Institute of Environment Remediation and Human Health, and College of Ecology and Environment, Southwest Forestry University, Kunming 650224, China.
Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
Environ Sci Technol. 2022 Jul 5;56(13):9196-9219. doi: 10.1021/acs.est.2c00099. Epub 2022 Jun 8.
Phytate (-inositol hexakisphosphate salts) can constitute a large fraction of the organic P in soils. As a more recalcitrant form of soil organic P, up to 51 million metric tons of phytate accumulate in soils annually, corresponding to ∼65% of the P fertilizer application. However, the availability of phytate is limited due to its strong binding to soils via its highly-phosphorylated inositol structure, with sorption capacity being ∼4 times that of orthophosphate in soils. Phosphorus (P) is one of the most limiting macronutrients for agricultural productivity. Given that phosphate rock is a finite resource, coupled with the increasing difficulty in its extraction and geopolitical fragility in supply, it is anticipated that both economic and environmental costs of P fertilizer will greatly increase. Therefore, optimizing the use of soil phytate-P can potentially enhance the economic and environmental sustainability of agriculture production. To increase phytate-P availability in the rhizosphere, plants and microbes have developed strategies to improve phytate solubility and mineralization by secreting mobilizing agents including organic acids and hydrolyzing enzymes including various phytases. Though we have some understanding of phytate availability and phytase activity in soils, the limiting steps for phytate-P acquisition by plants proposed two decades ago remain elusive. Besides, the relative contribution of plant- and microbe-derived phytases, including those from mycorrhizas, in improving phytate-P utilization is poorly understood. Hence, it is important to understand the processes that influence phytate-P acquisition by plants, thereby developing effective molecular biotechnologies to enhance the dynamics of phytate in soil. However, from a practical view, phytate-P acquisition by plants competes with soil P fixation, so the ability of plants to access stable phytate must be evaluated from both a plant and soil perspective. Here, we summarize information on phytate availability in soils and phytate-P acquisition by plants. In addition, agronomic approaches and biotechnological strategies to improve soil phytate-P utilization by plants are discussed, and questions that need further investigation are raised. The information helps to better improve phytate-P utilization by plants, thereby reducing P resource inputs and pollution risks to the wider environment.
植酸盐（肌醇六磷酸盐）可构成土壤中有机磷的很大一部分。作为土壤有机磷中更难分解的形式，每年有高达 5100 万吨的植酸盐在土壤中积累，相当于磷肥料施用量的 65%。然而，由于其高度磷酸化的肌醇结构与土壤强烈结合，其可用性受到限制，土壤中植酸盐的吸附能力是正磷酸盐的 4 倍。磷（P）是农业生产力的最主要限制因素之一。鉴于磷酸盐岩是一种有限的资源，再加上其提取难度增加以及供应的地缘政治脆弱性，预计磷肥料的经济和环境成本将大大增加。因此，优化土壤植酸盐-P 的利用可能会提高农业生产的经济和环境可持续性。为了提高根际中植酸盐-P 的可用性，植物和微生物通过分泌包括有机酸在内的动员剂和包括各种植酸酶在内的水解酶来提高植酸盐的溶解度和矿化作用，从而开发出提高植酸盐溶解度和矿化作用的策略。尽管我们对土壤中植酸盐的可用性和植酸酶活性有了一些了解，但 20 年前提出的植物获取植酸盐-P 的限制步骤仍然难以捉摸。此外，植物和微生物来源的植酸酶（包括菌根来源的植酸酶）在提高植酸盐-P 利用率方面的相对贡献还知之甚少。因此，了解影响植物获取植酸盐-P 的过程，从而开发有效的分子生物技术来增强土壤中植酸盐的动态变化非常重要。然而，从实际的角度来看，植物获取植酸盐-P 与土壤 P 固定竞争，因此必须从植物和土壤两个角度来评估植物获取稳定植酸盐的能力。在这里，我们总结了土壤中植酸盐的可用性和植物对植酸盐-P 的获取信息。此外，还讨论了提高植物利用土壤植酸盐-P 的农业方法和生物技术策略，并提出了需要进一步研究的问题。这些信息有助于更好地提高植物对植酸盐-P 的利用，从而减少磷资源的投入和对更广泛环境的污染风险。
