P3 Institute for Plant and Soil Biology, University of Sheffield, Sheffield, S10 2TN, UK.
Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
New Phytol. 2018 May;218(3):1205-1216. doi: 10.1111/nph.15062. Epub 2018 Feb 21.
β-Aminobutyric acid (BABA) induces broad-spectrum disease resistance, but also represses plant growth, which has limited its exploitation in crop protection. BABA perception relies on binding to the aspartyl-tRNA synthetase (AspRS) IBI1, which primes the enzyme for secondary defense activity. This study aimed to identify structural BABA analogues that induce resistance without stunting plant growth. Using site-directed mutagenesis, we demonstrate that the (l)-aspartic acid-binding domain of IBI1 is critical for BABA perception. Based on interaction models of this domain, we screened a small library of structural BABA analogues for growth repression and induced resistance against biotrophic Hyaloperonospora arabidopsidis (Hpa). A range of resistance-inducing compounds were identified, of which (R)-β-homoserine (RBH) was the most effective. Surprisingly, RBH acted through different pathways than BABA. RBH-induced resistance (RBH-IR) against Hpa functioned independently of salicylic acid, partially relied on camalexin, and was associated with augmented cell wall defense. RBH-IR against necrotrophic Plectosphaerella cucumerina acted via priming of ethylene and jasmonic acid defenses. RBH-IR was also effective in tomato against Botrytis cinerea. Metabolic profiling revealed that RBH, unlike BABA, does not majorly affect plant metabolism. RBH primes distinct defense pathways against biotrophic and necrotrophic pathogens without stunting plant growth, signifying strong potential for exploitation in crop protection.
β-氨基丁酸（BABA）诱导广谱抗病性，但也抑制植物生长，这限制了它在作物保护中的应用。BABA 的感知依赖于与天冬氨酰-tRNA 合成酶（AspRS）IBI1 的结合，这使酶为次级防御活性做好准备。本研究旨在鉴定诱导抗性而不抑制植物生长的结构 BABA 类似物。通过定点突变，我们证明 IBI1 的（l）-天冬氨酸结合域对于 BABA 的感知至关重要。基于该结构域的相互作用模型，我们筛选了一个结构 BABA 类似物的小文库，以寻找抑制生长和诱导对生物亲和性 Hyaloperonospora arabidopsidis（Hpa）的抗性。鉴定出了一系列具有诱导抗性的化合物，其中（R）-β-高丝氨酸（RBH）最为有效。令人惊讶的是，RBH 的作用途径与 BABA 不同。RBH 诱导的对 Hpa 的抗性（RBH-IR）独立于水杨酸，部分依赖于几丁质，与增强的细胞壁防御有关。RBH-IR 对坏死性 Plectosphaerella cucumerina 的作用是通过乙烯和茉莉酸防御的激活。RBH-IR 在番茄中对 Botrytis cinerea 也有效。代谢组学分析表明，RBH 与 BABA 不同，不会主要影响植物代谢。RBH 对生物亲和性和坏死性病原体启动不同的防御途径，而不抑制植物生长，这表明在作物保护中有很大的利用潜力。
