Key message

Overexpression of CiNPR4 enhanced resistance of transgenic citrus plants to Huanglongbing by perceiving the salicylic acid and jasmonic acid signals and up-regulating the transcriptional activities of plant–pathogen interaction genes.

Abstract

Developing transgenic citrus plants with enhanced immunity is an efficient strategy to control citrus Huanglongbing (HLB). Here, a nonexpressor of pathogenesis-related gene 1 (NPR1) like gene from HLB-tolerant ‘Jackson’ grapefruit (Citrus paradisi Macf.), CiNPR4, was introduced into ‘Wanjincheng’ orange (Citrus sinensis Obseck). CiNPR4 expression was determined in transgenic citrus plants using quantitative real-time PCR analyses. The Candidatus Liberibacter asiaticus (CLas) pathogen of HLB was successfully transmitted to transgenic citrus plants by grafting infected buds. HLB symptoms developed in transgenic and wild-type (WT) plants by 9 months after inoculation. A CLas population analysis showed that 26.9% of transgenic lines exhibited significantly lower CLas titer levels compared with the CLas-infected WT plants at 21 months after inoculation. Lower starch contents and anatomical aberration levels in the phloem were observed in transgenic lines having enhanced resistance compared with CLas-infected WT plants. CiNPR4 overexpression changed the jasmonic acid, but not salicylic acid, level. Additionally, the jasmonic acid and salicylic acid levels increased after CLas infection. Transcriptome analyses revealed that the enhanced resistance of transgenic plants to HLB resulted from the up-regulated transcriptional activities of plant–pathogen interaction-related genes.

中文翻译：

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过表达来自天堂柑桔的 NPR1 样基因增强了中华柑桔的黄龙病抗性

关键信息

CiNPR4的过表达通过感知水杨酸和茉莉酸信号并上调植物-病原体相互作用基因的转录活性来增强转基因柑橘植物对黄龙病的抗性。

抽象的

开发具有增强免疫力的转基因柑橘植物是控制柑橘黄龙病（HLB）的有效策略。在这里，将来自 HLB 耐受的“杰克逊”葡萄柚 ( Citrus paradisi Macf.)的致病相关基因 1 ( NPR1 ) 的非表达基因CiNPR4引入到“万金城”橙 ( Citrus sinensis Obseck) 中。使用定量实时 PCR 分析在转基因柑橘植物中确定CiNPR4表达。Candidatus Liberibacter asiaticus ( C通过嫁接受感染的芽，成功地将HLB的Las)病原体传播给转基因柑橘植物。接种后 9 个月，在转基因和野生型 (WT) 植物中出现 HLB 症状。C Las 群体分析表明，在接种后 21 个月，与 C Las 感染的 WT 植物相比， 26.9 % 的转基因品系表现出显着降低的C Las 滴度水平。与C Las 感染的 WT 植物相比，在具有增强抗性的转基因系中观察到韧皮部中较低的淀粉含量和解剖异常水平。CiNPR4过表达改变了茉莉酸水平，但不改变水杨酸水平。此外，茉莉酸和水杨酸水平增加后C Las 感染。转录组分析表明，转基因植物对 HLB 的抗性增强是由于植物-病原体相互作用相关基因的转录活性上调所致。