via a transamidase reaction catalyzed by PhzH. Mutation of phzH caused loss of biocontrol activity, showing that the l-carboxamide group of PCN is crucial for control of tomato foot and root rot. PCN production and biocontrol activity of the mutant were restored by complementing the phzH gene in trans. Moreover, transfer of phzH under control of the tac promoter to the PCA-producing biocontrol strains P,fluorescens 2-79 and P, aureofaciens 30-84 enabled these strains to produce PCN instead of PCA and suppress tomato foot and root rot. Thus, we have shown, for what we believe is the first time, that the introduction of a single gene can efficiently extend the range of the biocontrol ability of bacterial strains.