Hybrid Speciation, Transposable Elements, and Genome Evolution in Wild Sunflowers

转座因子是能够在其宿主基因组中移动或增殖的DNA序列。转座因子活跃和增殖的自然条件，以及增殖事件对宿主物种进化的后果，知之甚少。这项研究将调查基因组和环境条件，可能促进大规模和独立的增殖事件的吉普赛样长末端重复序列（LTR）逆转录转座子在三个二倍体杂交向日葵物种适应极端环境。这三种杂交向日葵物种的进化历史特别相关，因为杂交和环境压力都涉及反转录转座子激活的驱动因素。反转录转座子的动员和增殖活性（以及可以促进这种事件的基因组修饰）将在天然存在的向日葵杂交种以及在温室中合成并经受胁迫的杂交个体中进行研究和表征。这个项目将大大增加我们对转座因子在器官进化中的作用的理解。参与这个项目的学生将通过KSU发展学者计划招募。该计划将来自代表性不足的群体的KSU本科生与教师导师配对，为学生提供早期研究机会。其他学生将通过KSU暑期研究机会计划（SUROP）来，该计划也针对来自代表性不足群体的学生。PI将通过NSF资助的GROW（女孩研究我们的世界）夏季研讨会参与外展活动。这是一个为期三天的夏季科学讲习班，在KSU校园和附近的Konza Prairie生物站举行的中学年龄的女孩。向日葵在堪萨斯东部的弗林特山高草草原的自然历史中扮演着重要的角色。外联工作将针对设计和提供一个简短的研讨会，解释向日葵的自然历史，驯化和美洲土著人民使用这些植物的基本方面。该研讨会将在拟议的研究期间每年夏天举行。

Transposable elements are DNA sequences capable of mobilizing or proliferating in the genomes of their host. The natural conditions under which transposable elements become active and proliferate, and the consequences of proliferation events on host species evolution, are poorly understood. This research will investigate the genomic and environmental conditions that likely facilitated massive and independent proliferation events of gypsy-like long terminal repeat (LTR) retrotransposons in three diploid hybrid sunflower species adapted to extreme environments. The evolutionary history of the three hybrid sunflower species is especially relevant because both hybridization and environmental stress have been implicated as drivers of retrotransposon activation. Mobilization and proliferation activity of retrotransposons (as well as genomic modifications that can facilitate such events) will be investigated and characterized both in naturally occurring sunflower hybrids as well as in hybrid individuals synthesized and subjected to stress in the greenhouse. This project will greatly increase our understanding of the role of transposable elements in organismic evolution.Students involved in this project will be recruited through the KSU Developing Scholars Program. This program pairs KSU undergraduates from under-represented groups with faculty mentors to provide students with early opportunities for research endeavors. Other students will come through the KSU Summer Research Opportunities Program (SUROP) which also targets students from under-represented groups. The PI will participate in outreach through the NSF-funded GROW (Girls Researching Our World) Summer Workshop. This is a three-day summer science workshop for middle school age girls held on the KSU campus and at the nearby Konza Prairie Biological Station. Sunflowers play a prominent role in the natural history of the Flint Hills tall grass prairie in eastern Kansas. Outreach efforts will be directed towards the design and deliver a short workshop explaining basic aspects of sunflower natural history,domestication, and the use of these plants by Native American Peoples. This workshop will be delivered each summer for the duration of the proposed research.