转录组动态与四种小麦基因型对赤霉病抗性和易感性的关系。
Transcriptome dynamics associated with resistance and susceptibility against fusarium head blight in four wheat genotypes.
机构信息
Digital Technologies Research Centre, NRC, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada.
Ottawa Research and Development Centre, AAFC, 960 Carling Ave, Ottawa, ON, K1A 0C6, Canada.
出版信息
BMC Genomics. 2018 Aug 29;19(1):642. doi: 10.1186/s12864-018-5012-3.
BACKGROUND
Fusarium head blight (FHB) of wheat in North America is caused mostly by the fungal pathogen Fusarium graminearum (Fg). Upon exposure to Fg, wheat initiates a series of cellular responses involving massive transcriptional reprogramming. In this study, we analyzed transcriptomics data of four wheat genotypes (Nyubai, Wuhan 1, HC374, and Shaw), at 2 and 4 days post inoculation (dpi) with Fg, using RNA-seq technology.
RESULTS
A total of 37,772 differentially expressed genes (DEGs) were identified, 28,961 from wheat and 8811 from the pathogen. The susceptible genotype Shaw exhibited the highest number of host and pathogen DEGs, including 2270 DEGs associating with FHB susceptibility. Protein serine/threonine kinases and LRR-RK were associated with susceptibility at 2 dpi, while several ethylene-responsive, WRKY, Myb, bZIP and NAC-domain containing transcription factors were associated with susceptibility at 4 dpi. In the three resistant genotypes, 220 DEGs were associated with resistance. Glutathione S-transferase (GST), membrane proteins and distinct LRR-RKs were associated with FHB resistance across the three genotypes. Genes with unique, high up-regulation by Fg in Wuhan 1 were mostly transiently expressed at 2 dpi, while many defense-associated genes were up-regulated at both 2 and 4 dpi in Nyubai; the majority of unique genes up-regulated in HC374 were detected at 4 dpi only. In the pathogen, most genes showed increased expression between 2 and 4 dpi in all genotypes, with stronger levels in the susceptible host; however two pectate lyases and a hydrolase were expressed higher at 2 dpi, and acetyltransferase activity was highly enriched at 4 dpi.
CONCLUSIONS
There was an early up-regulation of LRR-RKs, different between susceptible and resistant genotypes; subsequently, distinct sets of genes associated with defense response were up-regulated. Differences in expression profiles among the resistant genotypes indicate genotype-specific defense mechanisms. This study also shows a greater resemblance in transcriptomics of HC374 to Nyubai, consistent with their sharing of two FHB resistance QTLs on 3BS and 5AS, compared to Wuhan 1 which carries one QTL on 2DL in common with HC374.
背景
北美小麦镰孢穗枯病（FHB）主要由真菌病原体禾谷镰孢菌（Fg）引起。在接触 Fg 后，小麦会启动一系列涉及大规模转录重编程的细胞反应。在这项研究中，我们使用 RNA-seq 技术分析了四个小麦基因型（Nyubai、Wuhan 1、HC374 和 Shaw）在接种 Fg 后 2 天和 4 天的转录组学数据。
结果
共鉴定出 37772 个差异表达基因（DEGs），其中 28961 个来自小麦，8811 个来自病原体。易感基因型 Shaw 表现出最高数量的宿主和病原体 DEGs，包括 2270 个与 FHB 易感性相关的 DEGs。2 dpi 时，蛋白丝氨酸/苏氨酸激酶和 LRR-RK 与易感性相关，而 4 dpi 时，几个乙烯响应、WRKY、Myb、bZIP 和 NAC 结构域包含转录因子与易感性相关。在三个抗性基因型中，有 220 个 DEGs 与抗性相关。谷胱甘肽 S-转移酶（GST）、膜蛋白和不同的 LRR-RK 与三个基因型的 FHB 抗性有关。在 Wuhan 1 中，由 Fg 高度上调的基因具有独特性，主要在 2 dpi 时瞬时表达，而在 Nyubai 中，许多与防御相关的基因在 2 dpi 和 4 dpi 时都上调；在 HC374 中检测到的大多数独特上调基因仅在 4 dpi 时出现。在病原体中，大多数基因在所有基因型中都表现出 2 到 4 天之间的表达增加，在易感宿主中表达水平更高；然而，两个果胶裂解酶和一个水解酶在 2 dpi 时表达更高，乙酰转移酶活性在 4 dpi 时高度富集。
结论
在易感和抗性基因型之间，LRR-RK 存在早期上调，而不同的基因则与防御反应相关。抗性基因型之间表达谱的差异表明存在特定的防御机制。本研究还表明，HC374 的转录组学与 Nyubai 更为相似，这与它们在 3BS 和 5AS 上共享两个 FHB 抗性 QTL 一致，而与 Wuhan 1 相比，HC374 仅在 2DL 上携带一个 QTL 共同。
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