The cytokinins: signaling molecules within plants and among biota.

像动物一样，植物在它们的发育过程中使用激素。细胞分裂素是一种荷尔蒙家族，由于其形式繁多且浓度极低，使用起来具有挑战性。 20多年来，我的实验室已经证明，细胞分裂素增强了种子的生长和作物的产量。一路上，有些事情我们不能仅仅用植物生理学来解释。很明显，细菌也制造细胞分裂素，在某些情况下，还用它们来控制植物的生长。最奇怪的是，当我们继续观察时，我们发现我们研究的每一种不同的生命形式都会产生细胞分裂素。 真菌就是这种情况，我们也证明了真菌可以产生细胞分裂素。起初，我们认为真菌制造细胞分裂素只是为了抑制植物的生长；但我们发现，所有的真菌都会制造细胞分裂素--甚至那些与植物无关的真菌也是如此。在这项提案中，我们将了解细胞分裂素如何控制真菌生长本身。为了做到这一点，我们设计了一种真菌(玉米黑穗病)，使其不能产生细胞分裂素。这种突变真菌的生长将与正常品种进行比较，看看这些细胞分裂素是否也可以作为真菌激素。此外，我们将使用这个系统来确定致病的玉米黑粉菌和植物如何通过细胞分裂素的产生相互“交谈”来协调肿瘤的产生。 在第二个项目中，我们将调查昆虫如何利用细胞分裂素产生导致植物肿瘤(瘤)。我们的早期结果表明，昆虫会产生细胞分裂素，而不管它们是否会引起虫胆；但是，产生虫子的虫子会产生不同数量和类型的细胞分裂素。这种差异可能是由于一些昆虫与产生细胞分裂素的细菌相联系的能力造成的。我们将通过检测产生虫卵和不产生虫卵的昆虫、成虫和幼虫产生的细胞分裂素的数量和类型来测试这一想法。然后，我们将确定用抗生素杀灭昆虫体内的细菌是否会消除昆虫产生的任何细胞分裂素。 细胞分裂素活性在细菌、真菌、植物和昆虫中的普遍存在，引发了一个问题--它们在整个进化过程中在生物体中扮演着什么角色？为了回答这个问题，项目3将研究一种名为Dictyostelials的粘菌。在进化中，它位于植物、真菌和动物的交界处，可以洞察细胞分裂素在王国中的共同或不同角色。在其不同寻常的生命周期中，细胞可以独立存在，也可以组合形成多细胞有机体。我们将研究细胞分裂素，因为细胞以这些不同的方式组织。在细胞分裂素合成或代谢改变的野生型和突变菌株的生命周期中，将对细胞分裂素进行分析。 总体而言，这些实验将揭示“植物”荷尔蒙如何在植物之外发挥作用，从而影响其他几种生命形式。它将为理解生物体如何交流提供基础，这可能对作物如何生长以及它们如何抵抗真菌、细菌和虫害产生影响。

Like animals, plants use hormones in their development. The cytokinins, are a family of hormones, which are challenging to work with because of their numerous forms and extremely low concentrations. Over 20 years my lab has shown that cytokinins strengthen the growth of seeds and yield of crops. Along the way, there were things we couldn't explain just with plant physiology. It became apparent that bacteria also made cytokinins and, in some cases, used them to control plant growth. Most curiously, as we kept looking, we found that every different life form we studied, also produced cytokinins. This is the case with fungi, which we also showed can make cytokinins. Initially we believed fungi made cytokinin just to hijack the growth of plants; but, we discovered that all fungi make cytokinins - even those not associated with plants. In this proposal we will find out how cytokinins may control fungal growth itself. To do this, we engineered a fungus (corn smut) so that it can't make cytokinin. Growth of this mutant fungus will be compared to the normal variety to see if these cytokinins may also act as fungal hormones. Furthermore, we will use this system to determine how the pathogenic corn smut fungus and plants "talk" to each other, through cytokinin production, to orchestrate tumor production. In a second project, we will investigate how insects use cytokinin production to cause plant tumors (galls). Our early results indicate that insects make cytokinins regardless of whether they can cause galls; but the ones that make galls have different amounts and types of cytokinin. The difference may be caused by the ability of some insects to associate with cytokinin-producing bacteria. We will test this idea by examining the amounts and types of cytokinin made by gall producing and non-gall producing insect adults and larvae. We will then determine if killing bacteria in the insects with antibiotics will eliminate any of the cytokinin made by insects. The prevalence of cytokinin activity in bacteria, fungi, plants and insects, provokes a question - what is their role in organisms throughout evolution? To answer this, project 3 will work on a slime mold called Dictyostelium. In evolution it sits at a juncture between plants, fungi and animals and can provide insight into the common or diverging roles of cytokinin among kingdoms. In its unusual life cycle, cells can exist separately or assemble to form multicellular organisms. We will study cytokinins as cells organize in these different ways. Cytokinins will be analyzed during the Dictyostelium life cycle in wild-type and mutant strains with altered cytokinin synthesis or metabolism. Overall, these sets of experiments will reveal how "plant" hormones play roles well beyond plants to impact several other forms of life. It will provide a basis for understanding how organisms communicate, which can have impact for how crops grow and how they resist fungal, bacterial and insect pests.