LA 杂交百合 GA 成花诱导途径的转录调控网络。
Transcriptional Regulatory Network of GA Floral Induction Pathway in LA Hybrid Lily.
机构信息
Beijing Key Laboratory of Ornamental Germplasm Innovation and Molecular Breeding, China National Engineering Research Center for Floriculture, College of Landscape Architecture, Beijing Forestry University, Beijing 100083, China.
出版信息
Int J Mol Sci. 2019 May 31;20(11):2694. doi: 10.3390/ijms20112694.
BACKGROUND
The LA hybrid lily 'Aladdin' has both excellent traits of Longiflorum hybrids and Asiatic hybrids-such as big and vivid flower, strong stem, high self-propagation coefficient, and shorter low temperature time required to release bulb dormancy in contrast to Oriental hybrids. A genome-wide transcriptional analysis using transcriptome RNA-Seq was performed in order to explore whether there is a gibberellin floral induction pathway in the LA hybrid lily. Subsequently, gene co-expression network analysis was used to analyze the possible interactions of key candidate genes screened from transcriptome data. At the same time, a series of physiological, biochemical, and cultivation tests were carried out.
RESULTS
The content of five endogenous hormones changed sharply in the shoot apex during the treatment of 200 mg/L exogenous gibberellin and the ratio of ABA/GA dropped and stayed at a lower level after 4 hours' treatment from the higher levels initially, reaching a dynamic balance. In addition, the metabolism of carbohydrates in the bulbs increase during exogenous gibberellin treatment. A total of 124,041 unigenes were obtained by RNA-seq. With the transcriptome analysis, 48,927 unigenes and 48,725 unigenes respectively aligned to the NR database and the Uniprot database. 114,138 unigenes, 25,369 unigenes, and 19,704 unigenes respectively aligned to the COG, GO, and KEGG databases. 2148 differentially expression genes (DEGs) were selected with the indicators RPKM ≥ 0, FDR ≤ 0.05 and |log2(ratio)| ≥ 2. The number of the upregulated unigenes was significantly more than the number of the downregulated unigenes. Some MADS-box genes related to flowering transformation-such as , , and -were found to be upregulated. A large number of gibberellin biosynthesis related genes such as , , ox, , , and gibberellin signal transduction genes such as , , and were significantly differentially expressed. The plant hormones related genes such as and sugar metabolism related genes such as , , and so on were also found expressing differentially. In addition, stress resistance related genes such as , , , , , , and epigenetic related genes in DNA methylation, histone methylation, acetylation, ubiquitination of ribose were also found. Particularly, a large number of transcription factors responsive to the exogenous gibberellin signal including , and were found to be specially expressing. 30 gene sequences were selected from a large number of differentially expressed candidate genes for qRT-PCR expression verification (0, 2, 4, 8, and 16 h) and compared with the transcriptome expression levels.
CONCLUSIONS
200mg/L exogenous GA can successfully break the bulb's dormancy of the LA hybrid lily and significantly accelerated the flowering process, indicating that gibberellin floral induction pathway is present in the LA lily 'Aladdin'. With the GCNs analysis, two second messenger G protein-coupled receptor related genes that respond to gibberellin signals in the cell were discovered. The downstream transport proteins such as , , and were also discovered participating in GA signal transduction. Transcription factors including , , , and specially regulated phosphorylation and glycosylation during the ubiquitination degradation process of proteins. These transcription factors also activated in abscisic acid metabolism. A large number of transcription factors such as , , , , , , and that both regulate gibberellin signaling and low-temperature signals have also been found. Finally, the molecular mechanism of GA floral induction pathway in the LA hybrid lily 'Aladdin' was constructed.
背景
LA 杂种百合“阿拉丁”具有长梗百合杂种和亚洲百合杂种的优良特性——花大而鲜艳，茎粗壮，自我繁殖系数高，与东方百合杂种相比，低温时间要求较短，以释放球茎休眠。为了探索 LA 杂种百合是否存在赤霉素花诱导途径，我们使用转录组 RNA-Seq 进行了全基因组转录分析。随后，使用基因共表达网络分析分析了从转录组数据中筛选出的关键候选基因的可能相互作用。同时，进行了一系列生理、生化和栽培试验。
结果
外源赤霉素处理后，茎尖内源激素含量在 200mg/L 时急剧变化，最初较高，4 小时后 ABA/GA 比值下降并保持在较低水平，达到动态平衡。此外，外源赤霉素处理过程中，鳞茎内碳水化合物代谢增加。通过 RNA-seq 共获得 124041 个 unigenes。通过转录组分析，分别有 48927 个和 48725 个 unigenes分别与 NR 数据库和 Uniprot 数据库对齐。114138 个 unigenes、25369 个 unigenes 和 19704 个 unigenes分别与 COG、GO 和 KEGG 数据库对齐。用 RPKM≥0、FDR≤0.05 和 |log2(比值)|≥2 的指标筛选到 2148 个差异表达基因（DEGs）。上调 unigenes的数量明显多于下调 unigenes的数量。发现了一些与花转化相关的 MADS-box 基因，如 、 、 等，它们被上调。大量与赤霉素生物合成相关的基因，如 、 、 ox 、 、 等，以及与赤霉素信号转导相关的基因，如 、 、 等，均表现出显著的差异表达。发现了与植物激素相关的基因，如 、 等，以及与糖代谢相关的基因，如 、 、 等，也存在差异表达。此外，还发现了与应激反应相关的基因，如 、 、 、 、 等，以及与 DNA 甲基化、组蛋白甲基化、乙酰化、核糖泛素化相关的表观遗传相关基因。特别是，发现了大量响应外源赤霉素信号的转录因子，包括 、 等，它们专门表达。从大量差异表达的候选基因中选择了 30 个基因序列进行 qRT-PCR 表达验证（0、2、4、8 和 16 h），并与转录组表达水平进行比较。
结论
200mg/L 外源 GA 能成功打破 LA 杂种百合鳞茎休眠，显著加速开花进程，表明赤霉素花诱导途径存在于 LA 百合“阿拉丁”中。通过 GCNs 分析，发现了两个响应细胞中赤霉素信号的第二信使 G 蛋白偶联受体相关基因。还发现了下游转运蛋白，如 、 、 等，参与 GA 信号转导。转录因子，如 、 、 、 等，专门调节蛋白质的磷酸化和糖基化过程中的泛素化降解。这些转录因子也参与了脱落酸代谢的调节。还发现了大量转录因子，如 、 、 、 、 、 等，它们既能调节赤霉素信号，又能调节低温信号。最后，构建了 LA 杂种百合“阿拉丁”中 GA 花诱导途径的分子机制。
Zotero 插件