The barley miR393 has multiple roles in regulation of seedling growth, stomatal density, and drought stress tolerance

miRNAs: Primary modulators of plant drought tolerance

Drought is a principal environmental factor that affects the growth and development of plants. Accordingly, plants have evolved adaptive mechanisms to cope with adverse environmental conditions. One of the mechanisms is gene regulation mediated by microRNAs (miRNAs). miRNAs are regarded as primary modulators of gene expression at the post-transcriptional level and have been shown to participate in drought stress response, including ABA response, auxin signaling, antioxidant defense, and osmotic regulation through downregulating the corresponding targets. miRNA-based genetic reconstructions have the potential to improve the tolerance of plants to drought. However, there are few precise classification and discussion of miRNAs in specific response behaviors to drought stress and their applications. This review summarized and discussed the specific response behaviors of miRNAs under drought stress and the role of miRNAs as regulators in the response of plants to drought and highlighted that the modification of miRNAs might effectively improve the tolerance of plants to drought.

Creating Climate-Resilient Crops by Increasing Drought, Heat, and Salt Tolerance

Over the years, the changes in the agriculture industry have been inevitable, considering the need to feed the growing population. As the world population continues to grow, food security has become challenged. Resources such as arable land and freshwater have become scarce due to quick urbanization in developing countries and anthropologic activities; expanding agricultural production areas is not an option. Environmental and climatic factors such as drought, heat, and salt stresses pose serious threats to food production worldwide. Therefore, the need to utilize the remaining arable land and water effectively and efficiently and to maximize the yield to support the increasing food demand has become crucial. It is essential to develop climate-resilient crops that will outperform traditional crops under any abiotic stress conditions such as heat, drought, and salt, as well as these stresses in any combinations. This review provides a glimpse of how plant breeding in agriculture has evolved to overcome the harsh environmental conditions and what the future would be like.

Stomatal improvement for crop stress resistance

The growth and yield of crop plants are threatened by environmental challenges such as water deficit, soil flooding, high salinity, and extreme temperatures, which are becoming increasingly severe under climate change. Stomata contribute greatly to plant adaptation to stressful environments by governing transpirational water loss and photosynthetic gas exchange. Increasing evidence has revealed that stomata formation is shaped by transcription factors, signaling peptides, and protein kinases, which could be exploited to improve crop stress resistance. The past decades have seen unprecedented progress in our understanding of stomata formation, but most of these advances have come from research on model plants. This review highlights recent research in stomata formation in crops and its multifaceted functions in abiotic stress tolerance. Current strategies, limitations, and future directions for harnessing stomatal development to improve crop stress resistance are discussed.

The Emerging Role of Non-Coding RNAs (ncRNAs) in Plant Growth, Development, and Stress Response Signaling

Plant species utilize a variety of regulatory mechanisms to ensure sustainable productivity. Within this intricate framework, numerous non-coding RNAs (ncRNAs) play a crucial regulatory role in plant biology, surpassing the essential functions of RNA molecules as messengers, ribosomal, and transfer RNAs. ncRNAs represent an emerging class of regulators, operating directly in the form of small interfering RNAs (siRNAs), microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs). These ncRNAs exert control at various levels, including transcription, post-transcription, translation, and epigenetic. Furthermore, they interact with each other, contributing to a variety of biological processes and mechanisms associated with stress resilience. This review primarily concentrates on the recent advancements in plant ncRNAs, delineating their functions in growth and development across various organs such as root, leaf, seed/endosperm, and seed nutrient development. Additionally, this review broadens its scope by examining the role of ncRNAs in response to environmental stresses such as drought, salt, flood, heat, and cold in plants. This compilation offers updated information and insights to guide the characterization of the potential functions of ncRNAs in plant growth, development, and stress resilience in future research.

Whole-Transcriptome Sequencing Reveals the Global Molecular Responses and NAC Transcription Factors Involved in Drought Stress in Dendrobium catenatum

Dendrobium catenatum is a highly drought-tolerant herb, which usually grows on cliffs or in the branches of trees, yet the underlying molecular mechanisms for its tolerance remain poorly understood. We conducted a comprehensive study utilizing whole-transcriptome sequencing approaches to investigate the molecular response to extreme drought stress in D. catenatum. A large number of differentially expressed mRNAs, lncRNAs, and circRNAs have been identified, and the NAC transcription factor family was highly enriched. Meanwhile, 46 genes were significantly up-regulated in the ABA-activated signaling pathway. In addition to the 89 NAC family members accurately identified in this study, 32 members were found to have different expressions between the CK and extreme drought treatment. They may regulate drought stress through both ABA-dependent and ABA-independent pathways. Moreover, the 32 analyzed differentially expressed DcNACs were found to be predominantly expressed in the floral organs and roots. The ceRNA regulatory network showed that DcNAC87 is at the core of the ceRNA network and is regulated by miR169, miR393, and four lncRNAs. These investigations provided valuable information on the role of NAC transcription factors in D. catenatum's response to drought stress.

Update on stomata development and action under abiotic stress

Stomata, key gatekeepers of plant hydration, have long been known to play a pivotal role in mitigating the impacts of abiotic stressors. However, the complex molecular mechanisms underscoring this role remain unresolved fully and continue to be the subject of research. In the context of water-use efficiency (WUE), a key indicator of a plant's ability to conserve water, this aspect links intrinsically with stomatal behavior. Given the pivotal role of stomata in modulating water loss, it can be argued that the complex mechanisms governing stomatal development and function will significantly influence a plant's WUE under different abiotic stress conditions. Addressing these calls for a concerted effort to strengthen plant adaptability through advanced, targeted research. In this vein, recent studies have illuminated how specific stressors trigger alterations in gene expression, orchestrating changes in stomatal pattern, structure, and opening. This reveals a complex interplay between stress stimuli and regulatory sequences of essential genes implicated in stomatal development, such as MUTE, SPCH, and FAMA. This review synthesizes current discoveries on the molecular foundations of stomatal development and behavior in various stress conditions and their implications for WUE. It highlights the imperative for continued exploration, as understanding and leveraging these mechanisms guarantee enhanced plant resilience amid an ever-changing climatic landscape.

MicroRNA: A Dynamic Player from Signalling to Abiotic Tolerance in Plants

MicroRNAs (miRNAs) are a class of non-coding single-stranded RNA molecules composed of approximately 20-24 nucleotides in plants. They play an important regulatory role in plant growth and development and as a signal in abiotic tolerance. Some abiotic stresses include drought, salt, cold, high temperature, heavy metals and nutritional elements. miRNAs affect gene expression by manipulating the cleavage, translational expression or DNA methylation of target messenger RNAs (mRNAs). This review describes the current progress in the field considering two aspects: (i) the way miRNAs are produced and regulated and (ii) the way miRNA/target genes are used in plant responses to various abiotic stresses. Studying the molecular mechanism of action of miRNAs' downstream target genes could optimize the genetic manipulation of crop growth and development conditions to provide a more theoretically optimized basis for improving crop production. MicroRNA is a novel signalling mechanism in interplant communication relating to abiotic tolerance.

Abiotic Stress in Crop Production

The vast majority of agricultural land undergoes abiotic stress that can significantly reduce agricultural yields. Understanding the mechanisms of plant defenses against stresses and putting this knowledge into practice is, therefore, an integral part of sustainable agriculture. In this review, we focus on current findings in plant resistance to four cardinal abiotic stressors—drought, heat, salinity, and low temperatures. Apart from the description of the newly discovered mechanisms of signaling and resistance to abiotic stress, this review also focuses on the importance of primary and secondary metabolites, including carbohydrates, amino acids, phenolics, and phytohormones. A meta-analysis of transcriptomic studies concerning the model plant Arabidopsis demonstrates the long-observed phenomenon that abiotic stressors induce different signals and effects at the level of gene expression, but genes whose regulation is similar under most stressors can still be traced. The analysis further reveals the transcriptional modulation of Golgi-targeted proteins in response to heat stress. Our analysis also highlights several genes that are similarly regulated under all stress conditions. These genes support the central role of phytohormones in the abiotic stress response, and the importance of some of these in plant resistance has not yet been studied. Finally, this review provides information about the response to abiotic stress in major European crop plants—wheat, sugar beet, maize, potatoes, barley, sunflowers, grapes, rapeseed, tomatoes, and apples.

Yellowhorn Xso-miR5149-XsGTL1 enhances water-use efficiency and drought tolerance by regulating leaf morphology and stomatal density

Yellowhorn (Xanthoceras sorbifolium) is a unique edible woody oil tree species in China. Drought stress is the major yield-limiting factor of yellowhorn. MicroRNAs play an important role in regulating the response of woody plants to drought stress. However, the regulatory function of miRNAs in yellowhorn remains unclear. Here, we first constructed coregulatory networks integrated with miRNAs and their target genes. According to GO function and expression pattern analysis, we selected the Xso-miR5149-XsGTL1 module for further study. Xso-miR5149 is a key regulator of leaf morphology and stomatal density by directly mediating the expression of the transcription factor XsGTL1. Downregulation of XsGTL1 in yellowhorn led to increased leaf area and reduced stomatal density. RNA-seq analysis indicated that downregulation of XsGTL1 increased the expression of genes involved in the negative control of stomatal density, leaf morphology, and drought tolerance. After drought stress treatments, the XsGTL1-RNAi yellowhorn plants were less damaged and had higher water-use efficiency than the WT plants, while destruction of Xso-miR5149 or overexpression of XsGTL1 had the opposite effect. Our findings indicated that the Xso-miR5149-XsGTL1 regulatory module plays a critical role in controlling leaf morphology and stomatal density; hence, it's a potential candidate module for engineering enhanced drought tolerance in yellowhorn.

How Does Stomatal Density and Residual Transpiration Contribute to Osmotic Stress Tolerance?

Osmotic stress that is induced by salinity and drought affects plant growth and development, resulting in significant losses to global crop production. Consequently, there is a strong need to develop stress-tolerant crops with a higher water use efficiency through breeding programs. Water use efficiency could be improved by decreasing stomatal transpiration without causing a reduction in CO₂ uptake under osmotic stress conditions. The genetic manipulation of stomatal density could be one of the most promising strategies for breeders to achieve this goal. On the other hand, a substantial amount of water loss occurs across the cuticle without any contribution to carbon gain when the stomata are closed and under osmotic stress. The minimization of cuticular (otherwise known as residual) transpiration also determines the fitness and survival capacity of the plant under the conditions of a water deficit. The deposition of cuticular wax on the leaf epidermis acts as a limiting barrier for residual transpiration. However, the causal relationship between the frequency of stomatal density and plant osmotic stress tolerance and the link between residual transpiration and cuticular wax is not always straightforward, with controversial reports available in the literature. In this review, we focus on these controversies and explore the potential physiological and molecular aspects of controlling stomatal and residual transpiration water loss for improving water use efficiency under osmotic stress conditions via a comparative analysis of the performance of domesticated crops and their wild relatives.

Plant responses to drought stress: microRNAs in action

Drought is common in most regions of the world, and it has a significant impact on plant growth and development. Plants, on the other hand, have evolved their own defense systems to deal with the extreme weather. The reprogramming of gene expression by microRNAs (miRNAs) is one of these defense mechanisms. miRNAs are short noncoding RNAs that have emerged as key post-transcriptional gene regulators in a variety of species. Drought stress modulates the expression of certain miRNAs that are functionally conserved across plant species. These characteristics imply that miRNA-based genetic changes might improve drought resistance in plants. This study highlights current knowledge of plant miRNA biogenesis, regulatory mechanisms and their role in drought stress responses. miRNAs functions and their adaptations by plants during drought stress has also been explained that can be exploited to promote drought-resistance among economically important crops.

What Do We Know about Barley miRNAs?

Plant miRNAs are powerful regulators of gene expression at the post-transcriptional level, which was repeatedly proved in several model plant species. miRNAs are considered to be key regulators of many developmental, homeostatic, and immune processes in plants. However, our understanding of plant miRNAs is still limited, despite the fact that an increasing number of studies have appeared. This systematic review aims to summarize our current knowledge about miRNAs in spring barley (Hordeum vulgare), which is an important agronomical crop worldwide and serves as a common monocot model for studying abiotic stress responses as well. This can help us to understand the connection between plant miRNAs and (not only) abiotic stresses in general. In the end, some future perspectives and open questions are summarized.

Maize Lethal Necrosis disease: review of molecular and genetic resistance mechanisms, socio-economic impacts, and mitigation strategies in sub-Saharan Africa

BACKGROUND

Maize lethal necrosis (MLN) disease is a significant constraint for maize producers in sub-Saharan Africa (SSA). The disease decimates the maize crop, in some cases, causing total crop failure with far-reaching impacts on regional food security.

RESULTS

In this review, we analyze the impacts of MLN in Africa, finding that resource-poor farmers and consumers are the most vulnerable populations. We examine the molecular mechanism of MLN virus transmission, role of vectors and host plant resistance identifying a range of potential opportunities for genetic and phytosanitary interventions to control MLN. We discuss the likely exacerbating effects of climate change on the MLN menace and describe a sobering example of negative genetic association between tolerance to heat/drought and susceptibility to viral infection. We also review role of microRNAs in host plant response to MLN causing viruses as well as heat/drought stress that can be carefully engineered to develop resistant varieties using novel molecular techniques.

CONCLUSIONS

With the dual drivers of increased crop loss due to MLN and increased demand of maize for food, the development and deployment of simple and safe technologies, like resistant cultivars developed through accelerated breeding or emerging gene editing technologies, will have substantial positive impact on livelihoods in the region. We have summarized the available genetic resources and identified a few large-effect QTLs that can be further exploited to accelerate conversion of existing farmer-preferred varieties into resistant cultivars.

Integration of mRNA and microRNA analysis reveals the molecular mechanisms underlying drought stress tolerance in maize (Zea mays L.)

Drought is among the most serious environmental issue globally, and seriously affects the development, growth, and yield of crops. Maize (Zea mays L.), an important crop and industrial raw material, is planted on a large scale worldwide and drought can lead to large-scale reductions in maize corn production; however, few studies have focused on the maize root system mechanisms underlying drought resistance. In this study, miRNA-mRNA analysis was performed to deeply analyze the molecular mechanisms involved in drought response in the maize root system under drought stress. Furthermore, preliminary investigation of the biological function of miR408a in the maize root system was also conducted. The morphological, physiological, and transcriptomic changes in the maize variety "M8186" at the seedling stage under 12% PEG 6000 drought treatment (0, 7, and 24 h) were analyzed. With prolonged drought stress, seedlings gradually withered, the root system grew significantly, and abscisic acid, brassinolide, lignin, glutathione, and trehalose content in the root system gradually increased. Furthermore, peroxidase activity increased, while gibberellic acid and jasmonic acid gradually decreased. Moreover, 32 differentially expressed miRNAs (DEMIRs), namely, 25 known miRNAs and 7 new miRNAs, and 3,765 differentially expressed mRNAs (DEMRs), were identified in maize root under drought stress by miRNA-seq and mRNA-seq analysis, respectively. Through combined miRNA-mRNA analysis, 16 miRNA-target gene pairs, comprising 9 DEMIRs and 15 DEMRs, were obtained. In addition, four metabolic pathways, namely, "plant hormone signal transduction", "phenylpropane biosynthesis", "glutathione metabolism", and "starch and sucrose metabolism", were predicted to have important roles in the response of the maize root system to drought. MiRNA and mRNA expression results were verified by real-time quantitative PCR. Finally, miR408a was selected for functional analysis and demonstrated to be a negative regulator of drought response, mainly through regulation of reactive oxygen species accumulation in the maize root system. This study helps to elaborate the regulatory response mechanisms of the maize root system under drought stress and predicts the biological functions of candidate miRNAs and mRNAs, providing strategies for subsequent mining for, and biological breeding to select for, drought-responsive genes in the maize root system.

The miR393-Target Module Regulates Plant Development and Responses to Biotic and Abiotic Stresses

MicroRNAs (miRNAs), a class of endogenous small RNAs, are broadly involved in plant development, morphogenesis and responses to various environmental stresses, through manipulating the cleavage, translational expression, or DNA methylation of target mRNAs. miR393 is a conserved miRNA family present in many plants, which mainly targets genes encoding the transport inhibitor response1 (TIR1)/auxin signaling F-box (AFB) auxin receptors, and thus greatly affects the auxin signal perception, Aux/IAA degradation, and related gene expression. This review introduces the advances made on the miR393/target module regulating plant development and the plant’s responses to biotic and abiotic stresses. This module is valuable for genetic manipulation of optimized conditions for crop growth and development and would also be helpful in improving crop yield through molecular breeding.

Identification and profiling of conserved microRNAs in different developmental stages of crown imperial (Fritillaria imperialis L.) using high-throughput sequencing

BACKGROUND

Novel strategies for improvement of ornamental plants and their properties relay on miRNA control of differential plant gene expression modulation. Still, in response to the same abiotic stresses, some conserved miRNA families show different expression patterns in different plant species. In parallel, the use of deep sequencing technologies reveals new levels of complexity of regulatory networks in plants through identification of new miRNAs.

METHODS AND RESULTS

Fritillaria imperialis plants were collected from their natural habitats in Koohrang, Chaharmahal va Bakhtiari, Iran. Several tissues including stamen, pistil, petal, sepal, leaf, stem, bulb and fruit were collected during three developmental stages (stem elongation, flower development and seed head stages). Using RNAseq and qRT-PCR approach, this research revealed 21 conserved miRNAs, matching 15 miRNA families, in Fritilaria imperialis.

CONCLUSIONS

The expression of seven conserved miRNAs (Fim-miR156b, Fim-miR159, Fim-miR166a-5p, Fim-miR169d-5p, Fim-miR171c, Fim-miR393 and Fim-miR396e-3p) was further investigated in different tissues and three developmental stages, suggesting different roles for these miRNAs during growth and development of crown imperial. Gained knowledge from this research can open the door to find efficient ways to secure crown imperial survival, preservation and utilization and if proven useful may be applied in other plant species as well.

Integrated analysis of miRNA-mRNA regulatory networks of potato (Solanum tuberosum L.) in response to cadmium stress

Cadmium (Cd) stress is a ubiquitous abiotic stress affecting plant growth worldwide and negatively impacting crop yield and food safety. Potato is the most important non-grain crop globally, but there is limited research available on the response of this crop to Cd stress. This study explored the coping mechanism for Cd stress in potato through analyses of miRNA and mRNA. Tissue culture seedlings (20-day-old) of potato variety 'Atlantic' were cultured for up to 48 h in liquid medium containing 5 mmol/L CdCl2, and phenotypic, physiological, and transcriptomic changes were observed at specific times. With the extension of Cd stress time, the potato leaves gradually wilted and curled, and root salicylic acid (SA), glutathione (GSH), and lignin contents and peroxidase (POD) activity increased, while indole-3-acetic acid (IAA) and zeatin (ZT) contents decreased. Using miRNA-seq, 161 existing miRNAs, 383 known miRNAs, and 7361 novel miRNAs were identified, and, 18 miRNAs were differentially expressed in response to Cd stress. Based on mRNA-seq, 7340 differentially expressed mRNAs (DEGs) were found. Through mRNA-miRNA integrated analysis, miRNA-target gene pairs consisting of 23 DEGs and 33 miRNAs were identified. Furthermore, "glutathione metabolism" "plant hormone signal transduction" and "phenylpropanoid biosynthesis" were established as crucial pathways in the Cd stress response of potato. Novel miRNAs novel-m3483-5p and novel-m2893-5p participate in these pathways through targeted regulation of cinnamic alcohol dehydrogenase (CAD; PG0005359) and alanine aminotransferase (POP; PG0024281), respectively. This study provides information that will help elucidate the complex mechanism of the Cd stress response in potato. Moreover, candidate miRNAs and mRNAs could yield new strategies for the development of Cd-tolerant potato breeding.

Knockdown of miR393 Promotes the Growth and Biomass Production in Poplar

Short tandem target mimic (STTM), which is composed of two short sequences mimicking small RNA target sites, separated by a linker of optimal size, can block the functions of all members in a miRNA family. microRNA393 (miR393), which is one of the conserved miRNA families in plants, can regulate plant root growth, leaf development, plant architecture, and stress resistance. In order to verify the role of miR393 in the secondary growth of trees, we created its STTM transgenic poplar lines (STTM393). The expression of miR393 in STTM393 lines was reduced by over 10 times compared with the control plants. STTM393 lines showed promoted growth with about 20% higher, 15% thicker, and 2-4 more internodes than the control plants after 3 months of growth. The cross-section of the stems showed that STTM393 lines had wider phloem, xylem, and more cambium cell layers than control plants, and the lignin content in STTM393 lines was also higher as revealed by staining and chemical determination. Based on the transcriptome analysis, the genes related to the auxin signaling pathway, cell cyclin, cell expansion, and lignin synthesis had higher expression in STTM393 lines than that in control plants. The higher expression levels of FBL family members suggested that the auxin signaling pathway was strengthened in STTM393 lines to promote plant growth. Therefore, the knockdown of miR393 using the STTM approach provides a way to improve poplar growth and biomass production.

Mdm-MIR393b-mediated adventitious root formation by targeted regulation of MdTIR1A expression and weakened sensitivity to auxin in apple rootstock

Adventitious root (AR) formation is of great significance for apple rootstock breeding. It is widely accepted that miR393 influences AR formation in many plant species; however, the molecular mechanism by which factors regulate AR formation remains insufficient. In this study, the evolutionary relationship of mdm-miR393 and candidate target genes MdTIR1/AFB was systematically identified, and the expression patterns were analysed. Multisequence alignment analysis of miR393 family members suggests that miR393 conservatively evolved between different species. The evolutionary relationship of the TIR1/AFBs can be divided into G1, G2 and G3 subgroups. During AR formation, the expression level of mdm-miR393a/b/c was significantly upregulated at 1 d and 7 d by exogenous auxin treatment. Furthermore, the expression levels of MdTIR1A, MdTIR1D, MdAFB1, MdAFB2, MdAFB3, MdAFB4 and MdAFB8 also appeared to be significantly changed by exogenous auxin induction. Subsequently, tissue-specific expression analysis showed that the expression levels of mdm-miR393 and MdTIR1/AFBs in different tissues exhibited significant differences. The promoter of mdm-miR393 contains multiple elements that respond to ABA, adversity and light signals; auxin treatment can activate the mdm-MIR393b promoter but is obviously inhibited by NPA treatment. The targeting relationship between mdm-MIR393b and MdTIR1A was verified by expression patterns, degradation group data, transient tobacco conversion results, and genes functions experiments. Heterologous overexpression of mdm-MIR393b (35S::mdm-MIR393b) decreased the number of ARs in the phenotype and reduced the expression level of the target gene NtTIR1 in tobacco. Compared to the wild type, the 35S::mdm-MIR393b transgenic plants demonstrated insensitivity to auxin. Furthermore, tir1 mutant exhibited reduced root system structure relative to the control. The above results illustrated that mdm-MIR393b is involved in mediating AR formation by targeted regulation of MdTIR1A expression in apple rootstock.

Crosstalk between phytohormones and secondary metabolites in the drought stress tolerance of crop plants: A review

Drought stress negatively affects crop performance and weakens global food security. It triggers the activation of downstream pathways, mainly through phytohormones homeostasis and their signaling networks, which further initiate the biosynthesis of secondary metabolites (SMs). Roots sense drought stress, the signal travels to the above-ground tissues to induce systemic phytohormones signaling. The systemic signals further trigger the biosynthesis of SMs and stomatal closure to prevent water loss. SMs primarily scavenge reactive oxygen species (ROS) to protect plants from lipid peroxidation and also perform additional defense-related functions. Moreover, drought-induced volatile SMs can alert the plant tissues to perform drought stress mitigating functions in plants. Other phytohormone-induced stress responses include cell wall and cuticle thickening, root and leaf morphology alteration, and anatomical changes of roots, stems, and leaves, which in turn minimize the oxidative stress, water loss, and other adverse effects of drought. Exogenous applications of phytohormones and genetic engineering of phytohormones signaling and biosynthesis pathways mitigate the drought stress effects. Direct modulation of the SMs biosynthetic pathway genes or indirect via phytohormones' regulation provides drought tolerance. Thus, phytohormones and SMs play key roles in plant development under the drought stress environment in crop plants.

Response of Root Growth and Development to Nitrogen and Potassium Deficiency as well as microRNA-Mediated Mechanism in Peanut (Arachis hypogaea L.)

The mechanism of miRNA-mediated root growth and development in response to nutrient deficiency in peanut (Arachis hypogaea L.) is still unclear. In the present study, we found that both nitrogen (N) and potassium (K) deficiency resulted in a significant reduction in plant growth, as indicated by the significantly decreased dry weight of both shoot and root tissues under N or K deficiency. Both N and K deficiency significantly reduced the root length, root surface area, root volume, root vitality, and weakened root respiration, as indicated by the reduced O₂ consuming rate. N deficiency significantly decreased primary root length and lateral root number, which might be associated with the upregulation of miR160, miR167, miR393, and miR396, and the downregulation of AFB3 and GRF. The primary and lateral root responses to K deficiency were opposite to that of the N deficiency condition. The upregulated miR156, miR390, NAC4, ARF2, and AFB3, and the downregulated miR160, miR164, miR393, and SPL10 may have contributed to the growth of primary roots and lateral roots under K deficiency. Overall, roots responded differently to the N or K deficiency stresses in peanuts, potentially due to the miRNA-mediated pathway and mechanism.