Responses of root architecture development to low phosphorus availability: a review

Per- and polyfluoroalkyl substances (PFAS) in homegrown crops: Accumulation and human risk assessment

Homegrown crops can present a significant exposure source of per- and polyfluoroalkyl substances (PFAS) to humans. Field studies studying PFAS accumulation in multiple vegetable food categories and examining the potential influence of soil characteristics on vegetable bioavailability under realistic exposure conditions are very scarce. Crop PFAS accumulation depends on a complex combination of factors. The physicochemical differences among the numerous PFAS makes risk assessment very challenging. Thus, simplification of this complexity into key factors that govern crop PFAS accumulation is critical. This study analyzed 29 targeted legacy, precursor and emerging PFAS in the vertical soil profile (0-45 cm depth), rainwater and edible crop parts of 88 private gardens, at different distances from a major fluorochemical plant. Gardens closer to the plant site showed higher soil concentrations which could be linked with historical and recent industrial emissions. Most compounds showed little variation along the soil depth profile, regardless of the distance from the plant site, which could be due to gardening practices. Annual crops consistently accumulated higher sum PFAS concentrations than perennials. Highest concentrations were observed in vegetables, followed by fruits and walnuts. Single soil-crop relationships were weak, which indicated that other factors (e.g., porewater) may be better measures of bioavailability in homegrown crop accumulation. Regression models, which additionally considered soil characteristics showed limited predictive power (all R2 ≤ 35%), possibly due to low variability in crop concentrations. Human intake estimations revealed that the PFAS exposure risk via crop consumption was similar nearby and remotely from the plant site, although the contribution to the overall dietary exposure can be relatively large. The tolerable weekly intake was frequently exceeded with respect to fruit and vegetable consumption, thus potential health risks cannot be ruled out.

Soybean PHR1-regulated low phosphorus-responsive GmRALF22 promotes phosphate uptake by stimulating the expression of GmPTs

Phosphorus (P) is an essential macronutrient for plant growth and development. Rapid alkalisation factors (RALFs) play crucial roles in plant responses to nutrient stress. However, the functions of Glycine max RALFs (GmRALFs) under low P (LP) stress remain elusive. In this study, we first identified 27 GmRALFs in soybean and then revealed that, under LP conditions, GmRALF10, GmRALF11, and GmRALF22 were induced in both roots and leaves, whereas GmRALF5, GmRALF6, and GmRALF25 were upregulated in leaves. Furthermore, GmRALF22 was found to be the target gene of the transcription factor GmPHR1, which binds to the P1BS cis-element in the promoter of GmRALF22 via electrophoretic mobility shift assay and dual-luciferase experiments. Colonisation with Bacillus subtilis which delivers GmRALF22, increases the expression of the high-affinity phosphate (Pi) transporter genes GmPT2, GmPT11, GmPT13, and GmPT14, thus increasing the total amount of dry matter and soluble Pi in soybeans. RNA sequencing revealed that GmRALF22 alleviates LP stress by regulating the expression of jasmonic acid- (JA-), salicylic acid- (SA-), and immune-related genes. Finally, we verified that GmRALF22 was dependent on FERONIA (FER) to promote Arabidopsis primary root growth under LP conditions. In summary, the GmPHR1-GmRALF22 module positively regulates soybean tolerance to LP.

TaMYB-CC5 gene specifically expressed in root improve tolerance of phosphorus deficiency and drought stress in wheat

Phosphate deficiency and drought are significant environmental constraints that impact both the productivity and quality of wheat. The interaction between phosphorus and water facilitates their mutual absorption processes in plants. Under conditions of both phosphorus deficiency and drought stress, we observed a significant upregulation in the expression of wheat MYB-CC transcription factors through the transcriptome analysis. 52 TaMYB-CC genes in wheat were identified and analyzed their evolutionary relationships, structures, and expression patterns. The TaMYB-CC5 gene exhibited specific expression in roots and demonstrated significant upregulation under phosphorus deficiency and drought stress compared to other TaMYB-CC genes. The overexpression of TaMYB-CC5A in Arabidopsis resulted in a significant increase of root length under stress conditions, thereby enhancing tolerance to phosphate starvation and drought stress. The wheat lines with silenced TaMYB-CC5 genes exhibited reduced root length under stress conditions and increased sensitivity to phosphate deficiency and drought stress. In addition, silencing the TaMYB-CC5 genes resulted in altered phosphorus content in leaves but did not lead to a reduction in phosphorus content in roots. Enrichment analysis the co-expression genes of TaMYB-CC5 transcription factors, we found the zinc-induced facilitator-like (ZIFL) genes were prominent associated with TaMYB-CC5 gene. The TaZIFL1, TaZIFL2, and TaZIFL5 genes were verified specifically expressed in roots and regulated by TaMYB-CC5 transcript factor. Our study reveals the pivotal role of the TaMYB-CC5 gene in regulating TaZIFL genes, which is crucial for maintaining normal root growth under phosphorus deficiency and drought stress, thereby enhanced resistance to these abiotic stresses in wheat.

Spatiotemporal patterns of leaf nutrients of wild apples in a wild fruit forest plot in the Ili Valley, China

Malus sieversii, commonly known as wild apples, represents a Tertiary relict plant species and serves as the progenitor of globally cultivated apple varieties. Unfortunately, wild apple populations are facing significant degradation in localized areas due to a myriad of factors. To gain a comprehensive understanding of the nutrient status and spatiotemporal variations of M. sieversii, green leaves were collected in May and July, and the fallen leaves were collected in October. The concentrations of leaf nitrogen (N), phosphorus (P), and potassium (K) were measured, and the stoichiometric ratios as well as nutrient resorption efficiencies were calculated. The study also explored the relative contributions of soil, topographic, and biotic factors to the variation in nutrient traits. The results indicate that as the growing period progressed, the concentrations of N and P in the leaves significantly decreased (P < 0.05), and the concentration of K in October was significantly lower than in May and July. Throughout plant growth, leaf N-P and N-K exhibited hyperallometric relationships, while P-K showed an isometric relationship. Resorption efficiency followed the order of N < P < K (P < 0.05), with all three ratios being less than 1; this indicates that the order of nutrient limitation is K > P > N. The resorption efficiencies were mainly regulated by nutrient concentrations in fallen leaves. A robust spatial dependence was observed in leaf nutrient concentrations during all periods (70.1-97.9% for structural variation), highlighting that structural variation, rather than random factors, dominated the spatial variation. Nutrient resorption efficiencies (NRE, PRE, and KRE) displayed moderate structural variation (30.2-66.8%). The spatial patterns of nutrient traits varied across growth periods, indicating they are influenced by multifactorial elements (in which, soil property showed the highest influence). In conclusion, wild apples manifested differentiated spatiotemporal variability and influencing factors across various leaf nutrient traits. These results provide crucial insights into the spatiotemporal patterns and influencing factors of leaf nutrient traits of M. sieversii at the permanent plot scale for the first time. This work is of great significance for the ecosystem restoration and sustainable management of degrading wild fruit forests.

Comparative stress physiological analysis of aluminium stress tolerance of indigenous maize (Zea mays L.) cultivars of eastern Himalaya

Yield potential of maize having distinct genetic diversity in Eastern Himalayan Region (EHR) hill ecologies is often limited by Al toxicity caused due to soil acidity. Stress physiological analysis of local check exposed to 0-300 μM Al under sand culture revealed that 150 μM Al as critical and 200 μM Al as tolerable limit. Increase in Al from 0 to 300 μM reduced total chlorophyll, carotenoids by 74.8 % and 44.7 % respectively and enhanced anthocyanin by 35.3 % whereas LA, SLW and SL have reduced by 81.3%, 21.3 % and 47.8 % respectively. R/S ratio was 51.0 and 13.7 % higher at lower Al levels (50 μM and 100 μM) and photosynthetic, transpiration rate and TDM were 62.5 %, 42.9 % and 78.6 % lower at higher Al (300 μM) as compared to control. TRL, RSA, RDW and RV at higher Al (300 μM) were 92.6 %, 98.7 %, 78.7 and 97.5 % lower over control respectively. Root and shoot Al and PUpE at higher Al (300 μM) was 194.0, 69.2 and 830 % higher whereas PUE decreased to 88.5 % over control. Evaluation of 31 indigenous maize cultivars at 0, 150, and 250 μM Al in sand culture, alongside tolerance scoring and assessment, revealed that Megha-9, Megha-10, and MZM-19 exhibits high Al tolerance, Megha-1, MZM-22, and MZM-42 demonstrated moderate tolerance, whereas Uruapara, Sublgarh, and BRL Para were identified as Al-sensitive. Stress physiological parameters like SDW, TDM, TRL, SL and LA contributed 46.02 % of variability to PC1, whereas A, RV, RSA, anthocyanin and Chlorophyll_b, contributed 13.56 % of variability to PC2. Highest values of CMS, SL, LP, LA, TRL and anthocyanin were recorded in cluster I having sensitive cultivars while highest CMS, SL, LA, LP, TRL and RSA were found in cluster II having moderately tolerant cultivars and highest mean values for TRL, RSA, LP, LA, CMS and SL were recorded in cluster III having highly Al stress tolerant cultivars. The traits viz., A, RV, RSA, anthocyanin and Chlorophyll_b, total chlorophyll and TDM were emanated as physio-morphological for assessing Al toxicity stress tolerance in Maize with high divergence values. Tolerant cultivars showing 63.4 % and 22.4 % higher anthocyanin at 150 μM Al and 250 μM Al than moderately tolerant one in acid soil experiment with increased root Al, shoot Al, root P and shoot P by 42.6 %, 11 %, 95.1 % and 34 % respectively were emerged as promising for novel maize improvement under acid soils of EHR.

Visualizing and quantifying 33P uptake and translocation by maize plants grown in soil

Phosphorus (P) availability severely limits plant growth due to its immobility and inaccessibility in soils. Yet, visualization and measurements of P uptake from different root types or regions in soil are methodologically challenging. Here, we explored the potential of phosphor imaging combined with local injection of radioactive 33P to quantitatively visualize P uptake and translocation along roots of maize grown in soils. Rhizoboxes (20 × 40 × 1 cm) were filled with sandy field soil or quartz sand, with one maize plant per box. Soil compartments were created using a gravel layer to restrict P transfer. After 2 weeks, a compartment with the tip region of a seminal root was labeled with a NaH2 33PO4 solution containing 12 MBq of 33P. Phosphor imaging captured root P distribution at 45 min, 90 min, 135 min, 180 min, and 24 h post-labeling. After harvest, 33P levels in roots and shoots were quantified. 33P uptake exhibited a 50% increase in quartz sand compared to sandy soil, likely attributed to higher P adsorption to the sandy soil matrix than to quartz sand. Notably, only 60% of the absorbed 33P was translocated to the shoot, with the remaining 40% directed to growing root tips of lateral or seminal roots. Phosphor imaging unveiled a continuous rise in 33P signal in the labeled seminal root from immediate post-labeling until 24 h after labeling. The highest 33P activities were concentrated just above the labeled compartment, diminishing in locations farther away. Emerging laterals from the labeled root served as strong sinks for 33P, while a portion was also transported to other seminal roots. Our study quantitatively visualized 33P uptake and translocation dynamics, facilitating future investigations into diverse root regions/types and varying plant growth conditions. This improves our understanding of the significance of different P sources for plant nutrition and potentially enhances models of plant P uptake.

Exploring the dynamic adaptive responses of Epimedium pubescens to phosphorus deficiency by Integrated transcriptome and miRNA analysis

Phosphorus, a crucial macronutrient essential for plant growth and development. Due to widespread phosphorus deficiency in soils, phosphorus deficiency stress has become one of the major abiotic stresses that plants encounter. Despite the evolution of adaptive mechanisms in plants to address phosphorus deficiency, the specific strategies employed by species such as Epimedium pubescens remain elusive. Therefore, this study observed the changes in the growth, physiological reponses, and active components accumulation in E. pubescensunder phosphorus deficiency treatment, and integrated transcriptome and miRNA analysis, so as to offer comprehensive insights into the adaptive mechanisms employed by E. pubescens in response to phosphorus deficiency across various stages of phosphorus treatment. Remarkably, our findings indicate that phosphorus deficiency induces root growth stimulation in E. pubescens, while concurrently inhibiting the growth of leaves, which are of medicinal value. Surprisingly, this stressful condition results in an augmented accumulation of active components in the leaves. During the early stages (30 days), leaves respond by upregulating genes associated with carbon metabolism, flavonoid biosynthesis, and hormone signaling. This adaptive response facilitates energy production, ROS scavenging, and morphological adjustments to cope with short-term phosphorus deficiency and sustain its growth. As time progresses (90 days), the expression of genes related to phosphorus cycling and recycling in leaves is upregulated, and transcriptional and post-transcriptional regulation (miRNA regulation and protein modification) is enhanced. Simultaneously, plant growth is further suppressed, and it gradually begins to discard and decompose leaves to resist the challenges of long-term phosphorus deficiency stress and sustain survival. In conclusion, our study deeply and comprehensively reveals adaptive strategies utilized by E. pubescens in response to phosphorus deficiency, demonstrating its resilience and thriving potential under stressful conditions. Furthermore, it provides valuable information on potential target genes for the cultivation of E. pubescens genotypes tolerant to low phosphorus.

Comparative transcriptomic and physiological analyses unravel wheat source root adaptation to phosphorous deficiency

Phosphorus (P) is a crucial macronutrient for plant growth and development. Basic metabolic processes regulate growth; however, the molecular detail of these pathways under low phosphorous (LP) in wheat is still unclear. This study aims to elucidate the varied regulatory pathways responses to LP stress in wheat genotypes. Phenotypic, physiological, and transcriptome analyses were conducted on Fielder (P efficient) and Ardito (P inefficient) wheat genotypes after four days of normal phosphorous (NP) and LP stress. In response to LP, Fielder outperformed Ardito, displaying higher chlorophyll content-SPAD values (13%), plant height (45%), stem diameter (12%), shoot dry weight (42%), and root biomass (75%). Root structure analysis revealed that Fielder had greater total root length (50%), surface area (56%), volume (15%), and diameter (4%) than Ardito under LP. These findings highlight Fielder's superior performance and adaptation to LP stress. Transcriptome analysis of wheat genotype roots identified 3029 differentially expressed genes (DEGs) in Fielder and 1430 in Ardito, highlighting LP-induced changes. Key DEGs include acid phosphatases (PAPs), phosphate transporters (PHT1 and PHO1), SPX, and transcription factors (MYB, bHLH, and WRKY). KEGG enrichment analysis revealed key pathways like plant hormones signal transduction, biosynthesis of secondary metabolites, and carbohydrate biosynthesis metabolism. This study unveils crucial genes and the intricate regulatory process in wheat's response to LP stress, offering genetic insights for enhancing plant P utilization efficiency.

Control of Plant Height and Lateral Root Development via Stu-miR156 Regulation of SPL9 Transcription Factor in Potato

MicroRNAs (miRNAs) are a class of endogenous, non-coding small-molecule RNAs that usually regulate the expression of target genes at the post-transcriptional level. miR156 is one of a class of evolutionarily highly conserved miRNA families. SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factor is one of the target genes that is regulated by miR156. SPL transcription factors are involved in regulating plant growth and development, hormone response, stress response, and photosynthesis. In the present study, transgenic potato plants with overexpressed miR156 were obtained via the Agrobacterium-mediated transformation method. The results showed that the expression levels of the target gene, StSPL9, were all downregulated in the transgenic plants with overexpressed Stu-miR156. Compared with those of the control plants, the plant height and root length of the transgenic plants were significantly decreased, while the number of lateral roots was significantly increased. These results revealed that the miR156/SPLs module was involved in regulating potato plant height and root growth.

The MYB-CC Transcription Factor PHOSPHATE STARVATION RESPONSE-LIKE 7 (PHL7) Functions in Phosphate Homeostasis and Affects Salt Stress Tolerance in Rice

Inorganic phosphate (Pi) homeostasis plays an important role in plant growth and abiotic stress tolerance. Several MYB-CC transcription factors involved in Pi homeostasis have been identified in rice (Oryza sativa). PHOSPHATE STARVATION RESPONSE-LIKE 7 (PHL7) is a class II MYC-CC protein, in which the MYC-CC domain is located at the N terminus. In this study, we established that OsPHL7 is localized to the nucleus and that the encoding gene is induced by Pi deficiency. The Pi-responsive genes and Pi transporter genes are positively regulated by OsPHL7. The overexpression of OsPHL7 enhanced the tolerance of rice plants to Pi starvation, whereas the RNA interference-based knockdown of this gene resulted in increased sensitivity to Pi deficiency. Transgenic rice plants overexpressing OsPHL7 produced more roots than wild-type plants under both Pi-sufficient and Pi-deficient conditions and accumulated more Pi in the shoots and roots. In addition, the overexpression of OsPHL7 enhanced rice tolerance to salt stress. Together, these results demonstrate that OsPHL7 is involved in the maintenance of Pi homeostasis and enhances tolerance to Pi deficiency and salt stress in rice.

Organic fertilizer type and dose affect growth, morphological and physiological parameters, and mineral nutrition of watermelon seedlings

Background

Organic agriculture has grown rapidly in recent years due to its environmental friendliness, sustainability, and improved farm profitability. Transplants are commonly used for fruits and vegetables to achieve consistent quality, uniformity, and easy field spacing control. The efficacy and optimal amounts of fertilizers for organic transplant production need to be investigated.

Methods

The effects of three organic fertilizers (Sustane 4-6-4, Nature Safe 7-7-7, and Dramatic 2-4-1) and one conventional fertilizer Peters Professional 20-20-20 (Conventional) with four doses (nitrogen (N) content was matched among fertilizers in each level, as 0.14 g/L, 0.28 g/L, 0.56 g/L, and 0.84 g/L N, respectively) on watermelon seedlings were compared in this study.

Results

The results showed that all organic fertilizer treatments were not significantly different from the Conventional group in terms of watermelon germination. The only exception was the highest dose of Sustane 4-6-4 (0.84 g/L N) which decreased the germination rate and relative emergence index. Generally, growth index, shoot fresh and dry weights, true leaf number, and stem diameter increased as the amount of N increased within each fertilizer type. The best shoot growth was observed in the highest doses of Conventional and Dramatic 2-4-1 treatments (0.84 g/L N). However, Dramatic 2-4-1 treatments resulted in the lowest root growth when compared to other fertilizers at the same N dose. The second highest fertilization dose (0.56 g/L N) of Sustane 4-6-4 had the best root growth according to root fresh weight, root volume, root area, total root length, as well as the numbers of root tip and crossing when compared to other treatments. For seedlings, a well-developed root system can ensure a good seedling establishment and high survival rate under stressful field conditions after transplanting. Thus, Sustane 4-6-4 at 14 g/L (0.56 g/L N) is recommended to produce high-quality organic watermelon seedlings among the treatments applied in this study.

Unlocking dynamic root phenotypes for simultaneous enhancement of water and phosphorus uptake

Phosphorus (P) and water are crucial for plant growth, but their availability is challenged by climate change, leading to reduced crop production and global food security. In many agricultural soils, crop productivity is confronted by both water and P limitations. The diminished soil moisture decreases available P due to reduced P diffusion, and inadequate P availability diminishes tissue water status through modifications in stomatal conductance and a decrease in root hydraulic conductance. P and water display contrasting distributions in the soil, with P being concentrated in the topsoil and water in the subsoil. Plants adapt to water- and P-limited environments by efficiently exploring localized resource hotspots of P and water through the adaptation of their root system. Thus, developing cultivars with improved root architecture is crucial for accessing and utilizing P and water from arid and P-deficient soils. To meet this goal, breeding towards multiple advantageous root traits can lead to better cultivars for water- and P-limited environments. This review discusses the interplay of P and water availability and highlights specific root traits that enhance the exploration and exploitation of optimal resource-rich soil strata while reducing metabolic costs. We propose root ideotype models, including 'topsoil foraging', 'subsoil foraging', and 'topsoil/subsoil foraging' for maize (monocot) and common bean (dicot). These models integrate beneficial root traits and guide the development of water- and P-efficient cultivars for challenging environments.

Comparative physiological and transcriptomic analysis of two salt-tolerant soybean germplasms response to low phosphorus stress: role of phosphorus uptake and antioxidant capacity

BACKGROUND

Phosphorus (P) and salt stress are common abiotic stressors that limit crop growth and development, but the response mechanism of soybean to low phosphorus (LP) and salt (S) combined stress remains unclear.

RESULTS

In this study, two soybean germplasms with similar salt tolerance but contrasting P-efficiency, A74 (salt-tolerant and P-efficient) and A6 (salt-tolerant and P-inefficient), were selected as materials. By combining physiochemical and transcriptional analysis, we aimed to elucidate the mechanism by which soybean maintains high P-efficiency under salt stress. In total, 14,075 differentially expressed genes were identified through pairwise comparison. PageMan analysis subsequently revealed several significantly enriched categories in the LP vs. control (CK) or low phosphorus + salt (LPS) vs. S comparative combination when compared to A6, in the case of A74. These categories included genes involved in mitochondrial electron transport, secondary metabolism, stress, misc, transcription factors and transport. Additionally, weighted correlation network analysis identified two modules that were highly correlated with acid phosphatase and antioxidant enzyme activity. Citrate synthase gene (CS), acyl-coenzyme A oxidase4 gene (ACX), cytokinin dehydrogenase 7 gene (CKXs), and two-component response regulator ARR2 gene (ARR2) were identified as the most central hub genes in these two modules.

CONCLUSION

In summary, we have pinpointed the gene categories responsible for the LP response variations between the two salt-tolerant germplasms, which are mainly related to antioxidant, and P uptake process. Further, the discovery of the hub genes layed the foundation for further exploration of the molecular mechanism of salt-tolerant and P-efficient in soybean.

Low phosphorus promotes NSP1-NSP2 heterodimerization to enhance strigolactone biosynthesis and regulate shoot and root architecture in rice

Phosphorus is an essential macronutrient for plant development and metabolism, and plants have evolved ingenious mechanisms to overcome phosphate (Pi) starvation. However, the molecular mechanisms underlying the regulation of shoot and root architecture by low phosphorus conditions and the coordinated utilization of Pi and nitrogen remain largely unclear. Here, we show that Nodulation Signaling Pathway 1 (NSP1) and NSP2 regulate rice tiller number by promoting the biosynthesis of strigolactones (SLs), a class of phytohormones with fundamental effects on plant architecture and environmental responses. We found that NSP1 and NSP2 are induced by Oryza sativa PHOSPHATE STARVATION RESPONSE2 (OsPHR2) in response to low-Pi stress and form a complex to directly bind the promoters of SL biosynthesis genes, thus markedly increasing SL biosynthesis in rice. Interestingly, the NSP1/2-SL signaling module represses the expression of CROWN ROOTLESS 1 (CRL1), a newly identified early SL-responsive gene in roots, to restrain lateral root density under Pi deficiency. We also demonstrated that GR244DO treatment under normal conditions inhibits the expression of OsNRTs and OsAMTs to suppress nitrogen absorption but enhances the expression of OsPTs to promote Pi absorption, thus facilitating the balance between nitrogen and phosphorus uptake in rice. Importantly, we found that NSP1p:NSP1 and NSP2p:NSP2 transgenic plants show improved agronomic traits and grain yield under low- and medium-phosphorus conditions. Taken together, these results revealed a novel regulatory mechanism of SL biosynthesis and signaling in response to Pi starvation, providing genetic resources for improving plant architecture and nutrient-use efficiency in low-Pi environments.

Integrating genome-wide association study with transcriptomic data to predict candidate genes influencing Brassica napus root and biomass-related traits under low phosphorus conditions

BACKGROUND

Rapeseed (Brassica napus L.) is an essential source of edible oil and livestock feed, as well as a promising source of biofuel. Breeding crops with an ideal root system architecture (RSA) for high phosphorus use efficiency (PUE) is an effective way to reduce the use of phosphate fertilizers. However, the genetic mechanisms that underpin PUE in rapeseed remain elusive. To address this, we conducted a genome-wide association study (GWAS) in 327 rapeseed accessions to elucidate the genetic variability of 13 root and biomass traits under low phosphorus (LP; 0.01 mM P +). Furthermore, RNA-sequencing was performed in root among high/low phosphorus efficient groups (HP1/LP1) and high/low phosphorus stress tolerance groups (HP2/LP2) at two-time points under control and P-stress conditions.

RESULTS

Significant variations were observed in all measured traits, with heritabilities ranging from 0.47 to 0.72, and significant correlations were found between most of the traits. There were 39 significant trait-SNP associations and 31 suggestive associations, which integrated into 11 valid quantitative trait loci (QTL) clusters, explaining 4.24-24.43% of the phenotypic variance observed. In total, RNA-seq identified 692, 1076, 648, and 934 differentially expressed genes (DEGs) specific to HP1/LP1 and HP2/LP2 under P-stress and control conditions, respectively, while 761 and 860 DEGs common for HP1/LP1 and HP2/LP2 under both conditions. An integrated approach of GWAS, weighted co-expression network, and differential expression analysis identified 12 genes associated with root growth and development under LP stress. In this study, six genes (BnaA04g23490D, BnaA09g08440D, BnaA09g04320D, BnaA09g04350D, BnaA09g04930D, BnaA09g09290D) that showed differential expression were identified as promising candidate genes for the target traits.

CONCLUSION

11 QTL clusters and 12 candidate genes associated with root and development under LP stress were identified in this study. Our study's phenotypic and genetic information may be exploited for genetic improvement of root traits to increase PUE in rapeseed.

Allelic variations of ClACO gene improve nitrogen uptake via ethylene-mediated root architecture in watermelon

KEY MESSAGE

The ClACO gene encoding 1-aminocyclopropane-1-carboxylate oxidase enabled highly efficient 15N uptake in watermelon. Nitrogen is one of the most essential nutrient elements that play a pivotal role in regulating plant growth and development for crop productivity. Elucidating the genetic basis of high nitrogen uptake is the key to improve nitrogen use efficiency for sustainable agricultural productivity. Whereas previous researches on nitrogen absorption process are mainly focused on a few model plants or crops. To date, the causal genes that determine the efficient nitrogen uptake of watermelon have not been mapped and remains largely unknown. Here, we fine-mapped the 1-aminocyclopropane-1-carboxylate oxidase (ClACO) gene associated with nitrogen uptake efficiency in watermelon via bulked segregant analysis (BSA). The variations in the ClACO gene led to the changes of gene expression levels between two watermelon accessions with different nitrogen uptake efficiencies. Intriguingly, in terms of the transcript abundance of ClACO, it was concomitant with significant differences in ethylene evolutions in roots and root architectures between the two accessions and among the different genotypic offsprings of the recombinant BC2F1(ZJU132)-18. These findings suggest that ethylene as a negative regulator altered nitrogen uptake efficiency in watermelon by controlling root development. In conclusion, our current study will provide valuable target gene for precise breeding of 'green' watermelon varieties with high-nitrogen uptake efficiencies.

Phosphorus Plays Key Roles in Regulating Plants' Physiological Responses to Abiotic Stresses

Phosphorus (P), an essential macronutrient, plays a pivotal role in the growth and development of plants. However, the limited availability of phosphorus in soil presents significant challenges for crop productivity, especially when plants are subjected to abiotic stresses such as drought, salinity and extreme temperatures. Unraveling the intricate mechanisms through which phosphorus participates in the physiological responses of plants to abiotic stresses is essential to ensure the sustainability of agricultural production systems. This review aims to analyze the influence of phosphorus supply on various aspects of plant growth and plant development under hostile environmental conditions, with a special emphasis on stomatal development and operation. Furthermore, we discuss recently discovered genes associated with P-dependent stress regulation and evaluate the feasibility of implementing P-based agricultural practices to mitigate the adverse effects of abiotic stress. Our objective is to provide molecular and physiological insights into the role of P in regulating plants' tolerance to abiotic stresses, underscoring the significance of efficient P use strategies for agricultural sustainability. The potential benefits and limitations of P-based strategies and future research directions are also discussed.

Mowing accelerates phosphorus cycling without depleting soil phosphorus pool

Mowing, as a common grassland utilization strategy, affects nutrient status in soil by plant biomass removal. Phosphorus (P) cycle plays an important role in determining grassland productivity. However, few studies have addressed the impacts of mowing on P cycling in grassland ecosystems. Here, we investigated the effects of various mowing regimes on soil P fractions and P accumulation in plants and litters. We specifically explored the mechanisms by which mowing regulates ecosystem P cycling by linking aboveground community with soil properties. Our results showed that mowing increased soil dissolvable P concentrations, which probably met the demand for P absorption and utilization by plants, thus contributing to an increased P accumulation by plants. Mowing promoted grassland P cycling by a reciprocal relationship between plants and microbes. Short-term mowing enhanced P cycling mainly through increased root exudation-evoked the extracellular enzyme activity of microbes rather than the alternations in microbial biomass and community composition. Long-term mowing increased P cycling mainly by promoting carbon allocation to roots, thereby leading to greater microbial metabolic activity. Although mowing-stimulation of organic P mineralization lasted for 15 consecutive years, mowing did not result in soil P depletion. These results demonstrate that P removal by mowing will not necessarily lead to soil P limitation. Our findings would advance the knowledge on soil P dynamic under mowing and contribute to resource-efficient grassland management.

CsBPC2 is a key regulator of root growth and development

BASIC PENTACYSTEINE (BPCs) transcription factors are important regulators of plant growth and development. However, the regulatory mechanism of BPC2 in roots remains unclear. In our previous study, we created Csbpc2 cucumber mutants by the CRISPR/Cas9 system, and our studies on the phenotype of Csbpc2 mutants showed that the root growth was inhibited compared with wide-type (WT). Moreover, the surface area, volume and number of roots decreased significantly, with root system architecture changing from dichotomous branching to herringbone branching. Compared with WT, the leaf growth of the Csbpc2 mutants was not affected. However, the palisade and spongy tissue were significantly thinner, which was not beneficial for photosynthesis. The metabolome of root exudates showed that compared with WT, amino acids and their derivatives were significantly decreased, and the enriched pathways were mainly regulated by amino acids and their derivatives, indicating that knockout of CsBPC2 mainly affected the amino acid content in root exudates. Importantly, transcriptome analysis showed that knockout of CsBPC2 mainly affected root gene expression. Knockout of CsBPC2 significantly reduced the gene expression of gibberellins synthesis. However, the expression of genes related to amino acid synthesis, nitrogen fixation and PSII-related photosynthesis increased significantly, which may be due to the effect of knocking out CsBPC2 on gibberellins synthesis, resulting in the inhibition of seedling growth, thus forming negative feedback regulation. Generally, we showed for the first time that BPC2 is a key regulator gene of root growth and development, laying the foundation for future mechanisms of BPC2 regulation in roots.

Silencing of SbPPCK1-3 Negatively Affects Development, Stress Responses and Productivity in Sorghum

Phosphoenolpyruvate carboxylase (PEPC) plays central roles in photosynthesis, respiration, amino acid synthesis, and seed development. PEPC is regulated by different post-translational modifications. Between them, the phosphorylation by PEPC-kinase (PEPCk) is widely documented. In this work, we simultaneously silenced the three sorghum genes encoding PEPCk (SbPPCK1-3) by RNAi interference, obtaining 12 independent transgenic lines (Ppck1-12 lines), showing different degrees of SbPPCK1-3 silencing. Among them, two T2 homozygous lines (Ppck-2 and Ppck-4) were selected for further evaluation. Expression of SbPPCK1 was reduced by 65% and 83% in Ppck-2 and Ppck-4 illuminated leaves, respectively. Expression of SbPPCK2 was higher in roots and decreased by 50% in Ppck-2 and Ppck-4 in this tissue. Expression of SbPPCK3 was low and highly variable. Despite the incomplete gene silencing, it decreased the degree of phosphorylation of PEPC in illuminated leaves, P-deficient plants, and NaCl-treated plants. Both leaves and seeds of Ppck lines had altered metabolic profiles and a general decrease in amino acid content. In addition, Ppck lines showed delayed flowering, and 20% of Ppck-4 plants did not produce flowers at all. The total amount of seeds was lowered by 50% and 36% in Ppck-2 and Ppck-4 lines, respectively. The quality of seeds was lower in Ppck lines: lower amino acid content, including Lys, and higher phytate content. These data confirm the relevance of the phosphorylation of PEPC in sorghum development, stress responses, yield, and quality of seeds.

Involvement of the 4-coumarate:coenzyme A ligase 4CL4 in rice phosphorus acquisition and rhizosphere microbe recruitment via root growth enlargement

MAIN CONCLUSION

The 4-coumarate:coenzyme A ligase 4CL4 is involved in enhancing rice P acquisition and use in acid soil by enlarging root growth and boosting functional rhizosphere microbe recruitment. Rice (Oryza sativa L.) cannot easily acquire phosphorus (P) from acid soil, where root growth is inhibited and soil P is fixed. The combination of roots and rhizosphere microbiota is critical for plant P acquisition and soil P mobilization, but the associated molecular mechanism in rice is unclear. 4CL4/RAL1 encodes a 4-coumarate:coenzyme A ligase related to lignin biosynthesis in rice, and its dysfunction results in a small rice root system. In this study, soil culture and hydroponic experiments were conducted to examine the role of RAL1 in regulating rice P acquisition, fertilizer P use, and rhizosphere microbes in acid soil. Disruption of RAL1 markedly decreased root growth. Mutant rice plants exhibited decreased shoot growth, shoot P accumulation, and fertilizer P use efficiency when grown in soil-but not under hydroponic conditions, where all P is soluble and available for plants. Mutant ral1 and wild-type rice rhizospheres had distinct bacterial and fungal community structures, and wild-type rice recruited some genotype-specific microbial taxa associated with P solubilization. Our results highlight the function of 4CL4/RAL1 in enhancing rice P acquisition and use in acid soil, namely by enlarging root growth and boosting functional rhizosphere microbe recruitment. These findings can inform breeding strategies to improve P use efficiency through host genetic manipulation of root growth and rhizosphere microbiota.

Effect of Deep Placement Fertilization on the Distribution of Biomass, Nutrients, and Root System Development in Potato Plants

The study was carried out in designed pots-rhizoboxes. Root systems were evaluated using computer scanning to determine total length, root area, and root diameter. The study showed a favorable effect of deep placement of fertilizers on total yield, increasing biomass yield by 7-17% relative to surface fertilization. The largest biomass increase under the influence of deep fertilization was obtained in the case of tuber yield, in which a yield increase of 18-34% was obtained. Higher yields of potato tubers were obtained under depth fertilization compared to surface application of fertilizers. Under the influence of deep fertilization at a depth of 20 cm, the uptake of nitrogen and phosphorus by potato biomass increased by 20-21%. Increased depth of fertilization increased the proportion of nitrogen accumulated in the tubers, while in the case of phosphorus, no effect of depth on P distribution was shown. An analysis of root system parameters showed a positive effect on increases in length and total root area under deep fertilization of potato plants. Based on the study, it was found that the distribution of dry matter, nutrients, and potato root development parameters were most optimal when fertilizer granules were applied at a depth of 20 cm.

NtNCED3 regulates responses to phosphate deficiency and drought stress in Nicotiana tabacum

Plants are sessile and encounter to abiotic environmental stressors, such as nutrient deficiency and drought stress. Identifying stress tolerance genes and their mechanisms is vital to ensuring plant survival. In this study, we characterized NCED3 in the tobacco plant Nicotiana tabacum, a key enzyme in the biosynthesis of abscisic acid that is widely involved in abiotic stress responses, using overexpression and RNA interference knockdown. Overexpression of NtNCED3 promoted primary root development, leading to increased dry weight, root-to-shoot ratio, photosynthetic capacity, and acid phosphatase activity, coinciding with highly increased phosphate uptake capability under low phosphate conditions. Under both drought and extreme phosphate deficiency conditions, the phosphate starvation response preceded the drought stress response. However, under high phosphate conditions, the drought stress phenotype emerged before the symptoms of phosphate deficiency. Plants overexpressing NtNCED3 grew better than the wild-type and NtNCED3 knockdown plants, with more developed root systems and higher biomass, phosphorus content, and hormone content. This study provides evidence that NtNCED3 enzyme participates in plant responses to phosphate deficiency and drought stress in N. tabacum, and NtNCED3 may serve as a potentially valuable gene for genetic modification of plant tolerance to both drought stress and phosphate starvation.

Comparative proteome analysis of phosphorus-responsive genotypes reveals the proteins differentially expressed under phosphorous starvation stress in rice

Phosphorus (P)-deficiency is one of the major nutrient constraints for global rice production. P-deficiency tolerance in rice involves complex regulatory mechanisms. To gain insights into the proteins involved in phosphorus acquisition and use efficiency in rice, proteome analysis of a high-yielding rice cultivar Pusa-44 and its near-isogenic line (NIL)-23 harboring a major phosphorous uptake (Pup1) QTL, grown under control and P-starvation stress, was performed. Comparative proteome profiling of shoot and root tissues from the plants grown hydroponically with P (16 ppm, +P) or without P (0 ppm, -P) resulted in the identification of 681 and 567 differentially expressed proteins (DEPs) in shoot of Pusa-44 and NIL-23, respectively. Similarly, 66 and 93 DEPs were identified in root of Pusa-44 and NIL-23, respectively. These P-starvation responsive DEPs were annotated to be involved in metabolic processes like photosynthesis, starch-, sucrose-, energy-metabolism, transcription factors (mainly ARF, ZFP, HD-ZIP, MYB), and phytohormone signaling. Comparative analysis of the expression patterns observed by proteome analysis with that reported at the transcriptome level indicated the Pup1 QTL-mediated post-transcriptional regulation plays an important role under -P stress. Thus, the present study describes the molecular aspect of the regulatory functions of Pup1 QTL under P-starvation stress in rice, which might help develop an efficient rice cultivar with enhanced P acquisition and assimilation for better performance in P-deficient soil.

Molecular mechanisms and genetic improvement of low-phosphorus tolerance in rice

Phosphorus (P) is a macronutrient required for plant growth and reproduction. Orthophosphate (Pi), the preferred P form for plant uptake, is easily fixed in the soil, making it unavailable to plants. Limited phosphate rock resources, low phosphate fertilizer use efficiency and high demands for green agriculture production make it important to clarify the molecular mechanisms underlying plant responses to P deficiency and to improve plant phosphate efficiency in crops. Over the past 20 years, tremendous progress has been made in understanding the regulatory mechanisms of the plant P starvation response. Here, we systematically review current research on the mechanisms of Pi acquisition, transport and distribution from the rhizosphere to the shoot; Pi redistribution and reuse during reproductive growth; and the molecular mechanisms of arbuscular mycorrhizal symbiosis in rice (Oryza sativa L.) under Pi deficiency. Furthermore, we discuss several strategies for boosting P utilization efficiency and yield in rice.

Mineral-Solubilizing Bacteria-Mediated Enzymatic Regulation and Nutrient Acquisition Benefit Cotton’s (Gossypium hirsutum L.) Vegetative and Reproductive Growth

Many farmers’ incomes in developing countries depend on the cultivation of major crops grown in arid and semi-arid regions. The agricultural productivity of arid and semi-arid areas primarily relies on chemical fertilizers. The effectiveness of chemical fertilizers needs to improve by integration with other sources of nutrients. Plant growth-promoting bacteria can solubilize nutrients, increase plant nutrient uptake, and supplement chemical fertilizers. A pot experiment evaluated the promising plant growth-promoting bacterial strain’s effectiveness in promoting cotton growth, antioxidant enzymes, yield, and nutrient uptake. Two phosphate solubilizing bacterial strains (Bacillus subtilis IA6 and Paenibacillus polymyxa IA7) and two zinc solubilizing bacterial strains (Bacillus sp. IA7 and Bacillus aryabhattai IA20) were coated on cotton seeds in a single as well as co-inoculation treatments. These treatments were compared with uninoculated controls in the presence and absence of recommended chemical fertilizer doses. The results showed the co-inoculation combination of Paenibacillus polymyxa IA7 and Bacillus aryabhattai IA20 significantly increased the number of bolls, seed cotton yield, lint yield, and antioxidants activities, including superoxide dismutase, guaiacol peroxidase, catalase, and peroxidase. Co-inoculation combination of Bacillus subtilis IA6 and Bacillus sp. IA16 promoted growth attributes, including shoot length, root length, shoot fresh weight, and root fresh weight. This co-inoculation combination also increased soil nutrient content. At the same time, Paenibacillus polymyxa IA7 + Bacillus aryabhattai IA20 increased nutrient uptake by plant shoots and roots compared.

Phosphorus Use Efficiency of Leafy Brassica sp. Grown in Three Contrasting Soils: Growth, Enzyme Activity and Phosphorus Fractionation

Plant adaptations to low soil phosphorus (P) availability have been intensively studied in Brassica sp. in an attempt to identify the mechanisms involved in P uptake and utilization. The present pot experiment was conducted to evaluate the relationships between plant shoot and root growth, P uptake and use efficiency parameters, and P fractions and enzyme activity, in two species grown in three soil types. The aim of this study was to determine whether adaptation mechanisms are soil-dependent. Two kale species were grown in soils typical for coastal Croatia (terra rossa, rendzina, and fluvisol) with low P availability. Plants grown in fluvisol had the highest shoot biomass and accumulated most P, whereas plants developed the longest roots in terra rossa. Phosphatase activity differed among soils. P use efficiency differed among soils and species. Genotype IJK 17 showed better adaptation to low P availability, which was related to better uptake efficiency. In general, soils differed in inorganic and organic P fractions in rhizosphere soil, but no difference between genotypes was found. The activities of alkaline phosphatase and phosphodiesterase were negatively correlated with most organic P fractions, suggesting their function in the mineralization of soil organic P. Kale species activate different mechanisms of P uptake and utilization when grown in contrasting soil types, suggesting that specific responses to the soil type were more important than the genotypic difference.

Phosphorus Application Enhances Root Traits, Root Exudation, Phosphorus Use Efficiency, and Seed Yield of Soybean Genotypes

Phosphorus (P) is a vital macronutrient required for soybean growth and development but is a finite resource in agriculture worldwide. Low inorganic P availability in soil is often a significant constraint for soybean production. However, little is known about the response of P supply on agronomic, root morphology, and physiological mechanisms of contrasting soybean genotypes at various growth stages and the possible effects of different P on soybean yield and yield components. Therefore, we conducted two concurrent experiments using the soil-filled pots with six genotypes (deep-root system: PI 647960, PI 398595, PI 561271, PI 654356; and shallow-root system: PI 595362, PI 597387) and two P levels [0 (P0) and 60 (P60) mg P kg^-1 dry soil] and deep PVC columns with two genotypes (PI 561271 and PI 595362) and three P levels [0 (P0), 60 (P60), and 120 (P120) mg P kg^-1 dry soil] in a temperature-controlled glasshouse. The genotype × P level interaction showed that increased higher P supply increased leaf area, shoot and root dry weights, total root length, shoot, root, and seed P concentrations and contents, P use efficiency (PUE), root exudation, and seed yield at different growth stages in both experiments. At the vegetative stage (Experiment 1), shallow-rooted genotypes with shorter life cycles had more root dry weight (39%) and total root length (38%) than deep-rooted genotypes with longer life cycles under different P levels. Genotype PI 654356 produced significantly higher (22% more) total carboxylates than PI 647960 and PI 597387 under P60 but not at P0. Total carboxylates positively correlated with root dry weight, total root length, shoot and root P contents, and physiological PUE. The deep-rooted genotypes (PI 398595, PI 647960, PI 654356, and PI 561271) had the highest PUE and root P contents. In Experiment 2, at the flowering stage, genotype PI 561271 had the greatest leaf area (202%), shoot dry weight (113%), root dry weight (143%), and root length (83%) relative to the short-duration, shallow-rooted genotype PI 595362 with external P applied (P60 and P120), with similar trends at maturity. PI 595362 had a greater proportion of carboxylates as malonate (248%), malate (58%), and total carboxylates (82%) than PI 561271 under P60 and P120 but no differences at P0. At maturity, the deep-rooted genotype PI 561271 had greater shoot, root, and seed P contents and PUE than the shallow-rooted genotype PI 595362 under increased P rates but no differences at P0. Further, the genotype PI 561271 had higher shoot (53%), root (165%), and seed yield (47%) than PI 595362 with P60 and P120 than P0. Therefore, inorganic P application enhances plant resistance to the soil P pool and maintains high soybean biomass production and seed yield.

Transcriptome analysis provides insights into the response of Lotus corniculatus roots to low-phosphorus stress

INTRODUCTION

A lack of soil phosphorus (P) is a principal factor restricting the normal growth of Lotus corniculatus in the karst area of Guizhou Province, China, but the response mechanism of L. corniculatus under low-phosphorus stress remains unclear.

METHODS

Therefore, we treated two selected L. corniculatus lines (low-P-intolerant line 08518 and low-P-tolerant line 01549) from 13 L. corniculatus lines with normal phosphorus (0.5 mmol/L KH₂PO₄, NP) and low phosphorus (0.005 mmol/L KH₂PO₄, LP) concentrations to study changes in morphological, physiological and transcriptome data under low-phosphorus stress.

RESULTS

The low-P-tolerant line 01549 exhibited better performance under low-phosphorus stress. Compared with the NP treatment, all root morphological indicators of the low-P-tolerant line 01549 increased, and those of the low-P-intolerant line 08518 decreased under low-P stress. Compared with the NP treatment, acid phosphatase (ACP), catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) activities, and the malondialdehyde (MDA), soluble sugar (SS), soluble protein (SP) and proline (Pro) contents of the two L. corniculatus lines increased under low-P stress. A transcriptome analysis of L. corniculatus showed that a total of 656 and 2243 differentially expressed genes (DEGs) were identified in line 01549 and line 08518, respectively. Meanwhile, the main pathways, such as carbohydrate metabolism, acid phosphatases, phosphate transporters and biosynthesis of secondary metabolites, as well as related genes were also screened by performing a KEGG enrichment analysis.

DISCUSSION

The findings provide an essential point of reference for studying the physiological and molecular mechanism of the response to low-P stress in L. corniculatus.

Phosphorus and carbohydrate metabolism contributes to low phosphorus tolerance in cotton

Low phosphorus (P) is one of the limiting factors in sustainable cotton production. However, little is known about the performance of contrasting low P tolerant cotton genotypes that might be a possible option to grow in low P condition. In the current study, we characterized the response of two cotton genotypes, Jimian169 a strong low P tolerant, and DES926 a weak low P tolerant genotypes under low and normal P conditions. The results showed that low P greatly inhibited growth, dry matter production, photosynthesis, and enzymatic activities related to antioxidant system and carbohydrate metabolism and the inhibition was more in DES926 as compared to Jimian169. In contrast, low P improved root morphology, carbohydrate accumulation, and P metabolism, especially in Jimian169, whereas the opposite responses were observed for DES926. The strong low P tolerance in Jimian169 is linked with a better root system and enhanced P and carbohydrate metabolism, suggesting that Jimian169 is a model genotype for cotton breeding. Results thus indicate that the Jimian169, compared with DES926, tolerates low P by enhancing carbohydrate metabolism and by inducing the activity of several enzymes related to P metabolism. This apparently causes rapid P turnover and enables the Jimian169 to use P more efficiently. Moreover, the transcript level of the key genes could provide useful information to study the molecular mechanism of low P tolerance in cotton.

The Integrated Application of Phosphorous and Zinc Affects the Physiological Status, Yield and Quality of Canola Grown in Phosphorus-suffered Deficiency Saline Soil

Despite the soil could contain high amount of phosphorus (P), salinity reduce its availability for crop plants. Hence, farmers should practice several tactics to ameliorate P deficiency in soils. The current study aimed to assess the importance of zinc (Zn) supply for mitigating the deficiency of P for canola grown in saline soil. The effects of three Zn rates (0, 150 and 300 mg L−1, Zn0, Zn150 and Zn300, respectively) under three P rates (0, 36 and 72 kg P2O5 ha−1, P0, P36, and P72, respectively) on physiological status, yield and quality of canola were measured. Treatments were arranged in the strip plot design based on completely randomized blocks with three replicates. Findings exhibited that P36 recorded the highest values of membrane stability index in the 2nd season, while statistically leveled P72 for relative water content and chlorophyll fluorescence in both seasons. Zn300 exhibited potent effect on all canola physiological traits in both seasons. In both seasons, P36 × Zn300, P72 × Zn150 and P72 × Zn300 showed the maximum chlorophyll fluorescence and performance index values. Plots treated with P72 achieved 70.0% increase in canola seed yield, greater than the untreated ones. Seed yield obtained with Zn300 were higher than Zn0 and Zn150 by1.30 and 1.10 times in 2019/20 season and 1.23 and 1.05 times in 2020/21 season. The highest oil % was recorded with P0 × Zn150 and P72 × Zn0 in the 1st season and with P72 × Zn150 in the 2nd season.

Effects of Co-Inoculating Saccharomyces spp. with Bradyrhizobium japonicum on Atmospheric Nitrogen Fixation in Soybeans (Glycine max (L.))

Crop production encounters challenges due to the dearth of nitrogen (N) and phosphorus (P), while excessive chemical fertilizer use causes environmental hazards. The use of N-fixing microbes and P-solubilizing microbes (PSMs) can be a sustainable strategy to overcome these problems. Here, we conducted a greenhouse pot experiment following a completely randomized blocked design to elucidate the influence of co-inoculating N-fixing bacteria (Bradyrhizobium japonicum) and PSMs (Saccharomyces cerevisiae and Saccharomyces exiguus) on atmospheric N₂-fixation, growth, and yield. The results indicate a significant influence of interaction on Indole-3-acetic acid production, P solubilization, seedling germination, and growth. It was also found that atmospheric N₂-fixation, nodule number per plant, nodule dry weight, straw, and root dry weight per plant at different growth stages were significantly increased under dual inoculation treatments relative to single inoculation or no inoculation treatment. Increased seed yield and N and P accumulation were also noticed under co-inoculation treatments. Soil available N was highest under sole bacterial inoculation and lowest under the control treatment, while soil available P was highest under co-inoculation treatments and lowest under the control treatment. We demonstrated that the co-inoculation of N-fixing bacteria and PSMs enhances P bioavailability and atmospheric N₂-fixation in soybeans leading to improved soil fertility, raising crop yields, and promoting sustainable agriculture.

Impacts of iron on phosphate starvation-induced root hair growth in Arabidopsis

In Arabidopsis, phosphate starvation (-Pi)-induced responses of primary root and lateral root growth are documented to be correlated with ambient iron (Fe) status. However, whether and how Fe participates in -Pi-induced root hair growth (RHG) remains unclear. Here, responses of RHG to different Fe concentrations under Pi sufficiency/deficiency were verified. Generally, distinct dosage effects of Fe on RHG appeared at both Pi levels, due to the generation of reactive oxygen species. Following analyses using auxin mutants and the phr1 mutant revealed that auxin and the central regulator PHR1 are required for Fe-triggered RHG under -Pi. A further proteomic study indicated that processes of vesicle trafficking and auxin synthesis and transport were affected by Fe under -Pi, which were subsequently validated by using a vesicle trafficking inhibitor, brefeldin A, and an auxin reporter, R2D2. Moreover, vesicle trafficking-mediated recycling of PIN2, an auxin efflux transporter, was notably affected by Fe under -Pi. Correspondingly, root hairs of pin2 mutant displayed attenuated responses to Fe under -Pi. Together, we propose that Fe affects auxin signalling probably by modulating vesicle trafficking, chiefly the PIN2 recycling, which might work jointly with PHR1 on modulating -Pi-induced RHG.

Leading nutrient foraging strategies shaping by root system characteristics along the elevations in rubber (Hevea brasiliensis) plantations

When it comes to root and mycorrhizal associations that define resource acquisition strategy, there is a need to identify the leading dimension across root physiology, morphology, architecture and whole plant biomass allocation to better predict the plant's responses to multiple environmental constraints. Here, we developed a new framework for understanding the variation in roots and symbiotic fungi by quantifying multiple-scale characteristics, ranging from anatomy to the whole plant. We chose the rubber (Hevea brasiliensis) grown at three elevations to test our framework and to identify the key dimensions for resource acquisition. Results showed that the quantities of absorptive roots and root system architecture, rather than single root traits, played the leading role in belowground resource acquisition. As the elevation increased from the low to high elevation, root length growth, productivity and root mass fraction (RMF) increased by 2.9-, 2.3- and 13.8-fold, respectively. The contribution of RMF to the changes in total root length was 3.6-fold that of specific root length (SRL). Root architecture exhibited higher plasticity than anatomy and morphology. Further, mycorrhizal colonization was highly sensitive to rising elevations with a non-monotonic pattern. By contrast, both leaf biomass and specific leaf area (traits) co-varied with increasing elevation. In summary, rubber trees changed root system architecture by allocating more biomass and lowering the reliance on mycorrhizal fungi rather than improving single root efficiency in adapting to high elevation. Our framework is instructive for traits-based ecology; accurate assessments of forest carbon cycling in response to resource gradient should account for the leading dimension of root system architecture.

An exopolysaccharide-producing novel Agrobacterium pusense strain JAS1 isolated from snake plant enhances plant growth and soil water retention

A peculiar bacterial growth was very often noticed in leaf-initiated tissue cultures of Sansevieria trifasciata, a succulent belonging to the Asparagaceae family. The isolate left trails of some highly viscous material on the walls of the suspension vessels or developed a thick overlay on semisolid media without adversities in plant growth. FTIR identified this substance to be an extracellular polysaccharide. Various morphological, biochemical tests, and molecular analyses using 16S rRNA, atpD, and recA genes characterized this isolate JAS1 as a novel strain of Agrobacterium pusense. Its mucoidal growth over Murashige and Skoog media yielded enormous exopolysaccharide (7252 mg l^-1), while in nutrient agar it only developed fast-growing swarms. As a qualifying plant growth-promoting bacteria, it produces significant indole-3-acetic acid (86.95 mg l^-1), gibberellic acid (172.98 mg l^-1), ammonia (42.66 µmol ml^-1). Besides, it produces siderophores, 1-aminocyclopropane-1-carboxylic acid deaminase, fixes nitrogen, forms biofilms, and productively solubilizes soil inorganic phosphates, and zinc. Under various treatments with JAS1, wheat and chickpea resulted in significantly enhanced shoot and root growth parameters. PGP effects of JAS1 positively enhanced plants' physiological growth parameters reflecting significant increments in overall chlorophyll, carotenoids, proline, phenols, flavonoids, and sugar contents. In addition, the isolated strain maintained both plant and soil health under an intermittent soil drying regime, probably by both its PGP and EPS production attributes, respectively.

Specific roles of strigolactones in plant physiology and remediation of heavy metals from contaminated soil

Strigolactones (SLs) have been implicated in various developmental processes of the plant, including the response against several abiotic stresses. It is well known as a class of endogenous phytohormones that regulates shoot branching, secondary growth and root morphology. This hormone facilitates plants in responding to nitrogen and phosphorus starvation by shaping the above and below ground structural design. SLs actively participate within regulatory networks of plant stress adaptation that are governed by phytohormones. Heavy metals (HMs) in soil are considered a serious environmental problem that causes various harmful effects on plants. SLs along with other plant hormones imply the role in plant architecture is far from being fully understood. Strategy to remove/remediation of HMs from the soil with the help of SLs has not been defined yet. Therefore, the present review aims to comprehensively provide an overview of SLs role in fine-tuning plant architectures, relation with other plant hormones under abiotic stress, and remediation of HMs contaminated soil using SLs.

Effect of carrier gas change during sewage sludge or sewage sludge and willow pyrolysis on ecotoxicity of biochar-amended soil

Different pyrolysis conditions determine the properties of the biochar. The properties of biochar may affect directly or indirectly their influence on living organisms. The aim of this study was to determine the toxicity of biochar obtained under different conditions (temperature: 500 or 700 °C, carrier gas: N₂ or CO₂, feedstock: sewage sludge or sewage sludge/biomass mixture) after adding to the soil in long-term pot experiment (180 days). Biochars were added to the podzolic loamy sand at a 2% (w/w) dose. Samples were collected at the beginning of the experiment and after 30, 90 and 180 days. The bacteria Aliivibrio fischeri (luminescence inhibition - Microtox), the plant Lepidium sativum (root growth and germination inhibition test - Phytotoxkit F), and the invertebrate Folsomia candida (mortality and reproduction inhibition test - Collembolan test) were used as the test organisms. In the long-term perspective for most tests, changing the carrier gas from N₂ to CO₂ resulted in reduced toxicity of the biochar. A particularly beneficial effect of changing the gas to CO₂ was observed for the solid-phase test with L. sativum. The CO₂ during pyrolysis had the least beneficial effect on toxicity towards A. fischeri.

Genetic variation in morphological traits in cotton and their roles in increasing phosphorus-use-efficiency in response to low phosphorus availability

Phosphorus (P) is an essential macronutrient required for fundamental processes in plants. Trait plasticity is crucial for plant adaptation to environmental change. Variations in traits underlie diverse phosphorus (P) acquisition strategies among plants. Nevertheless, how the intraspecific plasticity and integration of morphological traits contribute to Phosphorus-Use-Efficiency (PUE) in cotton is unknown. In this study, 25 morphological traits were evaluated in 384 cotton genotypes grown with low P (LP, 10μmol. L^-1) and normal nutrition (CK, 500μmol. L^-1) to assess the genetic variability of morphological traits and their relationship to phosphorus use efficiency. Results revealed a large genetic variation in mostly morphological traits under low P. Significant enhancement in root traits and phosphorus efficiency-related traits like PUE was observed at LP as compared to CK conditions. In response to low P availability, cotton genotypes showed large plasticity in shoot and total dry biomass, phosphorus, and nitrogen efficiency-related traits (i.e., phosphorus/nitrogen use efficiency, phosphorus/nitrogen uptake efficiency), and most root traits, but a limited response in root dry biomass, taproot length, root surface area, root volume, and SPAD value. In addition, significant correlations were observed between PUtE (phosphorus uptake efficiency), NUE (nitrogen use efficiency), TDB (total dry biomass), and RTD (root tissue density) with PUE under both P supply level and phosphorus stress index, which may be a key indicator for improving PUE under LP conditions. Most root traits are most affected by genotypes than nutrition level. Conserved PUE is more affected by the nutrition level than the genotype effect. Principal component analysis depicted the comprehensive indicators under two P supply conditions were mainly reflected in root-related traits and morphological indicators such as dry matter biomass. These results indicate that interspecific variations exist within these cotton genotypes and traits. Our study provides suggestions for future research to enhance the ability of the earth system model to predict how crops respond to environmental interference and provide target quality for cotton breeding in phosphorus-deficient areas.

Integrating transcriptomic and metabolomic analysis in roots of wild soybean seedlings in response to low-phosphorus stress

INTRODUCTION

Plants undergo divergent adaptations to form different ecotypes when exposed to different habitats. Ecotypes with ecological adaptation advantages are excellent germplasm resources for crop improvement.

METHODS

his study comprehensively compared the differences in morphology and physiological mechanisms in the roots of two different ecotypes of wild soybean (Glycine soja) seedlings under artificially simulated low-phosphorus (LP) stress.

RESULT

The seedlings of barren-tolerant wild soybean (GS2) suffered less damage than common wild soybean (GS1). GS2 absorbed more phosphorus (P) by increasing root length. In-depth integrated analyses of transcriptomics and metabolomics revealed the formation process of the ecological adaptability of the two different ecotypes wild soybean from the perspective of gene expression and metabolic changes. This study revealed the adaptation process of GS2 from the perspective of the adaptation of structural and molecular metabolism, mainly including: (1) Enhancing the metabolism of phenolic compounds, lignin, and organic acid metabolism could activate unavailable soil P; (2) Up-regulating genes encoding pectinesterase and phospholipase C (PLC) specifically could promote the reuse of structural P; (3) Some factors could reduce the oxidative damage to the membranes caused by LP stress, such as accumulating the metabolites putrescine and ascorbate significantly, up-regulating the genes encoding SQD2 (the key enzyme of sulfolipid substitution of phospholipids) substantially and enhancing the synthesis of secondary antioxidant metabolite anthocyanins and the AsA-GSH cycle; (4) enhancing the uptake of soil P by upregulating inorganic phosphate transporter, acid phosphatase ACP1, and purple acid phosphatase genes; (5) HSFA6b and MYB61 are the key TFs to resist LP stress.

DISCUSSION

In general, GS2 could resist LP stress by activating unavailable soil P, reusing plant structural P, rebuilding membrane lipids, and enhancing the antioxidant membrane protection system. Our study provides a new perspective for the study of divergent adaptation of plants.

'Root of all success': Plasticity in root architecture of invasive wild radish for adaptive benefit

Successful plant establishment in a particular environment depends on the root architecture of the seedlings and the extent of edaphic resource utilization. However, diverse habitats often pose a predicament on the suitability of the fundamental root structure of a species that evolved over a long period. We hypothesized that the plasticity in the genetically controlled root architecture in variable habitats provides an adaptive advantage to worldwide-distributed wild radish (Raphanus raphanistrum, Rr) over its close relative (R. pugioniformis, Rp) that remained endemic to the East Mediterranean region. To test the hypothesis, we performed a reciprocal comparative analysis between the two species, growing in a common garden experiment on their native soils (Hamra/Sandy for Rr, Terra Rossa for Rp) and complementary controlled experiments mimicking the major soil compositions. Additionally, we analyzed the root growth kinetics via semi-automated digital profiling and compared the architecture between Rr and Rp. In both experiments, the primary roots of Rr were significantly longer, developed fewer lateral roots, and showed slower growth kinetics than Rp. Multivariate analyses of seven significant root architecture variables revealed that Rr could successfully adapt to different surrogate growth conditions by only modulating their main root length and number of lateral roots. In contrast, Rp needs to modify several other root parameters, which are very resource-intensive, to grow on non-native soil. Altogether the findings suggest an evo-devo adaptive advantage for Rr as it can potentially establish in various habitats with the minimal tweak of key root parameters, hence allocating resources for other developmental requirements.

Integrating advancements in root phenotyping and genome-wide association studies to open the root genetics gateway

Plant adaptation to challenging environmental conditions around the world has made root growth and development an important research area for plant breeders and scientists. Targeted manipulation of root system architecture (RSA) to increase water and nutrient use efficiency can minimize the adverse effects of climate change on crop production. However, phenotyping of RSA is a major bottleneck since the roots are hidden in the soil. Recently the development of 2- and 3D root imaging techniques combined with the genome-wide association studies (GWASs) have opened up new research tools to identify the genetic basis of RSA. These approaches provide a comprehensive understanding of the RSA, by accelerating the identification and characterization of genes involved in root growth and development. This review summarizes the latest developments in phenotyping techniques and GWAS for RSA, which are used to map important genes regulating various aspects of RSA under varying environmental conditions. Furthermore, we discussed about the state-of-the-art image analysis tools integrated with various phenotyping platforms for investigating and quantifying root traits with the highest phenotypic plasticity in both artificial and natural environments which were used for large scale association mapping studies, leading to the identification of RSA phenotypes and their underlying genetics with the greatest potential for RSA improvement. In addition, challenges in root phenotyping and GWAS are also highlighted, along with future research directions employing machine learning and pan-genomics approaches.

Soil Fertility Clock-Crop Rotation as a Paradigm in Nitrogen Fertilizer Productivity Control

The Soil Fertility Clock (SFC) concept is based on the assumption that the critical content (range) of essential nutrients in the soil is adapted to the requirements of the most sensitive plant in the cropping sequence (CS). This provides a key way to effectively control the productivity of fertilizer nitrogen (Nf). The production goals of a farm are set for the maximum crop yield, which is defined by the environmental conditions of the production process. This target can be achieved, provided that the efficiency of Nf approaches 1.0. Nitrogen (in fact, nitrate) is the determining yield-forming factor, but only when it is balanced with the supply of other nutrients (nitrogen-supporting nutrients; N-SNs). The condition for achieving this level of Nf efficiency is the effectiveness of other production factors, including N-SNs, which should be set at ≤1.0. A key source of N-SNs for a plant is the soil zone occupied by the roots. N-SNs should be applied in order to restore their content in the topsoil to the level required by the most sensitive crop in a given CS. Other plants in the CS provide the timeframe for active controlling the distance of the N-SNs from their critical range.

Root hair-specific transcriptome reveals response to low phosphorus in Cicer arietinum

Root hairs (RH) are a single-cell extension of root epidermal cells. In low phosphorus (LP) availability, RH length and density increase thus expanding the total root surface area for phosphate (Pi) acquisition. However, details on genes involved in RH development and response to LP are missing in an agronomically important leguminous crop, chickpea. To elucidate this response in chickpea, we performed tissue-specific RNA-sequencing and analyzed the transcriptome modulation for RH and root without RH (Root-RH) under LP. Root hair initiation and cellular differentiation genes like RSL TFs and ROPGEFs are upregulated in Root-RH, explaining denser, and ectopic RH in LP. In RH, genes involved in tip growth processes and phytohormonal biosynthesis like cell wall synthesis and loosening (cellulose synthase A catalytic subunit, CaEXPA2, CaGRP2, and CaXTH2), cytoskeleton/vesicle transport, and ethylene biosynthesis are upregulated. Besides RH development, genes involved in LP responses like lipid and/or pectin P remobilization and acid phosphatases are induced in these tissues summarizing a complete molecular response to LP. Further, RH displayed preferential enrichment of processes involved in symbiotic interactions, which provide an additional benefit during LP. In conclusion, RH shows a multi-faceted response that starts with molecular changes for epidermal cell differentiation and RH initiation in Root-RH and later induction of tip growth and various LP responses in elongated RH.

Low phosphorus induces differential metabolic responses in eucalyptus species improving nutrient use efficiency

Phosphorus (P) is a vital nutrient for plant growth. P availability is generally low in soils, and plant responses to low P availability need to be better understood. In a previous study, we studied the growth and physiological responses of 24 species to low P availability in the soil and verified of eucalypts, five (Eucalyptus acmenoides, E. grandis, E. globulus, E. tereticornis, and Corymbia maculata) contrasted regarding their efficiency and responsiveness to soil P availability. Here, we obtained the metabolomic and lipidomic profile of leaves, stems, and roots from these species growing under low (4.5 mg dm^-3) and sufficient (10.8 mg dm^-3) P in the soil. Disregarding the level of P in the soils, P allocation was always higher in the stems. However, when grown in the P-sufficient soil, the stems steadily were the largest compartment of the total plant P. Under low P, the relative contents of primary metabolites, such as amino acids, TCA cycle intermediates, organic acids and carbohydrates, changed differently depending on the species. Additionally, phosphorylated metabolites showed enhanced turnover or reductions. While photosynthetic efficiencies were not related to higher biomass production, A/Ci curves showed that reduced P availability increased the eucalypt species' Vcmax, Jmax and photosynthetic P-use efficiency. Plants of E. acmenoides increased galactolipids and sulfolipids in leaves more than other eucalypt species, suggesting that lipid remodelling can be a strategy to cope with the P shortage in this species. Our findings offer insights to understand genotypic efficiency among eucalypt species to accommodate primary metabolism under low soil P availability and eventually be used as biochemical markers for breeding programs.

Association of Root Hair Length and Density with Yield-Related Traits and Expression Patterns of TaRSL4 Underpinning Root Hair Length in Spring Wheat

Root hairs play an important role in absorbing water and nutrients in crop plants. Here we optimized high-throughput root hair length (RHL) and root hair density (RHD) phenotyping in wheat using a portable Dinolite™ microscope. A collection of 24 century wide spring wheat cultivars released between 1911 and 2016 were phenotyped for RHL and RHD. The results revealed significant variations for both traits with five and six-fold variation for RHL and RHD, respectively. RHL ranged from 1.01 mm to 1.77 mm with an average of 1.39 mm, and RHD ranged from 17.08 mm^-2 to 20.8 mm^-2 with an average of 19.6 mm^-2. Agronomic and physiological traits collected from five different environments and their best linear unbiased predictions (BLUPs) were correlated with RHL and RHD, and results revealed that relative-water contents (RWC), biomass and grain per spike (GpS) were positively correlated with RHL in both water-limited and well-watered conditions. While RHD was negatively correlated with grain yield (GY) in four environments and their BLUPs. Both RHL and RHD had positive correlation indicating the possibility of simultaneous selection of both phenotypes during wheat breeding. The expression pattern of TaRSL4 gene involved in regulation of root hair length was determined in all 24 wheat cultivars based on RNA-seq data, which indicated the differentially higher expression of the A- and D- homeologues of the gene in roots, while B-homeologue was consistently expressed in both leaf and roots. The results were validated by qRT-PCR and the expression of TaRSL4 was consistently high in rainfed cultivars such as Chakwal-50, Rawal-87, and Margallah-99. Overall, the new phenotyping method for RHL and RHD along with correlations with morphological and physiological traits in spring wheat cultivars improved our understanding for selection of these phenotypes in wheat breeding.

A major quantitative trait locus for wheat total root length associated with precipitation distribution

Optimizing root system architecture (RSA) allows crops to better capture water and nutrients and adapt to harsh environment. Parental reproductive environment (PRE) has been reported to significantly affect growth and development throughout the life cycle of the next generation. In this study, 10 RSA-related traits were evaluated in seedling stage from five independent hydroponic tests using seeds harvested from five different PREs. Based on the Wheat55K SNP array-based genetic map, quantitative trait loci (QTL) for these traits were detected in a recombinant inbred line population. Twenty-eight putative QTL for RSA-related traits were detected, covering thirteen chromosomal regions. A major QTL, QTrl.sicau-2SY-4D for total root length (TRL), which was likely independent of PREs, explained 15.81-38.48% of phenotypic variations and was located at 14.96-19.59 Mb on chromosome arm 4DS. Interestingly, it showed pleiotropic effects on TRL, root area, root volume, root forks, root dry weight, and shoot dry weight. The functional marker KASP-Rht-D1 for Rht-D1 was used to genotype 2SY population and remapping QTL for TRL showed that QTrl.sicau-2SY-4D was not linked to Rht-D1. The kompetitive allele-specific PCR (KASP) marker, KASP-AX-110527441 linked to this major QTL, was developed and used to successfully validate its effect in three different genetic populations. Further analysis suggested that the positive allele at QTrl.sicau-2SY-4D was mainly utilized in wheat breeding of northwest China where precipitation was significantly lower, indicating that wheat requires longer TRL to capture water and nutrients in arid or semi-arid regions due to deficient precipitation. Additionally, four genes (TraesCS4D03G0059800, TraesCS4D03G0057800, TraesCS4D03G0064000, and TraesCS4D03G0064400) possibly related to root development were predicted in physical interval of QTrl.sicau-2SY-4D. Taken together, these results enrich our understanding on the genetic basis of RSA and provide a potentially valuable TRL QTL for wheat breeding.

Band Phosphorus and Sulfur Fertilization as Drivers of Efficient Management of Nitrogen of Maize (Zea mays L.)

Increasing the efficiency of nitrogen use (NUE) from mineral fertilizers is one of the most important priorities of modern agriculture. The objectives of the present study were to assess the role of different nitrogen (N), phosphorus (P) and sulfur (S) rates on maize grain yield (GY), crop residue biomass, NUE indices, N concentration in plants during the growing season, N management indices and to select the most suitable set of NUE indicators. The following factors were tested: band application of di-ammonium phosphate and ammonium sulphate mixture (NPS fertilizer at rates 0, 8.7, 17.4, 26.2 kg ha⁻¹ of P) and different total N rates (0, 60, 120, 180 kg ha⁻¹ of N). In each year of the study, a clear trend of increased GY after NP(S) band application was observed. A particularly positive influence of that factor was confirmed at the lowest level of N fertilization. On average, the highest GY values were obtained for N2P3 and N3P1 treatments. The total N uptake and NUE indices also increased after the band application. In addition, a trend of improved N remobilization efficiency and the N contribution of remobilized N to grain as a result of band application of NP(S) was observed. Among various NUE indices, internal N utilization efficiency (IE) exhibited the strongest, yet negative, correlation with GY, whereas IE was a function of the N harvest index.

Genome Editing Targets for Improving Nutrient Use Efficiency and Nutrient Stress Adaptation

In recent years, the development of RNA-guided genome editing (CRISPR-Cas9 technology) has revolutionized plant genome editing. Under nutrient deficiency conditions, different transcription factors and regulatory gene networks work together to maintain nutrient homeostasis. Improvement in the use efficiency of nitrogen (N), phosphorus (P) and potassium (K) is essential to ensure sustainable yield with enhanced quality and tolerance to stresses. This review outlines potential targets suitable for genome editing for understanding and improving nutrient use (NtUE) efficiency and nutrient stress tolerance. The different genome editing strategies for employing crucial negative and positive regulators are also described. Negative regulators of nutrient signalling are the potential targets for genome editing, that may improve nutrient uptake and stress signalling under resource-poor conditions. The promoter engineering by CRISPR/dead (d) Cas9 (dCas9) cytosine and adenine base editing and prime editing is a successful strategy to generate precise changes. CRISPR/dCas9 system also offers the added advantage of exploiting transcriptional activators/repressors for overexpression of genes of interest in a targeted manner. CRISPR activation (CRISPRa) and CRISPR interference (CRISPRi) are variants of CRISPR in which a dCas9 dependent transcription activation or interference is achieved. dCas9-SunTag system can be employed to engineer targeted gene activation and DNA methylation in plants. The development of nutrient use efficient plants through CRISPR-Cas technology will enhance the pace of genetic improvement for nutrient stress tolerance of crops and improve the sustainability of agriculture.

OsCKX2 regulates phosphate deficiency tolerance by modulating cytokinin in rice

Cytokinin oxidase/dehydrogenases (CKXs) are key enzymes that degrade cytokinins (CTKs) and play an essential role in plant growth and development. The present study analyzed the phenotypic and physiological characteristics of OsCKX2 overexpressing (OE) and knockout (KO) rice plants after exposure to phosphate (Pi) deficiency and the transcriptome and metabolome to investigate the function of OsCKX2 in response to Pi deficiency. OsCKX2 KO plants demonstrated higher endogenous CTK levels than wild-type (WT) under Pi deficiency. Further analysis indicated more robust tolerance of OsCKX2 KO plants to Pi deficiency, which exhibited higher phosphorus concentration, larger shoot biomass, and lesser leaf yellowing under Pi deficiency; whereas the opposite was observed for OsCKX2 OE plants. Transcriptome and metabolome analyses revealed that overexpression of OsCKX2 downregulated the transcriptional levels of genes related to Pi transporters, membrane lipid metabolism, and glycolysis, and reduced the consumption of metabolites in membrane lipid metabolism and glycolysis. On the contrary, knockout of OsCKX2 upregulated the expression of Pi transporters, and increased the consumption of metabolites in membrane lipid metabolism and glycolysis. These results indicated that OsCKX2 impacted Pi uptake, recycling, and plant growth via Pi transporters, phospholipid hydrolysis, and glycolysis under Pi deficiency. Overall, OsCKX2 negatively regulated Pi deficiency tolerance by modulating CTKs in rice.