Improving crop nutrient status: discovery, innovation, and translation

Improving crop nutrient status is an essential consideration and target for environmentally friendly and sustainable agriculture. This Special Issue brings together the knowledge of experts in a wide range of disciplines and different aspects of plant biology, including metabolism, genetics, and physiology, applied to address the nutritional quality of crop plants for human consumption in a changing environment. The content of this Special Issue directly addresses the challenge highlighted by the Food and Agriculture Organization of the United Nations, that >700 million people were undernourished in 2024, representing almost 10% of the global population (FAO, 2024). This Special Issue brings together reviews and original articles that reveal new insights and provide new information that highlights the breadth of research currently being undertaken to address this urgent global problem by addressing the nutritional quality of plants.

The challenge associated with increasing crop production in a sustainable manner to feed a growing global population in an increasingly uncertain environment is ongoing.. For example, a recent meta-analysis found that total global food demand is anticipated to rise by between 35% and 56% between 2010 and 2050 (van Dijk et al., 2021) while at the same time, in the absence of mitigation, the yield of key crop staples is likely to remain similar or decrease in response to changing global conditions (Rezaei et al., 2023). Several scenarios thus predict an increase in those at risk of hunger due to climate change of up to 73 million by 2050, with the majority of those people living in sub-Saharan Africa and South Asia (Janssens et al., 2020).

Current food production systems are unsustainable, with agriculture accounting for ~1700 TgCO₂ equivalents per annum or 35% of total anthropogenic greenhouse gas (GHG) emissions, of which almost 60% arise from animal-based foods, twice that of those generated from the production of plant-based foods (Xu et al., 2021). Meat-based diets similarly have a higher GHG burden than plant-based diets, where meat-based UK diets resulted in the production of 60% higher GHGs than vegetarian diets (Rippin et al., 2021). Moreover, it is estimated that a global shift towards the EAT-Lancet planetary health diet which emphasizes vegetables and grains over meat and dairy products would result in a 17% fall in dietary GHG emissions (Li et al., 2024). These data indicate a need to switch to more plant-based dietary and farming systems to minimize the impact of food production on climate change.

More recently, focus has shifted towards the role of agriculture in sustaining biodiversity where agricultural land accounts for almost 40% of the ice-free terrestrial surface (DeClerck et al., 2023). While the role of plant-based diets in the maintenance of agricultural biodiversity has been examined less than its role in reductions of GHG emission, evidence suggests that traditional plant-based diets such as those of the Mediterranean region have a higher biodiversity due to their greater diversity in food plants (Mattas et al., 2023). Moreover, a switch to a more plant-based diet could lead to significant land sparing and restoration for biodiversity, providing 13–25% of global land restoration needs (Kozicka et al., 2023).

An increase in plant-based foods is widely recognized as providing substantial health benefits associated with increases in the consumption of phytonutrients and fibre (Harris et al., 2023). However, it is also the case that a significant shift to plant-based foods can lead to difficulties in obtaining sufficient quantities of specific nutrients, particularly some minerals and certain essential amino acids (Langyan et al., 2022), and some regions that have predominantly plant-based diets exhibit high levels of deficiencies of some essential minerals such as iron and zinc in their population (Huertas et al., 2023). Moreover, these deficiencies are likely be exacerbated by atmospheric change, where free-air CO₂ enrichment experiments provide robust data indicating that the protein and mineral content of crops could fall by ~10% under atmospheric concentrations anticipated by the end of the century (Myers et al., 2014), which could result in an increase in 175 million people suffering zinc deficiency, 122 million protein deficiency, and 1.4 billion additional people suffering from iron deficiency (Smith and Myers, 2018). This highlights a need to consider how a shift to more sustainable diets globally may have unanticipated consequences for human health that can be addressed via a greater understanding of the underpinning mechanisms that lead to the accumulation of nutrients in the edible parts of crop plants and the deployment of that understanding in targeted breeding and crop management.

The manuscripts contained in the Special Issue highlight the diversity of contemporary research concerning the interactions between plants, genetics, and environment that shape the nutritional value of crops and how nutrient availability feeds back via genetics to impact crop performance.

The study by Rathore et al. (2025) highlights the value of taking a rational engineering approach to enhancing crop nutritional quality. Working with rice, the third most produced crop globally (https://www.fao.org/faostat/), they used a modelling approach to identify amino acids in dihydrodipicolinate synthase (DHDPS), the enzyme which catalyses the penultimate lysine biosynthetic step, that are essential for feedback inhibition by lysine. These amino acids were then substituted using site-directed mutagenesis and the mutated protein was expressed in rice under an endosperm-specific promoter, resulting in not only a 30% increase in grain lysine content but also a 15% increase in total protein content without an impact on yield or grain quality traits. Interestingly, transgenic plants exhibited improved resistance to drought and salinity stress that was associated with enhanced antioxidant enzyme activity and photosynthetic parameters. These results indicate the potential for engineering combined nutritional quality and stress resilience to generate crop plants that can maintain both quality and yield under increasingly challenging growing conditions. However, important questions remain regarding the mechanisms by which alteration of grain metabolism feeds back to protect leaf metabolism under stress, and these might represent fruitful avenues for future research.

Ishihara et al. (2025) similarly explore the role of the growing environment on crop nutritional quality with application in the expanding protected horticulture or indoor farming sector. Their work with kale revealed cultivar-dependent changes in the content of nutritionally significant anthocyanins and glucosinolates in response to changes in light intensity and temperature. By building wider metabolic and transcriptional networks, the authors identified potential transcriptional regulatory mechanisms that differed from closely related Arabidopsis and highlighted trade-offs in central metabolic pathways necessary to balance anthocyanin and glucosinolate biosynthesis. These studies underline the need to focus nutritional quality research on the crop plants of interest where model plants might provide misleading hypotheses. Moreover, they demonstrate the significance of a systems-level understanding in underpinning breeding efforts where one nutritional trait may be in competition with another.

Two original research articles further expand the exploration of genetic variation in crop responses to mineral availability and highlight the potential for breeding not only for resource efficiency by crops but also for the enhancement of crop nutritional quality. Chen et al. (2025) explored variation in photosynthetic phosphorus- (P) use efficiency in a wild relative–to landrace–to cultivar gradient in soybean. Their analysis revealed improved photosynthetic assimilation based on either a leaf mass or leaf area basis as soybean was domesticated, irrespective of the presence of sufficient or limiting P. This was strongly associated with leaf chlorophyll content as estimated by SPAD. This was in part explained by changes in leaf anatomy, with domesticated genotypes having a lower palisade to spongy mesophyll ratio. Phosphate pools in the inorganic, nucleic acid, and lipid fractions were strongly reduced by P limitation and, while there were differences dependent on genotype classification, there were no clear trends associated with greater domestication. On the contrary, the concentration of P in the soluble metabolite pool was independent of P availability but strongly correlated with greater domestication, suggesting that photosynthetic P use efficiency is highly dependent on the P-containing metabolite pool.

Ahmad et al. (2025) mapped wheat root traits in response to nutrient deficiency, highlighting the potential for exploiting root traits in breeding for mineral nutrient crops. A particular advance was the authors’ examination of combined deficiencies where N, P, or K deficiency was combined with Fe deficiency. This analysis revealed that many of the observed root responses to single deficiencies were dependent on the presence of Fe and, in its absence, responses were often attenuated or abolished. While the mechanisms by which Fe influences root architecture in response to nutrient deficiencies were not further explored, an intriguing possibility was the observation that in some cultivars, root responses to nutrient deficiency were reactive oxygen species (ROS) dependent, and the addition of the antioxidant ascorbate reduced those responses. Previous work has highlighted the interplay between Fe, ferritin, and ROS in the regulation of root growth via numerous mechanisms including ROS-mediated cell cycle arrest (Reyt et al., 2015), and the work in this Special Issue highlights the need to extend these molecular analyses into multiple nutrient deficiencies.

The role of iron in plant responses to environmental signals is further explored in a review by Distéfano et al. (2025). Here ferroptosis, iron-dependent cell death, is discussed in the context of heat stress where it is a response to extreme heat and proposed to occur following failure to acclimatize through mechanisms including Ca- and ROS-dependent activation of kinase signalling that influences gene expression responses via heat shock factor transcriptional activity. A key issue raised by the authors is that as global temperatures rise, the likelihood of triggering the ferroptosis pathway increases, hence there is a need to understand and mitigate against the triggers of ferroptosis to prevent catastrophic crop failure.

A further review highlights potential conflicts between efforts to improve human mineral nutrition and risks of toxicity associated with a lack of mineral transporter specificity. For example, up to 1 billion people are estimated to have insufficient dietary selenium uptake (Jones et al., 2017). As discussed by Sharma et al. (2025), selenium is taken up by a specific group of aquaporins, the nodulin 26-like intrinsic proteins group III, which also take up other metalloids including boron, silicon, and toxic arsenic with differing degrees of specificity. Arsenate can also be taken up by phosphate transporters, and the review highlights the need to understand the molecular determinants of transport specificity and the interplay of different transporters in the determination of crop mineral composition.

The third review (Kimani, 2025) provides a historic overview of bean breeding for nutritional quality in Africa. This work highlights the need for natural scientists to work with humanities experts, civil society, NGOs, governments, and end-users if we are to achieve impact for our work. Despite our many and rapid advances in the molecular and genetic understanding of crop nutritional quality, this review highlights the huge quantity of collaborative work that needs to be conducted post-lab bench to supply the crops we will need to provide the world with environmentally benign, safe, and nutritious food in a rapidly changing climate.

The papers presented in this Special Issue provide a snapshot of contemporary research associated with our understanding of the mechanisms underpinning crop nutritional value and how that intersects with physiological and biochemical processes underlying plant biology. Advances in current knowledge have provided new insights into the genetic and regulatory networks underpinning crop nutrient accumulation, which is being exploited in breeding programmes for crop nutritional improvement. Similarly, our understanding of crop responses to the biotic and abiotic environment is extensive. Thus, there are significant opportunities to bring these two areas of knowledge together to breed resilient nutritious crops. One area of pressing research need is greater understanding of the mechanisms underpinning the well-documented decline in nutritional quality under elevated CO₂. Several mechanisms have been proposed such as dilution due to increased biomass and C assimilation, reduced transpiration reducing xylem translocation of mineral nutrients, and disrupted N assimilation due to reduced photorespiration (Gojon et al., 2023). However, significant questions remain regarding the relative impacts of different processes, genetic variation in eCO₂ resilience, and the signalling mechanisms underpinning molecular responses to eCO₂. These fruitful avenues for future research provide a roadmap for the improved nutritional quality of crops.

We hope the community finds this Special Issue as interesting to read as it was to put together, and inspires future work towards resolving the remaining questions.

Conflict of interest

The authors declare no conflicts of interest.

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