Maize Genomics and Genetics 2025, Vol.16, No.4, 219-228 http://cropscipublisher.com/index.php/mgg 219 Research Report Open Access Functional Validation of Maize Phosphate Transporters Using Overexpression Lines Shanjun Zhu, Wei Wang Institute of Life Sciences, Jiyang College of Zhejiang A&F University, Zhuji, 311800, Zhejiang, China Corresponding author: wei.wang@jicat.org Maize Genomics and Genetics, 2025, Vol.16, No.4 doi: 10.5376/mgg.2025.16.0019 Received: 13 Jun., 2025 Accepted: 28 Jul., 2025 Published: 18 Aug., 2025 Copyright © 2025 Zhu and Wang, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Zhu S.J., and Wang W., 2025, Functional validation of maize phosphate transporters using overexpression lines, Maize Genomics and Genetics, 16(4): 219-228 (doi: 10.5376/mgg.2025.16.0019) Abstract Phosphate transport is essential for maize growth, development, and yield, as it regulates nutrient uptake, allocation, and signaling pathways critical for plant productivity. In this study, we conducted a comprehensive functional validation of maize phosphate transporters through overexpression strategies, focusing on key members of the PHT1, PHT2, and PHT3 families. We characterized the genomic organization, expression patterns, and regulatory features of these genes, followed by Agrobacterium-mediated transformation to generate targeted overexpression lines under constitutive and tissue-specific promoters. Phenotypic assessments revealed enhanced phosphate uptake efficiency, improved root architecture, increased biomass, and greater stress tolerance in transgenic lines. Molecular analyses, including transcriptomic profiling, protein localization studies, and metabolic flux measurements, confirmed the functional enhancement of phosphate transport and related metabolic pathways. A case study on a specific PHT1 transporter demonstrated significant agronomic benefits, including improved yield under phosphate-limited conditions. These findings provide critical insights into the roles of phosphate transporters in maize physiology and highlight their potential for breeding phosphate-efficient cultivars, contributing to sustainable agriculture and phosphorus resource conservation. Keywords Maize; Phosphate transporter; Overexpression; Nutrient absorption; Sustainable agriculture 1 Introduction Phosphorus is very important for plants, especially in high-yield crops like corn. Phosphorus is involved in both leaf growth and grain filling. But the problem is that although the soil may contain a considerable amount of phosphorus, the portion that plants can actually absorb is very limited (Zhang and Xu, 2024). In reality, this often leads farmers to have to rely on excessive fertilization to maintain yields (Wang et al., 2020a). Interestingly, some corn can still grow normally when there is insufficient phosphorus, which brings up a key topic: How do they manage to efficiently absorb and rationally allocate phosphorus resources? (Liu et al., 2016). Behind this, there is something called a "phosphate transporter", especially the proteins of the PHT1 family. They act like porters, transporting phosphorus from the soil into plants and completing its redistribution within the plants (Nagy et al., 2006). In corn, there are more than one type of such proteins. Some are actively expressed in the root system, while others work in the leaves. Moreover, certain transporter proteins become particularly "active" once phosphorus deficiency occurs or when symbiosis occurs with arbuscular mycorrhizal fungi (Liu et al., 2018). They can even help transport phosphorus from the old leaves to the newly grown parts, while participating in some phosphorus-related regulatory mechanisms and signal feedback (Hu et al., 2024). Although researchers have identified multiple maize genes involved in phosphorus transport, their respective roles and the regulatory details behind them are still not clear enough. To further understand the functions of these genes, a common approach is to conduct overexpression experiments to see what effects increasing the "working intensity" of a certain protein will have on phosphorus uptake, phosphorus regulation and overall development of plants (Xu et al., 2020). For instance, research has found that enhancing the expression levels of ZmPT7 or ZmPt9 not only boosts absorption but also improves phosphorus distribution within the body, and can even influence traits such as plant height and root systems. This approach is actually quite intuitive and effective.
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