Three cis-Regulatory Motifs, AuxRE, MYCRS1 and MYCRS2, are Required for Modulating the Auxin- and Mycorrhiza-Responsive Expression of a Tomato GH3 Gene
Three cis-Regulatory Motifs, AuxRE, MYCRS1 and MYCRS2, are Required for Modulating the Auxin- and Mycorrhiza-Responsive Expression of a Tomato GH3 Gene
复制标题
调节番茄 GH3 基因的生长素和菌根响应性表达需要三个顺式调节基序 AuxRE、MYCRS1 和 MYCRS2
DOI：
10.1093/pcp/pcx013
复制
发表时间：
2017-04-01
影响因子：
4.9
通讯作者：
Xu, Guohua
中科院分区：
文献类型：
--
作者：
Chen, Xiao;Liao, Dehua;Xu, Guohua
生长素是植物生长过程中几乎所有生理过程以及植物与微生物相互作用的关键调节因子。然而，到目前为止，生长素介导的植物丛枝菌根（AM）真菌共生的调控机制还没有得到很好的破译。以前，我们确定了一个GH 3基因，SlGH3.4，强烈响应生长素诱导和菌根共生。在这里，我们报道了使用β-葡萄糖醛酸酶（GUS）报告基因对SlGH3.4启动子活性的精细解剖。SlGH3.4启动子在大豆和水稻的菌根根中以及在IAA处理的大豆根中可以强烈驱动GUS表达，但在IAA处理的水稻根中不能。启动子缺失分析揭示了三个顺式作用基序，即生长素响应元件，MYCRSRE，和两个新鉴定的基序命名为MYCRS 1和MYCRS 2，参与激活生长素和AM介导的SlGH3.4的表达。从SlGH3.4启动子中删除GSHRE几乎完全消除了响应于外部IAA诱导的GUS染色。7个重复序列的GUS RE融合花椰菜花叶病毒（CaMV）35 S最小启动子可以指导GUS基因在IAA处理和AM真菌定殖的烟草植物的根中表达。与CaMV 35 S最小启动子融合的MYCRS 1或MYCRS 2的四个重复序列足以驱动GUS在含丛枝的细胞中表达，但在IAA处理的烟草根中不表达。总之，我们的研究结果提供了新的见解潜在的串扰之间的生长素和AM调节途径在调制AM响应GH 3基因在不同的菌根植物的表达的分子机制。
Auxin is well known to be a key regulator that acts in almost all physiological processes during plant growth, and in interactions between plants and microbes. However, to date, the regulatory mechanisms underlying auxin-mediated plant-arbuscular mycorrhizal (AM) fungi symbiosis have not been well deciphered. Previously we identified a GH3 gene, SlGH3.4, strongly responsive to both auxin induction and mycorrhizal symbiosis. Here, we reported a refined dissection of the SlGH3.4 promoter activity using the β-glucuronidase (GUS) reporter. The SlGH3.4 promoter could drive GUS expression strongly in mycorrhizal roots of soybean and rice plants, and in IAA-treated soybean roots, but not in IAA-treated rice roots. A promoter deletion assay revealed three cis-acting motifs, i.e. the auxin-responsive element, AuxRE, and two newly identified motifs named MYCRS1 and MYCRS2, involved in the activation of auxin- and AM-mediated expression of SlGH3.4. Deletion of the AuxRE from the SlGH3.4 promoter caused almost complete abolition of GUS staining in response to external IAA induction. Seven repeats of AuxRE fused to the Cauliflower mosaic virus (CaMV) 35S minimal promoter could direct GUS expression in both IAA-treated and AM fungal-colonized roots of tobacco plants. Four repeats of MYCRS1 or MYCRS2 fused to the CaMV35S minimal promoter was sufficient to drive GUS expression in arbuscule-containing cells, but not in IAA-treated tobacco roots. In summary, our results offer new insights into the molecular mechanisms underlying the potential cross-talk between the auxin and the AM regulatory pathways in modulating the expression of AM-responsive GH3 genes in diverse mycorrhizal plants.