Department of Botany, University of Wisconsin-Madison, Madison, WI, USA.
Department of Geography, University of Wisconsin-Madison, Madison, WI, USA.
J Exp Bot. 2022 Oct 18;73(18):6352-6366. doi: 10.1093/jxb/erac260.
Secondary chemistry often differs between sexes in dioecious plant species, a pattern attributed to its possible role in the evolution and/or maintenance of dioecy. We used GC-MS to measure floral volatiles emitted from, and LC-MS to quantitate non-volatile secondary compounds contained in, female and male Salix purpurea willow catkins from an F2 family. Using the abundance of these chemicals, we then performed quantitative trait locus (QTL) mapping to locate them on the genome, identified biosynthetic candidate genes in the QTL intervals, and examined expression patterns of candidate genes using RNA-seq. Male flowers emitted more total terpenoids than females, but females produced more benzenoids. Male tissue contained greater amounts of phenolic glycosides, but females had more chalcones and flavonoids. A flavonoid pigment and a spermidine derivative were found only in males. Male catkins were almost twice the mass of females. Forty-two QTL were mapped for 25 chemical traits and catkin mass across 16 of the 19 S. purpurea chromosomes. Several candidate genes were identified, including a chalcone isomerase associated with seven compounds. A better understanding of the genetic basis of the sexually dimorphic chemistry of a dioecious species may shed light on how chemically mediated ecological interactions may have helped in the evolution and maintenance of dioecy.
雌雄异株植物物种中的次生化学物质在性别间通常存在差异，这种模式归因于其在雌雄异株进化和/或维持中的可能作用。我们使用 GC-MS 测量了来自 F2 家系的雌性和雄性柳属紫柳树穗花发出的挥发性化合物，并使用 LC-MS 定量分析了其中包含的非挥发性次生化合物。然后，我们使用这些化学物质的丰度进行数量性状位点 (QTL) 映射，以将它们定位在基因组上，鉴定 QTL 区间中的生物合成候选基因，并使用 RNA-seq 检查候选基因的表达模式。雄性花朵比雌性花朵释放出更多的总萜类化合物，但雌性花朵产生的苯丙素类化合物更多。雄性组织中含有更多的酚糖苷，但雌性组织中含有更多的查尔酮和类黄酮。一种类黄酮色素和一种亚精胺衍生物仅存在于雄性中。雄性花序的质量几乎是雌性的两倍。在 19 条柳属紫柳树染色体中的 16 条上，为 25 种化学性状和花序质量共定位了 42 个 QTL。鉴定出了几个候选基因，包括与 7 种化合物相关的查尔酮异构酶。更好地了解雌雄异株物种的性别二态化学物质的遗传基础，可能有助于阐明化学介导的生态相互作用如何有助于雌雄异株的进化和维持。
