月季基因聚合调控分子机制的转录组学解析

The MtDREB1C, a dehydration- responsive element binding protein gene cloned from Medicago truncatula, was transformed into China Rose (Rosa chinensis) together with a xyloglucan endotransglycosylase gene from R. chinensis, RcXET. The transgenic plants showed enhanced cold-tolerance and higher growth rate in contrast to the nontransgenic plants. Interestingly, many transgenic plants were flowered in flask, while this phenomenon was rarely found in nontransgenic plants in flask. Advanced research results showed that three flowering-related genes were expressed earlier controlled by the pyramided genes. We presume that both nutritional growth and generative growth were systematically controlled by the pyramided genes in gene transcription and expression levels. The high-throughput sequencing technology is proposed to be applied using both transgenic and nontransgenic plants, to reveal more information of the R. chinensis transcriptome. Through gene BLAST, clustering analysis and expressing detection, more and more important genes, especially those in relation to cold-tolerance, growth or flowering in low transcription level will be discovered. The regulation network of gene pyramiding molecules in R. chinensis will be constructed and the molecular mechanism of gene pyramiding in relation to cold-tolerance, growth or flowering will subsequently be revealed in transcription level. The revealed information of R. chinensis transcriptome will greatly promote the research of rose transcriptomics. Hence, this project will be significantly meaningful for illustrating the cross-regulation mechanism of gene pyramiding transformation, discovering useful gene resources, and even improving molecule design for breeding woody ornamentals.

我们将耐寒相关基因MtDREB1C和生长相关基因RcXET聚合转化中国月季，聚合转化植株的耐寒性和生长势明显增强，而且有在组培瓶内开花的现象。进一步研究发现，转化植株中有3个成花相关基因表达。据此推测，聚合基因协同表达，对植株的营养生长和生殖生长等相关基因转录与表达进行了系统调控。以转化植株为材料，采用转录组高通量测序系统，检测转基因前、转基因后、转化植株现蕾期三阶段的转录本信息，进行基因拼接、聚类分析；筛查转基因植株中耐寒、生长、成花相关重要基因，并对这些重要基因的表达规律进行分析；发掘转录水平低的新基因；构建聚合表达分子调控网络，从转录水平解析聚合转导调控月季耐寒、生长、开花的分子机制。本研究也将揭晓中国月季转基因前后的全部转录组信息，促进月季转录组学研究，对阐明基因聚合转化的交叉调控机制、发现可利用基因资源、改良木本观赏植物分子育种设计，有深远意义。

前期研究中，将耐寒相关基因MtDREB1C和生长相关基因RcXET聚合转化中国月季，聚合转化植株的耐寒性和生长势明显增强，而且有在组培瓶内开花的现象。进一步研究发现，转化植株中有3个成花相关基因表达。据此推测，聚合基因协同表达，对植株的营养生长和生殖生长等相关基因转录与表达进行了系统调控。本研究以转化植株为材料，采用转录组高通量测序系统，检测转转化植株转录本信息，进行基因拼接、聚类分析；筛查转基因植株中耐寒、生长、成花相关重要基因，并对这些重要基因的表达规律进行分析，构建聚合表达分子调控网络。具体结果和结论总结如下：.1）获得月季双基因聚合调控相关基因信息：获得12万个月季转录本信息，差异表达基因片断2988个，其中，1400多个基因已有类似功能标注，58个与失水胁迫相关，还有1500多个为没有标注信息的新基因。经分析，差异基因片段中，一类基因为双基因和冷胁迫共调控，能提高耐逆性、促进光合生长和开花，一类基因由双基因调控且与花器官分化有关，还有一类基因由冷胁迫诱导，与开花抑制、生长抑制等相关。.2）发现月季体胚发生关键技术因子及其形态建成机制：月季体胚发生的关键技术因子主要有激素和光照两方面，2,4－D、TDZ和ABA为关键的体胚发育初期的激素因子，光照则与体胚形态的建成密切相关。本研究还发现体胚发生和器官发生可能是同源的——即都来源于球形胚。.3）双基因聚合转化株系耐逆性提高可能主要是由于细胞中脯氨酸含量和可溶性含量增加引起的，受到一定胁迫后仍有较高的光合效率、较低的负水势和质壁分离点。该转化株系瓶内开花及开花歧形可能是花发育相关基因AG、AP2、FPF1等相关基因受表达调控引起的。