Individual and additive stress impacts of Na+ and Cl‾ on proline metabolism and nitrosative responses in rice

Exogenous proline enhances salt acclimation in soybean seedlings: Modifying physicochemical properties and controlling proline metabolism through the ornithine-glutamate dual pathway

Soil salinization has emerged as a major factor negatively affecting soil quality and plant productivity. Proline, functioning as an osmotic regulator, has been proposed as an effective strategy for enhancing plant tolerance to salt stress. This study aimed to investigate the effects of exogenous proline on salt tolerance in soybeans. A hydroponic experiment was conducted with different salt treatments (without NaCl, -NaCl; with 100 mM NaCl, +NaCl) and with or without 150 mM proline (+Pro, -Pro). The results showed that proline application alleviated salt stress-induced reductions in plant growth, photosynthetic parameters, and chlorophyll content while aiding recovery from leaf chlorosis. Proline treatment improved ion homeostasis by reducing Na+ levels and increasing K+ and Ca2+ contents in the leaves. Salt stress increased malondialdehyde (MDA) and reactive oxygen species (ROS) levels, along with leaf peroxidase (POD) and catalase (CAT) activities, while decreasing superoxide dismutase (SOD) activity. Moreover, salt stress obviously enhanced proline accumulation, accompanied by increases in glutamate (Glu), glutamate-1-semialdehyde (GSA), and pyrroline-5-carboxylate (P5C) content, as well as the activities of pyrroline-5-carboxylate synthase (P5CS) and pyrroline-5-carboxylate reductase (P5CR) in the glutamate pathway, while reducing proline dehydrogenase (ProDH) activity. Exogenous proline treatment further elevated proline content and increased key substances and enzyme activities in both the glutamate (Glu and P5C content, P5CS and P5CR activity) and ornithine (Orn content and OAT activity) pathways while also reducing ProDH activity. Collectively, our results revealed that exogenous proline contributed to an attenuation of salt stress in soybeans by regulating both the glutamate and ornithine pathways to stimulate endogenous proline accumulation, mediate Na+/K+ homeostasis, and inhibit oxidative damage.

Improved Salt Tolerance in Brassica napus L. Overexpressing a Synthetic Deinocuccus Stress-Resistant Module DICW

Salt stress adversely impacts plant physiology by causing ionic, osmotic, and oxidative stress, ultimately hindering growth and yield. The genus Deinococcus contains unique stress resistance genes, and previous studies have shown that proteins such as IrrE, Csp, and WHy enhance stress tolerance in plants and microbial cells. However, their role in Brassica napus L. (oilseed rape) remains unexamined. In this study, a synthetic stress-resistance module, DICW, was constructed using the Deinococcus-derived genes IrrE, Csp, and WHy and heterologously overexpressed in B. napus to assess its impact on salt tolerance. The results demonstrated that the DICW module significantly improved seed germination and seedling growth under salt stress. Transgenic B. napus plants exhibited reduced membrane damage, higher leaf relative water content, enhanced accumulation of osmoregulatory substances, and elevated antioxidant enzyme activity compared to wild-type plants. Additionally, qRT-PCR analysis revealed the upregulation of stress-related genes (BnRD29A, BnP5CS, BnKIN1, BnLEA1, BnNHX1, and BnSOS1) and antioxidant enzyme-related genes (BnSOD, BnPOD, and BnCAT) in transgenic lines. In conclusion, the DICW module plays a crucial role in enhancing salt tolerance in B. napus by regulating stress responses and antioxidant mechanisms. This study provides valuable molecular insights into improving the survival and growth of B. napus in saline environments.

The Association of Sorghum Growth and Physiology with Soil Carbon Sink Source Captivity in Saline Soil

The vast expanse of saline-alkali land in China represents a significant reserve of land resources for agricultural development. Therefore, it is essential to explore the saline-alkali tolerance of crops, the benefits of saline-alkali soil improvement, and their carbon sequestration potential. This study utilized the sorghum variety Jinliang 211 as the experimental material, conducting trials in saline-alkali woodland. A control and four different treatments combining organic fertilizers and soil amendments were established to investigate the effects of these mixtures on sorghum growth, antioxidant enzyme activity, soil improvement, and carbon sequestration characteristics. The results indicated that the combined application of organic fertilizer and rice husk biochar could enhance the salt tolerance of Jinliang 211, improve soil quality, and increase soil carbon sequestration capacity. Among the measured plant indicators, the T2 treatment (combined application of organic fertilizer and rice husk biochar) resulted in the highest dry matter accumulation, which was 68.4% higher than the control. Concurrently, the activities of antioxidant enzymes such as SOD, POD, and CAT significantly increased during the jointing stage post-treatment, with the highest enzyme activities observed in the T2 treatment. Regarding soil indicators, the soil organic carbon content initially increased and then decreased, with the T2 treatment showing the highest soil organic carbon content, 9.8% higher than the control. The soil pH initially decreased and then increased, with the T2 treatment exhibiting the lowest soil pH, 5.6% lower than the control. Importantly, the T2 treatment demonstrated the most pronounced "net carbon sink" characteristics in the soil. In summary, the T2 mixed treatment performed the best in enhancing sorghum antioxidant enzyme activity, increasing dry matter accumulation, and strengthening the carbon sequestration characteristics of saline-alkali soil.

Enhancing salinity tolerance in cultivated rice through introgression of African rice genes and application of moringa leaf extract

BACKGROUND

Salinity is a major threat to rice growth and productivity. Utilizing wild rice-derived genes and biostimulants with high growth promoting- and stress-alleviating potential can significantly improve salinity tolerance in cultivated rice. Herein, we investigated the vegetative growth and physiological responses of Giza 177 (Oryza sativa, salinity sensitive, high-yielding cultivar) and a promising introgression salt tolerant line (sativa/glaberrima; SG 65) from a population of Giza 177 × African rice (Oryza glaberrima) under low (2.75 mS/cm) and high (5.5 mS/cm) salinity stress. The possible ameliorative effects of priming rice seeds in moringa leaf extract (MLE) on these responses were also tested.

RESULTS

The two salinity levels induced differential reduction in plant growth in both cultivars. In the MLE-unprimed plants, salinity induced 34-54% and 30-45% reductions in biomass accumulation in Giza 177 and SG 65, respectively. These responses were associated with significant differential reductions in relative water content, chlorophylls, carotenoids, and gas exchange parameters (transpiration rate, net photosynthetic rate, stomatal conductance, and intercellular CO2 concentration), ascorbic acid, and total protein. Conversely, salinity induced the accumulation of H2O2, malondialdehyde, proline, carbohydrate fractions, and membrane injury. MLE treatment mitigated the above salinity-induced adverse effects in both cultivars via reducing the salt-induced oxidative stress through the induction of non-enzymic (total phenols, and flavonoids) and enzymic antioxidants including ascorbate peroxidase, catalase, peroxidase, and polyphenol oxidase in both cultivars. SG 65 plants exhibited consistently higher salt tolerance and responsiveness to MLE than Giza 177.

CONCLUSIONS

This study reports significant differences in an array of critical physiological and biochemical indices that underpin the divergent responses between the two salinized cultivars. It demonstrates the potential of African rice-derived genomic fragments and MLE priming in mitigating salinity stress, highlighting their use as a sustainable strategy for increasing rice production in salt-affected soils.

Advances and mechanisms of fungal symbionts in improving the salt tolerance of crops

Soil salinization leads to reduced crop yields and waste of land resources, thereby impacting global food security. To meet the increasing demand for food and simultaneously alleviate pressure on soil resources, the development of sustainable agriculture is imperative. In contrast to physical and chemical methods, bioremediation represents an efficient and environmentally friendly approach. Fungal symbionts have been found to be associated with most plants in natural ecosystems, colonizing and residing within the internal tissues of host plants. Moreover, the potential of fungal symbionts in improving saline-alkaline soil has been widely recognized and confirmed. Numerous reports have documented the effectiveness of arbuscular mycorrhizal fungi in alleviating salt stress in plants. Meanwhile, research on other endophytic fungi for mitigating plant salt stress has emerged in recent years, which contributes to refining mechanisms for enhancing plant salt tolerance. In this review, we summarized various mechanisms by which endophytic fungi enhance plant salt tolerance. We also provided an overview of the challenges and development directions in the field of fungal symbiosis, with the aim of offering a viable strategy for the bioremediation of saline-alkali soils.

Knockdown of SlYTHDF2 Accelerates Dark-Induced Tomato Leaf Senescence by Affecting the ABA Pathway

N6-methyladenosine (m6A) is a widespread post-transcriptional modification in eukaryotic mRNAs. Proteins with the YTH structural domain act as m6A-binding proteins by recognizing the m6A modification and regulating mRNA through this recognition. In this study, SlYTHDF2, a prototypical m6A -binding protein gene in the YTH family was expressed in various tissues, and subcellular localization analyses indicated that the SlYTHDF2 protein was localized in the nucleus and cytoplasm. SlYTHDF2 knockout lines were obtained using CRISPR/Cas9 technology and showed the senesced leaves prematurely increased endogenous ABA accumulation compared with the wild type. Moreover, we found that dark promoted leaf senescence in SlYTHDF2 knockout lines and exogenous ABA further accelerated leaf senescence under dark conditions. The qRT-PCR analysis revealed significant alterations in the expression of genes associated with the ABA pathway. Relative to the wild type, the CR-slythdf2 plants exhibited reduced levels of photosynthetic pigments, higher accumulation of reactive oxygen species, and increased damage to cell membranes. Additionally, we discovered that SlYTHDF2 interacts with the chloroplast-binding protein SlRBCS3 through yeast two-hybrid and BiFC experiments. Overall, our data suggest the important role of SlYTHDF2 in regulating tomato leaf senescence.

Unlocking the versatility of nitric oxide in plants and insights into its molecular interplays under biotic and abiotic stress

In plants, nitric oxide (NO) has become a versatile signaling molecule essential for mediating a wide range of physiological processes under various biotic and abiotic stress conditions. The fundamental function of NO under various stress scenarios has led to a paradigm shift in which NO is now seen as both a free radical liberated from the toxic product of oxidative metabolism and an agent that aids in plant sustenance. Numerous studies on NO biology have shown that NO is an important signal for germination, leaf senescence, photosynthesis, plant growth, pollen growth, and other processes. It is implicated in defense responses against pathogensas well as adaptation of plants in response to environmental cues like salinity, drought, and temperature extremes which demonstrates its multifaceted role. NO can carry out its biological action in a variety of ways, including interaction with protein kinases, modifying gene expression, and releasing secondary messengers. In addition to these signaling events, NO may also be in charge of the chromatin modifications, nitration, and S-nitrosylation-induced posttranslational modifications (PTM) of target proteins. Deciphering the molecular mechanism behind its essential function is essential to unravel the regulatory networks controlling the responses of plants to various environmental stimuli. Taking into consideration the versatile role of NO, an effort has been made to interpret its mode of action based on the post-translational modifications and to cover shreds of evidence for increased growth parameters along with an altered gene expression.

Overexpression of SlALC Increases Drought and Salt Tolerance and Affects Fruit Dehiscence in Tomatoes

The bHLH transcription factors are important plant regulators against abiotic stress and involved in plant growth and development. In this study, SlALC, a gene coding for a prototypical DNA-binding protein in the bHLH family, was isolated, and SlALC-overexpression tomato (SlALC-OE) plants were generated by Agrobacterium-mediated genetic transformation. SlALC transgenic lines manifested higher osmotic stress tolerance than the wild-type plants, estimated by higher relative water content and lower water loss rate, higher chlorophyll, reducing sugar, starch, proline, soluble protein contents, antioxidant enzyme activities, and lower MDA and reactive oxygen species contents in the leaves. In SlALC-OE lines, there were more significant alterations in the expression of genes associated with stress. Furthermore, SlALC-OE fruits were more vulnerable to dehiscence, with higher water content, reduced lignin content, SOD/POD/PAL enzyme activity, and lower phenolic compound concentrations, all of which corresponded to decreased expression of lignin biosynthetic genes. Moreover, the dual luciferase reporter test revealed that SlTAGL1 inhibits SlALC expression. This study revealed that SlALC may play a role in controlling plant tolerance to drought and salt stress, as well as fruit lignification, which influences fruit dehiscence. The findings of this study have established a foundation for tomato tolerance breeding and fruit quality improvement.

Differential response of proline metabolism defense, Na+ absorption and deposition to salt stress in salt-tolerant and salt-sensitive rapeseed (Brassica napus L.) genotypes

Soil salinization is a major abiotic factor threatening rapeseed yields and quality worldwide, yet the adaptive mechanisms underlying salt resistance in rapeseed are not clear. Therefore, this study aimed to explore the differences in growth potential, sodium (Na+) retention in different plant tissues, and transport patterns between salt-tolerant (HY9) and salt-sensitive (XY15) rapeseed genotypes, which cultivated in Hoagland's nutrient solution in either the with or without of 150 mM NaCl stress. The results showed that the inhibition of growth-related parameters of the XY15 genotype was higher than those of the HY9 in response to salt stress. The XY15 had lower photosynthesis, chloroplast disintegration, and pigment content but higher oxidative damage than the HY9. Under NaCl treatment, the proline content in the root of HY9 variety increased by 8.47-fold, surpassing XY15 (5.41-fold). Under salt stress, the HY9 maintained lower Na+ content, while higher K+ content and exhibited a relatively abundant K+/Na+ ratio in root and leaf. HY9 also had lower Na+ absorption, Na+ concentration in xylem sap, and Na+ transfer factor than XY15. Moreover, more Na+ contents were accumulated in the root cell wall of HY9 with higher pectin content and pectin methylesterase (PME) activity than XY15. Collectively, our results showed that salt-tolerant varieties absorbed lower Na+ and retained more Na+ in the root cell wall (carboxyl group in pectin) to avoid leaf salt toxicity and induced higher proline accumulation as a defense and antioxidant system, resulting in higher resistance to salt stress, which provides the theoretical basis for screening salt resistant cultivars.

Mitigating salt toxicity and overcoming phosphate deficiency alone and in combination in pepper (Capsicum annuum L.) plants through supplementation of hydrogen sulfide

While it is widely recognized that hydrogen sulfide (H2S) promotes plant stress tolerance, the precise processes through which H2S modulates this process remains unclear. The processes by which H2S promotes phosphorus deficiency (PD) and salinity stress (SS) tolerance, simulated individually or together, were examined in this study. The adverse impacts on plant biomass, total chlorophyll and chlorophyll fluorescence were more pronounced with joint occurrence of PD and SS than with individual application. Malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL) levels in plant leaves were higher in plants exposed to joint stresses than in plants grown under an individual stress. When plants were exposed to a single stress as opposed to both stressors, sodium hydrosulfide (NaHS) treatment more efficiently decreased EL, MDA, and H2O2 concentrations. Superoxide dismutase, peroxidase, glutathione reductase and ascorbate peroxidase activities were increased by SS alone or in conjunction with PD, whereas catalase activity decreased significantly. The favorable impact of NaHS on all the evaluated attributes was reversed by supplementation with 0.2 mM hypotaurine (HT), a H2S scavenger. Overall, the unfavorable effects caused to NaHS-supplied plants by a single stress were less severe compared with those caused by the combined administration of both stressors.

Say "NO" to plant stresses: Unravelling the role of nitric oxide under abiotic and biotic stress

Nitric oxide (NO) is a diatomic gaseous molecule, which plays different roles in different strata of organisms. Discovered as a neurotransmitter in animals, NO has now gained a significant place in plant signaling cascade. NO regulates plant growth and several developmental processes including germination, root formation, stomatal movement, maturation and defense in plants. Due to its gaseous state, it is unchallenging for NO to reach different parts of cell and counterpoise antioxidant pool. Various abiotic and biotic stresses act on plants and affect their growth and development. NO plays a pivotal role in alleviating toxic effects caused by various stressors by modulating oxidative stress, antioxidant defense mechanism, metal transport and ion homeostasis. It also modulates the activity of some transcriptional factors during stress conditions in plants. Besides its role during stress conditions, interaction of NO with other signaling molecules such as other gasotransmitters (hydrogen sulfide), phytohormones (abscisic acid, salicylic acid, jasmonic acid, gibberellin, ethylene, brassinosteroids, cytokinins and auxin), ions, polyamines, etc. has been demonstrated. These interactions play vital role in alleviating plant stress by modulating defense mechanisms in plants. Taking all these aspects into consideration, the current review focuses on the role of NO and its interaction with other signaling molecules in regulating plant growth and development, particularly under stressed conditions.

Interaction between selenium and essential micronutrient elements in plants: A systematic review

Nutrient imbalance (i.e., deficiency and toxicity) of microelements is an outstanding environmental issue that influences each aspect of ecosystems. Although the crucial roles of microelements in entire lifecycle of plants have been widely acknowledged, the effective control of microelements is still neglected due to the narrow safe margins. Selenium (Se) is an essential element for humans and animals. Although it is not believed to be indispensable for plants, many literatures have reported the significance of Se in terms of the uptake, accumulation, and detoxification of essential microelements in plants. However, most papers only concerned on the antagonistic effect of Se on metal elements in plants and ignored the underlying mechanisms. There is still a lack of systematic review articles to summarize the comprehensive knowledge on the connections between Se and microelements in plants. In this review, we conclude the bidirectional effects of Se on micronutrients in plants, including iron, zinc, copper, manganese, nickel, molybdenum, sodium, chlorine, and boron. The regulatory mechanisms of Se on these micronutrients are also analyzed. Moreover, we further emphasize the role of Se in alleviating element toxicity and adjusting the concentration of micronutrients in plants by altering the soil conditions (e.g., adsorption, pH, and organic matter), promoting microbial activity, participating in vital physiological and metabolic processes, generating element competition, stimulating metal chelation, organelle compartmentalization, and sequestration, improving the antioxidant defense system, and controlling related genes involved in transportation and tolerance. Based on the current understanding of the interaction between Se and these essential elements, future directions for research are suggested.

How Do Plants Respond to Combined Drought and Salinity Stress?-A Systematic Review

Plants are frequently exposed to one or more abiotic stresses, including combined salinity-drought, which significantly lowers plant growth. Many studies have been conducted to evaluate the responses of plants to combined salinity and drought stress. However, a meta-analysis-based systematic review has not been conducted yet. Therefore, this study analyzed how plants respond differently to combined salinity-drought stress compared to either stress alone. We initially retrieved 536 publications from databases and selected 30 research articles following a rigorous screening. Data on plant growth-related, physiological, and biochemical parameters were collected from these selected articles and analyzed. Overall, the combined salinity-drought stress has a greater negative impact on plant growth, photosynthesis, ionic balance, and oxidative balance than either stress alone. In some cases, salinity had a greater impact than drought stress and vice versa. Drought stress inhibited photosynthesis more than salinity, whereas salinity caused ionic imbalance more than drought stress. Single salinity and drought reduced shoot biomass equally, but salinity reduced root biomass more than drought. Plants experienced more oxidative stress under combined stress conditions because antioxidant levels did not increase in response to combined salinity-drought stress compared to individual salinity or drought stress. This study provided a comparative understanding of plants' responses to individual and combined salinity and drought stress, and identified several research gaps. More comprehensive genetic and physiological studies are needed to understand the intricate interplay between salinity and drought in plants.

Deciphering the Molecular Mechanisms of Chilling Tolerance in Lsi1-Overexpressing Rice

Improving tolerance to low-temperature stress during the rice seedling stage is of great significance in agricultural science. In this study, using the low silicon gene 1 (Lsi1)-overexpressing (Dular-OE) and wild-type rice (Dular-WT), we showed that Lsi1 overexpression enhances chilling tolerance in Dular-OE. The overexpression of the Lsi1 increases silicon absorption, but it was not the main reason for chilling tolerance in Dular-OE. Instead, our data suggest that the overexpression of a Lsi1-encoding NIP and its interaction with key proteins lead to chilling tolerance in Dular-OE. Additionally, we show that the high-mobility group protein (HMG1) binds to the promoter of Lsi1, positively regulating its expression. Moreover, Nod26-like major intrinsic protein (NIP)’s interaction with α and β subunits of ATP synthase and the 14-3-3f protein was validated by co-immunoprecipitation (Co-IP), bimolecular fluorescent complementary (BiFC), and GST-pulldown assays. Western blotting revealed that the overexpression of NIP positively regulates the ATP-synthase subunits that subsequently upregulate calcineurin B-like interacting protein kinases (CIPK) negatively regulating 14-3-3f. Overall, these NIP-mediated changes trigger corresponding pathways in an orderly manner, enhancing chilling tolerance in Dular-OE.

Silencing of SlMYB55 affects plant flowering and enhances tolerance to drought and salt stress in tomato

The transcription factors of the MYB family are involved in plant growth and development and responses to biotic and abiotic stresses. Here, we isolated the R2R3-MYB transcription factor gene SlMYB55 and found that it is responsive to abscisic acid (ABA), drought, and salt stress. Notably, the expression levels of multiple stress-related and inflorescence and flowering time-related genes were changed in SlMYB55-RNAi plants compared to wild-type plants. Transient tobacco expression experiments indicated that SlMYB55 directly targets the WUS and 4CL genes to regulate the development of inflorescence and flavonoid biosynthesis. Yeast two-hybrid experiments showed that the SlMYB55 protein interacts with the MADS-box family protein MBP21. Based on these results, we concluded that SlMYB55 affects the biosynthesis of ABA, regulates drought and salt responses through ABA-mediated signal transduction pathways, and directly or indirectly affects the expression of genes related to drought and salt response, flowering time, sepal size and inflorescence, thereby regulating stress tolerance and flower development. In summary, this study identified essential roles for SlMYB55 in regulating drought and salt tolerance and flower development.

Nitric oxide, crosstalk with stress regulators and plant abiotic stress tolerance

Nitric oxide is a dynamic gaseous molecule involved in signalling, crosstalk with stress regulators, and plant abiotic-stress responses. It has great exploratory potentials for engineering abiotic stress tolerance in crops. Nitric oxide (NO), a redox-active gaseous signalling molecule, though present uniformly through the eukaryotes, maintain its specificity in plants with respect to its formation, signalling, and functions. Its cellular concentrations are decisive for its function, as a signalling molecule at lower concentrations, but triggers nitro-oxidative stress and cellular damage when produced at higher concentrations. Besides, it also acts as a potent stress alleviator. Discovered in animals as neurotransmitter, NO has come a long way to being a stress radical and growth regulator in plants. As a key redox molecule, it exhibits several key cellular and molecular interactions including with reactive chemical species, hydrogen sulphide, and calcium. Apart from being a signalling molecule, it is emerging as a key player involved in regulations of plant growth, development and plant-environment interactions. It is involved in crosstalk with stress regulators and is thus pivotal in these stress regulatory mechanisms. NO is getting an unprecedented attention from research community, being investigated and explored for its multifaceted roles in plant abiotic stress tolerance. Through this review, we intend to present the current knowledge and updates on NO biosynthesis and signalling, crosstalk with stress regulators, and how biotechnological manipulations of NO pathway are leading towards developing transgenic crop plants that can withstand environmental stresses and climate change. The targets of various stress responsive miRNA signalling have also been discussed besides giving an account of current approaches used to characterise and detect the NO.

Drought, Salinity, and Low Nitrogen Differentially Affect the Growth and Nitrogen Metabolism of Sophora japonica (L.) in a Semi-Hydroponic Phenotyping Platform

Abiotic stresses, such as salinity, drought, and nutrient deficiency adversely affect nitrogen (N) uptake and assimilation in plants. However, the regulation of N metabolism and N pathway genes in Sophora japonica under abiotic stresses is unclear. Sophora japonica seedlings were subjected to drought (5% polyethylene glycol 6,000), salinity (75mM NaCl), or low N (0.01mM NH₄NO₃) for 3weeks in a semi-hydroponic phenotyping platform. Salinity and low N negatively affected plant growth, while drought promoted root growth and inhibited aboveground growth. The NH₄ ⁺/NO₃ ^- ratio increased under all three treatments with the exception of a reduction in leaves under salinity. Drought significantly increased leaf NO₂ ^- concentrations. Nitrate reductase (NR) activity was unaltered or increased under stresses with the exception of a reduction in leaves under salinity. Drought enhanced ammonium assimilation with increased glutamate synthase (GOGAT) activity, although glutamine synthetase (GS) activity remained unchanged, whereas salinity and low N inhibited ammonium assimilation with decreased GS activity under salt stress and decreased GOGAT activity under low N treatment. Glutamate dehydrogenase (GDH) activity also changed dramatically under different stresses. Additionally, expression changes of genes involved in N reduction and assimilation were generally consistent with related enzyme activities. In roots, ammonium transporters, especially SjAMT1.1 and SjAMT2.1a, showed higher transcription under all three stresses; however, most nitrate transporters (NRTs) were upregulated under salinity but unchanged under drought. SjNRT2.4, SjNRT2.5, and SjNRT3.1 were highly induced by low N. These results indicate that N uptake and metabolism processes respond differently to drought, salinity, and low N conditions in S. japonica seedlings, possibly playing key roles in plant resistance to environmental stress.