DataSheet_3_Tissue-specific transcriptome responses to Fusarium head blight and Fusarium root rot.docx

Fusarium head blight (FHB) and Fusarium root rot (FRR) are important diseases of small-grain cereals caused by Fusarium species. While host response to FHB has been subject to extensive study, very little is known about response to FRR and the transcriptome responses of FHB and FRR have not been thoroughly compared. Brachypodium distachyon (Bd) is an effective model for investigating host responses to both FHB and FRR. In this study the transcriptome response of Bd to F. graminearum (Fg) infection of heads and roots was investigated. An RNA-seq analysis was performed on both Bd FHB and FRR during the early infection. Additionally, an RNA-seq analysis was performed on in vitro samples of Fg for comparison with Fg gene expression in planta. Differential gene expression and gene-list enrichment analyses were used to compare FHB and FRR transcriptome responses in both Bd and Fg. Differential expression of selected genes was confirmed using RT-qPCR. Most genes associated with receptor signalling, cell-wall modification, oxidative stress metabolism, and cytokinin and auxin biosynthesis and signalling genes were generally upregulated in FHB or were downregulated in FRR. In contrast, Bd genes involved in jasmonic acid and ethylene biosynthesis and signalling, and antimicrobial production were similarly differentially expressed in both tissues in response to infection. A transcriptome analysis of predicted Fg effectors with the same infected material revealed elevated expression of core tissue-independent genes including cell-wall degradation enzymes and the gene cluster for DON production but also several tissue-dependent genes including those for aurofusarin production and cutin degradation. This evidence suggests that Fg modulates its transcriptome to different tissues of the same host.

禾谷镰孢穗腐病（Fusarium head blight, FHB）与镰孢菌根腐病（Fusarium root rot, FRR）是由镰孢菌属（Fusarium）物种引发的小粒谷类作物重要病害。尽管寄主对穗腐病的应答已得到广泛研究，但目前对其应对根腐病的分子机制却知之甚少，且二者的转录组应答尚未得到全面比较。二穗短柄草（Brachypodium distachyon, Bd）是探究寄主对穗腐病与根腐病应答的有效模式植物。本研究针对二穗短柄草在禾谷镰孢（Fusarium graminearum, Fg）侵染穗部与根部后的转录组应答展开了探究：在侵染早期对受镰孢菌侵染的二穗短柄草穗腐病、根腐病样本开展了RNA测序（RNA-seq）分析；同时对体外培养的禾谷镰孢样本进行RNA测序，以与其在寄主植物体内的基因表达水平进行对照比较。研究通过差异基因表达分析与基因集富集分析，分别在二穗短柄草与禾谷镰孢两个层面，比较了穗腐病与根腐病的转录组应答模式，并通过实时定量聚合酶链反应（RT-qPCR）验证了部分候选基因的差异表达情况。结果显示，多数与受体信号转导、细胞壁修饰、氧化应激代谢，以及细胞分裂素、生长素的生物合成与信号通路相关的基因，在穗腐病样本中通常呈上调表达，而在根腐病样本中则多为下调表达。与之相反，参与茉莉酸、乙烯生物合成与信号转导，以及抗菌物质合成的二穗短柄草基因，在受侵染的穗部与根部组织中均呈现相似的差异表达趋势。对同一批侵染样本中预测的禾谷镰孢效应因子开展转录组分析后发现，两类基因均呈现高表达：一类是不依赖侵染组织的核心基因，包括细胞壁降解酶编码基因与脱氧雪腐镰孢菌烯醇（deoxynivalenol, DON）合成基因簇；另一类则是组织依赖性基因，例如金黄镰孢菌素（aurofusarin）合成相关基因与角质降解酶编码基因。上述结果表明，禾谷镰孢会针对同一寄主的不同组织，对自身的转录组进行精准调控。