Zimmerli L, Jakab G, Metraux J P, Mauch-Mani B
Department of Biology, Plant Biology, University of Fribourg, Route Albert Gockel 3, 1700 Fribourg, Switzerland.
Proc Natl Acad Sci U S A. 2000 Nov 7;97(23):12920-5. doi: 10.1073/pnas.230416897.
The nonprotein amino acids gamma-aminobutyric acid (GABA) and beta-aminobutyric acid (BABA) have known biological effects in animals and plants. Their mode of action has been the object of thorough research in animals but remains unclear in plants. Our objective was to study the mode of action of BABA in the protection of Arabidopis plants against virulent pathogens. BABA protected Arabidopsis against the oomycete pathogen Peronospora parasitica through activation of natural defense mechanisms of the plant such as callose deposition, the hypersensitive response, and the formation of trailing necroses. BABA was still fully protective against P. parasitica in transgenic plants or mutants impaired in the salicylic acid, jasmonic acid, and ethylene signaling pathways. Treatment with BABA did not induce the accumulation of mRNA of the systemic acquired resistance (SAR)-associated PR-1 and the ethylene- and jasmonic acid-dependent PDF1.2 genes. However, BABA potentiated the accumulation of PR-1 mRNA after attack by virulent pathogenic bacteria. As a result, BABA-treated Arabidopsis plants were less diseased compared with the untreated control. In the case of bacteria, BABA protected mutants insensitive to jasmonic acid and ethylene but was not active in plants impaired in the SAR transduction pathway. Thus, BABA protects Arabidopsis against different virulent pathogens by potentiating pathogen-specific plant resistance mechanisms. In addition, we provide evidence that BABA-mediated papilla formation after P. parasitica infection is independent of the SAR signaling pathway.
非蛋白质氨基酸γ-氨基丁酸（GABA）和β-氨基丁酸（BABA）在动植物中具有已知的生物学效应。它们的作用方式在动物中已成为深入研究的对象，但在植物中仍不清楚。我们的目标是研究BABA在保护拟南芥植物免受毒性病原体侵害方面的作用方式。BABA通过激活植物的天然防御机制，如胼胝质沉积、过敏反应和拖尾坏死的形成，保护拟南芥免受卵菌病原体寄生霜霉的侵害。在水杨酸、茉莉酸和乙烯信号通路受损的转基因植物或突变体中，BABA对寄生霜霉仍具有完全的保护作用。用BABA处理不会诱导系统获得性抗性（SAR）相关的PR-1和乙烯及茉莉酸依赖性PDF1.2基因的mRNA积累。然而，在毒性病原菌攻击后，BABA增强了PR-1 mRNA的积累。结果，与未处理的对照相比，用BABA处理的拟南芥植物病害较轻。在细菌的情况下，BABA保护对茉莉酸和乙烯不敏感的突变体，但在SAR转导途径受损的植物中没有活性。因此，BABA通过增强病原体特异性的植物抗性机制来保护拟南芥免受不同毒性病原体的侵害。此外，我们提供证据表明，寄生霜霉感染后BABA介导的乳突形成独立于SAR信号通路。
