Phosphorus (P) is an essential macronutrient for marine phytoplankton responsible for ~50% of global carbon fixation. As P availability is variable and likely will decrease in future warming oceans, phytoplankton growth will be constrained by their strategies to scavenge dissolved organophosphate. To enhance our mechanistic understanding of these strategies, here we employ CRISPR/Cas9 to create mutants of alkaline phosphatase (AP) PhoA and PhoD and a putative regulator in the diatom model Phaeodactylum tricornutum, coupled with transcriptomic profiling to interrogate their modes of function and P- regulatory network. Results indicate that these two AP isoforms are differentiated in subcellular localization and substrate specialization, and are mutually compensatory and replaceable. Further analyses reveal a regulatory cascade of P scavenging and potential roles of AP in iron and ammonium uptake as well as diverse metabolic pathways. These findings have important implications in how phytoplankton community will respond to future changing microenvironments of global oceans.

中文翻译：

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一种酶面临许多挑战：基于碱性磷酸酶的磷营养策略和CRISPR / Cas9基因敲除揭示的调控级联

磷（P）是海洋浮游植物不可或缺的重要营养素，约占全球固碳量的50％。由于磷的可用性是可变的，并且在未来变暖的海洋中可能会减少，因此浮游植物的清除策略将限制其浮游生物的生长。为了增强我们对这些策略的机械理解，在这里我们使用CRISPR / Cas9在硅藻模型Phaeodactylum tricornutum中创建碱性磷酸酶（AP）PhoA和PhoD的突变体以及推定的调节剂。，再加上转录组分析来询问其功能模式和P-调节网络。结果表明，这两种AP同工型在亚细胞定位和底物特异性上有所区别，并且相互补偿和可替换。进一步的分析揭示了P清除的调控级联以及AP在铁和铵吸收以及多种代谢途径中的潜在作用。这些发现对于浮游植物群落如何应对全球海洋未来变化的微环境具有重要意义。