Key Laboratory of Horticultural Plant Biology (Ministry of Education), Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region, Ministry of Agriculture), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, P.R. China.
Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg, PB Wageningen, Netherlands.
J Exp Bot. 2018 Oct 12;69(21):5255-5264. doi: 10.1093/jxb/ery283.
The perennial woody plants of citrus are one of the most important fruit crops in the world and largely depends on arbuscular mycorrhizal symbiosis (AMS) to obtain essential nutrients from soil. However, the molecular aspects of AMS in citrus and perennial woody plants in general have largely been understudied. We used RNA-sequencing to identify differentially expressed genes in roots of Poncirus trifoliata upon mycorrhization by the AM fungus Glomus versiforme and evaluated their conservation by comparative transcriptome analyses with four herbaceous model plants. We identified 282 differentially expressed genes in P. trifoliata, including orthologs of 21 genes with characterized roles in AMS and 83 genes that are considered to be conserved in AM-host plants. Comparative transcriptome analysis revealed a 'core set' of 156 genes from P. trifoliata whose orthologous genes from at least three of the five species also exhibited similar transcriptional changes during AMS. Functional analysis of one of these conserved AM-induced genes, a 3-keto-acyl-ACP reductase (FatG) involved in fatty acid biosynthesis, confirmed its involvement in AMS in Medicago truncatula. Our results identify a core transcriptional program for AMS that is largely conserved between P. trifoliata and other plants. The comparative transcriptomics approach adds to previous phylogenomics studies to identify conserved genes required for AMS.
柑橘类多年生木本植物是世界上最重要的水果作物之一，它们在很大程度上依赖丛枝菌根共生（AMS）从土壤中获取必需的营养物质。然而，柑橘类植物以及一般的多年生木本植物中 AMS 的分子方面在很大程度上仍未得到充分研究。我们使用 RNA 测序技术，在柑橘属枳通过 AM 真菌球囊霉属（Glomus versiforme）共生时，鉴定了根系中差异表达的基因，并通过与四种草本模式植物的比较转录组分析评估了它们的保守性。我们在 P. trifoliata 中鉴定出 282 个差异表达的基因，包括 21 个具有已知 AMS 作用的基因的同源基因和 83 个被认为在 AM-宿主植物中保守的基因。比较转录组分析揭示了一个由 156 个基因组成的“核心集”，这些基因来自 P. trifoliata 的同源基因，至少有 5 个物种中的 3 个物种的同源基因在 AMS 过程中也表现出相似的转录变化。对这些保守的 AM 诱导基因之一，涉及脂肪酸生物合成的 3-酮酰-ACP 还原酶（FatG）的功能分析，证实了它在 Medicago truncatula 中参与 AMS。我们的研究结果确定了一个 AMS 的核心转录程序，该程序在 P. trifoliata 和其他植物之间基本保守。比较转录组学方法补充了以前的系统发育基因组学研究，以确定 AMS 所需的保守基因。
