ABSTRACT An alternative approach to control Huanglongbing disease in Citrus is the development of transgenic plants expressing genes that may influence pathogen development. We report herein the production of sweet orange transgenic plants bearing gene constructs containing the antimicrobial gene attacin A (attA) under the control of phloem-specific promoters. Transcripts of the attA gene were accumulated in the transgenic lines bearing the three gene constructs. However, phloem protein 2 promoters drive higher levels of attA mRNA than sucrose transporter 2 promoter. Candidatus Liberibacter asiaticus (CLas) were transmitted to transgenic plants via infected Asian citrus psyllid or by grafting infected budwood. The efficiency of CLas transmission via infected psyllids was very low and therefore did not allow evaluating the influence of attA expression on bacteria multiplication. On the other hand, CLas transmission via grafting infected budwood was very efficient. Huanglongbing (HLB) symptoms were detected five months after inoculation in both transgenic and non-transgenic inoculated plants. CLas titers, determined 12 months after inoculation, were similar in both transgenic and non-transgenic inoculated plants. However, non-transgenic inoculated plants showed a significant reduction in shoot development comparing to transgenic inoculated plants indicating that the expression of attA gene may influence the plant tolerance to HLB disease.

中文翻译：

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在韧皮部特异性启动子控制下用 attacin A 基因进行甜橙遗传转化并接种 Candidatus Liberibacter asiaticus

摘要 控制柑橘黄龙病的另一种方法是开发表达可能影响病原体发育的基因的转基因植物。我们在本文中报告了甜橙转基因植物的生产，该植物带有包含在韧皮部特异性启动子控制下的抗微生物基因 attacin A (attA) 的基因构建体。attA 基因的转录物在带有三种基因构建体的转基因品系中积累。然而，韧皮部蛋白 2 启动子比蔗糖转运蛋白 2 启动子驱动更高水平的 attA mRNA。Candidatus Liberibacter asiaticus (CLas) 通过受感染的亚洲柑橘木虱或通过嫁接受感染的芽木传播给转基因植物。CLas 通过受感染木虱传播的效率非常低，因此无法评估 attA 表达对细菌繁殖的影响。另一方面，通过嫁接受感染的芽木进行CLas传播非常有效。在转基因和非转基因接种植物中接种 5 个月后检测到黄龙病 (HLB) 症状。接种后 12 个月测定的 Clas 滴度在转基因和非转基因接种植物中相似。然而，与转基因接种植物相比，非转基因接种植物的枝条发育显着降低，表明 attA 基因的表达可能影响植物对 HLB 病的耐受性。在转基因和非转基因接种植物中接种 5 个月后检测到黄龙病 (HLB) 症状。接种后 12 个月测定的 Clas 滴度在转基因和非转基因接种植物中相似。然而，与转基因接种植物相比，非转基因接种植物的枝条发育显着降低，表明 attA 基因的表达可能影响植物对 HLB 病的耐受性。在转基因和非转基因接种植物中接种 5 个月后检测到黄龙病 (HLB) 症状。接种后 12 个月测定的 Clas 滴度在转基因和非转基因接种植物中相似。然而，与转基因接种植物相比，非转基因接种植物的枝条发育显着降低，表明 attA 基因的表达可能影响植物对 HLB 病的耐受性。