Department of Microbiology and Plant Pathology, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521.
Contained Research Facility, University of California, Davis, CA 95616.
Proc Natl Acad Sci U S A. 2021 Feb 9;118(6). doi: 10.1073/pnas.2019628118.
Citrus Huanglongbing (HLB), caused by a vector-transmitted phloem-limited bacterium Liberibacter asiaticus (Las), is the most devastating citrus disease worldwide. Currently, there are no effective strategies to prevent infection or to cure HLB-positive trees. Here, using comparative analysis between HLB-sensitive citrus cultivars and HLB-tolerant citrus hybrids and relatives, we identified a novel class of stable antimicrobial peptides (SAMPs). The SAMP from can rapidly kill (), a culturable Liberibacter strain, and inhibit infections of Las and L. solanacearum in plants. In controlled greenhouse trials, SAMP not only effectively reduced Las titer and disease symptoms in HLB-positive trees but also induced innate immunity to prevent and inhibit infections. Importantly, unlike antibiotics, SAMP is heat stable, making it better suited for field applications. Spray-applied SAMP was taken up by citrus leaves, stayed stable inside the plants for at least a week, and moved systemically through the vascular system where Las is located. We further demonstrate that SAMP is most effective on α-proteobacteria and causes rapid cytosol leakage and cell lysis. The α-helix-2 domain of SAMP is sufficient to kill Future field trials will help determine the efficacy of SAMP in controlling HLB and the ideal mode of application.
黄龙病（HLB）由韧皮部局限细菌韧皮部杆菌属亚洲种（Las）引起，是世界上最具破坏性的柑橘病害。目前，尚无有效的预防感染或治疗 HLB 阳性树的策略。在这里，我们通过对 HLB 敏感的柑橘品种和 HLB 耐受的柑橘杂种及其亲缘种的比较分析，鉴定了一类新型稳定的抗菌肽（SAMPs）。 中的 SAMP 可迅速杀死（），一种可培养的韧皮部杆菌菌株，并抑制植物中 Las 和 L. solanacearum 的感染。在温室控制试验中，SAMP 不仅有效降低了 HLB 阳性树上的 Las 滴度和病症，还诱导了先天免疫以预防和抑制感染。重要的是，与抗生素不同，SAMP 热稳定性好，更适合田间应用。喷雾施用的 SAMP 被柑橘叶片吸收，在植物体内至少稳定一周，并通过韧皮部杆菌所在的维管束系统系统性移动。我们进一步证明 SAMP 对α-变形菌最有效，导致细胞质迅速渗漏和细胞裂解。SAMP 的α-螺旋-2 结构域足以杀死 未来的田间试验将有助于确定 SAMP 在控制 HLB 中的功效和理想的应用方式。
