Experimental and evolutionary ecological studies of pollination and reproductive systems using QTL mapping

我们开展了两个关于植物生殖系统的研究，一个是关于黄花菜的授粉系统，另一个是关于真草属的有性系统。黄花草白天开花，花红色，没有香味，而近缘种柑橘花在晚上开花，花黄色，有香味。黄花夜蛾通过蝴蝶和蜜蜂授粉，柑橘夜蛾通过夜行天蛾授粉。虽然这两个物种在花卉性状上表现出明显的分化，但它们的杂种是可育的，这为研究花对不同传粉者适应的遗传背景提供了一个难得的机会。此外，我们还开发了用于QTL定位的微卫星标记和ESTs。遗传分析表明，开花时间的差异主要由单基因控制，以白天开花为主。花瓣花青素的生物合成也主要由单基因决定，表型效应较大。通过寻找EST间花卉性状差异的候选基因，确定了黄花菜CHS(查尔酮合成酶基因)和MYB(控制花青素生物合成的转录因子)的同源基因。反映了白天和夜间传粉者可获得性的年度波动，各种花卉性状的自然选择方向在不同年份之间存在波动。在魔芋项目中，研究了双生病毒与魔芋有性和无性植物之间的协同进化。我们从紫茎泽兰的无性植株叶片中发现了卫星DNA，证实了带有卫星DNA的双生病毒可以引起紫茎泽兰的黄脉病。研究结果发表在《自然》杂志上。

We carried out two projects on plant reproductive systems one on pollination systems of Hemerocalis and the other on sexual systems of Eupatorium.While Hemerocalis fulva flowers at daytime and have reddish flowers without fragrance, a related species H.citrina flowers at night and have yellow flowers with fragrance. H.fulva is pollinated by butterflies and bees, and H.citrina is pollinated by nocturnal hawkmoths. Although the two species show conspicuous differentiation in floral traits, their hybrids are fertile, providing an extraordinary opportunity for studying genetic backgrounds of floral adaptation to different pollinators.We crossed the two species and obtained F1 and F2 hybrids. In addition, we developed microsatellite markers and ESTs for QTL mapping.Genetic analyses revealed that difference in flowering time is mostly controlled by single gene, the daytime flowering being dominant. Anthocyanin biosynthesis in petals of H.fulva is also determined mostly by single gene with a large phenotypic effect.By searching candidate genes responsible for the contrasting floral traits among ESTs, we determined homologues of CHS (chalcon synthase gene) and MYB (transcription factor controlling anthocyanin biosynthesis) in Hemerocalis.In a hybridizing population of H.fulva and H.citrina in the field, we observed natural selection on floral traits by various pollinators during four years. Reflecting yearly fluctuation of availability of diurnal and nocturnal pollinators, direction of natural selection on various floral traits fluctuated between years.In the Eupatorium project, coevolution between geminiviruses and sexual and asexual plants of Eupatorium was studied. We discovered satellite DNA from leaves of asexual plants of Eupatorium and confirmed that geminivirus with satellite DNA can cause yellow vein disease in Eupatorium. The result is published on Nature.