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Background Fulvic acid enhances plant growth and interacts synergistically with phosphate fertilizer to alleviate the agricultural production problem of low phosphorus fertilizer utilization efficiency. However, the underlying mechanism of its action remains poorly understood. In this study, we investigated the impact of fulvic acid application with varying concentrations (0, 40, 60, 80 and 120 mg/L) on rice performance in plants grown in a hydroponic system subjected to low phosphorus stress. The rice growth phenotypes, biomass, root morphology, phosphorus uptake, and the impact of fulvic acid on the rhizosphere environment of rice, were assessed. Results The findings showed that adding appropriate concentrations of exogenous fulvic acid could promote the growth performance of rice under low phosphorus stress. Particularly at T1 (40 mg/L) and T2 (60 mg/L) over the control effectively increased rice biomass by 25.42% and 24.56%, respectively. Fulvic acid treatments stimulated root morphogenesis, up-regulated phosphate transporter genes, and facilitated phosphorus absorption and accumulation. Especially T1 (20.52%), T2 (18.10%) and T3 (20.48%) treatments significantly increased phosphorus uptake in rice, thereby alleviating low phosphorus stress. Additionally, fulvic acid elevated organic acids concentration in roots and up-regulated plasma membrane H + -ATPase genes, promoting organic acids secretion. This metabolic alteration can also alleviate low phosphorus stress in rice. Conclusions The effect of exogenous fulvic acid on physiological indicators is concentration-dependent under low phosphorus stress, enhances rice performance and reduces reliance on phosphorus fertilizer. This provides new insights to shed light on the mechanism of alleviating low phosphorus stress in rice through fulvic acid application, an eco-friendly tool.

In plant and animal breeding, genomic prediction models are established to select new lines based on genomic data, without the need for laborious phenotyping. Prediction models can be trained on recent or historic phenotypic data and increasingly available genotypic data. This enables the adoption of genomic selection also in under-used legume crops such as common bean. Beans are an important staple food in the tropics and mainly grown by smallholders under limiting environmental conditions such as drought or low soil fertility. Therefore, genotype-by-environment interactions (G × E) are an important consideration when developing new bean varieties. However, G × E are often not considered in genomic prediction models nor are these models implemented in current bean breeding programs. Here we show the prediction abilities of four agronomic traits in common bean under various environmental stresses based on twelve field trials. The dataset includes 481 elite breeding lines characterized by 5,820 SNP markers. Prediction abilities over all twelve trials ranged between 0.6 and 0.8 for yield and days to maturity, respectively, predicting new lines into new seasons. In all four evaluated traits, the prediction abilities reached about 50-80% of the maximum accuracies given by phenotypic correlations and heritability. Predictions under drought and low phosphorus stress were up to 10 and 20% improved when G × E were included in the model, respectively. Our results demonstrate the potential of genomic selection to increase the genetic gain in common bean breeding. Prediction abilities improved when more phenotypic data was available and G × E could be accounted for. Furthermore, the developed models allowed us to predict genotypic performance under different environmental stresses. This will be a key factor in the development of common bean varieties adapted to future challenging conditions.

Background Wheat is one of the main grain crops in the world, and the tiller number is a key factor affecting the yield of wheat. Phosphorus is an essential element for tiller development in wheat. However, due to decreasing phosphorus content in soil, there has been increasing use of phosphorus fertilizer, while imposing risk of soil and water pollution. Hence, it is important to identify low phosphorus tolerance genes and utilize them for stress resistance breeding in wheat. Results We subjected the wheat variety Kenong 199 (KN199) to low phosphorus stress and observed a reduced tiller number. Using transcriptome analysis, we identified 1651 upregulated genes and 827 downregulated of genes after low phosphorus stress. The differentially expressed genes were found to be enriched in the enzyme activity regulation related to phosphorus, hormone signal transduction, and ion transmembrane transport. Furthermore, the transcription factor analysis revealed that TaWRKY74 s were important for low phosphorus tolerance. TaWRKY74 s have three alleles: TaWRKY74 -A, TaWRKY74 -B, and TaWRKY74 -D, and they all belong to the WRKY family with conserved WRKYGQK motifs. These proteins were found to be located in the nucleus, and they were expressed in axillary meristem, shoot apical meristem(SAM), young leaves, leaf primordium, and spikelet primordium. The evolutionary tree showed that TaWRKY74 s were closely related to OsWRKY74 s in rice. Moreover, TaWRKY74 s-RNAi transgenic plants displayed significantly fewer tillers compared to wild-type plants under normal conditions. Additionally, the tiller numebr of the RNAi transgenic plants was also significantly lower than that of the wild-type plants under low-phosphorus stress, and increased the decrease amplitude. This suggestd that TaWRKY74 s are related to phosphorus response and can affect the tiller number of wheat. Conclusions The results of this research showed that TaWRKY74 s were key genes in wheat response to low phosphorus stress, which might regulate wheat tiller number through abscisic acid (ABA) and auxin signal transduction pathways. This research lays the foundation for further investigating the mechanism of TaWRKY74 s in the low phosphorus environments and is significant for wheat stress resistance breeding.

Phosphate (P) deficiency severely limits the growth and production of plants. Adventitious root development plays an essential role in responding to low phosphorus stress for apple plants. However, the molecular mechanisms regulating adventitious root growth and development in response to low phosphorus stress have remained elusive. In this study, a mutation (C-T) in the coding region of the apple AUXIN/INDOLE-3-ACETIC ACID 27 (IAA27) gene was identified. MdIAA27T-overexpressing transgenic apple improved the tolerance to phosphorus deficiency, which grew longer and denser adventitious roots and presented higher phosphorous content than the control plants under low phosphorus conditions, while the overexpression of MdIAA27C displayed the opposite trend. Moreover, the heterologous overexpression of MdIAA27 in tobacco yielded the same results, supporting the aforementioned findings. In vitro and in vivo assays showed that MdIAA27 directly interacted with AUXIN RESPONSE FACTOR (ARF8), ARF26 and ARF27, which regulated Small Auxin-Up RNA 76 (MdSAUR76) and lateral organ boundaries domain 16 (MdLBD16) transcription. The mutation in IAA27 resulted in altered interaction modes, which in turn promoted the release of positive ARFs to upregulate SAUR76 and LBD16 expression in low phosphorus conditions. Altogether, our studies provide insights into how the allelic variation of IAA27 affects adventitious root development in response to low phosphorus stress.

Background Phosphorus (P) deficiency is a major constraint on soybean ( Glycine max (L.) Merr.) productivity, a key global source of edible oil and protein. Enhancing low-phosphorus (LP) tolerance through improved phosphorus-use efficiency is therefore crucial for sustainable soybean cultivation. Results This study elucidates the molecular mechanism by which GmAux/IAA16 regulates root morphogenesis and coordinates LP responses. Bioinformatics analysis showed that GmAux/IAA16 shares 92.43% sequence identity with its wild soybean ( Glycine soja ) ortholog, and subcellular localization confirmed its nuclear-specific accumulation. Stable overexpression of GmAux/IAA16 in tobacco via Agrobacterium -mediated transformation enhanced root development and maintained physiological stability under phosphate deprivation. Under LP stress, transgenic plants exhibited significant increases in key root enzyme activities: increased by 27.75% for indole‑3‑acetic acid oxidase (IAAO), 11.99% for superoxide dismutase (SOD), 42.59% for acid phosphatase (ACP), and 123.55% for catalase (CAT), alongside elevated ATP levels, reduced malondialdehyde (MDA) accumulation, and increased proline (Pro) content. Furthermore, endogenous levels of indole-3-acetic acid (IAA), jasmonic acid (JA), and salicylic acid (SA) were significantly higher in both leaves and roots, indicating a coordinated hormonal response that facilitates LP adaptation. Transcriptome analysis revealed that GmAux/IAA16 overexpression substantially reshapes the transcriptional landscape of tobacco roots under phosphorus stress. Conclusion These findings demonstrate that GmAux/IAA16 positively regulates low-phosphorus tolerance, likely through cascading regulation of downstream phosphate-starvation response genes. This study provides novel insights into the role of the Aux/IAA gene family in soybean root development and phosphorus-use efficiency, and identifies GmAux/IAA16 as a promising genetic target for molecular breeding of phosphorus-efficient soybean cultivars.

Soybean is a high phosphorus (P) demand species that is sensitive to low-P stress. Although many quantitative trait loci (QTL) for P efficiency have been identified in soybean, but few of these have been cloned and agriculturally applied mainly due to various limitations on identifying suitable P efficiency candidate genes. Here, we combined QTL mapping, transcriptome profiling, and plant transformation to identify candidate genes underlying QTLs associated with low-P tolerance and response mechanisms to low-P stress in soybean. By performing QTL linkage mapping using 152 recombinant inbred lines (RILs) that were derived from a cross between a P-efficient variety, Nannong 94–156, and P-sensitive Bogao, we identified four major QTLs underlying P efficiency. Within these four QTL regions, 34/81 candidate genes in roots/leaves were identified using comparative transcriptome analysis between two transgressive RILs, low-P tolerant genotype B20 and sensitive B18. A total of 22 phosphatase family genes were up-regulated significantly under low-P condition in B20. Overexpression of an acid phosphatase candidate gene, GmACP2 , in soybean hairy roots increased P efficiency by 15.43–24.54 % compared with that in controls. Our results suggest that integrating QTL mapping and transcriptome profiling could be useful for rapidly identifying candidate genes underlying complex traits, and phosphatase-encoding genes, such as GmACP2 , play important roles involving in low-P stress tolerance in soybean.

Background and aimsAs the immobility of inorganic phosphorus (P) in soil, the acquisition of P by sessile plants is limited. γ-Aminobutyric acid (GABA) as a signal molecule and a metabolite can regulate plants to cope with various stresses. However, whether GABA could contribute to the adaption to low P stress in apple plants remains unclear.MethodsThis study combined different methods to detect the induction of auxin (IAA) synthesis by GABA to improve the tolerance of apple seedlings to low P stress (including growth and development analysis, reactive oxygen species (ROS) clearance effect, root structure analysis, multiple factorial analysis (MFA), gene expression analysis).ResultsExogenous GABA improved the growth of apple seedlings under low P conditions, reduced the ROS accumulation, and promoted the photosynthetic capacity. GABA contributed to the root system architecture and the development of mature area of root tips. In addition, the intervention of exogenous GABA interfered with the homeostasis of endogenous IAA and activated the expression of P starvation induction (PSI) gene, leading to the significantly increase of the P uptake in apple plants. Meanwhile, transgenic roots with overexpressing MdGAD1 enhanced the tolerance of apple seedlings to low P stress, improved the root development through regulating IAA signaling pathway, and significantly improved the P uptake of apple seedlings under low P conditions.ConclusionAll results suggested that GABA could contribute to the adaption of apple seedlings to low P conditions, by decreasing ROS accumulation, maintaining photosynthetic capacity, and increasing IAA level to improve the root development and the P absorption.

The regulatory effects of uneven phosphorus supplies on phosphorus transport in soybean roots are still unclear. To further analyze the regulatory effects of low-phosphorus stress on phosphorus transport in soybean roots and the effects of uneven phosphorus application on the physiological mechanism of phosphorus transport in soybean roots, dual-root soybean plants were prepared via grafting, and a sand culture experiment was performed. From the unfolded cotyledon stage to the initial flowering stage, one side of each dual-root soybean system was irrigated with a low-phosphorus-concentration solution (phosphorus-application [P+] side), and the other side was irrigated with a phosphorus-free nutrient solution (phosphorus-free [P-] side); this setup allowed the study of the effects of different phosphorus supply levels on the expression of genes and proteins and the accumulation of metabolites in soybean roots on the P- side to clarify the method through which phosphorus transport is regulated in soybean roots and to provide a theoretical basis for improving the use rate of phosphorus fertilizer. The results revealed that the unilateral supply of low-concentration phosphorus promoted the uptake of phosphorus by soybean roots and the transport of phosphorus from the P+ side to the P- side. Compared with the normal concentration of phosphorus supply and the phosphorus-free supply, the low concentration phosphorus supply affected the regulation of the metabolic pathways involved in starch and sucrose metabolism, glycolysis, fructose, and mannose metabolism, etc., thereby affecting soybean root phosphorus transport. The low-phosphorus stress inhibited fructose synthesis and sucrose synthase synthesis in the soybean roots and the synthesis of hexokinase (HK) and fructose kinase, which catalyzes the conversion of fructose to fructose-6-phosphate. Low-phosphorus stress promoted the synthesis of sucrose invertase and the conversion of sucrose into maltose by the activity of starch synthase (StS) and stimulated the synthesis of UDPG pyrophosphorylase (UGP) and phosphoglucose isomerase (GP1), which is involved in the conversion of UDP-glucose to glucose-6-phosphate. The phosphorus transport pathway of soybean roots was then affected, which promoted phosphorus allocation to UTP and glucose-6-phosphate. Additionally, low-phosphorus stress hastened glycolysis in the soybean roots and inhibited the synthesis of malic acid, thereby promoting the transport of phosphorus in the roots. In addition, low-phosphorus stress inhibited the synthesis of fructose, mannose, and mannose-1-phosphate and the synthesis of other enzymes involved in phosphorus transport as well as invertase, thereby inhibiting the transport and synthesis of several organic phosphorus-containing compounds.

This study aims to explore the low phosphorus (P) tolerance of saplings from different Gleditsia sinensis Lam. families. It also seeks to screen for Gleditsia sinensis families with strong low P tolerance and identify key indicators for evaluating their tolerance. This research provides a foundation for the breeding of superior families of Gleditsia sinensis and the study of mechanisms underlying low P tolerance. Using saplings from 30 Gleditsia sinensis families as the research subjects, a sand culture pot experiment was conducted. This study set up low P treatment (0.01 mmol L −1 ) and normal P treatment (1 mmol L −1 ). Twenty-five indicators including growth morphology, biomass, root morphology, and P content were measured. The low P tolerance coefficient was used as the basic data for assessing the low P tolerance of Gleditsia sinensis . The fuzzy comprehensive evaluation method was employed to comprehensively assess the low P tolerance types of Gleditsia sinensis a stepwise regression model was established to identify the key evaluation indicators for low P tolerance. The results indicate that low P stress reduced plant height, stem diameter, and biomass in most Gleditsia sinensis families, but increased the root morphological indicators, root-shoot ratio and PUE of various organs. Principal component analysis transformed the 25 indicators into 6 independent comprehensive indicators, with a cumulative contribution rate of 86.743%. The fuzzy comprehensive evaluation method calculated a comprehensive evaluation value (D value), enabling the screening of Gleditsia sinensis families into low P tolerant and low P sensitive types. Cluster analysis grouped the 30 Gleditsia sinensis families into 4 types. Among them, F13, F10, F9, F18, F15, and F28 were classified as low P tolerant types; F6, F23, F3, F17, F20, F2, F12, F11, F16, F8, F5, F27, F1, and F26 were categorized as intermediate types; F30, F7, F22, F4, F19, F29, F24, F14 and F25 were considered low P sensitive types, and F21 was classified as extremely low P sensitive types. The stepwise regression analysis identified the indicators stem diameter, total root volume, shoot dry weight, total root projection area, and leaf P content as the key factors for discriminating the low P tolerance of Gleditsia sinensis . The regression model is as follows: D=-0.005 + 0.323 stem diameter *+0.154 * total root volume + 0.196* shoot dry weight + 0.139* total root projection area − 0.112* leaf P content. In summary, low P stress inhibited the growth of Gleditsia sinensis saplings, but it increased the root morphological indicators, root-shoot ratio and PUE of various organs to cope with low P environments. The screening identified F13, F10, F9, F18, F15, and F28 as low P tolerant Gleditsia sinensis families. The evaluation indicators for low P tolerance in Gleditsia sinensis were identified as stem diameter, total root volume, shoot dry weight, total root projection area and leaf P content.

Phosphorus is one of the key limiting factors for maize growth and productivity, and low-phosphorus stress severely restricts crop yield and stability. Enhancing the ability of maize to grow under low-phosphorus stress and improving phosphorus use efficiency (PUE) are crucial for achieving high and stable yields. Phosphate transporter (PHT) family proteins play a crucial role in the absorption, transport, and utilization of phosphorus in plants. In this study, we systematically identified the PHT gene family in maize, followed by the phylogenetic, gene structure, and expression profiles. The results show that these genes are widely distributed across the 10 chromosomes of maize, forming multiple subfamilies, with the PHT1 subfamily having the largest number. Cis-regulatory element analysis revealed that these genes might play key roles in plant stress responses and hormone regulation. Transcriptome analysis under phosphorus-deficient and normal conditions demonstrated developmental stage- and tissue-specific expression patterns, identifying candidate genes, such as ZmPHT1-3, ZmPHT1-4, ZmPHT1-10, and ZmPHO1-H3, involved in phosphorus stress response. This study presents a comprehensive and systematic analysis of the PHT gene family in maize, providing key molecular resources for improving phosphorus use efficiency and breeding phosphorus-efficient maize varieties.