Department of Natural Sciences and Mathematics, Pontificia Universidad Javeriana Cali, Cali, Colombia.
Instituto de Biología, Universidad de Antioquia, Medellín, Colombia.
J Exp Bot. 2023 Nov 21;74(21):6588-6607. doi: 10.1093/jxb/erad345.
Trichomes are specialized epidermal cells in aerial plant parts. Trichome development proceeds in three stages, determination of cell fate, specification, and morphogenesis. Most genes responsible for these processes have been identified in the unicellular branched leaf trichomes from the model Arabidopsis thaliana. Less is known about the molecular basis of multicellular trichome formation across flowering plants, especially those formed in floral organs of early diverging angiosperms. Here, we aim to identify the genetic regulatory network (GRN) underlying multicellular trichome development in the kettle-shaped trap flowers of Aristolochia (Aristolochiaceae). We selected two taxa for comparison, A. fimbriata, with trichomes inside the perianth, which play critical roles in pollination, and A. macrophylla, lacking specialized trichomes in the perianth. A detailed morphoanatomical characterization of floral epidermis is presented for the two species. We compared transcriptomic profiling at two different developmental stages in the different perianth portions (limb, tube, and utricle) of the two species. Moreover, we present a comprehensive expression map for positive regulators and repressors of trichome development, as well as cell cycle regulators. Our data point to extensive modifications in gene composition, expression, and putative roles in all functional categories when compared with model species. We also record novel differentially expressed genes (DEGs) linked to epidermis patterning and trichome development. We thus propose the first hypothetical genetic regulatory network (GRN) underlying floral multicellular trichome development in Aristolochia, and pinpoint key factors responsible for the presence and specialization of floral trichomes in phylogenetically distant species of the genus.
表皮毛是气生植物部分的特化表皮细胞。表皮毛的发育经历三个阶段：细胞命运的决定、特化和形态发生。在拟南芥的单细胞分枝叶表皮毛中，已经鉴定出负责这些过程的大多数基因。关于开花植物，尤其是早期分化的被子植物的花器官中多细胞表皮毛形成的分子基础，人们知之甚少。在这里，我们旨在鉴定 Aristolochia（马兜铃科）壶状陷阱花中多细胞表皮毛发育的遗传调控网络（GRN）。我们选择了两个分类群进行比较，一种是具有内被表皮毛的 A. fimbriata，它在授粉中起着关键作用，另一种是 A. macrophylla，其被表皮中没有特化的表皮毛。我们对这两个物种的花表皮进行了详细的形态解剖学描述。我们比较了两个不同物种的不同花被部分（瓣、管和囊）在两个不同发育阶段的转录组分析。此外，我们还展示了一个用于表皮毛发育、细胞周期调节因子的正调控因子和负调控因子的综合表达图谱。与模式物种相比，我们的数据表明在所有功能类别中，基因组成、表达和潜在作用都发生了广泛的改变。我们还记录了与表皮模式和表皮毛发育相关的新差异表达基因（DEGs）。因此，我们提出了第一个与 Aristolochia 花多细胞表皮毛发育相关的假设遗传调控网络（GRN），并指出了负责属中亲缘关系较远物种的花表皮毛存在和特化的关键因素。
