Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, United States of America.
Atlantic Oceanographic and Meteorological Laboratory, National Oceanographic and Atmospheric Administration, Miami, Florida, United States of America.
PLoS One. 2020 Oct 22;15(10):e0228514. doi: 10.1371/journal.pone.0228514. eCollection 2020.
Coral disease outbreaks are expected to increase in prevalence, frequency and severity due to climate change and other anthropogenic stressors. This is especially worrying for the Caribbean branching coral Acropora palmata which has already seen an 80% decrease in cover primarily due to disease. Despite the importance of this keystone species, there has yet to be a characterization of its transcriptomic response to disease exposure. In this study we provide the first transcriptomic analysis of 12 A. palmata genotypes and their symbiont Symbiodiniaceae exposed to disease in 2016 and 2017. Year was the primary driver of gene expression variance for A. palmata and the Symbiodiniaceae. We hypothesize that lower expression of ribosomal genes in the coral, and higher expression of transmembrane ion transport genes in the Symbiodiniaceae indicate that a compensation or dysbiosis may be occurring between host and symbiont. Disease response was the second driver of gene expression variance for A. palmata and included a core set of 422 genes that were significantly differentially expressed. Of these, 2 genes (a predicted cyclin-dependent kinase 11b and aspartate 1-decarboxylase) showed negative Log2 fold changes in corals showing transmission of disease, and positive Log2 fold changes in corals showing no transmission of disease, indicating that these may be important in disease resistance. Co-expression analysis identified two modules positively correlated to disease exposure, one enriched for lipid biosynthesis genes, and the other enriched in innate immune genes. The hub gene in the immune module was identified as D-amino acid oxidase, a gene implicated in phagocytosis and microbiome homeostasis. The role of D-amino acid oxidase in coral immunity has not been characterized but could be an important enzyme for responding to disease. Our results indicate that A. palmata mounts a core immune response to disease exposure despite differences in the disease type and virulence between 2016 and 2017. These identified genes may be important for future biomarker development in this Caribbean keystone species.
珊瑚疾病爆发的频率、严重程度预计会因气候变化和其他人为压力因素而增加。这对加勒比分枝珊瑚 Acropora palmata 来说尤其令人担忧，由于疾病，其覆盖率已经减少了 80%。尽管这种关键物种非常重要，但尚未对其暴露于疾病时的转录组反应进行特征描述。在这项研究中，我们对 2016 年和 2017 年 12 种 A. palmata 基因型及其共生体 Symbiodiniaceae 进行了首次转录组分析。年份是 A. palmata 和 Symbiodiniaceae 基因表达方差的主要驱动因素。我们假设珊瑚中核糖体基因表达较低，而共生体中跨膜离子转运基因表达较高，这表明宿主和共生体之间可能存在补偿或失调。疾病反应是 A. palmata 基因表达方差的第二个驱动因素，包括一组 422 个显著差异表达的核心基因。其中，2 个基因（预测的细胞周期蛋白依赖性激酶 11b 和天冬氨酸 1-脱羧酶）在表现出疾病传播的珊瑚中显示出负的 Log2 折叠变化，而在没有表现出疾病传播的珊瑚中显示出正的 Log2 折叠变化，表明这些基因可能在疾病抗性中很重要。共表达分析确定了两个与疾病暴露呈正相关的模块，一个模块富集了脂质生物合成基因，另一个模块富集了先天免疫基因。免疫模块的枢纽基因被鉴定为 D-氨基酸氧化酶，该基因与吞噬作用和微生物组稳态有关。D-氨基酸氧化酶在珊瑚免疫中的作用尚未得到表征，但它可能是应对疾病的重要酶。我们的研究结果表明，A. palmata 对疾病暴露会产生核心免疫反应，尽管 2016 年和 2017 年的疾病类型和毒力不同。这些鉴定出的基因可能对未来在这种加勒比关键物种中开发生物标志物很重要。
