Nectary structure and function in relation to angiosperm reproductive success: Developmental and evolutionary perspectives

蜜腺是分泌花蜜的植物腺体，花蜜是一种富含碳水化合物的溶液，但也含有浓度较低的其他溶质。尽管蜜腺很小且隐蔽，但在生态学上对促进植物和生物在其环境中有益的相互作用极其重要，无论是在加拿大还是在国际上。花蜜通常居住在一些重要的位置，这些位置可以引导游客接触花药（产生花粉的器官）和柱头（接受花粉的地方，授粉发生）。因此，当蜜蜂和其他昆虫等访花动物从花蜜中采集花蜜作为重要的食物来源，最终导致种子和果实形成时，互惠关系就出现了。我们日常饮食的主要部分可以直接归因于昆虫授粉，因此是蜜腺。一些花基甚至有刺，管状的延伸部分隐藏着花蜜，只有有足够舌头长度的动物才能获得花蜜。对于一个非常有益的物种，蜜蜂（Apis mellifera），花蜜是加拿大和世界范围内一种非常有价值的商品-蜂蜜的前身。蜜腺的研究需要显微镜。每个蜜腺通常有三个结构组成部分：表皮（一层覆盖细胞），几个表皮下的腺细胞层，以及血管供应（管道）。我们将通过寻找细胞生长和发育的机制来研究这三个组成部分，从而在进化的背景下获得关于蜜腺形式和功能的新知识。我们将研究I)产花蜜的花刺，它们的独特之处在于在顶端形成分叉（如字母Y）。有趣的是，蜂鸟和某些昆虫有分叉的舌头。利用光镜、共聚焦显微镜和扫描电子显微镜，我们将放大马刺的整个发育过程，以确定这些y分支马刺是如何发育的。此外，定期将牙印材料应用于同一活的骨刺上，甚至可以让我们追踪表皮细胞分裂和伸长的单个文件；我们将在各种花蜜中研究植物管道中被称为韧皮部的糖传导形式，我们已经发现了伴随细胞的差异，伴随细胞是一种特殊的细胞，它们将到达的糖卸下，作为花蜜在外部分泌。此外，我们将调查一个非常大的科——菊科的花蜜腺，以扩大我们对表皮中形成的韧皮部的发现，这是植物中独特的现象；III)奇怪的不育花，被称为“无配偶型”，来自几个物种的突变体，在花瓣和萼片中形成蜜腺，有时仍然具有功能。我们将比较这些突变株和正常株的花蜜结构和花蜜产量，以进一步了解在授粉不能发生时仍然存在的花蜜的来源

Nectaries are plant glands that secrete nectar, a solution rich in carbohydrates but also containing other solutes at lower concentrations. Despite being small and cryptic, nectaries are extremely important ecologically for fostering beneficial interactions between plants and organisms in their environment, both in Canada and internationally. Floral nectaries typically reside in strategic locations leading to the visitor's contact of anthers (pollen-producing organs) and stigmas (pollen-receiving sites, where pollination occurs). Thus, mutualistic relationships occur when flower-visiting animals such as bees and other insects gather nectar as an important food source from floral nectaries, leading eventually to seed and fruit set. Major parts of our daily diets can be attributed directly to pollination by insects, and hence to nectaries. Some flower bases even possess spurs, tubular extensions that conceal nectar available only to animals with sufficient tongue length to attain it. And for an extremely beneficial species, the honey bee (Apis mellifera), nectar is the precursor of a highly valued commodity in Canada and worldwide - honey.***The study of nectaries requires microscopy. Each nectary typically has three structural components: an epidermis (a layer of covering cells), several subepidermal layers of glandular cells, plus a vascular supply (plumbing). We shall investigate these three components by searching for mechanisms of cellular growth and development leading to new knowledge about nectary form and function, in an evolutionary context. We shall study I) nectar-yielding floral spurs which are unique by the formation of a bifurcation (like the letter Y) at their tip. Interestingly, hummingbirds and certain insects have bifurcated tongues. Using light, confocal, and scanning-electron microscopy, we shall magnify the cells of spurs throughout their development, to determine how these Y-branched spurs develop. Also, use of a dental impression material applied at regular intervals to the same, living spur will even allow us to trace individual files of epidermal cells as they divide and elongate; II) the sugar-conducting form of plant plumbing called phloem will be examined in a variety of floral nectaries in which we have already discovered differences in companion cells, special cells that unload arriving sugar to be secreted externally as nectar. Also, we shall survey floral nectaries of a very large family, the Asteraceae, to expand our discovery of phloem that forms in the epidermis, a unique occurrence in plants; and III) strange sterile flowers called "agamous type" mutants from several species which form nectaries - sometimes still functional - amidst their petals and sepals. We shall compare nectary structure and nectar production in these mutant and normal plants, to learn more about the origin of floral nectaries still present when pollination cannot even occur.**