Food security is increasingly threatened by climate change and environmental pressures that hinder plant growth and development. Harnessing soil microorganisms, such as mycorrhizal fungi and plant growth-promoting bacteria, offers a promising approach to boost crop production. However, existing screening methods for these microorganisms often prove ineffective in real-world, stress-prone environments, limiting the efficacy of microbial biofertilizers. To address this challenge, this review proposes the integration of silicon-renowned for its stress-mitigating properties in plants-with biofertilizers. Silicon has been shown to work synergistically with plant growth-promoting microorganisms, enhancing plant resilience to environmental stress while improving colonization efficiency and plant-microbe interactions in stressful conditions. By combining silicon with biofertilizers to create silicon-enriched biofertilizers, this strategy has the potential to optimize microbial performance and fortify food security against global challenges. The review advocates for the co-application of silicon and microbial biofertilizers as a sustainable solution to boost plant resilience against environmental stressors, thereby contributing to agricultural sustainability.

Based on the research conducted so far, hydrogen sulphide (HS) plays a crucial role in the development and stress resilience of plants. HS, which acts as a signalling molecule, responds to different stresses such as heavy metals, drought, and salinity, and it regulates various aspects of plant growth and development including seed germination, root development, stomatal movement, flowering, and fruit ripening. Additionally, HS is involved in mediating legume-Rhizobium symbiosis signalling. It modulates plant responses to external environmental stimuli by interacting with other signalling molecules like phytohormones, nitric oxide, and reactive oxygen species. Furthermore, HS exerts these regulations since it can modify protein functions through a reversible thiol-based oxidative posttranslational modification called persulfidation, particularly in stress response and developmental processes. As a result, HS is recognised as an important emerging signalling molecule with multiple roles in plants. Research in this field holds promise for engineering stress tolerance in crops and may lead to potential biotechnological applications in agriculture and environmental management.

Flavonols are important plant photoprotectants to defence UV-B irradiation, however, the underlying transcriptional regulatory mechanism of rapid flavonol accumulation in response to UV-B remains unknown. In this study, content of flavonols was significantly induced from 0.11 to 3.80 mg/g fresh weight by UV-B irradiation in leaves of Morella rubra seedlings. MrERF34 was identified as an activator that can regulate the expression of MrFLS2, and promoted flavonol biosynthesis with activator MrMYB12 under UV-B treatment. Transient overexpression of MrERF34 resulted in higher flavonol accumulation, while virus-induced gene silencing of MrERF34 reduced the content of flavonols in bayberry leaves. We further demonstrated that a repressor MrERF4 inhibited the expression of MrERF34 and MrMYB12 as well as MrFLS2 via ERF-associated-amphiphilic repression motif. Exposure to UV-B reduced the promoter activity and transcription of MrERF4, which weakened the inhibitory effect of MrERF4 on MrERF34, MrMYB12, and MrFLS2, leading to a tremendous accumulation of flavonols. Such inhibitory roles of MrERF4 in regulation of flavonol biosynthesis were further validated by transient overexpression in leaves of Nicotiana benthamiana and M. rubra. These findings enrich the synergistical regulatory mechanisms between repressor and activators in flavonol biosynthesis, and provide new insights into photoprotectants biosynthesis to mitigate UV-B stress in plants.

Many plant viruses modify the phenotype of their hosts, which may influence the behaviour of their vectors and facilitate transmission. Among them is the turnip yellows virus (TuYV), which can modify the orientation, feeding, and performance of its main aphid vector, Myzus persicae. However, the virus factors driving these mechanisms have not been elucidated. In this study, we compared the feeding behaviour and fecundity of aphids on TuYV-infected and transgenic Arabidopsis thaliana expressing individual TuYV proteins (CP, RT and P0) to define the role of these proteins in aphid-plant interactions. Aphids on TuYV-infected plants had shorter pathway phases and ingested phloem sap for longer times, which is expected to promote the acquisition of the phloem-limited TuYV. No change in aphid fecundity was observed on TuYV-infected plants. The transmission-conducive feeding behaviour changes could be fully reproduced by phloem-specific expression of the capsid protein (CP) in transgenic plants, whereas expression of P0 had minor and RT had no effects on aphid feeding behaviour. We then carried out a metabolomic analysis to determine plant compounds that could be involved in the modification of the aphid behaviour. A few metabolites were specific for TuYV-infected or CP-transgenic A. thaliana, and are good candidates for inducing behavioural changes.

Understanding mechanisms driving tropical tree growth is essential for comprehending carbon sequestration and predicting the future of tropical forests amid rapid deforestation. We conducted a natural experiment in Mount Cameroon to identify climatic factors limiting diurnal and seasonal growth in dominant tree species across a 2200-m elevation gradient, from lowland rainforests to montane mist forests with distinct wet and dry seasons. Using high-precision automatic dendrometers, we recorded radial growth rates of 28 tropical tree species from 2015 to 2018, correlating them with rainfall (11 100-2500 mm) and temperatures (23-14°C) across elevations. Significant growth limitations were suggested at both extremes of water availability. Tree growth peaked during the dry and prewet seasons at humid lower elevations and during wet seasons at drier higher elevations. Growth rates increased with soil moisture at higher elevations and peaked at medium soil moisture at lower elevations. Trees grew fastest at lower temperatures relative to their elevation-specific means, with growth limited by high daytime temperatures and promoted by nighttime temperatures. Our results revealed significant interspecific diurnal and seasonal growth variations hindered by both water scarcity and excess in West African rainforests, essential for forecasting and modelling carbon sinks.

Soybean (Glycine max [L.] Merr.) is one of the world's most important sources of oil and vegetable protein. Much of the energy required for germination and early growth of soybean seeds is stored in fatty acids, mainly as triacylglycerols (TAGs), and the main seed storage proteins are β-conglycinin (7S) and glycinin (11S). Recent research advances have deepened our understanding of the biosynthetic pathways and transcriptional regulatory networks that control fatty acid and protein synthesis in organelles such as the plastid, ribosome and endoplasmic reticulum. Here, we review the composition and biosynthetic pathways of soybean oils and proteins, summarizing the key enzymes and transcription factors that have recently been shown to regulate oil and protein synthesis/metabolism. We then discuss the newest genomic strategies for manipulating these genes to increase the food value of soybeans, highlighting important priorities for future research and genetic improvement of this staple crop.

Symbiotic nitrogen fixation (SNF) profoundly alters plant and bacteroid metabolism; however, SNF impact on folates and one-carbon (1C) metabolism are unknown. To explore this, SNF was induced in Phaseolus Vulgaris with Rhizobium etli. Nodules accumulated the highest folate concentration yet reported in a plant tissue (60 nmol/g fresh weight). Folate upregulation was not exclusive of determinate nodules, moderate to high folate contents were also encounter in Medicago truncatula and sativa. Moreover, folates correlated partial and positively with N-fixation. 1C metabolism-associated amino acids (Ser, Gly, Cys, Thr, and Met) accumulated more in nodules than roots. Subcellular profiling of nodule folates revealed that the cytosol fraction primarily contained 5-methyl-tetrahydrofolate, cofactor for Met synthesis. 10-formyl-tetrahydrofolate, required for purine synthesis, was most abundant in nodule plastids, while bacteroids contained low folate levels. Differential transcriptome analysis from nodule legume studies revealed that only a few biosynthetic folate genes expression was increased in nodules whereas several genes for 1C reactions were upregulated. For the first time folates were detected in the xylem sap, with higher concentrations during SNF. We postulate that folates are needed during SNF to sustain purines, thymidylate, and Met synthesis, during both N-fixation and nodule growth; nodule metabolism is then a 1C-unit sink.

Individual effects of elevated ozone (O) and warming on wheat (Triticum aestivum L.) are well documented, their combined effects remain poorly understood. In the present study, we investigated the combined impacts of elevated O (1.5× ambient O) and rising canopy temperature (+2°C) on the photosynthesis of wheat leaves in an open-air field experiment. We found that O-induced oxidative stress reduced the biochemical capacity and inhibited leaf photosynthesis at the end of the grain-filling stage. Night-time warming (NW) increased leaf photosynthesis during the vegetative stage, but whole-day warming (WW) did not. Both WW and NW accelerated wheat development and decreased photosynthesis at the end of the reproductive stage. Neither elevated O nor warming stimulated antioxidant enzymes. Significant interaction between O and WW indicated that WW mitigated the adverse effect of O on leaf photosynthesis. Compared to NW, WW significantly increased daytime canopy temperature and canopy-to-air vapour pressure deficit across O treatments. Decreases in leaf water content and increases in grain oxygen isotope discrimination under warming suggested a link of WW-induced protection against O stress in photosynthesis with declines in stomatal O uptake rather than increases in the antioxidant capacity. Our results indicate the need to consider the warming-induced mitigation of O stress on leaf photosynthesis when predicting the effects of elevated O on crop growth under warmer climate in the future.

Fatty acid desaturase (FAD) is essential for plant growth and development and plant defence response. Although flax (Linum usitatissimum L.) is an important oil and fibre crop, but its FAD gene remains understudied. This study identified 43 LuFAD genes in the flax genome. The phylogenetic analysis divided the FAD genes into seven subfamilies. LuFAD is unevenly distributed on 15 chromosomes, and fragment duplication is the only driving force for the amplification of the LuFAD gene family. In the LuFAD gene promoter region, most elements respond to plant hormones (MeJA, ABA) and abiotic stresses (anaerobic and low temperature). The expression pattern analysis showed that the temporal and spatial expression patterns of all LuFAD genes in different tissues and the response patterns to abiotic stresses (heat and salt) were identified. Subcellular localisation showed that all LuFAD2-GFP were expressed in the endoplasmic reticulum membrane. RT-qPCR analysis revealed that LuFAD2 was significantly upregulated under cold, salt and drought stress, and its overexpression in Arabidopsis thaliana enhanced cold tolerance genes and reduced ROS accumulation. This study offers key insights into the FAD gene family's role in flax development and stress adaptation.

Nitric oxide (NO) is one of the byproducts of nitrogen metabolism. Excess amount of NO is scavenged by phytoglobins. The role of phytoglobin mediated NO homoeostasis in modulation of nitrate transporters was investigated using NO scavenger cPTIO, phytoglobin overexpressing rice and Arabidopsis. Growing plants under low nitrate leads to generation of reduced levels of NO accompanied by elevated expression of high affinity transporters (HATs) such as NRT2.1, NRT2.3 and NRT2.4. Scavenging of NO by cPTIO under optimal nitrate caused enhanced HATs expression. Phytoglobin overexpressing Arabidopsis showed improved growth and enhanced expression of HATs under low nitrogen in comparison to WT. Pretreatment of optimal nitrate grown plants with NO scavenger cPTIO enhanced HATs expression and shifting of these primed plants from optimal to low nitrate leads to further elevation of HATs expression accompanied by enhanced nitrogen uptake and its accumulation with positive effect on growth. Phytoglobin overexpression in rice leads to enhanced HATs expression, improved growth, nitrogen accumulation under low nitrate. Pgb OE lines showed enhanced accumulation of amino acids. Taken together our results suggest an important role of phytoglobins in nitrogen uptake and assimilation.

Salt-stress priming enhances the tolerance of plants against subsequent exposure to a similar stress. Priming-induced transcriptomic reprogramming is mediated by multiple epigenetic mechanisms, the best known of which is histone modifications. However, not much is known about other epigenetic responses. In this study, salt-stress priming resulted in global DNA hypomethylation in the leaves of soybean seedlings. The DNA methyltransferase activities in primed seedlings were reduced, contributing to the overall DNA hypomethylation. Genes associated with the hypomethylated DNA regions in primed seedlings also showed a higher mean level of the active histone mark, histone 3 lysine 4 trimethylation (H3K4me3), and a lower mean level of the repressive histone mark, H3K4me2. Transcriptomic analyses supported that DNA hypomethylation played a role in fine-tuning the chromatin status in primed seedlings to potentiate gene expressions. Motif and transcriptional network analyses revealed that DNA hypomethylation may facilitate the responses mediated by key transcription factors in the abscisic acid (ABA)-dependent pathway. A pre-treatment using a DNA methyltransferase inhibitor, 5-azacytidine, could enhance salt tolerance in non-primed soybean seedlings, similar to the priming effect, suggesting the role of DNA hypomethylation in salt-stress priming. Overall, this research furthers our understanding of the epigenetic mechanisms involved in salt-stress priming in soybean.

Over thousands of years of domestication, maize has undergone significant environmental changes. Understanding the genetic and metabolic trace during maize evolution can better contribute to molecular breeding and nutrition quality improvement. This study examines the metabolic profiles and transcriptomes of maize kernels from teosinte, landrace, and maize accessions at 15 days post-pollination. Differentially accumulated metabolites were enriched in sugar and lipid metabolism pathways. The metabolic selection profile exhibited four distinct patterns: continuous increases, constant decrease, initial decline or stability followed by an increase, and initial growth or stability followed by a subsequent decline. Sugars and JA were positive selection while LPCs/LPEs were negative selection during evolution. The expression level of genes related to sugar accumulation was significantly higher in maize, contrasting with enhanced glycolysis and lipid metabolism activity in teosinte. The correlation network highlighted distinct hormonal regulation of sugar and lipid metabolism. We identified 27 candidate genes associated with sugar, lipid, and JA that have undergone strong selection by population genomic regions. The positive selection of the PLD may explain the negative selection of LPCs/LPEs due to substrate competition. These findings enhance our understanding of the evolutionary trajectory of primary metabolism in maize and provide valuable resources for breeding and improvement.

Plant viruses rely on host factors for successful infection. Non-specific lipid transfer proteins (nsLTPs) play critical roles in plant-pathogen interactions; however, their functions and underlying molecular mechanisms in viral infections remain largely unknown. Jasmonic acid (JA) is a crucial regulatory hormone in the process of plant resistance to viral infection. In this study, we screened and verified that StLTP6, a previously identified pro-viral factor, interacts with the silencing suppressor triple gene block1 (TGB1) of potato virus S (PVS). The PVS TGB1 induces the expression of StLTP6, and both co-localize in the cytoplasm. Furthermore, StLTP6 interacts with allene oxide cyclase and inhibits its accumulation, thereby suppressing JA synthesis and attenuating RNA silencing antiviral resistance. In summary, we elucidated the molecular mechanism by which PVS TGB1 interacts with StLTP6 to facilitate PVS infection. These findings broaden our understanding of the biological roles of nsLTPs and provide a new antiviral target for potato research.

In recent years, the detection of numerous negative correlations between silicon (Si) and carbon (C)-based compounds in plants has suggested trade-offs between different stress resistance and/or mechanical support strategies. However, nearly all studies have involved whole-leaf analysis, and it is unclear how the trade-off operates mechanistically, at the cellular level. Here we combined leaf trait measurements and microscopic analyses (electron microscopy with elemental X-ray mapping and X-ray microtomography) of 17 species from a high-Si family: Cyperaceae. Accumulation of Si was strongly negatively correlated with C-based compounds, particularly tannins. Our microscopical investigations showed that the accumulation of phenolics and deposition of silica were mutually exclusive in the outer epidermal cell walls. This trade-off was independent of that between the construction of tough, sclerenchyma-rich leaves and growth potential (the leaf economics spectrum). We also identified a strong negative correlation between Si and accumulation of epicuticular waxes. Previous whole leaf analyses were, in effect, hiding the locations of the trade-off between Si and C-based compounds in plants. The epidermal location of this trade-off and the specific involvement of tannins and waxes suggest the existence of different strategies to resist environmental stresses. Our study provides key insights into plant Si utilization and highlights the multidimensionality of plant stress resistance strategies.

The increase in global climate variability has increased the frequency and severity of floods, profoundly affecting agricultural production and food security worldwide. Autophagy is an intracellular catabolic pathway that is dispensable for plant responses to submergence. However, the physiological role of autophagy in plant response to submergence remains unclear. In this study, a multi-omics approach was applied by combining transcriptomics, proteomics, and lipidomics to characterize molecular changes in the Arabidopsis autophagy-defective mutant (atg5-1) responding to submergence. Our results revealed that submergence resulted in remarkable changes in the transcriptome, proteome, and lipidome of Arabidopsis. Under submerged conditions, the levels of chloroplastidic lipids, including monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), and phosphatidylglycerol (PG), were lower in atg5-1 than in wild-type, suggesting that autophagy may affect photosynthesis by regulating lipid metabolism. Consistently, photosynthesis-related proteins and photosynthetic efficiency decreased in atg5-1 under submergence conditions. Phenotypic analysis revealed that inhibition of photosynthesis resulted in a decreased tolerance to submergence. Compared to wild-type plants, atg5-1 plants showed a significant decrease in starch content after submergence. Collectively, our findings reveal a novel role for autophagy in plant response to submergence via the regulation of underwater photosynthesis and starch content.

Sedum plumbizincicola (Sp) is a cadmium (Cd) hyperaccumulator found specifically in abandoned ancient mines where N is regularly deficient while Cd presents in excess. How Sp got adapted to this unique habitat remains unknown. Here, we reported relative abundant presence of NH in mine areas for Sp, and the isolation and functional characterisation of a putative NH transporter gene AMT1;2, which is highly expressed in Sp roots and encodes a pH-dependent dual affinity ammonium uptake transporter. Compared to SaAMT1;2, the homologous gene in the nonhyperaccumulating control Sedum alfredii (Sa), SpAMT1;2 expression is much higher and not inhibited by Cd. Only eight amino acid sequence polymorphisms were observed between SpAMT1;2 and SaAMT1;2, and the in-vitro NH uptake activity and subcellular localisation are identical between them with or without Cd stress. Moreover, in contrast in Sa, NH uptake in Sp is not inhibited by Cd, and NH at ambient level promotes Cd accumulation. These data suggest that SpAMT1;2 is likely an essential gene contributing to nitrogen nutrition and the interaction between NH and Cd uptake in Sp, which might represent a novel N utilisation pathway evolved in mines for the hyperaccumulator Sp.

High temperature can significantly affect the quality and yield of plants. However, there has been limited research investigating the thermotolerance of non-heading Chinese cabbage (NHCC). This study, identified BcWRKY23 through transcriptome analysis in NHCC with varying levels of thermotolerance. Overexpression and silencing experiments demonstrated that BcWRKY23 positively regulates the thermotolerance of NHCC by activating its own expression under short-term heat stress (HS). Additionally, BcWRKY23 was found to bind to the promoter of BcWRKY25 and activate its expression, which also enhanced thermotolerance. BcWRKY23 and BcWRKY25 enhanced the expression of HSR genes to improve thermotolerance. Furthermore, BcPAL1 was shown to be activated by BcWRKY23, while BcPAL2 was activated by both BcWRKY23 and BcWRKY25. Overexpression of BcPAL1 and BcPAL2 in NHCC significantly increased thermotolerance, accompanied by an enhancement of phenylalanine ammonia-lyase (PAL) activity. Moreover, under long-term HS, the significant accumulation of BcVQ11A was observed, and the interaction between BcVQ11A and BcWRKY23 as well as BcWRKY25 inhibited the activation of them to target genes, resulting in decreased PAL activity. This study proposes a HS response pathway involving BcVQ11A-BcWRKY23-BcWRKY25-BcPAL1/BcPAL2, providing valuable insights into the molecular mechanisms underlying thermotolerance in plants.

Low-temperature stress limits plant growth, and reduces aesthetics of many ornamental plants. Plants have developed different adaptive mechanisms to cope with low-temperature stress, in which NAC transcription factor family members playing an important role in low-temperature tolerance. However, their roles in petunia in response to low temperature are still largely unknown. Here, we found that a NAC transcription factor, namely, PhNH10, negatively regulates low-temperature response in petunia. PhNH10-silenced and -CRISPR/Cas9 mutant plants displayed higher survival rate, anthocyanin content and abscisic acid concentration than PhNH10-overexpression and wild-type plants under low-temperature condition. PhNH10 can directly bind to the PhABA8ox promoter to active its expression, which further promotes the abscisic acid catabolism, while silencing of PhABA8ox increased the ABA concentration and low-temperature tolerance. In addition, PhNH10 interact with a low-temperature-related E2 ubiquitin-conjugating enzyme, PhUBC2-1, which in turn inhibited the binding capacity of PhNH10 on PhABA8ox promoter. Our research has elucidated an extensive mechanistic network underlying the PhNH10-mediated regulation of low-temperature response in petunia. This finding not only presents a new viewpoint in understanding the low-temperature tolerance mechanisms but also delineates a promising pathway for transgenic petunia with improved low-temperature resistance.

Salivary proteins secreted by phytophagous insects play pivotal roles in plant-insect interactions. A salivary protein RpSP27, from the stinkbug Riptortus pedestris, a devastating pest on soybean, was selected for studying due to its ability to induce cell death and activate immune responses in plants. RpSP27 localized to the endoplasmic reticulum and triggered reactive oxygen species burst. Virus-induced gene silencing assays showed RAR1 plays an essential role in RpSP27-induced cell death in Nicotiana benthamiana. Expression analyses revealed that RpSP27 is predominantly expressed in R. pedestris salivary glands. RNA interference-mediated silencing of RpSP27 in R. pedestris significantly reduced insect survival rates and altered feeding behavior by decreasing the formation of salivary sheaths on soybeans and reducing probing and feeding duration. Furthermore, the silencing of RpSP27 in R. pedestris mitigated the staygreen syndrome in soybeans, characterized by delayed senescence and pod abnormalities. This study elucidated the role of RpSP27 in the interaction between R. pedestris and soybean, presenting a potential target for pest management strategies to protect soybean crops from the detrimental effects of R. pedestris feeding.

Plant hydraulic theory states that leaf and stem vulnerability to embolism is coordinated within individual plants. The hydraulic vulnerability segmentation hypothesis (HVSH) predicts higher vulnerability in leaves to protect the stem from hydraulic failure, preserving stem xylem, which is generally more metabolically expensive and slower to regenerate than leaf tissues. However, studies designed to test HVSH have reported wide ranges in vulnerability segmentation (VS), and patterns with the environment have been elusive. In this study, we tested HVSH in phylogenetically constrained tree species from contrasting ecosystems across the Australian landscape. In 12 species, we found no support for HVSH. While leaf vulnerability was strongly governed by climate, VS was universally absent or negative. Consistently, the onset of leaf embolism occurred after the loss of leaf turgor and seasonally low leaf water potentials, illustrating the rarity of embolism in leaves. Within the leaf, embolism primarily occurring first and last in the leaf midvein, suggesting redundancy in leaf architecture to preserve function. Overall, this multi-ecosystem study provides a more complete picture of drought resistance mechanisms: (1) leaf safety was greatest in trees from drier ecosystems and (2) hydraulic thresholds were mostly conserved across organs indicating environmentally driven drought resistance in both leaves and stems.

Both the activity of photosynthesis and the repair of damaged photosystems decline in cold environments, which may increase the extent of the damage of photosynthetic machinery by light, namely photoinhibition. We hypothesized that plants in colder habitats may possess greater tolerance to photoinhibition, especially in low-temperature conditions. We measured the rate of photoinhibition, rate of photoinhibition repair and other thylakoid activities in cold environments using 298 Arabidopsis thaliana ecotypes and studied the relationships among the indicators of photoinhibition tolerance and climatic data of the habitat of each ecotype. The plants acclimated to cold conditions (12°C) for 3 days showed a negative correlation between the rate of photoinhibition repair at 5°C and the mean annual temperature of habitats, although we could not see this correlation with the control plants grown at 22°C. This result would indicate that the acclimation capacity of photoinhibition tolerance in cold conditions can affect the distribution of plants, especially in colder regions.