番茄GRAS2基因调控果实发育的机理研究

发布时间：2018-02-20 04:21

本文关键词： 番茄 GWAS GRAS2 果实发育驯化　出处：《华中农业大学》2017年博士论文　论文类型：学位论文

【摘要】：番茄(Solanum lycopersicum)因其较短的生长周期、稳定的遗传特性、较小的基因组信息等优点,被视为研究浆果类果实发育的模式作物之一。通过利用传统的双亲连锁图定位的方法,已经鉴定出多个调控番茄果实重量的基因。但传统QTL定位的方法存在着不足之处,对已定位的果重QTL区域无法进行更细致的功能基因的发掘与验证。全基因组关联分析方法,是对传统定位方法很好的补充,极大的提高番茄果重QTL区域内关键基因的定位与克隆工作。本研究通过对288份番茄种质群体进行番茄果实重量性状的关联分析,鉴定出番茄GRAS2基因能调控果实的重量。主要研究结果如下:1.在对番茄果重性状的关联分析中,共发现9个信号与群体番茄果重的具有显著的相关性。其中,有4个显著信号与之前报道的lc、fw3.2、fascinated、fw11.3基因位点紧密相关,说明本研究中关联数据可靠、模型合理、分析结果准确。鉴于此,我们进一步对检测到的5个信号进行了定位,发现它们分别位于fw1.2、fw6.3、fw7.3、fw11.1、fw11.2区间附近,这为我们下一步克隆番茄果重QTL基因提供依据。2.通过QTL fw7.3的显著信号分析并结合转基因验证,发现距离显著SNP63492244的GRAS2可能为fw7.3关键功能基因。在其干涉植株中果实出现明显发育受阻,表型出花器官变小、子房的初始发育受阻、果皮的厚度变薄、细胞皱缩、种子的数目变少等形态改变。同时,干涉植株还出现植株变矮。说明GRAS2为植物体正常发育所需的功能基因。3.转录分析表明,GRAS2在盛花期的子房具有相对高的表达。同时,在发育种子的外包膜上具有持续的表达。说明GRAS2特异的表达时期和表达部位对果实初始发育是至关重要的。GRAS2参与植物体内赤霉素合成途径,GRAS2干涉植株体内的内源赤霉素诱导子房发育过程受到影响,导致最终果实的发育受阻。4.分子遗传进化分析显示,GRAS2在关联群体的基因型分布与群体果实的进化趋势具有相似性。分析发现,GRAS2在番茄早期驯化从野生番茄到樱桃番茄的过程中发生重大的变异,而从樱桃番茄到栽培番茄的改良过程变异幅度较小现象。5.其他茄果类蔬菜作物中,包括辣椒、茄子,其GRAS2具有相似度极高的同源基因,可能具有相似的调控机制。基于GRAS2在番茄果实发育的作用机制,为揭示其他茄科作物果实发育的机制具有重要的参考作用。
[Abstract]:Solanum lycopersicum is regarded as one of the model crops to study berry fruit development because of its short growth cycle, stable genetic characteristics and small genomic information. Several genes have been identified to regulate tomato fruit weight. However, the traditional QTL mapping method has some shortcomings, so it is impossible to identify and verify more detailed functional genes in the located fruit weight QTL region. It is a good supplement to the traditional mapping method and greatly improves the mapping and cloning of the key genes in the QTL region of tomato fruit weight. In this study, the correlation analysis of tomato fruit weight traits was carried out among 288 tomato germplasm populations. Tomato GRAS2 gene was identified to regulate fruit weight. The main results are as follows: 1. In the correlation analysis of fruit weight traits of tomato, 9 signals were found to be significantly correlated with tomato fruit weight. Four significant signals were closely related to the previously reported loci of lcfw3.2fascinated fw11.3 gene, indicating that the data in this study are reliable, the model is reasonable and the analysis results are accurate. In view of this, we further localize the five signals detected. It was found that they were located in the region of fw1.2 / fw6.3fw7.3 / fw11.1fw11.2 respectively, which provided the basis for cloning QTL gene of tomato fruit weight in the next step. 2. The significant signal analysis of QTL fw7.3 combined with transgenic verification was carried out. It was found that the GRAS2 with significant distance from SNP63492244 might be the key gene of fw7.3. The fruit development was blocked obviously, the flower organs became smaller, the initial development of ovary was blocked, the thickness of pericarp was thinned and the cells shrank in the intervening plants. At the same time, the number of seeds decreased and the number of seeds decreased. Meanwhile, the interference plants also appeared to be shorter. The results showed that GRAS2 was the functional gene required for the normal development of plant. 3. Transcriptional analysis showed that the expression of GRAAS2 was relatively high in the ovary of flowering stage. At the same time, the expression of GRAS2 in the ovary of flowering stage was relatively high. There is persistent expression on the outer membrane of the developing seeds. It is suggested that the specific expression period and expression site of GRAS2 are very important for the initial fruit development. GRAS2 is involved in the biosynthesis pathway of gibberellin in plants. The process of gibberellin induced ovary development was affected. The molecular genetic evolution analysis showed that the genotype distribution of GRAS2 in the associated population was similar to the evolutionary trend of the fruit of the population. It was found that GRAAS2 was domesticated from wild tomato to cherry in the early stage of tomato. There was a major mutation in the tomato process, However, the variation range of improvement process from cherry tomato to cultivated tomato was small. 5. Other tomato vegetable crops, including capsicum and eggplant, had high similarity homologous genes in GRAS2. Based on the mechanism of GRAS2 in tomato fruit development, it has an important reference role in revealing the mechanism of fruit development of other eggplant crops.
【学位授予单位】：华中农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S641.2

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