In 2015, sweetpotato producers in the United States experienced one of the worst outbreaks of black rot recorded in history, with up to 60% losses reported in the field and packing houses and at shipping ports. Host resistance remains the ideal management tool to decrease crop losses. Lack of knowledge of Ceratocystis fimbriata biology represents a critical barrier for the deployment of resistance to black rot in sweetpotato. In this study, we scanned the recent near chromosomal-level assembly for putative secreted effectors in the sweetpotato C. fimbriata isolate AS236 using a custom fungal effector annotation pipeline. We identified a set of 188 putative effectors on the basis of secretion signal and in silico prediction in EffectorP. We conducted a deep RNA time-course sequencing experiment to determine whether C. fimbriata modulates effectors in planta and to define a candidate list of effectors expressed during infection. We examined the expression profile of two C. fimbriata isolates, a pre-epidemic (1990s) isolate and a post-epidemic (2015) isolate. Our in planta expression profiling revealed clusters of co-expressed secreted effector candidates. Based on fold-change differences of putative effectors in both isolates and over the course of infection, we suggested prioritization of 31 effectors for functional characterization. Among this set, we identified several effectors that provide evidence for a marked biotrophic phase in C. fimbriata during infection of sweetpotato storage roots. Our study revealed a catalog of effector proteins that provide insight into C. fimbriata infection mechanisms and represent a core catalog to implement effector-assisted breeding in sweetpotato.

Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

2015年，美国的甘薯生产商经历了历史上最严重的黑腐病爆发之一，田间、包装厂和运输港口的损失高达60%。宿主抗性仍然是减少作物损失的理想管理工具。缺乏对Ceratocystis fimbriata生物学的了解是在甘薯中部署黑腐病抗性的关键障碍。在这项研究中，我们使用定制的真菌效应子注释管道扫描了甘薯C. fimbriata分离株 AS236中推定分泌效应子的最新近染色体水平组装。我们根据 EffectorP 中的分泌信号和计算机预测确定了一组 188 个推定效应器。我们进行了深度 RNA 时程测序实验，以确定C. fimbriata是否调节植物中的效应子，并确定感染期间表达的效应子候选列表。我们检查了两种C. fimbriata分离株的表达谱，一种是流行前（1990 年代）分离株，另一种是流行后（2015 年）分离株。我们的植物内表达谱揭示了共表达的分泌效应候选物的簇。根据两种分离株和感染过程中假定效应器的倍数变化差异，我们建议优先考虑 31 个效应器进行功能表征。在这组中，我们鉴定了几个效应子，这些效应子为甘薯贮藏根感染期间C. fimbriata的显着生物营养阶段提供了证据。我们的研究揭示了一个效应蛋白目录，它提供了对C. fimbriata感染机制的深入了解，并代表了在甘薯中实施效应子辅助育种的核心目录。

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