Evolutionary developmental genetics of fruit opening in Brassicaceae

本项目旨在以油菜属（Lepidium campestre）和appelianum（不开裂）为模式系统，更好地了解油菜科植物进化过程中果实从开裂到不开裂反复转变的发育遗传基础和生态学意义。在项目的前一阶段，我们发现了L. appelianum APETALA2 （AP2）同源基因的表达变化，这可能是通过抑制开裂带识别基因导致开裂带形成的丧失。为了更好地理解AP2在不裂性进化中的作用，我们将对拟南芥（a.t aliana）、拟南芥（l.l campestre）和拟南芥（l.appelianum）中AP2位点的基因组序列和表达模式进行表征。我们还将确定在拟南芥和油菜中过表达任何AP2同源基因的cDNA是否足以将开裂果实转化为不开裂果实。此外，我们将把AP2同源基因的基因组位点转化为野生型和AP2敲除植株，并观察哪些转基因植株会产生开裂或不开裂的果实。这将揭示AP2位点是否含有果实不裂的致病突变。此外，我们还将比较开裂和不开裂果实的转录组，以更全面地了解这些果实类型之间的基因调控差异。在该项目的另一个分支中，我们将分析果实不开裂对种子和果实传播和发芽定时机制的影响。我们将确定开裂和不开裂果实的种子在休眠和萌发方面是否存在差异，以及果皮的磨损、火或真菌的帮助是否参与了果皮介导的不开裂果实的休眠释放。最后，我们将确定开裂和不开裂果实中硫代葡萄糖苷模式的差异是否代表与不同扩散策略相关的不同防御模式。

The aim of the project is to better understand the developmental genetic basis and ecological implications of the recurrent transition from dehiscent to indehiscent fruits during the evolution of Brassicaceae, using Lepidium campestre (dehiscent) and L. appelianum (indehiscent) as model systems. In the previous phase of the project we identified a change in the expression of the L. appelianum APETALA2 (AP2) ortholog which has probably caused the loss of dehiscence zone formation via the repression of dehiscence zone identity genes. To better understand the role of AP2 in the evolution of indehiscence we will characterize the genomic sequences and expression patterns of this locus in A. thaliana, L. campestre and L. appelianum. We will also determine whether over-expression of cDNA of any of the AP2 orthologs in A. thaliana and L. campestre is sufficient to transform dehiscent into indehiscent fruits. Moreover, we will transform the genomic loci of the AP2 orthologs into both wild-type and ap2 knock-out plants and will observe which transgenic plants develop dehiscent or indehiscent fruits. This will reveal whether the AP2 locus contains the causative mutation of fruit indehiscence. In addition, we also will compare the transcriptomes of dehiscent and indehiscent fruits to get a more comprehensive picture of the gene regulatory differences between these fruit types. In yet another branch of the project we will analyze the consequences of fruit indehiscence for seed and fruit dispersal and germination timing mechanisms. We will determine if seeds of dehiscent and indehiscent fruits differ in dormancy and germination, and whether abrasion of the pericarp, fire, or fungal assistance are involved in pericarp-mediated dormancy release in indehiscent fruits. Finally, we will determine whether differences in glucosinolate patterns of dehiscent and indehiscent fruits represent different modes of defense associated with different dispersal strategies.