The genetic and developmental basis of repeated phenotypic shifts in Penstemon

描述(申请人提供)：生物医学基础研究的一个主要目标是了解表型变异的发育遗传学基础。对新兴模式遗传类群中重复表型进化的遗传基础的研究为研究进化是否以及以多长时间进行一次类似的遗传和发育变化以及是否存在对表型进化的发育遗传限制提供了机会。这项拟议的研究制定了一项研究计划，旨在调查花授粉综合症的遗传和发育基础，花授粉综合症是一种复杂的适应性状，在彭斯敦属植物中是一种复杂的适应性状。这些初步实验将为这一研究计划的发展提供见解和宝贵的资源。在这个属中，至少有15次从祖先蜜蜂授粉综合征到非常典型的蜂鸟授粉综合征的独立进化转变。这项拟议研究的第一个目标是开发基因组资源，并为两个近缘关系密切、传粉综合征不同的彭斯敦物种绘制传粉综合征分歧图。具体地说，来自这两个物种之间杂交的F2作图群体将进行花卉性状的表型鉴定，并使用多重猎枪基因分型，这是一种通过测序进行基因分型的形式。这将使构建连锁图谱和鉴定授粉综合征个体成分的数量性状基因座成为可能。来自每个焦点物种的基因组DNA将被测序、组装并与连锁图谱比对，以产生一组有序的基因组重叠群，这构成了未来实验的宝贵资源。第二项研究的目的是通过比较不同蜂鸟综合症物种在不同发育阶段的花器官中的细胞数量、大小和形状与相关蜂鸟综合征物种之间的关系，来表征蜂鸟综合征三个不同来源之间花形态差异的发育基础。这一目的的方法包括显微镜和原位杂交来评估组蛋白4基因表达的模式，这标志着活跃的细胞分裂。最终目标是开发促进Penstemon稳定遗传转化的协议，这将是未来实验中验证候选基因功能的有价值的工具。

DESCRIPTION (provided by applicant): A major goal of biomedical basic research is to understand the developmental genetic basis of phenotypic variation. Investigations into the genetic basis of repeated phenotypic evolution in emerging model genetic taxa provide an opportunity to investigate whether, and how often, evolution proceeds through similar genetic and developmental changes and whether there are developmental genetic constraints on phenotypic evolution. The proposed research develops a research program designed to investigate the genetic and developmental basis of repeated shifts in floral pollination syndrome, a complex adaptive trait, in the plant genus Penstemon. These initial experiments will provide insights and valuable resources for the development of this research program. In this genus, there have been at least 15 independent evolutionary shifts from the ancestral bee pollination syndrome to a highly stereotypical hummingbird pollination syndrome. The first aim of the proposed research will develop genomic resources and map pollination syndrome divergence for a pair of closely related Penstemon species that differ in their pollination syndrome. Specifically, an F2 mapping population derived from a cross between these two species will be phenotyped for floral traits and genotyped using Multiplexed Shotgun Genotyping, a form of genotyping-by-sequencing. This will enable the construction of a linkage map and identification of quantitative trait loci underlying individual components of pollination syndrome. Genomic DNA from each focal species will be sequenced, assembled, and aligned to the linkage map to yield a set of ordered genome contigs, comprising a valuable resource for future experiments. The second research aim is to characterize the developmental basis of floral morphological divergence between three separate origins of the hummingbird syndrome by comparing cell number, size, and shape in floral organs across developmental stages for each hummingbird syndrome species relative to a related bee syndrome species. Methods for this aim include microscopy and in situ hybridization to assess patterns of histone4 gene expression, which marks active cell division. The final aim is to develop protocols facilitating stable genetic transformation in Penstemon, which will be a valuable tool for the functional verification of candidate genes in future experiments.