Boron and Phosphorus Act Synergistically to Modulate Absorption and Distribution of Phosphorus and Growth of Brassica napus

Imbalance between boron and phosphorus supply influences boron deficiency symptoms in Brassica napus L

BACKGROUND

The occurrence of boron (B) deficiency in Brassicaceae crops has increased in recent years. Inappropriate application of B with other nutrients often exacerbates symptoms of B deficiency. The aim of this study was to explore the interactive effects of B and phosphorus (P) on the B deficiency symptoms of rapeseed (Brassica napus L.). Two rapeseed cultivars ('W10' and 'ZS11') were treated with two B application rates (low and high B) and three P application rates (low, medium, and high P), and the growth parameters (root morphology, B absorption and distribution, and the P/B ratio) were examined in pot and hydroponic experiments.

RESULTS

Under low B conditions, plants showed severely reduced root and shoot growth but it was greatly improved when supplemented with medium P supply. Further analysis revealed that high P combined with low B decreased the B concentration of newly initiated leaves and seeds, and increased the P/B ratio in plants compared with the medium P and low B combination, resulting in the aggravation of B deficiency of rapeseed. In comparison with the B-inefficient cultivar 'W10', the B-efficient cultivar 'ZS11' had superior growth and seed yield under low B conditions. Furthermore, 'W10' and 'ZS11' displayed significant differences in the response of the interaction between B and P to plant P/B ratio and root morphological parameters, which may reflect distinct genotype characteristics.

CONCLUSION

The findings emphasize the importance of interactions between B and P in the growth and yield formation of rapeseed in B-deficient soils, as imbalanced B and P supply can exacerbate B deficiency symptoms in rapeseed. © 2025 Society of Chemical Industry.

Bridging Molecular Insights and Agronomic Innovations: Cutting-Edge Strategies for Overcoming Boron Deficiency in Sustainable Rapeseed Cultivation

Boron (B) is an essential micronutrient for the growth, development, and maintenance of cellular integrity in vascular plants, and is especially important in cell wall synthesis and reproductive development. Rapeseed (Brassica napus L.), one of the dominant oil crops globally, has a high boron demand and its yield is dramatically decreased under B-deficiency conditions. Rapeseed, which is very sensitive to boron deficiency, suffers from reduced growth and reproductive development, ultimately causing severe yield losses. Here, we reviewed the present state of knowledge on the physiological function of boron in rapeseed, mechanisms of boron uptake and transport, specific effects of boron deficiency in rapeseed, and approaches to alleviate boron deficiency in rapeseed at the agronomical and molecular levels. A specific focus is given to recent molecular breakthroughs and agronomic approaches that may improve boron efficiency. The review focuses on practices that may alleviate the problems caused by boron-deficient soils by investigating the genetic and physiological mechanisms of boron tolerance. In summary, this review describes the integration of molecular information with practical agronomy as an important aspect of breeding future nutrient-efficient rapeseed cultivars that can sustain increasing yields while being cultivated in regions with boron-deficient soils.

Multiomics dissection of Brassica napus L. lateral roots and endophytes interactions under phosphorus starvation

Many plants associate with endophytic microbes that improve root phosphorus (P) uptake. Understanding the interactions between roots and endophytes can enable efforts to improve P utilization. Here, we characterize the interactions between lateral roots of endophytes in a core collection of 50 rapeseed (Brassica napus L.) genotypes with differing sensitivities to low P conditions. With the correlation analysis result between bacterial abundance and plant physiological indices of rapeseeds, and inoculation experiments on plates and soil, we identify one Flavobacterium strain (C2) that significantly alleviates the P deficiency phenotype of rapeseeds. The underlying mechanisms are explored by performing the weighted gene coexpression network analysis (WGCNA), and conducting genome-wide association studies (GWAS) using Flavobacterium abundance as a quantitative trait. Under P-limited conditions, C2 regulates fatty acid and lipid metabolic pathways. For example, C2 improves metabolism of linoleic acid, which mediates root suberin biosynthesis, and enhances P uptake efficiency. In addition, C2 suppresses root jasmonic acid biosynthesis, which depends on α-linolenic acid metabolism, improving C2 colonization and activating P uptake. This study demonstrates that adjusting the endophyte composition can modulate P uptake in B. napus plants, providing a basis for developing agricultural microbial agents.

Role of boron and its interaction with other elements in plants

Boron (B) is an essential microelement for plants, and its deficiency can lead to impaired development and function. Around 50% of arable land in the world is acidic, and low pH in the soil solution decreases availability of several essential mineral elements, including B, magnesium (Mg), calcium (Ca), and potassium (K). Plants take up soil B in the form of boric acid (H3BO3) in acidic soil or tetrahydroxy borate [B(OH)4]- at neutral or alkaline pH. Boron can participate directly or indirectly in plant metabolism, including in the synthesis of the cell wall and plasma membrane, in carbohydrate and protein metabolism, and in the formation of ribonucleic acid (RNA). In addition, B interacts with other nutrients such as Ca, nitrogen (N), phosphorus (P), K, and zinc (Zn). In this review, we discuss the mechanisms of B uptake, absorption, and accumulation and its interactions with other elements, and how it contributes to the adaptation of plants to different environmental conditions. We also discuss potential B-mediated networks at the physiological and molecular levels involved in plant growth and development.

Reactive oxygen species-related genes participate in resistance to cucumber green mottle mosaic virus infection regulated by boron in Nicotiana benthamiana and watermelon

Cucumber green mottle mosaic virus (CGMMV) infection causes acidification and rot of watermelon flesh, resulting in serious economic losses. It is widely reported the interaction relationship between boron and reactive oxygen species (ROS) in regulating normal growth and disease resistance in plants. Our previous results demonstrated that exogenous boron could improve watermelon resistance to CGMMV infection. However, the roles of ROS-related genes regulated by boron in resistance to CGMMV infection are unclear. Here, we demonstrated that CGMMV symptoms were alleviated, and viral accumulations were decreased by boron application in Nicotiana benthamiana, indicating that boron contributed to inhibiting CGMMV infection. Meanwhile, we found that a number of differentially expressed genes (DEGs) associated with inositol biosynthesis, ethylene synthesis, Ca²⁺ signaling transduction and ROS scavenging system were up-regulated, while many DEGs involved in ABA catabolism, GA signal transduction and ascorbic acid metabolism were down-regulated by boron application under CGMMV infection. Additionally, we individually silenced nine ROS-related genes to explore their anti-CGMMV roles using a tobacco rattle virus (TRV) vector. The results showed that NbCat1, NbGME1, NbGGP and NbPrx Q were required for CGMMV infection, while NbGST and NbIPS played roles in resistance to CGMMV infection. The similar results were obtained in watermelon by silencing of ClCat, ClPrx or ClGST expression using a pV190 vector. This study proposed a new strategy for improving plant resistance to CGMMV infection by boron-regulated ROS pathway and provided several target genes for watermelon disease resistance breeding.

High level of zinc triggers phosphorus starvation by inhibiting root-to-shoot translocation and preferential distribution of phosphorus in rice plants

Since the urbanization and industrialization are wildly spread in recent decades, the concentration of Zn in soil has increased in various regions. Although the interactions between P and Zn has long been recognized, the effect of high level of Zn on P uptake, translocation and distribution in rice and its molecular mechanism are not fully understood. In this study, we conducted both hydroponic culture and field trial with different combined applications of P and Zn to analyze the rice growth and yield, the uptake, translocation and distribution of P and Zn, as well as the P- and Zn-related gene expression levels. Our results showed that high level of Zn decreased the rice biomass and yield production, and inhibited the root-to-shoot translocation and distribution of P into new leaves by down-regulating P transporter genes OsPT2 and OsPT8 in shoot, which was controlled by OsPHR2-OsmiR399-OsPHO2 module. High Zn supply triggered P starvation signal in root, thereafter increased the activities of both root-endogenous and -secreted acid phosphatase to release more Pi, and induced the expression OsPT2 and OsPT8 to uptake more P for plant growth. On the other hand, high level of P significantly decreased the Zn concentrations in both root and shoot, and the root uptake ability of Zn through altering the expression levels of OsZIPs, which were further confirmed by the P high-accumulated mutant osnla1-2 and OsPHR2-OE transgenic plant. Taken together, we revealed the physiological and molecular mechanisms of P-Zn interactions, and proposed a working model of the cross-talk between P and Zn in rice plants. Our results also indicated that appropriate application of P fertilizer is an effective strategy to reduce rice uptake of excessive Zn when grown in Zn-contaminated soil.

Hierarchical Reactivity of Enzyme-Mediated Phosphorus Recycling from Organic Mixtures by Aspergillus niger Phytase

Biological recycling of inorganic phosphorus (P_i) from organic phosphorus (P_o) compounds by phosphatase-type enzymes, including phytases, is an important contributor to the pool of bioavailable P to plants and microorganisms. However, studies of mixed-substrate reactions with these enzymes are lacking. Here, we explore the reactivity of a phytase extract from the fungus Aspergillus niger toward a heterogeneous mixture containing, in addition to phytate, different structures of environmentally relevant P_o compounds such as ribonucleotides and sugar phosphates. Using a high-resolution liquid chromatography-mass spectrometry method to monitor simultaneously the parent P_o compounds and their by-products, we captured sequential substrate-specific evolution of P_i from the mixture, with faster hydrolysis of multiphosphorylated compounds (phytate, diphosphorylated sugars, and di- and tri-phosphorylated ribonucleotides) than hydrolysis of monophosphorylated compounds (monophosphorylated sugars and monophosphorylated ribonucleotides). The interaction mechanisms and energies revealed by molecular docking simulations of each P_o compound within the enzyme's active site explained the substrate hierarchy observed experimentally. Specifically, the favorable orientation for binding of the negatively charged phosphate moieties with respect to the positive potential surface of the active site was important. Collectively, our findings provide mechanistic insights about the broad but hierarchical role of phytase-type enzymes in P_i recycling from the heterogeneous assembly of P_o compounds in agricultural soils or wastes.