Overexpression of oilseed rape trehalose-6-phosphate synthesis gene BnaC02.TPS8 confers sensitivity to low nitrogen and high sucrose-induced anthocyanin accumulation in Arabidopsis.

MAIN CONCLUSION: Overexpression of BnaC02.TPS8 increased low N and high sucrose-induced anthocyanin accumulation. Anthocyanin plays a crucial role in safeguarding photosynthetic tissues against high light, UV radiation, and oxidative stress. Their accumulation is triggered by low nitrogen (N) stress and elevated sucrose levels in Arabidopsis. Trehalose-6-phosphate (T6P) serves as a pivotal signaling molecule, sensing sucrose availability, and carbon (C) metabolism. However, the mechanisms governing the regulation of T6P synthase (TPS) genes responsible for anthocyanin accumulation under conditions of low N and high sucrose remain elusive. In a previous study, we demonstrated the positive impact of a cytoplasm-localized class II TPS protein 'BnaC02.TPS8' on photosynthesis and seed yield improvement in Brassica napus. The present research delves into the biological role of BnaC02.TPS8 in response to low N and high sucrose. Ectopic overexpression of BnaC02.TPS8 in Arabidopsis seedlings resulted in elevated shoot T6P levels under N-sufficient conditions, as well as an increased carbon-to-nitrogen (C/N) ratio, sucrose accumulation, and starch storage under low N conditions. Overexpression of BnaC02.TPS8 in Arabidopsis heightened sensitivity to low N stress and high sucrose levels, accompanied by increased anthocyanin accumulation and upregulation of genes involved in flavonoid biosynthesis and regulation. Metabolic profiling revealed increased levels of intermediate products of carbon metabolism, as well as anthocyanin and flavonoid derivatives in BnaC02.TPS8-overexpressing Arabidopsis plants under low N conditions. Furthermore, yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) analyses demonstrated that BnaC02.TPS8 interacts with both BnaC08.TPS9 and BnaA01.TPS10. These findings contribute to our understanding of how TPS8-mediated anthocyanin accumulation is modulated under low N and high sucrose conditions.

Rice transcription factor OsWRKY37 positively regulates flowering time and grain fertility under copper deficiency.

Efficient uptake, translocation, and distribution of Cu to rice (Oryza sativa) spikelets is crucial for flowering and yield production. However, the regulatory factors involved in this process remain unidentified. In this study, we isolated a WRKY transcription factor gene induced by Cu deficiency, OsWRKY37, and characterized its regulatory role in Cu uptake and transport in rice. OsWRKY37 was highly expressed in rice roots, nodes, leaf vascular bundles, and anthers. Overexpression of OsWRKY37 promoted the uptake and root-to-shoot translocation of Cu in rice under -Cu condition but not under +Cu condition. While mutation of OsWRKY37 significantly decreased Cu concentrations in the stamen, the root-to-shoot translocation and distribution ratio in brown rice affected pollen development, delayed flowering time, decreased fertility, and reduced grain yield under -Cu condition. yeast one-hybrid, transient co-expression and EMSAs, together with in situ RT-PCR and RT-qPCR analysis, showed that OsWRKY37 could directly bind to the upstream promoter region of OsCOPT6 (copper transporter) and OsYSL16 (yellow stripe-like protein) and positively activate their expression levels. Analyses of oscopt6 mutants further validated its important role in Cu uptake in rice. Our study demonstrated that OsWRKY37 acts as a positive regulator involved in the uptake, root-to-shoot translocation, and distribution of Cu through activating the expression of OsCOPT6 and OsYSL16, which is important for pollen development, flowering, fertility, and grain yield in rice under Cu deficient conditions. Our results provide a genetic strategy for improving rice yield under Cu deficient condition.

Trade-offs between root-secreted acid phosphatase and root morphology traits, and their contribution to phosphorus acquisition in Brassica napus.

Oilseed rape (Brassica napus) is one of the most important oil crops in the world and shows sensitivity to low phosphorus (P) availability. In many soils, organic P (Po) is the main component of the soil P pool. Po must be mineralised to Pi through phosphatases, and then taken up by plants. However, the relationship between root-secreted acid phosphatases (APase) and root morphology traits, two important P-acquisition strategies in response to P deficiency, is unclear among B. napus genotypes. This study aimed to understand their relationship and how they affect P acquisition, which is crucial for the sustainable utilisation of agricultural P resources. This study showed significant genotypic variations in root-secreted APase activity per unit root fresh weight (SAP) and total root-secreted APase activity per plant (total SAP) among 350 B. napus genotypes. Seed yield was positively correlated with total SAP but not significantly correlated with SAP. Six root traits of 18 B. napus genotypes with contrasting root biomass were compared under normal Pi, low Pi and Po. Genotypes with longer total root length (TRL) reduced SAP, but those with shorter TRL increased SAP under P deficiency. Additionally, TRL was important in P-acquisition under three P treatments, and total SAP was also important in P-acquisition under Po treatment. In conclusion, trade-offs existed between the two P-acquisition strategies among B. napus genotypes under P-deficient conditions. Total SAP was an important root trait under Po conditions. These results might help to breed B. napus with greater P-acquisition ability under low P availability conditions.

Identification and function characterization of BnaBOR4 genes reveal their potential for Brassica napus cultivation under high boron stress.

Boron (B) is essential for plant growth, but toxic in excess. In several countries, soil toxic B levels are always a severe agricultural problem in arid and semi-arid regions. Phytoremediation of excess B containing soil is still in its infancy, while high B tolerant plants with elevated protein abundance of B efflux transporter were successfully established or explored. Brassica napus (B. napus) is one of the most important oil crops. However, B efflux transporters underlying excess B tolerance in B. napus remain unknown. Here, we reported that in Brassicaceae species, B. napus had four homologous genes of Arabidopsis AtBOR4 , which were renamed BnaBOR4.1, BnaBOR4.2, BnaBOR4.3 and BnaBOR4.4. BnaBOR4.1, BnaBOR4.2 and BnaBOR4.3 showed constitutive expression and BnaBOR4.4 appeared to be a pseudogene. BnaBOR4.2 and BnaBOR4.3 were expressed in inner cell layers and BnaBOR4.1 in the outer cell layer in root tip, and all were expressed in vascular tissue in the mature zone. B efflux activity assays in yeast demonstrated that BnaBOR4.1, BnaBOR4.2 and AtBOR4 but not BnaBOR4.3 had comparable levels of B transport activity. Structure-functional analysis between BnaBOR4.3 and BnaBOR4.2 demonstrated that amino acid residue substitution at position 297 (Ala vs Pro) and 427 (Met vs Leu) is critical for the B transport activity. Mutant BnaBOR4.3M427L partially restored the B efflux activity, and both mutants BnaBOR4.3A297P and BnaBOR4.3A297P&M427L fully restored B efflux activity, indicating that the Pro297 residue is critical for their function. Further validation of BnaBOR4 was accomplished by growing transgenic Arabidopsis plants under high B conditions. Taken together, our study identified two functional B efflux genes BnaBOR4.1 and BnaBOR4.2 in B. napus, and a key amino acid residue proline 297 associated with B efflux activity. This study highlights the potential of BanBOR4 genes for B. napus cultivation under high B stress.

Trehalose-6-phosphate synthase 8 increases photosynthesis and seed yield in Brassica napus.

Trehalose-6-phosphate (T6P) functions as a vital proxy for assessing carbohydrate status in plants. While class II T6P synthases (TPS) do not exhibit TPS activity, they are believed to play pivotal regulatory roles in trehalose metabolism. However, their precise functions in carbon metabolism and crop yield have remained largely unknown. Here, BnaC02.TPS8, a class II TPS gene, is shown to be specifically expressed in mature leaves and the developing pod walls of Brassica napus. Overexpression of BnaC02.TPS8 increased photosynthesis and the accumulation of sugars, starch, and biomass compared to wild type. Metabolomic analysis of BnaC02.TPS8 overexpressing lines and CRISPR/Cas9 mutants indicated that BnaC02.TPS8 enhanced the partitioning of photoassimilate into starch and sucrose, as opposed to glycolytic intermediates and organic acids, which might be associated with TPS activity. Furthermore, the overexpression of BnaC02.TPS8 not only increased seed yield but also enhanced seed oil accumulation and improved the oil fatty acid composition in B. napus under both high nitrogen (N) and low N conditions in the field. These results highlight the role of class II TPS in impacting photosynthesis and seed yield of B. napus, and BnaC02.TPS8 emerges as a promising target for improving B. napus seed yield.

Optimal phosphorus management strategies to enhance crop productivity and soil phosphorus fertility in rapeseed-rice rotation.

Optimal phosphorus (P) managements can improve the crop yield without reducing soil P supply capacity over the long term. In this study, the rapeseed-rice rotation experiments were conducted to evaluate the effect of five optimal P fertilizer managements, including the addition of RA (rooting agents), PSB (phosphate solubilizing bacteria), CMP (calcium and magnesium phosphate fertilizer), DP1 (starter P) and DP2 (foliar fertilizer) with the reduction of 40% (in the 1st rapeseed season) and 75% (in the 2nd rapeseed season) P fertilizers of farmers' fertilizer practice (FFP) on crop productivity and soil P fertility in low and high P fertility soils. Seed yield, P partial factor productivity, and P recovery efficiency of both cultivars, Shengguang168 (SG168) and Zhongshuang 11 (ZS11), were significantly improved under optimal P managements, and the increase of them in low P fertility soil was more than that in high P fertility soil. Total P surplus was lower under optimal P managements than under FFP in both P fertility soils. The increasing amount of crop yields under optimal P managements for both cultivars was equivalent to that of 16.0-38.3 kg P2O5 hm-2 of P fertilizer application, and the order of the optimal P managements was as follows: RA > PSB > CMP > DP1 > DP2. In addition, the grain yield of rotated rice cultivar Longliangyou1212 (LLY1212) without P supply was not reduced in both fertility soils. Compared with low P fertility soil, yields of SG168, ZS11 and LLY1212 in high P fertility soil increased by 28.1%-71.7%, 28.3%-78.9% and 26.2%-47.2% at the same treatment, respectively. In summary, optimal P managements in the rapeseed season could stabilize the crop yield, promote P use efficiency and the capacity of soil P supply in the rapeseed-rice rotation, especially in low P fertility soil.

Integrating genome-wide association studies with selective sweep reveals genetic loci associated with tolerance to low phosphate availability in Brassica napus.

Oilseed rape (Brassica napus L.; B. napus) is an important oil crop worldwide. However, the genetic mechanisms of B. napus adaptations to low phosphate (P) stress are largely unknown. In this study, a genome-wide association study (GWAS) identified 68 SNPs significantly associated with seed yield (SY) under low P (LP) availability, and 7 SNPs significantly associated with phosphorus efficiency coefficient (PEC) in two trials. Among these SNPs, two, chrC07__39807169 and chrC09__14194798, were co-detected in two trials, and BnaC07.ARF9 and BnaC09.PHT1;2 were identified as candidate genes of them, respectively, by combining GWAS with quantitative reverse-transcription PCR (qRT-PCR). There were significant differences in the gene expression level of BnaC07.ARF9 and BnaC09.PHT1;2 between P-efficient and -inefficiency varieties at LP. SY_LP had a significant positive correlation with the gene expression level of both BnaC07.ARF9 and BnaC09.PHT1;2. BnaC07.ARF9 and BnaA01.PHR1 could directly bind the promoters of BnaA01.PHR1 and BnaC09.PHT1;2, respectively. Selective sweep analysis was conducted between ancient and derived B. napus, and detected 1280 putative selective signals. Within the selected region, a large number of genes related to P uptake, transport, and utilization were detected, such as purple acid phosphatase (PAP) family genes and phosphate transporter (PHT) family genes. These findings provide novel insights into the molecular targets for breeding P efficiency varieties in B. napus. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-023-01399-9.

Analysis of bacterial community structure of Fuzhuan tea with different processing techniques.

The composition and diversity of microbial communities are of considerable significance to the quality development of Camellia sinensis (Fuzhuan tea). In this study, we examined differences in the bacterial community structures of loose, lightly-pressed, hand-made, and machine-pressed Fuzhuan teas and raw dark tea. We observed notable differences in the bacterial communities of the five groups, where there were only 51 consensus sequences. ASV/OTU Venn diagram, Chao1, Ace, Simpson indices, and dilution curve analyses consistently revealed that machine-pressed tea exhibited the highest bacterial diversity. Taxonomically, Actinobacteria, Firmicutes, Proteobacteria, and Cyanobacteria were the dominant bacterial phyla in each group, whereas Corynebacterium, Methylobacterium, and Bifidobacterium were the dominant genera. Our findings revealed significant differences in the bacterial community structures of different Fuzhuan tea products derived from the same raw material, with bacterial diversity rising with increased product compaction.

Stabilization and Reinforcement Effect of Fibers on a Bitumen Binder.

This study investigated fibers' stabilization and reinforcement effect on a bitumen binder. The fibers' microstructures were primarily observed using scanning electron microscopy, and laboratory tests, including the oven heating and mesh-basket draindown, were designed and carried out on three different fiber-bitumen binders (lignin, mineral, and carbon fiber) in this paper to evaluate the bitumen adsorption and thermal stability, respectively. Then, the cone sink experiment was performed to check the rheological properties of these fiber-bitumen binders. These results reveal that the stabilization and reinforcement effect increases with the fiber content increasing to the optimal value. The optimal fiber content depends on the performance of the fiber-bitumen binder, and the value found in this paper is 0.4 wt %. The results indicate that the fiber enhances the toughness of the bitumen effectively via its spatial framework, adhesion, and stabilization of the fiber-bitumen binder. The rheological properties and rutting resistance were tested by a dynamic shear rheometer, and the results suggested that the fiber could effectively enhance the flow resistance and the rutting resistance of the fiber-bitumen binder.

Effects of Fiber Type on the Mechanical Properties of the Open-Graded Friction Course Mixture.

The open-graded friction courses (OGFCs) have a large number of interconnected voids, which may cause serious water damage to the pavement. Hence, the road performance needs to be investigated. In this study, the mechanical properties of OGFCs containing two different fibers (lignin and mineral fiber) were investigated. Based on the procedure proposed by the Chinese specification JTG F40-2004, OGFCs were designed with the asphalt content between 4.1 and 4.7 wt % to find the optimal asphalt content (OAC). The mesh-basket draindown test was used to check the fiber's stabilization and absorption of bitumen. OGFCs containing the lignin/mineral fiber with OAC would be preferred in terms of the bulk specific gravity. These results indicate that the fiber can bring higher air voids to the OGFCs, and the different specific gravities of fibers may primarily account for the result. Both the lignin and mineral fibers can bring much more asphalts padded in the pores of mineral aggregates and subsequently larger OAC in OGFCs due to their higher asphalt absorption. Performance experiments were carried out to check the dynamic stability and moisture susceptibility of OGFCs containing the lignin/mineral fiber. The study suggests that the lignin and mineral fiber can be used to adjust the internal environment of OGFCs, enhancing the moisture damage resistance and improving the rutting resistance of OGFCs at high temperatures.

Synergistic Interaction between Copper and Nitrogen-Uptake, Translocation, and Distribution in Rice Plant.

Interactions among nutrients have been widely recognized in plants and play important roles in crop growth and yield formation. However, the interplay of Cu and N in rice plants is not yet clear. In this study, rice plants were grown with different combinations of Cu and N supply. The effects of Cu-N interaction on the growth, yield production, Cu and N transport, and gene expression levels were analyzed. The results showed that the effect of N supply on rice growth and yield formation was more pronounced than that of Cu supply. The Cu supply significantly improved the uptake of N (by 9.52-30.64%), while the N supply significantly promoted the root-to-shoot translocation of Cu (by 27.28-38.45%) and distributed more Cu (1.85-19.16%) into the shoots and leaves. The results of qRT-PCR showed that +Cu significantly up-regulated the expression levels of both NO3- and NH4+ transporter genes OsNRTs and OsAMTs, including OsNRT1.1B, OsNRT2.1, OsNRT2.3a, OsNRT2.4, OsAMT1.2, OsAMT1.3, and OsAMT3.1. Meanwhile, +N significantly up-regulated the expression levels of Cu transporter genes OsHMA5 and OsYSL16. In addition, the supply of Cu up-regulated the expression levels of OsGS1;2, OsGS2, and OsNADH-GOGAT to 12.61-, 6.48-, and 6.05-fold, respectively. In conclusion, our study demonstrates a synergistic effect between Cu and N in rice plants. It is expected that our results would be helpful to optimize the application of N and Cu fertilizers in agriculture.

High Levels of Zinc Affect Nitrogen and Phosphorus Transformation in Rice Rhizosphere Soil by Modifying Microbial Communities.

Due to global industrialization in recent decades, large areas have been threatened by heavy metal contamination. Research about the impact of excessive Zn on N and P transformation in farmland has received little attention, and its mechanism is still not completely known. In this study, we planted rice in soils with toxic levels of Zn, and analyzed the plant growth and nutrient uptake, the N and P transformation, enzyme activities and microbial communities in rhizosphere soil to reveal the underlying mechanism. Results showed high levels of Zn severely repressed the plant growth and uptake of N and P, but improved the N availability and promoted the conversion of organic P into inorganic forms in rice rhizosphere soil. Moreover, high levels of Zn significantly elevated the activities of hydrolases including urease, protease, acid phosphatase, sucrase and cellulose, and dehydrogenase, as well as the abundances of Flavisolibacter, Sphingomonas, Gemmatirosa, and subgroup_6, which contributed to the mineralization of organic matter in soil. Additionally, toxic level of Zn repressed the nitrifying process by decreasing the abundance of nitrosifying bacteria Ellin6067 and promoted denitrification by increasing the abundance of Noviherbaspirillum, which resulted in decreased NO3- concentration in rice rhizosphere soil under VHZn condition.

Identification of vacuolar phosphate influx transporters in Brassica napus.

Recent progress has shown that vacuolar Pi transporters (VPTs) are important for cellular Pi homoeostasis in Arabidopsis thaliana and Oryza sativa under fluctuating external Pi supply, but the identity and involvement of VPTs in cellular Pi homoeostasis in Brassica napus is poorly understood. Here, we identified two vacuolar Pi influx transporters B. napus, BnA09PHT5;1b and BnCnPHT5;1b, and uncovered their necessity for cellular Pi homoeostasis through functional analysis. Both Brassica proteins are homologs of Arabidopsis AtPHT5;1 with a similar sequence, structure, tonoplast localization, and VPT activity. Brassica pht5;1b double mutants had smaller shoots and larger shoot cellular Pi concentrations than wild-type B. napus, which contrasts with a previous study of the Arabidopsis pht5;1 mutant, suggesting that PHT5;1-VPTs play different roles in cellular Pi homoeostasis in seedlings of B. napus and A. thaliana. Disruption of BnPHT5;1b genes also caused Pi toxicity in floral organs, reduced seed yield and impacted seed traits, consistent with the proposed role of AtPHT5;1 in floral Pi homoeostasis in Arabidopsis. Taken together, our studies identified two vacuolar Pi influx transporters in B. napus and revealed the distinct and conserved roles of BnPHT5;1bs in cellular Pi homoeostasis in this plant species.

Zinc application promotes nitrogen transformation in rice rhizosphere soil by modifying microbial communities and gene expression levels.

Application of Zn fertilizers to agricultural field is a simple and effective way for farmers to manage Zn deficient stress in soils to avoid yield lose. Although a synergistic effect of Zn on N transformation in soil has been reported, the mechanism is not fully understood yet. In this study, we planted rice in soils with different combinations of Zn and N supply, and analyzed the plant growth and N uptake, the N transformation, microbial communities, enzyme activities and gene expression levels in rhizosphere soil to reveal the underlying mechanism. Results showed that Zn application promoted the rice growth and N uptake, increased the soil alkali-hydrolyzed N and NH4+, but decreased NO3- and inhibited NH3 volatilization from the rhizosphere soil under optimal N condition. Zn supply significantly increased the relative abundances of Sphingomonas, Gaiella, subgroup_6, and Gemmatimonas, but decreased nitrosifying bacteria Ellin6067; while increased saprophytic fungi Schizothecium and Mortierella, but decreased pathogenic fungi Gaeumannomyces, Acremonium, Curvularia, and Fusarium in the rhizosphere soil under optimal N condition. Meanwhile, Zn application elevated the activities of protease, cellulase and dehydrogenase, and up-regulated the expression levels of napA, nirS, cnorB, and qnorB genes involved in the denitrification process in rice rhizosphere soil under optimal N condition. These results indicated Zn application could facilitate the soil N transformation and improved its availability by modifying both bacterial and fungal communities, and altering the soil enzyme activities and functional gene expression levels, ultimately promoted the N uptake and biomass of rice plant. However, this synergistic effect of Zn on rice growth, N uptake and soil N transformation strongly depended on the external N conditions, as no significant changes were observed under high N condition. Our results indicated that Zn co-fertilized with appropriate application of N is a useful strategy to improve the N bioavailability in rice rhizosphere soil and enhance the N uptake in rice plant.

Effect of Fibers on the Performance of a Porous Friction Course.

In this paper, the preparation of a porous friction course (PFC) with styrene-butadiene-styrene (SBS)-modified asphalt and fibers instead of a high-viscosity-modified asphalt was investigated. The aggregate gradation B was chosen to prepare the PFC, and the optimal asphalt content in the PFC containing lignin or basalt fibers was determined to be 4.5% by the Cantabro abrasion experiment and Schellenberg draindown experiment. The freeze-thaw split experiment and immersed Marshall experiment indicated that with the addition of the fiber, the residual stability increased by 7.6 and 2.4% for the PFC with the lignin and basalt fibers, respectively, indicating that fibers can enhance the moisture damage resistance of the PFC. Furthermore, the dynamic stability increased by 17.9 and 6.0% for the PFC with the lignin and basalt fibers, respectively, indicating that fibers can significantly enhance the rutting resistance of the PFC at high temperatures. These results prove that the PFC prepared by SBS-modified asphalt and lignin/basalt fibers reaches the standard of pavement performance.

Characterization of the PHOSPHATE RESPONSE 2-dependent and -independent Pi-starvation response secretome in rice.

Many proteins secreted from plant cells into the surrounding extracellular space help maintain cell structure and regulate stress responses in the external environment. In this study, under Pi-replete and depleted conditions, 652 high-confidence secreted proteins were quantified from wild-type (WT) and PHOSPHATE RESPONSE 2 (OsPHR2)-overexpressing suspension-cultured cells (SCCs). These proteins were functionally grouped as phosphatases, signal transduction proteins, pathogen-related (PR) proteins, cell wall-remodeling proteins, and reactive oxygen species (ROS) metabolism proteins. Although PHOSPHATE RESPONSE (PHR) transcription factors regulate two-thirds of Pi-responsive genes at the transcriptional level, only 30.6% of the Pi-starvation-regulated secreted proteins showed significant changes in OsPHR2-overexpressing SCCs. The OsPHR2-dependent systemic Pi signaling pathway mainly regulates phosphatases and PR proteins, which are involved in the utilization of organophosphate, pathogen resistance, and colonization by rhizosphere microorganisms. The OsPHR2-independent local Pi signaling pathway, on the other hand, largely regulated ROS metabolism proteins, cell wall-remodeling proteins, and signal transduction proteins, which are involved in modifying cell wall structure and root architecture. The functions of differentially expressed secreted proteins between WT and OsPHR2-overexpressing plants under Pi-sufficient and Pi-deficient conditions were further confirmed by analysis of the acid phosphatase activity, ROS content, and cell wall composition.

Local and systemic responses conferring acclimation of Brassica napus roots to low phosphorus conditions.

Due to the non-uniform distribution of inorganic phosphate (Pi) in the soil, plants modify their root architecture to improve acquisition of this nutrient. In this study, a split-root system was employed to assess the nature of local and systemic signals that modulate root architecture of Brassica napus grown with non-uniform Pi availability. Lateral root (LR) growth was regulated systemically by non-uniform Pi distribution, by increasing the second-order LR (2°LR) density in compartments with high Pi supply but decreasing it in compartments with low Pi availability. Transcriptomic profiling identified groups of genes regulated, both locally and systemically, by Pi starvation. The number of systemically induced genes was greater than the number of genes locally induced, and included genes related to abscisic acid (ABA) and jasmonic acid (JA) signalling pathways, reactive oxygen species (ROS) metabolism, sucrose, and starch metabolism. Physiological studies confirmed the involvement of ABA, JA, sugars, and ROS in the systemic Pi starvation response. Our results reveal the mechanistic basis of local and systemic responses of B. napus to Pi starvation and provide new insights into the molecular and physiological basis of root plasticity.

Genetic Control of Seed Phytate Accumulation and the Development of Low-Phytate Crops: A Review and Perspective.

Breeding low phytic acid (lpa) crops is a strategy that has potential to both improve the nutritional quality of food and feed and contribute to the sustainability of agriculture. Here, we review the lipid-independent and -dependent pathways of phytate synthesis and their regulatory mechanisms in plants. We compare the genetic variation of the phytate concentration and distribution in seeds between dicot and monocot species as well as the associated temporal and spatial expression patterns of the genes involved in phytate synthesis and transport. Quantitative trait loci or significant single nucleotide polymorphisms for the seed phytate concentration have been identified in different plant species by linkage and association mapping, and some genes have been cloned from lpa mutants. We summarize the effects of various lpa mutations on important agronomic traits in crop plants and propose SULTR3;3 and SULTR3;4 as optimal target genes for lpa crop breeding.

Zinc and nitrogen synergistic act on root-to-shoot translocation and preferential distribution in rice.

Introduction: Multiple studies have shown strong relationships between different nutrients in plants, and the important role of N in Zn acquisition and translocation has been recognized. Objectives: The aim of this study was to estimate the effect of Zn on N uptake, translocation, and distribution in rice as well as the corresponding molecular mechanisms. We also aimed to evaluate the impact of N on the Zn content in rice grains which is closely related to the Zn nutrition in humans with rice-based diets. Methods: We conducted both field trials and hydroponic cultures of two rice cultivars to analyze the growth and yield, the uptake, translocation, and distribution of N and Zn, as well as the expression of N transport and assimilation genes, and the Zn transporter genes under different combined applications of N and Zn. Results: Zn supply promoted the root-to-shoot translocation (12-70% increasing) and distribution of N into the leaves (19-49% increasing) and brown rice (6-9% increasing) and increased the rice biomass (by 14-35%) and yield (by 13-63%). Zn supply induced the expression of OsNRTs and OsAMTs in both roots and shoots, but repressed the expression of OsNiR2, OsGS1;2, and OsFd-GOGAT in roots, whereas it activated the expression of OsNiR2, OsGS1;1, OsGS2, and OsFd-GOGAT in the shoots. Moreover, the enzyme activities of nitrite reductase, nitrate reductase, and glutamine synthetase increased and the free NO3- concentration decreased, but the soluble protein concentration increased significantly in the shoots after Zn supply. Synergistically, N significantly facilitated the root-to-shoot translocation (1.68-11.66 fold) and distribution of Zn into the leaves (1.68-6.37 fold) and brown rice (7-12% increasing) and upregulated the expression levels of Zn transporter genes in both the roots and shoots. Conclusions: We propose a working model of the cross-talk between Zn and N in rice plants, which will aid in the appropriate combined application of Zn and N fertilizers in the field to improve both N utilization in plants and Zn nutrition in humans with rice-based diets.

Rice ACID PHOSPHATASE 1 regulates Pi stress adaptation by maintaining intracellular Pi homeostasis.

The concentration and homeostasis of intracellular phosphate (Pi) are crucial for sustaining cell metabolism and growth. During short-term Pi starvation, intracellular Pi is maintained relatively constant at the expense of vacuolar Pi. After the vacuolar stored Pi is exhausted, the plant cells induce the synthesis of intracellular acid phosphatase (APase) to recycle Pi from expendable organic phosphate (Po). In this study, the expression, enzymatic activity and subcellular localization of ACID PHOSPHATASE 1 (OsACP1) were determined. OsACP1 expression is specifically induced in almost all cell types of leaves and roots under Pi stress conditions. OsACP1 encodes an acid phosphatase with broad Po substrates and localizes in the endoplasmic reticulum (ER) and Golgi apparatus (GA). The phylogenic analysis demonstrates that OsACP1 has a similar structure with human acid phosphatase PHOSPHO1. Overexpression or mutation of OsACP1 affected Po degradation and utilization, which further influenced plant growth and productivity under both Pi-sufficient and Pi-deficient conditions. Moreover, overexpression of OsACP1 significantly affected intracellular Pi homeostasis and Pi starvation signalling. We concluded that OsACP1 is an active acid phosphatase that regulates rice growth under Pi stress conditions by recycling Pi from Po in the ER and GA.