Native core microbiomes represent a unique opportunity to support soil health and enhance plant quality. However, these microbiomes are often neglected in the development of synthetic communities (SynComs) aimed at improving agricultural ecology. Herein, by low-carbon enrichment, combination, and functional analysis, two strains of Paracoccus communis capable of improving soil acidity and promoting crop growth were identified and utilized to construct a SynCom. A microbial agent was prepared using filter mud as a carrier, and its ameliorative effect on acidic soil was investigated. The SynComs exhibited significant in vitro secretion of alkali and indole-3-acetic acid (IAA), with pH and indole acid production values recorded at 8.3 and 35.53 mg/L, respectively. Pot experiments demonstrated that SynComs effectively colonized the rhizosphere, resulting in a rhizosphere soil pH increase from 4.73 to 5.50. Application of the microbial agent led to a substantial enrichment of C-related genes, with the cbbL gene increasing by 25-fold, alongside enhanced dehydrogenase activity. Genes associated with ammonium N production and P solubilization were activated. Furthermore, key microbial species that drive C, N, and P dynamics were significantly enriched. Genes involved in rhizosphere-regulated production of indole-3-acetic acid were notably upregulated. The fixation of carbon and nitrogen, solubilization of P, and production of IAA collectively promoted plant growth, alleviating the stress of acidic soil on plants. These findings underscore the potential of microbial tools for advancing sustainable agriculture in acidic and infertile soils.

Manganese ion (Mn(Ⅱ)) toxicity in acidic soils is a global agricultural and environmental issue that severely constrains crop productivity and soil ecosystem functioning. Systematic understanding of the effects of Mn(Ⅱ) stress on soil nitrogen (N) transformation processes and their underlying mechanisms remains limited. A short-term pot experiment using sugarcane (Saccharum officinaru250-wordm) was conducted to investigate the effects of varying Mn(Ⅱ) concentrations on sugarcane N uptake, soil N transformation processes, and the underlying microbial mechanisms. High Mn(Ⅱ) concentrations (≥ 900 mg·kg⁻¹) significantly inhibited N uptake in sugarcane, reducing plant N accumulation by approximately 50%. Elevated Mn(Ⅱ) levels stimulated soil urease activity but suppressed ammonia monooxygenase (AMO) activity and nitrification potential. Concurrently, the concentration of soil soluble organic nitrogen dropped from 88.46 to 20.78 mg kg⁻¹ , whereas ammonium nitrogen (NH₄⁺-N) rose from 3.29 to 14.50 mg kg⁻¹ . This divergence suggests that nitrification was suppressed, leading to the accumulation of NH₄⁺-N. The α-diversity index of the soil bacterial community exhibited a U-shaped response to increasing Mn(Ⅱ) concentrations, although its composition remained relatively stable. Ammonia-oxidizing archaea (AOA) showed greater OTU richness and diversity than the ammonia-oxidizing bacteria (AOB). AMO activity correlated negatively with Nitrososphaera abundance but positively with Nitrosospira abundance. With increasing Mn(Ⅱ), Nitrosospira declined progressively while the tolerant genus Nitrosovibrio became dominant, reflecting community shifts under Mn stress. High Mn(Ⅱ) levels thus reshaped the AOB community structure, suppressed nitrification, and reduced plant N uptake efficiency. These findings offer a theoretical basis for improving nitrogen management and ecological remediation in Mn-contaminated acidic farmlands.

Nicotinic acid (NIA) is known to function in heavy metal detoxification; however, the regulation and physiological significance of its endogenous secretion in metal tolerance remain unclear. In this study, NIA was identified as a predominant component of Mn-induced root exudates in sugarcane by combining high performance liquid chromatography and ultra-high-performance liquid chromatography-tandem mass spectrometry. Low-Mn-accumulating cultivars (ZZ1 and GT44) exhibited 1.59-3.08-fold higher NIA secretion rates than in high-Mn-accumulating cultivars (F175 and GT55) under Mn stress. NIA secretion rates increased significantly with increasing duration of Mn exposure (6-24 h) in ZZ1. High-resolution mass spectrometry analysis revealed the formation of NIA-Mn complex in NIA/MnCl2 solution. Exogenous NIA significantly mitigated Mn toxicity, reducing plant Mn uptake and tissue Mn content by more than 50 %. It concurrently restored root elongation by 50 %, and reversed Mn-induced leaf chlorosis, elevating leaf SPAD values by 72.9 %. Furthermore, NIA fully reversed Mn-induced malondialdehyde and Evans blue accumulation in roots. Fluorescence microanalysis demonstrated that NIA completely abolished the Mn-induced red fluorescence in propidium iodide-stained root tips. However, NIA did not alter the Mn distribution ratio between roots and shoots or between young leaves and shoots. These findings demonstrate that the Mn-induced secretion of NIA from roots facilitates Mn resistance in sugarcane by excluding Mn uptake through Mn chelation.

Manganese toxicity severely restricts the growth and yield of sugarcane in acidic soil. However, the molecular mechanism of the specific tolerance of different genotypes to manganese remains unclear. This study aims to identify and functionally characterize the ZIP manganese transporter genes in sugarcane, and to elucidate the differences in manganese regulatory mechanisms between the sensitive type GT32 (Saccharum hybrid cultivar) and the tolerant type ZZ1 (Saccharum hybrid cultivar). Through phylogenetic analysis, conserved motifs and cis-acting element analysis, as well as Ka/Ks analysis, a total of 24 ZIP genes were identified in three different sugarcane genotypes. Combined with hydroponic manganese stress treatments, quantitative reverse transcription PCR (qRT-PCR), ion concentration measurements and chlorophyll analysis, physiological and transcriptional differences between ZZ1 and GT32 were compared. Yeast complementation experiments verified the manganese transport ability of ScIRT1 and ScZIP3. Under manganese stress conditions, the results showed that the chlorophyll content of ZZ1 was 41.14% higher than that of GT32, and the manganese accumulation in roots and stems was lower. Significant differences were also observed in the transcriptional patterns of ZIP genes in roots and stems. The qRT-PCR results indicated tissue-specific differences: the transcription level of ScZIP7 in the roots of GT32 was 10 times higher, while ZZ1 maintained the high transcription level of ScZIP3 under manganese stress. The genotype-dependent expression patterns of ScIRT1, ScZIP3, ScZIP6, and ScZIP7 may contribute to the regulation of manganese uptake and intracellular distribution, thereby contributing to the enhanced manganese tolerance observed in ZZ1. These findings provide valuable insights into the molecular basis of manganese tolerance and highlight potential candidate genes for the genetic improvement in manganese-tolerant sugarcane varieties.

ABSTRACT Straw return is widely used to improve soil quality, but it remains unclear which return mode better supports persistent soil organic carbon stabilization under highly weathered conditions. Based on a field experiment with more than 15 years of continuous straw return in an acidic red soil, we compared no straw return (CK), straw mulching (SM) and straw crushing (SC) across the 0–40 cm soil profile. Aggregate fractionation was combined with measurements of soil organic carbon (SOC), reactive metal‐bound organic carbon (BOC), and oxalate‐ and pyrophosphate‐extractable iron, aluminium and manganese pools. Both straw return modes increased aggregate‐associated carbon, with SOC increasing from 3.29–6.97 g kg −1 under CK to 6.70–15.06 g kg −1 under SM and 13.07–20.18 g kg −1 under SC, and BOC increasing from 1.07–3.26 g kg −1 to 2.33–9.17 and 6.74–11.85 g kg −1 , respectively. SM mainly favoured SOC and BOC enrichment in microaggregates, suggesting a stronger role of aggregate turnover and physical occlusion. In contrast, SC increased SOC and BOC across a wider range of aggregate fractions, especially in 1–2 mm aggregates and microaggregates in the subsoil. Reactive metal pools also increased under straw return, with the largest responses under SC. Molar ratio patterns suggested that newly accumulated carbon was preferentially associated with oxalate‐extractable reactive metal pools, while pyrophosphate‐extractable pools retained further binding capacity. Overall, these results show that the choice of straw return mode matters for long‐term carbon storage in acidic red soil, with straw crushing providing a stronger basis for enhancing mineral protection and improving carbon sequestration in red soil croplands.

IntroductionSugarcane (Saccharum spp.) is an economically important crop cultivated primarily for sugar and bioethanol production. In southern China, sugarcane grown in acidic soils often exhibits severe leaf chlorosis owing to excessive soil manganese (Mn) levels. However, the mechanisms by which Mn toxicity disrupts soil nitrogen (N) cycling, particularly the roles of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in regulating nitrification and N availability in sugarcane, remain unexplored.MethodsTo address this gap, we conducted laboratory soil incubation experiments and greenhouse pot trials using four treatments consisting of combinations of two N levels (N1:0.14 g·kg-1; N2:0.28 g·kg-1) and two Mn levels (−Mn: 0 mg·kg-1; +Mn: 328 mg·kg-1, simulated using anhydrous Mn sulfate), along with a blank control (CK). Key measurements included rhizosphere soil physicochemical properties, AOB/AOA community structure, nitrification potential, and sugarcane N uptake efficiency.ResultsResults showed that Mn toxicity significantly reduced soil pH and nitrification potential by 75.9–78.0% compared to non-Mn treatments, and AOB amoA gene abundance by 44.9–46.5%, while altering AOB/AOA community composition. Redundancy analysis (RDA) identified soil organic carbon, total nitrogen, and ammonium nitrogen as the primary drivers of AOB community shifts, whereas exchangeable Mn, ammonium nitrogen, and pH dominated AOA community changes. Correlation analysis confirmed that nitrification potential and AOB amoA abundance were strongly positively linked to sugarcane N accumulation and uptake efficiency, which decreased by 47.3–53.4% under Mn toxicity due to reduced nitrate availability.DiscussionThese findings indicate that Mn toxicity impairs sugarcane N utilization by disrupting ammonia-oxidizing microbial communities and suppressing nitrification, thereby providing insights for optimizing N management strategies in Mn-contaminated acidic soils.

Lysine acetylation and protein abundance both play crucial roles in regulating sucrose accumulation in sugarcane, with 73 dual-function proteins identified as potential targets for molecular breeding to enhance sucrose levels. Lysine acetylation plays a crucial role in regulating various biological processes in plants, but its role in sucrose accumulation in sugarcane remains unexplored In this study, we conducted a comprehensive quantitative proteome and acetylated proteome analysis on the leaves of two sugarcane genotypes with high and low sucrose levels at early, middle, and late stages of sucrose accumulation. Quantitative proteome analysis identified 2363 differentially abundant proteins (DAPs), of which 165 were associated with sugar metabolism pathways, providing more targets for improving sucrose content in sugarcane. The acetylated proteome analysis identified 1397 differentially acetylated proteins (DAcPs) with 2377 acetylation sites. Many DAcPs were also involved in sugar metabolism, demonstrating that lysine acetylation is associated with sucrose accumulation. A comparison of the DAPs and DAcPs identified 650 overlapping proteins, with 73 of them related to sugar metabolism, confirming dual regulatory roles of protein abundance and acetylation in sucrose accumulation in sugarcane. These 73 proteins serve as targets for sucrose improvement with dual regulatory effects. Our data also suggest that histone acetylation and nitrogen metabolism may be related to sucrose accumulation. This work enhances our understanding of the mechanisms regulating sucrose accumulation and proposes targets for improving sucrose content in sugarcane through molecular breeding.

IntroductionSugarcane (Saccharum spp.) is a crucial crop for sugar and bioethanol production. However, sugarcane grown in the acidic soils of southern China often suffers from severe leaf chlorosis due to excessive soil manganese (Mn). This study investigates the effects of Mn toxicity on the physicochemical properties and microbial communities in sugarcane rhizosphere soil, as well as its impact on sugarcane growth and nitrogen uptake and utilization.MethodsSoil samples were collected from sugarcane fields with varying levels of Mn toxicity. Physicochemical properties of the rhizosphere soil were analyzed, including soil pH, available nitrogen, and microbial community composition. The impact of Mn toxicity on sugarcane growth was assessed through measurements of plant biomass, leaf chlorosis, and nitrogen uptake efficiency.ResultsMn toxicity significantly lowered soil pH and altered the soil microbial community structure. Bacterial genera such as Nocardioides and Sinomonas, which are involved in ureolysis, cellulolysis, and Mn oxidation, were promoted. In contrast, genera like Nitrospirota, associated with nitrogen fixation, were inhibited. This disruption hindered the conversion of soil ammonium nitrogen to nitrate nitrogen, reducing soil available nitrogen. Consequently, sugarcane growth and development were suppressed, and nitrogen uptake was limited.DiscussionThe findings highlight the detrimental effects of Mn toxicity on sugarcane cultivation in high-Mn areas. The altered microbial community composition and reduced soil nitrogen availability directly impact sugarcane growth. These results underscore the importance of applying appropriate fertilizers to mitigate Mn toxicity and improve soil fertility in such regions. Future research should focus on developing strategies to enhance soil nitrogen cycling and promote beneficial microbial communities to support sustainable sugarcane production.

Calcineurin B-like proteins (CBLs) perceive calcium signals triggered by abiotic stress and interact with CBL-interacting protein kinases (CIPKs) to form a complex signal network. This study identified 21 SsCBL and 89 SsCIPK genes in Saccharum spontaneum, and 90 ScCBL and 367 ScCIPK genes in the sugarcane cultivar ZZ1. Phylogenetic analysis classified CBL genes into three groups and CIPK genes into twenty-five groups, with whole-genome duplication events promoting their expansion in sugarcane. RNA-seq analysis revealed their involvement in abiotic stress responses through ABA, JA, and SA pathways. Four ScCBLs and eight ScCIPKs were cloned from ZZ1. Three CBL-CIPK interactions were detected using a yeast two-hybrid system and Firefly luciferase complementation imaging, showing CBLs as membrane proteins and CIPKs as nuclear proteins. Spatial expression profiles indicate these genes are expressed in various tissues, with the highest expression in roots. Gene expression analyses suggested that CBL-CIPK signaling networks are involved in responses to drought, salt, and reactive oxygen species, possibly through Ca2+-induced hormone pathways. These findings establish three CBL-CIPK signaling networks responding to abiotic stress, providing a molecular basis for improving sugarcane stress resistance.

Cadmium (Cd) is one of the heavy metals that contaminate rice cultivation, and reducing Cd contamination in rice through agronomic measures is a hot research topic. In this study, foliar sprays of gibberellins (GA) and brassinolide (BR) were applied to rice under Cd stress in hydroponic and pot experiments. After foliar spraying of GR and BR, the biomass of rice plants grown in either hydroponics or soil culture was significantly higher or even exceeded that in the absence of Cd stress. In addition, photosynthetic parameters (maximum fluorescence values), root length and root surface area, and CAT, SOD and POD activities were significantly improved. The MDA content decreased in the shoots, suggesting that the application of GR and BA may have enhanced photosynthesis and antioxidant function to alleviate Cd stress. Furthermore, the BR and GA treatments decreased the Cd content of rice roots, shoots and grains as well as the Cd transfer coefficient. Cd chemical morphology analysis of rice roots and shoots showed that the proportion of soluble Cd (Ethanol-Cd and Water-Cd) decreased, whereas the proportion of NaCl-Cd increased. Analysis of the subcellular distribution of Cd in rice roots and above ground showed that the proportion of Cd in the cell wall increased after foliar spraying of GA and BR. The results indicate that after foliar application of GA and BR, more of the Cd in rice was transformed into immobile forms and was fixed in the cell wall, thus reducing the amount in the seeds. In summary, foliar sprays of GA and BR can reduce the toxic effects of Cd on rice plants and reduce the Cd content in rice grains, with GA being more effective.

Aluminium (Al) toxicity is one of the major constraint for crop production in acidic soil, and the inappropriate utilization of nitrogen fertilizer can accelerate soil acidification. Despite previous studies investigating the regulation of nitrogen forms in Al toxicity of plants, the underlying mechanism, particularly at the molecular level, remains unclear. This study aims to uncover the potentially regulatory mechanism of nitrate (NO3-) in the Al resistance of maize and Arabidopsis. NO3- conservatively improves Al resistance in maize and Arabidopsis, with nitrate-elevated citrate synthesis and exudation potentially playing critical roles in excluding Al from the root symplast. ZmSLAH2 in maize and AtSLAH1 in Arabidopsis are essential for the regulation of citrate exudation and NO3--promoted Al resistance, with ZmMYB81 directly targeting the ZmSLAH2 promoter to activate its activity. Additionally, NO3- transport is necessary for NO3--promoted Al resistance, with ZmNRT1.1A and AtNRT1.1 potentially playing vital roles. The suppression of NO3- transport in roots by ammonium (NH4+) may inhibit NO3--promoted Al resistance. This study provides novel insights into the understanding of the crucial role of NO3--mediated signalling in the Al resistance of plants and offers guidance for nitrogen fertilization on acid soils.

Manganese toxicity has limited sugarcane (Saccharum spp. hybrid.) growth and production in acidic soils in south China. The rhizosphere plays an irreplaceable role in plant adaptation to soil abiotic stress, but the responses of the sugarcane rhizosphere to manganese toxicity are still unknown. We designed pot experiments in Mn-rich acidic soil, collected the sugarcane rhizosphere and bulk soil samples, and then investigated the changes in Mn-related soil parameters and microbiome. The results indicated that the water-soluble and exchangeable manganese concentrations in the sugarcane rhizosphere were significantly lower than that in the bulk soil, which was not associated with soil pH changes. In contrast, the number of bacteria and the activity of peroxidase, sucrase, urease, and laccase in the rhizosphere were significantly higher. The 16S rDNA sequencing results showed that the bacterial diversity and quantity along with the abundance of Proteobacteria in the rhizosphere were significantly higher than in the bulk soil, while the abundance of Acidobacteria was lower than in the bulk soil. The soil laccase activity and the number of bacteria decreased significantly with the increase in the manganese toxicity stress. Finally, the relative abundance of proteins associated with manganese transportation and oxidation was significantly higher in the rhizosphere soil. In summary, the Mn-induced response of the rhizosphere is an important mechanism in sugarcane adaptation to manganese toxicity in acidic soil.

Coexistence of ammonium (NH4+) with manganese (Mn) in acid soils may facilitate the alleviation of Mn toxicity to plants. However, the effect of NH4+ on Mn toxicity and the corresponding mechanisms are unclear. In this study, the effects of NH4+ and nitrate (NO3-) on Mn toxicity, cell wall properties, and nitric oxide (NO) signaling in sugarcane were compared. NH4+ alleviated Mn-induced chlorosis in sugarcane seedlings and increased seedling biomass compared with NO3-. Exogenous application of NH4+ decreased the root cell wall pectin content and methyl esterase (PME) activity, but increased the degree of root pectin esterification (PMD). These changes were accompanied by reductions in the Mn content in roots, leaves, root cell wall, and cell wall pectin. An analysis of adsorption kinetic revealed less Mn-adsorption capacity in cell walls extracted from NH4+-fed than from NO3--fed sugarcane. Mn induced NO accumulation in sugarcane roots, but NH4+-fed seedlings accumulated less NO. Exogenous application of the NO donor sodium nitroprusside increased the Mn content of root cell wall pectin in NH4+-fed sugarcane, while the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxid decreased the Mn content in NO3--fed sugarcane. These treatments eliminated the difference in the pectin Mn content between NH4+-fed and NO3--fed sugarcane, as did a similar treatment with the nitrate reductase inhibitor tungstate, which decreased root cell wall pectin content and NO accumulation. These results suggest that (i) NH4+ alleviates Mn toxicity in sugarcane by reducing root pectin accumulation and root cell wall PME activity, thereby increasing cell wall PMD and decreasing both the Mn-binding capacity of cell wall and Mn accumulation, and (ii) NO mediates the accumulation of both pectin and Mn in response to different forms of nitrogen. The physiological mechanisms underlying the alleviation of ammonium on Mn phytotoxicity were clarified, which provided important implication for agricultural production and ecosystem functioning in acid soil.

Abstract Sugarcane is an established industrial crop providing sugar, ethanol and biomass‐derived electricity worldwide. Cane sugar content is an important breeding target, but its improvement remains very slow in many breeding programmes. Biotechnology strategies to improve sucrose accumulation made little progress at the crop level, mainly due to the limited understanding of its regulation. miRNAs regulate many metabolic processes in plants. However, their roles and target genes associated with sugarcane sucrose accumulation remain unknown. Here, we conducted high‐throughput sequencing of transcriptome, small RNAs and degradome of leaves and stem of two early‐maturing sugarcane genotypes with contrasting sucrose content from the early to late stages of sucrose accumulation stages, which provided more insights into miRNA‐associated gene regulation during sucrose accumulation. The stem sucrose content in both genotypes increased steadily with time during sucrose accumulation stage. Transcriptome analysis identified 18,722 differentially expressed genes (DEGs) between both genotypes during sucrose accumulation. The major DEGs identified were involved in starch and sucrose metabolism, and photosynthesis. miRNA sequencing identified 563 known and 281 novel miRNAs from both genotypes during sucrose accumulation. Of these, 311 miRNAs were differentially expressed. A combined transcriptome and miRNA data analysis revealed differentially expressed miRNA‐target mRNA pairs related to sugar metabolism, of which 46 targets were transcription factors (TFs). miR172, miR164, miR396 and miR169 appear to regulate AP2/ERF, NAC, GRF and bZIP TF members associated with sugar metabolism. This is the first report of sugarcane miRNAs associated with sugar accumulation.

Low phosphorus (P) availability in acid soils is one of the main limiting factors in sugarcane (Saccharum officinarum L.) production. Reconstruction of the root system architecture (RSA) is a vital mechanism for crop low P adaption, while the RSA of sugarcane has not been studied in detail because of its complex root system. In this study, reconstruction of the RSA and its relationship with P acquisition were investigated in a P-efficient sugarcane genotype ROC22 (R22) and two P-inefficient genotypes Yunzhe 03-103 (YZ) and Japan 2 (JP). An efficient dynamic observation room was developed to monitor the spatiotemporal alternation of sugarcane root length density (RLD) and root distribution in soil with heterogeneous P locations. The sugarcane RSA was reconstructed under P deficiency, and R22 had an earlier response than YZ and JP and presented an obvious feature of root shallowness. Compared with the normal P condition, the shallow RLD was increased by 112% in R22 under P deficiency while decreased by 26% in YZ and not modified in JP. Meanwhile, R22 exhibited a shallower root distribution than YZ and JP under P deficiency, supported by 51 and 24% greater shallow RLD, and 96 and 67% greater shallow root weight, respectively. The ratio of shallow RLD to total RLD in R22 was 91% greater than YZ, and the ratio of shallow root weight to total root weight in R22 was greater than that of YZ and JP by 94 and 30%, respectively. As a result, R22 had a higher shoot P accumulation than YZ and JP, which thereby increased the relative leaf sheath inorganic P concentration (RLPC) by 47 and 56%, relative shoot biomass (RSB) by 36 and 33%, and relative cane weight (RCW) by 31 and 36%, compared with YZ and JP under P deficiency, respectively. We verified the reliability and efficiency of a dynamic observation room and demonstrated that a shallower root distribution contributed to improving topsoil foraging, P acquisition, and low P adaption under P deficiency in sugarcane. Therefore, a shallower root distribution merits consideration as an evaluation trait for breeding P efficient sugarcane genotypes and genetic improvement.

近年来在广西主要的甘蔗种植区出现了土壤中锰含量过高所导致的甘蔗宿根蔗幼苗黄化问题,这严重降低了甘蔗的产量和品质,制约了甘蔗产业发展.一氧化氮(NO)是植物体内介导植物响应重金属胁迫的信号分子,在缓解重金属毒害方面起着重要作用.采用水培试验方法研究了锰胁迫下NO积累与甘蔗植株锰含量及细胞壁多糖组分的关系,旨在为揭示甘蔗锰毒耐受机制提供科学依据.结果 表明,锰处理后植株锰含量显著增加,并且植株中的锰主要积累在细胞壁及其果胶组分中;0.5、1.0 mmol/L锰处理24 h,后根尖中NO的积累量显著增加.在0.5 mmol/L锰溶液中添加NO供体硝普钠(SNP,0.2 mmol/L)增加植株NO积累后,根系锰含量为1215.4 mg/kg,叶片锰含量为525.5 mg/kg,相对于对照增加了37.1％,根及叶片中的锰含量、根细胞壁及其果胶组分中的锰含量均显著增加;一氧化氮清除剂(cPTIO,0.1 mmol/L)处理后,有效减少植株NO积累,并降低了根系、根系细胞壁及细胞壁果胶组分中的锰含量,根系锰含量相较于对照降低了78.2％,根系细胞壁和细胞壁果胶的锰含量相对于对照分别降低57.4％、40.6％;与此相同,硝酸还原酶抑制剂钨酸钠(0.3 mmol/L)处理抑制了硝酸还原酶(NR)活性并降低了植株NO积累,甘蔗植株、根系细胞壁及其果胶组分中的锰含量均显著下降.虽然钨酸钠处理后根系细胞壁中的半纤维素Ⅰ和半纤维素Ⅱ组分含量变化不显著,但细胞壁果胶组含量、果胶甲酯酶活性以及果胶去甲酯程度显著降低,从而减少了细胞壁的锰吸附.可见,锰胁迫引起甘蔗细胞积累NO,而NO通过调控细胞壁的多糖组分及果胶甲酯化程度介导植株锰积累与分布.

Manganese (Mn) toxicity-induced leaf chlorosis limits crop production in acidic soils, but its underlying mechanisms remain unknown. The effects of excessive Mn on chlorophyll (Chl) biosynthesis in sugarcane (Saccharum officinarum L.) leaves were investigated. Under Mn treatment, Chl concentration decreased with Mn accumulation and chlorosis appeared in expanding leaves. Before that, levels of the initial Chl precursor 5-aminolevulinic acid (ALA) and its downstream intermediates decreased, whereas magnesium-protoporphyrin IX monomethyl ester (MgPME) accumulated. Overaccumulation of Mn in leaves downregulated the ALA biosynthetic gene GluTR (encoding glutamyl-tRNA reductase) and MgPME conversion gene MgPMEC (encoding MgPME cyclase), upregulated the ALA biosynthesis inhibitor FLU (encoding FLUORESCENT), but had no significant effect on the expression of other Chl biosynthetic genes. The above Mn-induced changes of Chl precursors and expression of corresponding genes commenced before the Chl decline and leaf chlorosis, and were reversed by ALA supplementation. Thus, excessive Mn-induced chlorosis in sugarcane is mediated by a Chl-biosynthesis disorder resulting from the inhibition of ALA synthesis and MgPME conversion.

Abstract Alfalfa is a forage grass with excellent grass quality and high protein content. It is one of the most important feeds in the world.However, according to the conventional alfalfa planting method,long-term excessive application of chemical fertilizer will seriously affect soil fertility, enzyme activity and Alfalfa protein content. Biofertilizer can effectively change soil nutrients, activity of soil enzymes, and increase concentrations of crude protein and soluble protein.Therefore, it is necessary to fully understand the changes of transcriptome and metabolome under the condition of applying biological fertilizer to alfalfa. In this study, leaf transcriptome and metabolomics were used to study the effect of alfalfa treated with bio-organic fertilizer and chemical fertilizer(control group) on mature alfalfa. Compared with the control group (applying chemical fertilizer), the treatment group (applying biological fertilizer) has higher growth and higher nutrition index, and the soil enzyme activity has also been significantly improved. In addition, through the combined analysis of transcriptome and metabolomics, it was shown that the external application of biological fertilizer improved some signal transduction, tryptophan metabolism, phenylalanine metabolism, tyrosine metabolism and isoflavone metabolism of alfalfa.In conclusion, the study provides a notional basis for evaluating the induction of nutrients in alfalfa growth and maturity stage and the potential mechanism of remediation of fertilizer contaminated soil.

[目的]研究木耳菌渣对烟草生长、产量、品质和土壤理化性质的影响.[方法]采用大田试验方法,设对照组和试验组,对照组施用木耳菌渣0t/hm2,试验组施用木耳菌渣11.25t/hm2和15.00t/hm2,测定和分析旺长期烟田土壤理化性质和烟叶旺长生长期养分、农艺性状、评吸质量、产量和品质.[结果]两组试验组施用菌渣后,土壤有机质、碱解氮、速效磷、速效钾含量均有随着菌渣用量增加而呈现增加趋势;旺长期烟株叶数(16.9叶/株、17.0叶/株)高于对照;施用菌渣的烤烟中钾含量、氮碱比、糖氮比均较高,而烟碱、淀粉含量低于对照,且上等烟的比例及评吸质量也高于对照.但是施用15.00t/hm2菌渣后,烤烟的杂气有所增加.[结论]施用木耳菌渣是提高烤烟产量和品质的有效途径之一,既能提高植烟土壤肥力,又能促进烟草生长;施用11.25t/hm2木耳菌渣比较合适.