DISSERTATION RESEARCH: Assessing the Evolutionary Significance of Recurrent Horizontal Gene Transfer of a Chimeric Photoreceptor in Ferns

这项研究将使人们对蕨类植物的系统学和使它们能够在阴凉的栖息地生长的基因有更深入的了解。新色素是一种新型的嵌合光感受器，它将红感和蓝感光感受器融合到一个基因中，它的存在与蕨类植物在弱光条件下茁壮成长的能力有关。尽管新色素在适应中具有潜在的重要性，但其进化仍未被探索。本研究将探讨新色素的进化，并验证该基因的分布是蕨类植物间反复水平基因转移的结果。该奖项将支持一名女博士生和本科生在不同分子和系统方法方面的研究和培训。水平基因转移（HGT）在原核生物中很常见，通常是适应和进化的关键驱动因素。然而，大多数记录在案的植物间HGT涉及线粒体DNA和/或寄生虫-宿主转移；只有少数案例包含功能性核基因，而可能具有适应性影响的案例就更少了。因此，植物间HGT作为植物进化中一个值得注意的因素通常被忽视。本研究的目的是利用针对不同蕨类物种的新色素的下一代测序，进一步阐明蕨类植物中看似大量的新色素水平基因转移事件的频率和时间。由于新色素可能在促进蕨类植物在弱光环境下的辐射中发挥了重要作用，因此该研究对更好地理解植物间HGT的进化意义具有重要意义。

This study will provide a deeper understanding of the systematics of ferns and the genes that allow them to grow in shady habitats. The presence of neochrome -- a novel chimeric photoreceptor that fuses red-sensing and blue-sensing photoreceptors into a single gene -- is linked to the ability of ferns to thrive in low-light conditions. Despite its potential importance in adaptation, the evolution of neochrome has remained unexplored. This study will investigate the evolution of neochrome and test the hypothesis that the distribution of the gene is the result of recurrent horizontal gene transfer among ferns. This award will support the research and training of a female doctoral student and undergraduate researchers in diverse molecular and systematic methods. Horizontal gene transfer (HGT) is common in prokaryotes and is often a key driver of adaptation and evolution. However, most documented examples of plant-to-plant HGT involve mitochondrial DNA and/or parasite-host transfers; only a handful of cases include functional nuclear genes, and even fewer have possible adaptive implications. Consequently, plant-to-plant HGT generally has been overlooked as a noteworthy factor in plant evolution. The aim of this research is to use targeted next-generation sequencing of neochrome from diverse fern species to further elucidate the frequency and timing of the seemingly large number of neochrome horizontal gene transfer events in ferns. Because neochrome may have played a major role in promoting the radiation of ferns under low-light environments, this study has important implications for better understanding the evolutionary significance of plant-to-plant HGT.