Sweetgums (Liquidambar), members of the family Altingiaceae (Altingiales), have inflorescences and floral organs that are distinctive in structure compared with other angiosperms in which the roles of floral homeotic genes have been studied. To begin to understand the role of AGAMOUS (AG)—a floral homeotic gene that has a major role in stamen and carpel development—in development of the monosexual flowers of sweetgum, we used RNAi to reduce the expression of two members of the AG subfamily. Because AG suppression should induce floral sterility, RNAi might also provide a tool to mitigate the risks of invasiveness—and to reduce the production of its nuisance fruits or allergenic pollen—when sweetgum is used as an exotic shade or forest tree. We tested 33 independent transgenic events and non‐transgenic controls during 10 years in the field. The RNAi‐AG sweetgum trees maintained normal growth, phenology, and vivid fall coloration during the 10 years of study, but 8 insertion events had highly modified inflorescence and floral morphology. The modified flowers had anthers and carpels that were converted to flat leaf‐like structures lacking pollen grains and ovules, respectively. The female inflorescences developed into dry papery structures that failed to produce seeds. These infructescences were smaller than control infructescences, and lost a greater percentage of biomass in a controlled decay assay. RNAi against AG genes was highly effective at impairing fertility and modifying reproductive development without significant vegetative effects in sweetgum and gave phenotypes distinct from, but similar to, that of AG loss of function in other angiosperms.

中文翻译：

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枫香中 AGAMOUS 基因的 RNAi 改变了生殖器官的特性并降低了果实的持久性。


枫香 ( Liquitambar ) 是 Altingiaceae (Altingiales) 的成员，其花序和花器官的结构与其他被子植物不同，其中花同源基因的作用已被研究。为了开始了解 AGAMOUS (AG)（一种在雄蕊和心皮发育中起重要作用的花同源异型基因）在枫香单性花发育中的作用，我们使用 RNAi 来减少AG亚家族两个成员的表达。由于AG抑制会导致花不育，当枫香被用作外来树荫或林树时，RNAi 也可能提供一种工具来减轻入侵风险，并减少其令人讨厌的果实或过敏花粉的产生。 10 年来，我们在该领域测试了 33 个独立的转基因事件和非转基因对照。在 10 年的研究中，RNAi -AG枫香树保持了正常的生长、物候和鲜艳的秋季色彩，但 8 个插入事件的花序和花形态发生了高度改变。改良后的花的花药和心皮分别转化为缺乏花粉粒和胚珠的扁平叶状结构。雌性花序发育成干燥的纸状结构，无法产生种子。这些果序比对照果序小，并且在受控腐烂测定中损失了更大百分比的生物量。针对AG基因的 RNAi 在损害生育力和改变生殖发育方面非常有效，而对枫香没有显着的营养影响，并且产生与其他被子植物中AG功能丧失不同但相似的表型。