The pervasive impact of cytokinins: signaling within plants and among biota.

像动物一样，植物使用激素来协调其器官的发育和组装，如根、枝、叶、茎节、花和果实。其中一组激素被称为细胞分裂素，是一个由大约25-30个相关化合物组成的家族，由于它们的形式繁多且浓度极低，使用这些化合物非常具有挑战性。由于它们可能对种子生长产生强大的影响，它们是提高作物产量的有力候选者。为了帮助评估这一潜力，我们将了解细胞分裂素如何帮助种子在短柄植物中形成和发育，短柄植物是一种与燕麦和小麦等谷物相关的遗传模式植物。这将通过工程基因来完成，这些基因负责在年轻种子中制造、降解或激活细胞分裂素。转基因种子的细胞分裂素活性高于或低于正常水平，这将揭示细胞分裂素是促进还是抑制种子生长，以及可能的产量。奇怪的是，我们的实验室发现真菌可以产生包括细胞分裂素在内的植物激素。尽管它们使它们劫持植物的生长，但我们发现，即使是与植物无关的真菌也会产生细胞分裂素。为了找出它们可能如何影响真菌生长本身，我们通过基因工程改造了一种真菌(玉米黑穗病)，使其不再能够产生细胞分裂素。这种突变真菌的生长特征将与正常品种进行比较，看看这些细胞分裂素是否也是真菌激素。最后，我们将调查昆虫如何利用细胞分裂素的产生来引起植物肿瘤(肿瘤)。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。事实上，这种差异可能是由于一些昆虫与细菌结合的能力造成的，细菌也会产生几种类型的细胞分裂素。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。此外，我们将确定用抗菌素杀死昆虫体内的细菌是否会消除昆虫产生的任何细胞分裂素。这些实验将揭示“植物”荷尔蒙如何影响植物以外的许多其他形式的生命。

Like animals, plants use hormones to orchestrate development and assembly of their organs like: roots, branches, leaves, stem nodes, flowers and fruits. One group of hormones, known as the cytokinins, is a family of about 25-30 related compounds, which are are very challenging to work with because of the numerous forms and extremely low concentrations at which they operate. Because of their possible potent influence over seed growth they are strong candidates for increasing crop yield. To help evaluate this potential, we will see how cytokinins help seeds form and develop in Brachypodium, a genetic model plant related to cereals like oats and wheat. This will be done by engineering genes that are responsible for making, degrading or activating cytokinins in young seeds. The transgenic seeds have either higher or lower than normal cytokinin activity and will reveal whether cytokinins promote or inhibit seed growth, and possibly yield. Curiously our lab has found that fungi can make plant hormones, including the cytokinins. Although they make them to hijack the growth of plants, we discovered that even fungi, not associated with plants, make cytokinins. To find out how they might affect fungal growth itself, we have genetically engineered a fungus (corn smut) so that it can no longer make cytokinin. Growth characteristics of this mutant fungus will be compared to the normal variety to see if these cytokinins may also be fungal hormones. Lastly 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 in fact be caused by the ability of some insects to associate with bacteria which also make several types of cytokinins. 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. Furthermore we will determine if killing bacteria in the insects with anitbiotics will eliminate any of the cytokinin made by insects. These sets of experiments will reveal how "plant" hormones impact well beyond plants to influence many other forms of life.