Starter Grant: A Survey of Nuclear - and Plastid - Encoded Thylakoid Genes in the Scrophulariaceae/Orobanchaceae

9632675沃尔夫一组生物的详细和强有力的系统发生学为生长、发育和生活史的关键研究提供了一个框架或路线图。俄亥俄州立大学的安德里亚·沃尔夫博士正在利用这样的系统发育知识，探索寄生植物光合作用的分子进化变化。玄参科/萝卜科植物群包括自养的、完全光合作用的物种(如笛鱼)、形成附着在其他植物上的根的所谓的半寄生，以及异养的、非光合作用的寄生植物，如山毛榉属(Epifagus)等。寄生虫必须附着在宿主植物上才能吸收碳营养才能生存；这一组的系统发育树表明，寄生虫是从几个谱系的光合作用形式进化而来的。沃尔夫博士正在分析叶绿体捕光类囊体器的基因，以确定参与光合作用能量转移的核和叶绿体基因的变化。她正在解决的问题包括：在分子水平上是否存在将植物引向寄生的“关键创新”；随着光合作用功能的丧失，核基因和叶绿体基因的突变模式和序列是什么；是否存在叶绿体活动的备份或互补基因系统，因为突变破坏或破坏光合作用的关键酶？现代分子生物学工具使得对植物光合作用过程中捕光和能量捕获的酶过程进行精细的遗传解剖成为可能。利用包括寄生物种在内的植物群的系统发育知识，沃尔夫设计了一个富有想象力的研究计划，密切关注一系列植物物种的光合作用功能的衰退，这些植物物种进化出了越来越寄生的生活模式。在这样做的过程中，她正在分析生化途径进化的关键阶段，并帮助理解植物进化中生活史的变化。

9632675 Wolfe A detailed and strongly supported phylogeny of a group of organisms provides a framework or road map for critical studies of growth, development, and life history. Dr. Andrea Wolfe at Ohio State University is taking advantage of just such phylogenetic knowledge to explore molecular evolutionary changes in photosynthesis in plants that have become parasitic. The Scrophulariaceae/Orobanchaceae group of plants includes autotrophic, fully photosynthetic species (the snapdragons for example), so-called hemiparasites that form root attachments to other plants, and heterotrophic, non-photosynthetic parasites like beechdrops (genus Epifagus) and others. The parasites must attach themselves to host plants to absorb carbon nutrients for survival; the phylogenetic tree for this group demonstrates that parasites have evolved from photosynthetic forms in several lineages. Dr. Wolfe is analyzing genes for the light-harvesting thylakoid apparatus of the chloroplast, to determine changes in nuclear and plastid genes involved in photosynthetic energy transfer. Questions she is addressing include: are there "key innovations" at the molecular level that channel a plant toward parasitism; what are the patterns and sequence of mutations in nuclear and plastid genes as photosynthetic function is lost; are there backup or complementary gene systems to chloroplast activities, as mutations damage or destroy critical enzymes of photosynthesis? Modern tools of molecular biology make possible the fine-scale genetic dissection of enzymatic processes of light-harvesting and energy-capture during photosynthesis in plants. Taking advantage of phylogenetic knowledge of plant groups that include parasitic species, Dr. Wolfe has designed an imaginative program of study that looks closely at the decay of photosynthetic function in a series of plant species that have evolved an increasingly parasitic mode of life. In so doing, she is analyzing critical stages in the evolution of biochemical pathways and also help ing to understand shifts in life history in plant evolution.