Evolutionary genetics of flower color in lochroma (Solanaceae)

描述（由申请人提供）：识别适应性表型变化背后的遗传变化是进化生物学中的一个基本挑战。虽然作图方法对于检测影响性状变异的基因组区域是有用的，但在DNA序列水平上精确定位负责的特定变化仍然很困难，除非该区域内的候选基因是已知的。本研究以茄科番茄属植物茄科茄属植物茄属植物茄科茄属植物花色是研究适应性遗传基础的理想性状，因为它具有明确的适应性意义，并且因为色素生物合成途径在遗传水平上得到了很好的表征，并且在开花植物中高度保守。不同种类的lochroma的颜色差异主要是由于花青素色素的差异，这是一类黄酮类化合物。拟议的研究将调查花色素苷途径中的遗传变化，该途径负责从紫色到白色花的进化过渡。loxense和从紫色到红色的花在I。苦苣苔属。结合对途径的详细了解和对研究物种中存在哪些色素的了解，可以对哪些花青素基因参与颜色转换做出强有力的预测。候选花青素苷基因与颜色差异的关联将通过以下方式进行评估：（1）检查红色、白色和紫色物种间杂交中候选基因与花色表型的共分离，（2）克隆显示共分离的候选基因以测试其体外功能，以及（3）使用表达研究来检查可能的调控差异。研究结果将有助于解决适应过程中涉及的遗传变化的数量、位置和类型等基本问题。 此外，这项研究可以作为研究生物化学途径演变的模型，这反过来又对人类健康产生了广泛的影响，从基因治疗到改善药物靶向。此外，类黄酮（包括花青素）具有众所周知的抗氧化活性，似乎有助于预防慢性疾病，如心脏病和癌症。因此，更好地了解遗传变化如何改变类黄酮途径中的酶作用，增加了我们改进作物物种的潜力。

DESCRIPTION (provided by applicant): Identifying the genetic changes underlying adaptive phenotypic change is a fundamental challenge in evolutionary biology. While mapping approaches have been useful for detecting regions of the genome affecting trait variation, pinpointing the specific changes responsible at the DNA sequence level remains difficult, unless candidate genes within the region are known. This project uses a candidate gene approach to identify the genetic changes involved in adaptive transitions in flower color in lochroma, a genus in the tomato family, Solanaceae. Flower color is an ideal trait for studying the genetic basis of adaptation because it has clear adaptive significance and because the pigment biosynthetic pathways are well- characterized at the genetic level and highly conserved across flowering plants. Color differences among lochroma species are largely due to differences in anthocyanin pigments, a class of flavonoids. The proposed research will investigate the genetic changes in the anthocyanin pathway responsible for the evolutionary transition from purple to white flowers in I. loxense and from purple to red flowers in I. gesnerioides. Combining the detailed understanding of the pathway and knowledge of which pigments are present in the study species, strong predictions can be made about which anthocyanin genes were involved in the color transitions. The association of candidate anthocyanin genes and color differences will be assessed by (1) examining the cosegregation of candidate genes with flower color phenotypes in interspecific crosses between red, white, and purple species, (2) cloning candidate genes showing cosegregation to test their functionality in vitro, and (3) using expression studies to examine possible differences in regulation. The results will help to address basic questions regarding the number, location and types of genetic changes involved in the process of adaptation. Furthermore, this research may serve as a model for studying the evolution of biochemical pathways, which in turn, has broad implications for human health, from gene therapy to improved drug targeting. In addition, flavonoids (including anthocyanins) have well-known antioxidant activity, which appears to aid in preventing chronic diseases, such as heart disease and cancer. Thus, a better understanding of how genetic changes alter enzyme action in the flavonoid pathway adds to our potential for improving crop species.