Root growth regulation by requirement Plant productivity depends on the elemental nutrients nitrogen and phosphorus, which are drawn from the soil. Oldroyd and Leyser review how root growth patterns adjust according to the physiological needs of the above-ground plant. Systemic signals, including small peptide signals, mediate communication between the shoot's needs and the root's supply. Science, this issue p. eaba0196 BACKGROUND Although plants are dependent on the capture of a number of elemental nutrients from the soil, the principal nutrients that limit plant productivity are nitrogen (N) and phosphorus (P). Acquisition of these nutrients is essential for crop performance, but levels of these nutrients in most agricultural soils limit productivity. Therefore, these nutrients are typically applied at high concentrations in the form of inorganic fertilizers to support food production. However, overuse of fertilizers allows environmental nutrient release, which reduces biodiversity and contributes to climate change. Many farmers around the world lack the financial resources to access fertilizers, and their crop productivity suffers as a consequence. A more sustainable and equitable agriculture will be one that is less dependent on inorganic fertilizers. ADVANCES Accessibility of N and P in the soil is affected by many factors that create a variable spatiotemporal landscape of their availability, both at the local and global scale. Plants optimize uptake of the N and P available by modifications to their growth and development and through engagement with microorganisms that facilitate their capture. Where N and P are ample, the ratio of root:shoot biomass allocation can be low, with minimal root systems capturing sufficient nutrients. Typically, vegetative growth is extended, allowing resource accumulation and investment in seed production. In environments where these nutrients are limiting, overall growth is reduced but root systems are expanded and colonization by microorganisms is encouraged to facilitate nutrient capture. Plants can recognize a patchwork of nutrient availability and activate root growth within this patchwork to optimize nutrient capture. Plants are able to measure multiple facets of nutrient availability: local sensing of nutrients in the soil, roots experiencing nutrient deprivation, roots experiencing high nutrient availability, and the total nutrient requirements of the plant. Such sensing involves an integration of root and shoot signaling, with a variety of hormones moving between the root and the shoot to both signal nutrient availability and coordinate plant development. Such root-shoot-root signaling is essential to allow plants to make use of local nutrient patches, but to do so only when there is sufficient need for that nutrient. Some microorganisms have capabilities for the capture of N and P from the environment. For instance, N-fixing bacteria can access nitrogen from the atmosphere, something that plants are unable to do. Arbuscular mycorrhizal fungi can access insoluble forms of phosphate in the soil that are mostly inaccessible to plants. Under situations where plants are unable to access N and P from their immediate environment, they turn to these microorganisms to find new sources of these limiting nutrients. Many of the processes that coordinate the plants’ developmental response to nutrient availability also regulate the plants’ interaction with microorganisms. These processes regulate the plants’ receptiveness to their microbial communities, promoting symbiotic associations and restricting immunogenic processes. OUTLOOK Although our understanding of how plants engage with nutrients has advanced, there are few examples of how such knowledge has affected plant performance, perhaps because much of our understanding derives from studies in model, not crop, plants. Years of breeding crops for success under high-nutrient environments have left us with some crop varieties that are poor at optimizing use of limited nutrients. Nonetheless, many processes exist in plants to ensure productivity under poor nutrient conditions, some of which are already accessible in the diversity of crop species and wild near-relatives. We are poised to use the knowledge generated in model systems to optimize the performance of crop plants under nutrient limitation. N response and signaling. Root responses of Arabidopsis plants grown in uniform high N (NO3–; dark gray, left), uniform low N (light gray, middle), and differential treatments of high and low N (right). Note how the root responses are opposite to the local treatments in uniform versus differential treatments. Underpinning these responses are C-terminally encoded peptides (CEPs) produced in roots experiencing low N, cytokinins produced in roots experiencing high N, and an N-sufficiency signal in the shoot. All regulate shoot-to-root signaling, which involves CEP DOWNSTREAM 1 (CEPD) peptides. Systemic signaling is integrated with local signaling (indicated by red) that is induced by local perception of NO3–. As primary producers, plants rely on a large aboveground surface area to collect carbon dioxide and sunlight and a large underground surface area to collect the water and mineral nutrients needed to support their growth and development. Accessibility of the essential nutrients nitrogen (N) and phosphorus (P) in the soil is affected by many factors that create a variable spatiotemporal landscape of their availability both at the local and global scale. Plants optimize uptake of the N and P available through modifications to their growth and development and engagement with microorganisms that facilitate their capture. The sensing of these nutrients, as well as the perception of overall nutrient status, shapes the plant’s response to its nutrient environment, coordinating its development with microbial engagement to optimize N and P capture and regulate overall plant growth.

中文翻译：

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植物的饮食，在可变的营养环境中生存

根据需求调节根系生长 植物生产力取决于从土壤中提取的元素养分氮和磷。Oldroyd 和 Leyser 回顾了根系生长模式如何根据地上植物的生理需要进行调整。系统信号，包括小肽信号，介导芽的需求和根的供应之间的通信。科学，这个问题 p。eaba0196 背景虽然植物依赖于从土壤中获取多种元素养分，但限制植物生产力的主要养分是氮 (N) 和磷 (P)。获取这些养分对作物生长至关重要，但大多数农业土壤中这些养分的含量限制了生产力。所以，这些营养素通常以无机肥料的形式以高浓度施用，以支持粮食生产。然而，过度使用化肥会导致环境养分释放，从而减少生物多样性并导致气候变化。世界各地的许多农民缺乏获得化肥的资金，因此他们的作物生产力受到影响。一种更加可持续和公平的农业将是一种对无机肥料依赖较少的农业。进展 土壤中 N 和 P 的可及性受到许多因素的影响，这些因素在当地和全球范围内创造了一个可变的时空景观。植物通过改变它们的生长和发育以及通过与促进它们捕获的微生物的接触来优化对可用 N 和 P 的吸收。在 N 和 P 充足的情况下，根：地上部生物量分配的比率可能较低，最小的根系可以捕获足够的养分。通常情况下，营养生长得到延长，允许资源积累和种子生产投资。在这些养分有限的环境中，整体生长会减少，但根系会扩大，并鼓励微生物定植以促进养分捕获。植物可以识别养分可用性的拼凑并激活该拼凑中的根生长以优化养分捕获。植物能够测量养分有效性的多个方面：土壤中养分的局部感知、根部经历养分剥夺、根部经历高养分利用率以及植物的总养分需求。这种传感涉及根和芽信号的整合，各种激素在根和芽之间移动，以发出养分可用性和协调植物发育的信号。这种根-芽-根信号对于允许植物利用局部营养斑是必不可少的，但只有在对该营养有足够的需求时才这样做。一些微生物具有从环境中捕获 N 和 P 的能力。例如，固氮细菌可以从大气中获取氮，这是植物无法做到的。丛枝菌根真菌可以获取土壤中大部分植物无法获取的不溶性磷酸盐。在植物无法从其直接环境中获取 N 和 P 的情况下，他们求助于这些微生物来寻找这些限制性营养素的新来源。许多协调植物对养分有效性的发育反应的过程也调节植物与微生物的相互作用。这些过程调节植物对其微生物群落的接受度，促进共生关联并限制免疫原性过程。展望 尽管我们对植物如何吸收养分的理解有所进步，但很少有例子说明此类知识如何影响植物性能，这可能是因为我们的大部分理解来自对模型而非作物植物的研究。多年来在高营养环境下成功培育作物的做法让我们留下了一些无法优化有限营养利用的作物品种。尽管如此，许多过程存在于植物中，以确保在贫瘠营养条件下的生产力，其中一些过程已经可以在作物物种和野生近亲物种的多样性中获得。我们准备使用模型系统中产生的知识来优化作物在营养限制下的表现。N 响应和信令。生长在均匀高氮（NO3–；深灰色，左）、均匀低氮（浅灰色，中）和高低氮差异处理（右）中的拟南芥植物的根响应。请注意根响应如何与统一处理和差异处理中的局部处理相反。支持这些反应的是在经历低氮的根中产生的 C 末端编码肽 (CEP)、在经历高氮的根中产生的细胞分裂素，以及芽中的 N 充足信号。所有这些都调节从芽到根的信号传导，其中涉及 CEP 下游 1 (CEPD) 肽。全身信号与由局部感知 NO3– 诱导的局部信号（红色表示）相结合。作为初级生产者，植物依靠大面积的地上表面积来收集二氧化碳和阳光，并依靠大面积的地下表面积来收集支持其生长和发育所需的水和矿物质养分。土壤中必需营养素氮 (N) 和磷 (P) 的可及性受到许多因素的影响，这些因素在当地和全球范围内创造了其可用性的可变时空景观。植物通过改变其生长和发育以及与促进其捕获的微生物的接触来优化对可用 N 和 P 的吸收。