Yamagishi Masumi, Matsumura Yuuki, Inada Yuka, Oyama-Okubo Naomi, Nomizu Toshikazu, Shimura Hanako, Nakatsuka Takashi
Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan.
Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan.
Planta. 2025 Aug 26;262(4):89. doi: 10.1007/s00425-025-04806-x.
We reported the functional characterization of cDNAs encoding geranyl diphosphate synthase small subunit I (GPPS.SUU I) that determine the presence or absence of monoterpene emission from lily flowers. While monoterpene compounds are among the most important scent substances in lily flowers, their emission levels vary among lily cultivars. For example, Oriental hybrid cultivars emit sufficient monoterpenes, but Asiatic hybrid cultivars scarcely emit them. Geranyl diphosphate (GPP), a precursor of monoterpenes, is biosynthesized by GPP synthase (GPPS) in plastids. Angiosperm GPPSs are often heteromeric enzymes consisting of non-catalytic small subunits (GPPS.SSU) and catalytic large subunits (GPPS.LSU); the homomeric form of the latter functions as a geranylgeranyl diphosphate synthase (GGPPS). To determine which genes created large variations in monoterpene emission levels, we characterized Lilium hybrid GPPS.SSU I (LhGPPS.SSU I) and LhGGPPS/GPPS.LSU1, and compared their expression levels in scent and scentless lily flowers. Green fluorescent protein (GFP)-fused LhGGPPS/GPPS.LSU1 and LhGPPS.SSU I proteins were co-localized in the chloroplasts of tobacco cells, and LhGPPS.SSU I interacted physically with LhGGPPS/GPPS.LSU1 in the yeast two-hybrid system. LhGPPS.SSU I overexpression in tobacco (transient) and lily (stable) leaves promoted GPP biosynthesis. Thus, LhGPPS.SSU I interacted with LhGGPPS/GPPS.LSU1 to biosynthesize GPP. LhGPPS.SSU I expression in lily tepals occurred in Oriental but not in Asiatic hybrid cultivars, whereas LhGGPPS/GPPS.LSU1 expression occurred in both, irrespective of monoterpene emissions, indicating that LhGPPS.SSU I is a key determinant of monoterpene emissions from lily flowers. LhGPPS.SSU I was not expressed in seven wild species involved in Asiatic hybrid lily establishment but was expressed in Lilium cernuum, which can hybridize with Asiatic hybrid lilies, indicating that L. cernuum is a promising genetic resource for enhancing floral scent in Asiatic hybrids.
我们报道了编码香叶基二磷酸合酶小亚基I（GPPS.SUU I）的cDNA的功能特性，该亚基决定了百合花中是否有单萜类物质释放。虽然单萜类化合物是百合花中最重要的香气物质之一，但其释放水平在不同百合品种间存在差异。例如，东方杂交品种释放足够的单萜类物质，但亚洲杂交品种几乎不释放。单萜类物质的前体香叶基二磷酸（GPP）是由质体中的GPP合酶（GPPS）生物合成的。被子植物的GPPS通常是由非催化性小亚基（GPPS.SSU）和催化性大亚基（GPPS.LSU）组成的异源二聚体酶；后者的同源形式则作为香叶基香叶基二磷酸合酶（GGPPS）发挥作用。为了确定哪些基因导致了单萜类物质释放水平的巨大差异，我们对百合杂交种GPPS.SSU I（LhGPPS.SSU I）和LhGGPPS/GPPS.LSU1进行了特性分析，并比较了它们在有香气和无香气百合花中的表达水平。绿色荧光蛋白（GFP）融合的LhGGPPS/GPPS.LSU1和LhGPPS.SSU I蛋白在烟草细胞的叶绿体中共定位，并且在酵母双杂交系统中LhGPPS.SSU I与LhGGPPS/GPPS.LSU身体相互作用。在烟草（瞬时）和百合（稳定）叶片中过表达LhGPPS.SSU I促进了GPP的生物合成。因此，LhGPPS.SSU I与LhGGPPS/GPPS.LSU1相互作用以生物合成GPP。LhGPPS.SSU I在东方杂交百合品种的百合花被片中表达，但在亚洲杂交品种中不表达，而LhGGPPS/GPPS.LSU1在两者中均有表达，与单萜类物质的释放无关，这表明LhGPPS.SSU I是百合花中释放单萜类物质的关键决定因素。LhGPPS.SSU I在参与亚洲杂交百合培育的7个野生种中不表达，但在能与亚洲杂交百合杂交的细叶百合中表达，这表明细叶百合是增强亚洲杂交百合花香的有前景的遗传资源。
