Pratacultural College, Gansu Agricultural University, Lanzhou 730070, China.
Key Laboratory of Grassland Ecosystem, Ministry of Education, Lanzhou 730070, China.
Molecules. 2018 Mar 20;23(3):706. doi: 10.3390/molecules23030706.
Creeping bentgrass () is the preferred green lawn grass, with excellent turf characteristics but poor disease resistance. At present, the mechanisms of disease resistance in creeping bentgrass are poorly understood, especially the ethylene signal transduction pathway under the induced systemic resistance (ISR) response. In this study, butanediol (BDO), as a new type of disease-resistance compound, was applied to creeping bentgrass seedlings to induce the ISR response. Then, we measured ethylene production and related enzyme activities. Additionally, transcript profiling and gene identification were performed in association to ethylene signal transduction pathways. The changes of ethylene production and related enzyme 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) and 1-aminocyclopropane-1-carboxylic acid synthases (ACS) activities showed significant difference at 24 h after inoculation among five treatments of various BDO concentrations. After 100 µmol L BDO treatment, ethylene production and related enzyme activities reached their peak levels. Additionally, 208,672 unigenes of creeping bentgrass were obtained by de novo assembly. In total, 15,903 annotated unigenes were grouped into 33 canonical pathways in the KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis. Among those, 1803 unigenes were classified as 'signal transduction'. There were 6766 differentially expressed genes (DEGs) among B24 (inoculated-rhizobacteria in MS medium with 100 µmol L BDO for 24 h), NB24, B72 and NB24 (no rhizobacteria in MS medium with 100 µmol L BDO for 24 h) libraries, and 4,639 DEGs between B24 and B72 (inoculated-rhizobacteria in MS medium with 100 µmol L BDO for 72 h) libraries, with 4489 DEGs in all three libraries. As suggested by the RT-PCR assay, the expression levels of ethylene-responsive and defense-related genes were variable among treated samples during the BDO-induced ISR responses. The expression levels of , , and genes increased and reached their peaks in the first 24 h after infection in the BDO-induced ISR reaction compared with NB24 treatments. This results is consistent with the changes of important ethylene biosynthetic enzymes and ethylene concentrations during the BDO-induced ISR responses. We further found the intermediate substances for the signaling pathway, and the relationships between the expression levels of BDO-induced ISR disease-resistance genes and those of the response genes for ethylene signal pathway. Our findings present a genetic basis for systemic resistance of creeping bentgrass through transcriptomic analysis and our study provides a theoretical and practical basis for the improvement of turfgrass disease resistance and quality.
匍匐翦股颖（）是首选的草坪草，具有优良的草坪特性，但抗病性差。目前，匍匐翦股颖的抗病机制尚不清楚，特别是在诱导系统抗性（ISR）反应下的乙烯信号转导途径。在这项研究中，1,4-丁二醇（BDO）作为一种新型抗病化合物，被应用于匍匐翦股颖幼苗中，以诱导 ISR 反应。然后，我们测量了乙烯的产生和相关酶的活性。此外，还进行了转录谱分析和基因鉴定，以关联乙烯信号转导途径。在接种后 24 小时，不同 BDO 浓度的五种处理中，乙烯的产生和相关酶 1-氨基环丙烷-1-羧酸氧化酶（ACO）和 1-氨基环丙烷-1-羧酸合酶（ACS）的活性有明显差异。经过 100 μmol L BDO 处理后，乙烯的产生和相关酶的活性达到峰值。此外，通过从头组装获得了 208672 个匍匐翦股颖的基因。总共，在 KEGG（京都基因与基因组百科全书）分析中，将 15903 个注释基因分为 33 个经典途径。其中，1803 个基因被归类为“信号转导”。在 B24（在含有 100 μmol L BDO 的 MS 培养基中接种根际细菌 24 小时）、NB24、B72 和 NB24（在含有 100 μmol L BDO 的 MS 培养基中无根际细菌 24 小时）文库中，有 6766 个差异表达基因（DEGs），在 B24 和 B72（在含有 100 μmol L BDO 的 MS 培养基中接种根际细菌 72 小时）文库中，有 4639 个 DEGs，在所有三个文库中，有 4489 个 DEGs。如 RT-PCR 检测结果所示，在 BDO 诱导的 ISR 反应期间，处理样品中乙烯反应和防御相关基因的表达水平存在差异。与 NB24 处理相比，在 BDO 诱导的 ISR 反应中，在接种后前 24 小时内， 、 、 和 基因的表达水平增加并达到峰值。这一结果与 BDO 诱导的 ISR 反应中重要的乙烯生物合成酶和乙烯浓度的变化一致。我们进一步发现了信号通路的中间物质，并分析了 BDO 诱导的 ISR 抗病基因与乙烯信号通路响应基因之间的表达水平关系。我们的研究结果通过转录组分析为匍匐翦股颖的系统抗性提供了遗传基础，为提高草坪草的抗病性和质量提供了理论和实践基础。
