Potassium (K⁺) is one of the essential macronutrients required for many plant processes, its deficiency results in serious alterations in plant growth and physiology. As a fast-growing tropical tree, Neolamarckia cadamba is severely affected by K⁺ deficiency. However, the physiological and molecular response of N. cadamba to K⁺ deficiency is unclear. In this study, the responses of N. cadamba plants to K⁺ starvation were studied in hydroponic solution at different stages. Low K⁺ stress resulted in reduced biomass as well as reduced chlorophyll and photosynthetic ability especially during late stages of stress. With increased severity and duration of low K⁺ stress, an increase in lignification coupled with thicker cell wall was observed. Of note, reactive oxygen species (ROS) accumulation was increased under low K⁺. The transcriptome analysis revealed that the K⁺ uptake and transport related genes, NcAKT1, NcAKT2, and NcHAK5 were upregulated. However, most receptor-like protein kinase (RLK) were down-regulated in the root and upregulated in the stem and leaf. Low K⁺-associated transcription factors mostly belonging to the WRKY, ERF, MYB, and bHLH families were mainly upregulated. The upregulation of peroxidase, cytochrome P450 s and glutathione S-transferase related genes in the present study indicates their role in ROS scavenging. In addition, 18 auxin-related genes, 8 of which belonged to the PIN family, were down-regulated, indicating that polar auxin transport in N. cadamba was altered. Accordingly, many genes attributed to lignification pathway were upregulated. Our results shed light on physiological and molecular mechanisms to cope K⁺ deficiency in N. cadamba.

钾（K ⁺）是许多植物加工过程中必需的重要常量营养素之一，其缺乏会导致植物生长和生理发生严重变化。作为快速生长的热带树木，Neolamarckia cadamba受K ⁺缺乏症的严重影响。然而，的生理和分子响应N. cadamba至K ⁺缺乏是不清楚。在这项研究中，研究了卡迪巴猪笼草植物在不同时期水培溶液中对K ⁺饥饿的反应。低K ⁺胁迫导致生物量减少，叶绿素和光合能力降低，尤其是在胁迫后期。随着低K ⁺胁迫的严重性和持续时间的增加，观察到木质化的增加以及较厚的细胞壁。值得注意的是，在低K ⁺下，活性氧（ROS）积累增加。转录组分析显示，与K ⁺摄取和运输相关的基因NcAKT1，NcAKT2和NcHAK5被上调。但是，大多数受体样蛋白激酶（RLK）在根中被下调，在茎和叶中被上调。低K ⁺主要属于WRKY，ERF，MYB和bHLH家族的相关转录因子主要上调。本研究中过氧化物酶，细胞色素P450 s和谷胱甘肽S-转移酶相关基因的上调表明它们在清除ROS中的作用。此外，下调了与植物生长素相关的18个基因，其中8个属于PIN家族，这表明在cadamba猪笼草中极性植物生长素的运输发生了改变。因此，许多归因于木质化途径的基因被上调。我们的研究结果揭示生理和分子机制的光，以应付ķ ⁺在缺乏N. cadamba。