Division of Plant Sciences, Research School of Biology, The Australian National University, 134 Linnaeus Way, Canberra, ACT, 2601, Australia.
J Plant Physiol. 2022 Sep;276:153765. doi: 10.1016/j.jplph.2022.153765. Epub 2022 Jul 30.
Nitrogen fixing symbioses between plants and bacteria are ancient and, while not numerous, are formed in diverse lineages of plants ranging from microalgae to angiosperms. One symbiosis stands out as the most widespread one is that between legumes and rhizobia, leading to the formation of nitrogen-fixing nodules. The legume family is one of the largest and most diverse group of plants and legumes have been used by humans since the beginning of agriculture, both as high nitrogen food, as well as pastures and rotation crops. One open question is whether their ability to form a nitrogen-fixing symbiosis has contributed to legumes' success, and whether legumes have any unique characteristics that have made them more diverse and widespread than other groups of plants. This review examines the evolutionary journey that has led to the diversification of legumes, in particular its nitrogen-fixing symbiosis, and asks four questions to investigate which legume traits might have contributed to their success: 1. In what ways do legumes differ from other plant groups that have evolved nitrogen-fixing symbioses? In order to answer this question, the characteristics of the symbioses, and efficiencies of nitrogen fixation are compared between different groups of nitrogen fixing plants. 2. Could certain unique features of legumes be a reason for their success? This section examines the manifestations and possible benefits of a nitrogen-rich 'lifestyle' in legumes. 3. If nitrogen fixation was a reason for such a success, why have some species lost the symbiosis? Formation of symbioses has trade-offs, and while these are less well known for non-legumes, there are known energetic and ecological reasons for loss of symbiotic potential in legumes. 4. What can we learn from the unique traits of legumes for future crop improvements? While exploiting some of the physiological properties of legumes could be used to improve legume breeding, our increasing molecular understanding of the essential regulators of root nodule symbioses raise hope of creating new nitrogen fixing symbioses in other crop species.
植物与细菌之间的固氮共生关系历史悠久，虽然数量不多，但存在于从微藻到被子植物等多种植物谱系中。有一种共生关系尤为广泛，那就是豆科植物与根瘤菌之间的共生关系，这种共生关系导致了固氮结瘤的形成。豆科植物是最大和最多样化的植物群之一，自农业开始以来，人类就一直将豆科植物用作高蛋白食物、牧场和轮作作物。一个悬而未决的问题是，它们形成固氮共生关系的能力是否促进了豆科植物的成功，以及豆科植物是否具有任何独特的特征，使它们比其他植物群更加多样化和广泛。本综述探讨了导致豆科植物多样化的进化历程，特别是其固氮共生关系，并提出了四个问题来研究哪些豆科植物特征可能有助于它们的成功：1. 豆科植物与其他已进化出固氮共生关系的植物群体有何不同？为了回答这个问题，比较了不同固氮植物群体之间共生关系的特征和固氮效率。2. 豆科植物的某些独特特征是否是其成功的原因？本节研究了豆科植物中富含氮的“生活方式”的表现形式和可能的好处。3. 如果固氮是成功的原因，为什么有些物种失去了共生关系？共生关系的形成存在权衡，虽然这些权衡对于非豆科植物来说不太为人所知，但已知豆科植物失去共生潜力存在能量和生态方面的原因。4. 我们可以从豆科植物的独特特征中学到什么，以用于未来的作物改良？虽然利用豆科植物的一些生理特性可以用于改良豆科植物的育种，但我们对根瘤共生基本调控因子的日益深入的分子理解，为在其他作物物种中创造新的固氮共生关系带来了希望。
