Overexpression of AtERF019 delays plant growth and senescence, and improves drought tolerance in Arabidopsis

ACRE, a class of AP2/ERF transcription factors, activates the expression of sweet potato ß-amylase and sporamin genes through the sugar-responsible element CMSRE-1

Sugars, synthesized by photosynthesis in source organs, are loaded and utilized as an energy source and carbon skeleton in sink organs, and also known to be important signal molecules regulating gene expression in higher plants. The expression of genes coding for sporamin and β-amylase, the two most abundant proteins in storage roots of sweet potato, is coordinately induced by sugars. We previously reported on the identification of the carbohydrate metabolic signal-responsible element-1 (CMSRE-1) essential for the sugar-responsible expression of two genes. However, transcription factors that bind to this sequence have not been identified. In this study, we performed yeast one-hybrid screening using the sugar-responsible minimal promoter region of the ß-amylase gene as bait and a library composed only transcription factor cDNAs of Arabidopsis. Two clones, named Activator protein binding to CMSRE-1 (ACRE), encoding AP2/ERF transcription factors were isolated. ACRE showed transactivation activity of the sugar-responsible minimal promoter in a CMSRE-1-dependent manner in Arabidopsis protoplasts. Electric mobility shift assay (EMSA) using recombinant proteins and transient co-expression assay in Arabidopsis protoplasts revealed that ACRE could actually act to the CMSRE-1. Among the DEHYDRATION -RESPONSIVE ELEMENT BINDING FACTOR (DREB) subfamily, almost all homologs including ACRE, could act on the DRE, while only three ACREs could act to the CMSRE-1. Moreover, ACRE-homologs of Japanese morning glory also have the same property of DNA-binding preference and transactivation activity through the CMSRE-1. These findings suggested that ACRE plays an important role in the mechanism regulating the sugar-responsible gene expression through the CMSRE-1 conserved across plant species.

Identification of candidate regulators of the response to early heat stress in climate-adapted wheat landraces via transcriptomic and co-expression network analyses

Introduction

Climate change is likely to lead to not only increased global temperatures but also a more variable climate where unseasonal periods of heat stress are more prevalent. This has been evidenced by the observation of spring-time temperatures approaching 40°C in some of the main spring-wheat producing countries, such as the USA, in recent years. With an optimum growth temperature of around 20°C, wheat is particularly prone to damage by heat stress. A warming climate with increasingly common fluctuations in temperature therefore threatens wheat crops and subsequently the lives and livelihoods of billions of people who depend on the crop for food. To futureproof wheat against a variable climate, a better understanding of the response to early heat stress is required.

Methods

Here, we utilised DESeq2 to identify 7,827 genes which were differentially expressed in wheat landraces after early heat stress exposure. Candidate hub genes, which may regulate the transcriptional response to early heat stress, were identified via weighted gene co-expression network analysis (WGCNA), and validated by qRT-PCR.

Results

Two of the most promising candidate hub genes (TraesCS3B02G409300 and TraesCS1B02G384900) may downregulate the expression of genes involved in the drought, salinity, and cold responses-genes which are unlikely to be required under heat stress-as well as photosynthesis genes and stress hormone signalling repressors, respectively. We also suggest a role for a poorly characterised sHSP hub gene (TraesCS4D02G212300), as an activator of the heat stress response, potentially inducing the expression of a vast suite of heat shock proteins and transcription factors known to play key roles in the heat stress response.

Discussion

The present work represents an exploratory examination of the heat-induced transcriptional change in wheat landrace seedlings and identifies several candidate hub genes which may act as regulators of this response and, thus, may be targets for breeders in the production of thermotolerant wheat varieties.

Effect of ethylene pretreatment on tomato plant responses to salt, drought, and waterlogging stress

Salinity, drought, and waterlogging are common environmental stresses that negatively impact plant growth, development, and productivity. One of the responses to abiotic stresses is the production of the phytohormone ethylene, which induces different coping mechanisms that help plants resist or tolerate stress. In this study, we investigated if an ethylene pretreatment can aid plants in activating stress-coping responses prior to the onset of salt, drought, and waterlogging stress. Therefore, we measured real-time transpiration and CO2 assimilation rates and the impact on biomass during and after 3 days of abiotic stress. Our results showed that an ethylene pretreatment of 1 ppm for 4 h did not significantly influence the negative effects of waterlogging stress, while plants were more sensitive to salt stress as reflected by enhanced water losses due to a higher transpiration rate. However, when exposed to drought stress, an ethylene pretreatment resulted in reduced transpiration rates, reducing water loss during drought stress. Overall, our findings indicate that pretreating tomato plants with ethylene can potentially regulate their responses during the forthcoming stress period, but optimization of the ethylene pre-treatment duration, timing, and dose is needed. Furthermore, it remains tested if the effect is related to the stress duration and severity and whether an ethylene pretreatment has a net positive or negative effect on plant vigor during stress recovery. Further investigations are needed to elucidate the mode of action of how ethylene priming impacts subsequent stress responses.

Harnessing genetic resistance to rusts in wheat and integrated rust management methods to develop more durable resistant cultivars

Wheat is one of the most important staple foods on earth. Leaf rust, stem rust and stripe rust, caused by Puccini triticina, Puccinia f. sp. graminis and Puccinia f. sp. striiformis, respectively, continue to threaten wheat production worldwide. Utilization of resistant cultivars is the most effective and chemical-free strategy to control rust diseases. Convectional and molecular biology techniques identified more than 200 resistance genes and their associated markers from common wheat and wheat wild relatives, which can be used by breeders in resistance breeding programmes. However, there is continuous emergence of new races of rust pathogens with novel degrees of virulence, thus rendering wheat resistance genes ineffective. An integration of genomic selection, genome editing, molecular breeding and marker-assisted selection, and phenotypic evaluations is required in developing high quality wheat varieties with resistance to multiple pathogens. Although host genotype resistance and application of fungicides are the most generally utilized approaches for controlling wheat rusts, effective agronomic methods are required to reduce disease management costs and increase wheat production sustainability. This review gives a critical overview of the current knowledge of rust resistance, particularly race-specific and non-race specific resistance, the role of pathogenesis-related proteins, non-coding RNAs, and transcription factors in rust resistance, and the molecular basis of interactions between wheat and rust pathogens. It will also discuss the new advances on how integrated rust management methods can assist in developing more durable resistant cultivars in these pathosystems.

Transcriptome Sequencing and Metabolome Analysis Reveals the Molecular Mechanism of Drought Stress in Millet

As one of the oldest agricultural crops in China, millet (Panicum miliaceum) has powerful drought tolerance. In this study, transcriptome and metabolome analyses of ‘Hequ Red millet’ (HQ) and ‘Yanshu No.10’ (YS10) millet after 6 h of drought stress were performed. Transcriptome characteristics of drought stress in HQ and YS10 were characterized by Pacbio full-length transcriptome sequencing. The pathway analysis of the differentially expressed genes (DEGs) showed that the highly enriched categories were related to starch and sucrose metabolism, pyruvate metabolism, metabolic pathways, and the biosynthesis of secondary metabolites when the two millet varieties were subjected to drought stress. Under drought stress, 245 genes related to energy metabolism were found to show significant changes between the two strains. Further analysis showed that 219 genes related to plant hormone signal transduction also participated in the drought response. In addition, numerous genes involved in anthocyanin metabolism and photosynthesis were confirmed to be related to drought stress, and these genes showed significant differential expression and played an important role in anthocyanin metabolism and photosynthesis. Moreover, we identified 496 transcription factors related to drought stress, which came from 10 different transcription factor families, such as bHLH, C3H, MYB, and WRKY. Further analysis showed that many key genes related to energy metabolism, such as citrate synthase, isocitrate dehydrogenase, and ATP synthase, showed significant upregulation, and most of the structural genes involved in anthocyanin biosynthesis also showed significant upregulation in both strains. Most genes related to plant hormone signal transduction showed upregulated expression, while many JA and SA signaling pathway-related genes were downregulated. Metabolome analysis was performed on ‘Hequ red millet’ (HQ) and ‘Yanshu 10’ (YS10), a total of 2082 differential metabolites (DEMs) were identified. These findings indicate that energy metabolism, anthocyanins, photosynthesis, and plant hormones are closely related to the drought resistance of millet and adapt to adversity by precisely regulating the levels of various molecular pathways.

The AP2/ERF GmERF113 Positively Regulates the Drought Response by Activating GmPR10-1 in Soybean

Ethylene response factors (ERFs) are involved in biotic and abiotic stress; however, the drought resistance mechanisms of many ERFs in soybeans have not been resolved. Previously, we proved that GmERF113 enhances resistance to the pathogen Phytophthora sojae in soybean. Here, we determined that GmERF113 is induced by 20% PEG-6000. Compared to the wild-type plants, soybean plants overexpressing GmERF113 (GmERF113-OE) displayed increased drought tolerance which was characterized by milder leaf wilting, less water loss from detached leaves, smaller stomatal aperture, lower Malondialdehyde (MDA) content, increased proline accumulation, and higher Superoxide dismutase (SOD) and Peroxidase (POD) activities under drought stress, whereas plants with GmERF113 silenced through RNA interference were the opposite. Chromatin immunoprecipitation and dual effector-reporter assays showed that GmERF113 binds to the GCC-box in the GmPR10-1 promoter, activating GmPR10-1 expression directly. Overexpressing GmPR10-1 improved drought resistance in the composite soybean plants with transgenic hairy roots. RNA-seq analysis revealed that GmERF113 downregulates abscisic acid 8′-hydroxylase 3 (GmABA8’-OH 3) and upregulates various drought-related genes. Overexpressing GmERF113 and GmPR10-1 increased the abscisic acid (ABA) content and reduced the expression of GmABA8’-OH3 in transgenic soybean plants and hairy roots, respectively. These results reveal that the GmERF113-GmPR10-1 pathway improves drought resistance and affects the ABA content in soybean, providing a theoretical basis for the molecular breeding of drought-tolerant soybean.

MrERF, MrbZIP, and MrSURNod of Medicago ruthenica Are Involved in Plant Growth and Abiotic Stress Response

Abiotic stresses affect plant growth and productivity. The outstanding stress resistance of Medicago ruthenica makes it a desirable gene resource to improve the stress tolerance of other plants. The roles of three differently expressed genes [(DEGs) (MrERF, MrbZIP, and MrSURNod)] from M. ruthenica in stress resistance have not been fully elucidated. Therefore, we constructed their expression vectors, transformed them into tobacco, and subjected transgenic lines to abiotic stresses. Through comprehensive bioinformatics, transcriptomic, morphological, and physiological analyses of transgenic lines, we have revealed the critical role of these three DEGs in plant growth and abiotic stress response. The upregulation of genes enhanced the germination rate, biomass, root length number, etc. Additionally, the accumulation of osmolytes increased the activity of antioxidant enzymes. These genes are also associated with improved seed yield, increased branching, and early flowering, thereby shortening the growth period. Potentially, this is one of the ways for tobacco to cope with stress. Furthermore, the resistance of transgenic tobacco expressing MrERF or MrbZIP was better than that with MrSURNod. MrERF and MrbZIP can improve drought and salt tolerance of plants, whereas MrSURNod is beneficial in improving drought and cold resistance. Moreover, MrERF or MrbZIP can promote root elongation and increase the root number, whereas MrSURNod mainly promotes root elongation. This may be the reason why stress resistance conferred by MrSURNod is weaker than that associated with the other two genes. Overall, MrERF, MrbZIP, and MrSURNod positively modulate plant growth and stress tolerance.

Phytohormones Trigger Drought Tolerance in Crop Plants: Outlook and Future Perspectives

In the past and present, human activities have been involved in triggering global warming, causing drought stresses that affect animals and plants. Plants are more defenseless against drought stress; and therefore, plant development and productive output are decreased. To decrease the effect of drought stress on plants, it is crucial to establish a plant feedback mechanism of resistance to drought. The drought reflex mechanisms include the physical stature physiology and biochemical, cellular, and molecular-based processes. Briefly, improving the root system, leaf structure, osmotic-balance, comparative water contents and stomatal adjustment are considered as most prominent features against drought resistance in crop plants. In addition, the signal transduction pathway and reactive clearance of oxygen are crucial mechanisms for coping with drought stress via calcium and phytohormones such as abscisic acid, salicylic acid, jasmonic acid, auxin, gibberellin, ethylene, brassinosteroids and peptide molecules. Furthermore, microorganisms, such as fungal and bacterial organisms, play a vital role in increasing resistance against drought stress in plants. The number of characteristic loci, transgenic methods and the application of exogenous substances [nitric oxide, (C28H48O6) 24-epibrassinolide, proline, and glycine betaine] are also equally important for enhancing the drought resistance of plants. In a nutshell, the current review will mainly focus on the role of phytohormones and related mechanisms involved in drought tolerance in various crop plants.

Transcriptome-based identification and expression profiling of AP2/ERF members in Caragana intermedia and functional analysis of CiDREB3

BACKGROUND

The AP2/ERF transcription factor family plays important roles in regulation of plant growth and development as well as the response of plants to stress. However, there are currently few studies focusing on the function of the AP2/ERF-type transcription factors in Caragana intermedia Kuang et H. C. Fu. Here, the expression pattern of AP2/ERF transcription factors family in different tissues and under four stress treatments were evaluated, and the function of CiDREB3 was examined.

METHODS AND RESULTS

In this study, the genes encoding the AP2/ERF family of transcription factors were screened from the C. intermedia drought transcriptome database and subjected to bioinformatic analysis using the online tool and software. The expression pattern of the members of AP2/ERF transcription factors in C. intermedia were detected via quantitative real-time PCR (qRT-PCR). The function of CiDREB3 on growth, development and drought tolerance was evaluated by transgenic Arabidopsis. As a result, 22 sequences with complete ORFs were obtained and all sequences were divided into 13 sub-groups. Most of the AP2/ERF transcription factors exhibited tissue-specific expression and were induced by cold, heat, NaCl and mannitol treatments. Furthermore, heterologous expression of CiDREB3 altered the morphology of the transgenic Arabidopsis thaliana L. Heynh and improved its drought tolerance during seedlings development.

CONCLUSIONS

Taken together, the results of the present study helped to better understand the function of the AP2/ERF family transcription factors in response to multiple abiotic stresses and uncovered the role of CiDREB3 in affecting the morphology and abiotic stress tolerance of Arabidopsis.

Overexpression of OsERF83, a Vascular Tissue-Specific Transcription Factor Gene, Confers Drought Tolerance in Rice

Abiotic stresses severely affect plant growth and productivity. To cope with abiotic stresses, plants have evolved tolerance mechanisms that are tightly regulated by reprogramming transcription factors (TFs). APETALA2/ethylene-responsive factor (AP2/ERF) transcription factors are known to play an important role in various abiotic stresses. However, our understanding of the molecular mechanisms remains incomplete. In this study, we identified the role of OsERF83, a member of the AP2/ERF transcription factor family, in response to drought stress. OsERF83 is a transcription factor localized to the nucleus and induced in response to various abiotic stresses, such as drought and abscisic acid (ABA). Overexpression of OsERF83 in transgenic plants (OsERF83^OX) significantly increased drought tolerance, with higher photochemical efficiency in rice. OsERF83^OX was also associated with growth retardation, with reduced grain yields under normal growth conditions. OsERF83 is predominantly expressed in the vascular tissue of all organs. Transcriptome analysis revealed that OsERF83 regulates drought response genes, which are related to the transporter (OsNPF8.10, OsNPF8.17, OsLH1), lignin biosynthesis (OsLAC17, OsLAC10, CAD8D), terpenoid synthesis (OsTPS33, OsTPS14, OsTPS3), cytochrome P450 family (Oscyp71Z4, CYP76M10), and abiotic stress-related genes (OsSAP, OsLEA14, PCC13-62). OsERF83 also up-regulates biotic stress-associated genes, including PATHOGENESIS-RELATED PROTEIN (PR), WALL-ASSOCIATED KINASE (WAK), CELLULOSE SYNTHASE-LIKE PROTEIN E1 (CslE1), and LYSM RECEPTOR-LIKE KINASE (RLK) genes. Our results provide new insight into the multiple roles of OsERF83 in the cross-talk between abiotic and biotic stress signaling pathways.

Mitochondrial Small Heat Shock Proteins Are Essential for Normal Growth of Arabidopsis thaliana

Mitochondria play important roles in the plant stress responses and the detoxification of the reactive oxygen species generated in the electron transport chain. Expression of genes encoding stress-related proteins such as the mitochondrial small heat shock proteins (M-sHSP) is upregulated in response to different abiotic stresses. In Arabidopsis thaliana, three M-sHSPs paralogous genes were identified, although their function under physiological conditions remains elusive. The aim of this work is to uncover the in vivo function of all three M-sHSPs at the whole plant level. To accomplish this goal, we analyzed the phenotype, proteomic, and metabolic profiles of Arabidopsis knock-down lines of M-sHSPs (single, double, and triple knock-down lines) during normal plant growth. The triple knock-down plants showed the most prominent altered phenotype at vegetative and reproductive stages without any externally applied stress. They displayed chlorotic leaves, growth arrest, and low seed production. Concomitantly, they exhibited increased levels of sugars, proline, and citric, malic, and ascorbic acid, among other metabolites. In contrast, single and double knock-down plants displayed a few changes in their phenotype. A redundant function among the three M-sHSPs is indicated by the impairment in vegetative and reproductive growth associated with the simultaneous loss of all three M-sHSPs genes. The triple knock-down lines showed alteration of proteins mainly involved in photosynthesis and antioxidant defense compared to the control plants. On the other hand, heat stress triggered a distinct cytosolic response pattern and the upregulation of other sHSP members, in the knock-down plants. Overall, depletion of all three M-sHSPs in Arabidopsis severely impacted fundamental metabolic processes, leading to alterations in the correct plant growth and development. These findings expand our knowledge about the contribution of organelle-specific M-sHSPs to healthy plant growth under non-stress conditions.

Tobacco System for Studying Protein Colocalization and Interactions

Transient protein expression in a heterologous system has been very useful in many research fields. As a plant expression system, tobacco has some unique advantages including big leaves, simple infiltration and transformation, high activity in expressing transgenes, and easy sampling for microscopy. Because of these advantages, tobacco system has been extensively used for many purposes, such as large-scale expression and purification of proteins of interest, protein colocalization, protein degradation, protein-protein interaction assays including co-immunoprecipitation (CoIP), fluorescence resonance energy transfer (FRET), and bimolecular fluorescence complementation (BiFC), transcription regulation, plant-pathogen interactions, and functional verification of small RNAs. A large number of publications have used this system and generated critical results to support their conclusions. The results obtained from tobacco system are highly reproducible and mostly consistent with those generated from traditional techniques, indicating its reliability. Here we describe a protocol for studying protein-protein interactions in tobacco system, which could be applied to multiple experimental purposes as the procedure of tobacco leaf infiltration is basically shared among them.

PagERF16 of Populus Promotes Lateral Root Proliferation and Sensitizes to Salt Stress

The aggravation of soil salinization limits the growth and development of plants. The AP2/ERF transcription factors (TFs) have been identified and play essential roles in plant development and stress response processes. In this study, the function of PagERF16 was detected using the overexpressing (OX) and RNAi transgenic poplar 84K hybrids. Plant growth, stomatal conductance, antioxidant enzymes activity, and PagERF16 co-expressed TFs were analyzed using morphological, physiological, and molecular methods. OX showed a more robust lateral root system with a bigger diameter and volume compared to the wild-type plants (WT). Physiological parameters indicated the bigger stomatal aperture and lower stomatal density of OX along with the lower Catalase (CAT) activity and higher malondialdehyde (MDA) content contributed to the salt sensitivity. The plant height and rooting rate of OX and RNAi were significantly worse compared to WT. Other than that, the morphology and physiology of RNAi plants were similar to WTs, suggesting that the function of PagERF16 may be redundant with other TFs. Our results indicate that when PagERF16 expression is either too high or too low, poplar growth and rooting is negatively affected. In addition, a downstream target TF, NAC45, involved in Auxin biosynthesis, was identified and PagERF16 could directly bind to its promoter to negatively regulate its expression. These results shed new light on the function of ERF TFs in plant root growth and salt stress tolerance.

Structure and expression analysis of seven salt-related ERF genes of Populus

Ethylene response factors (ERFs) are plant-specific transcription factors (TFs) that play important roles in plant growth and stress defense and have received a great amount of attention in recent years. In this study, seven ERF genes related to abiotic stress tolerance and response were identified in plants of the Populus genus. Systematic bioinformatics, including sequence phylogeny, genome organisation, gene structure, gene ontology (GO) annotation, etc. were detected. Expression-pattern of these seven ERF genes were analyzed using RT-qPCR and cross validated using RNA-Seq. Data from a phylogenetic tree and multiple alignment of protein sequences indicated that these seven ERF TFs belong to three subfamilies and contain AP2, YRG, and RAYD conserved domains, which may interact with downstream target genes to regulate the plant stress response. An analysis of the structure and promoter region of these seven ERF genes showed that they have multiple stress-related motifs and cis-elements, which may play roles in the plant stress-tolerance process through a transcriptional regulation mechanism; moreover, the cellular_component and molecular_function terms associated with these ERFs determined by GO annotation supported this hypothesis. In addition, the spatio-temporal expression pattern of these seven ERFs, as detected using RT-qPCR and RNA-seq, suggested that they play a critical role in mediating the salt response and tolerance in a dynamic and tissue-specific manner. The results of this study provide a solid basis to explore the functions of the stress-related ERF TFs in Populus abiotic stress tolerance and development process.

Shaping Durum Wheat for the Future: Gene Expression Analyses and Metabolites Profiling Support the Contribution of BCAT Genes to Drought Stress Response

Global climate change, its implications for agriculture, and the complex scenario presented by the scientific community are of worldwide concern. Drought is a major abiotic stress that can restrict plants growth and yields, thus the identification of genotypes with higher adaptability to drought stress represents one of the primary goals in breeding programs. During abiotic stress, metabolic adaptation is crucial for stress tolerance, and accumulation of specific amino acids and/or as secondary metabolites deriving from amino acid metabolism may correlate with the increased tolerance to adverse environmental conditions. This work, focused on the metabolism of branched chain-amino acids (BCAAs) in durum wheat and the role of branched-chain amino acid aminotransferases (BCATs) in stress response. The role of BCATs in plant response to drought was previously proposed for Arabidopsis, where the levels of BCAAs were altered at the transcriptional level under drought conditions, triggering the onset of defense response metabolism. However, in wheat the role of BCAAs as a trigger of the onset of the drought defense response has not been elucidated. A comparative genomic approach elucidated the composition of the BCAT gene family in durum wheat. Here we demonstrate a tissue and developmental stage specificity of BCATs regulation in the drought response. Moreover, a metabolites profiling was performed on two contrasting durum wheat cultivars Colosseo and Cappelli resulting in the detection of a specific pattern of metabolites accumulated among genotypes and, in particular, in an enhanced BCAAs accumulation in the tolerant cv Cappelli further supporting a role of BCAAs in the drought defense response. The results support the use of gene expression and target metabolomic in modern breeding to shape new cultivars more resilient to a changing climate.

Expression of AhDREB1, an AP2/ERF Transcription Factor Gene from Peanut, Is Affected by Histone Acetylation and Increases Abscisic Acid Sensitivity and Tolerance to Osmotic Stress in Arabidopsis

Drought stress negatively affects plant growth and development. An increasing number of reports have revealed the involvement of APETALA2/Ethylene Responsive Factor (AP2/ERF) transcription factors (TFs) in biotic and abiotic stress regulation in plants. However, research on these TFs in the peanut plant (Arachis hypogaea) has been limited. Here, we isolated a full-length coding sequence (CDS) of the AP2/ERF family gene AhDREB1 from the peanut plant and showed that its expression was induced by Polyethylene Glycol (PEG) 6000 and exogenous abscisic acid (ABA) treatment. When overexpressed in Arabidopsis, AhDREB1 increased both ABA levels and ABA sensitivity, affected the ABA signaling pathway and increased the expression of downstream drought stress-related genes RD29A, P5CS1, P5CS2 and NCED1. These results demonstrate that AhDREB1 can improve tolerance to drought via the ABA-dependent pathway in Arabidopsis. In the peanut plant, the specific histone deacetylases (HDACs) inhibitor trichostatin A (TSA) promotes AhDREB1 transcription and the enrichment level of H3ac was increased in regions of the AhDREB1 gene during TSA and PEG treatment. In summary, histone acetylation can affect the expression of AhDREB1 under osmotic stress conditions, thereby improving plant drought resistance.

Ethylene Responsive Factor MeERF72 Negatively Regulates Sucrose synthase 1 Gene in Cassava

Cassava, an important food and industrial crop globally, is characterized by its powerful starch accumulation in its storage root. However, the underlying molecular mechanism for this feature remains unclear. Sucrose synthase initializes the conversion of sucrose to starch, and, to a certain extent, its enzyme activity can represent sink strength. To understand the modulation of MeSus gene family, the relatively high expressed member in storage root, MeSus1, its promoter was used as bait to screen cassava storage root full-length cDNA library through a yeast one-hybrid system. An ethylene responsive factor cDNA, designated as MeERF72 according to its homolog in Arabidopsis, was screened out. The transcript level of MeERF72 was induced by ethylene, drought, and salt treatments and repressed by abscisic acid, Auxin, gibberellin, salicylic acid, and low and high temperatures. The MeERF72 protein has a conserved APETALA2 domain in its N-terminus and an activated domain of 30 amino acids in its C-terminus, can bind to MeSus1 promoter in vitro and in vivo, and represses the promoter activity of MeSus1. MeERF72 is a transcription factor that can negatively regulate the expression level of MeSus1 in cassava.

Drought Response in Wheat: Key Genes and Regulatory Mechanisms Controlling Root System Architecture and Transpiration Efficiency

Abiotic stresses such as, drought, heat, salinity, and flooding threaten global food security. Crop genetic improvement with increased resilience to abiotic stresses is a critical component of crop breeding strategies. Wheat is an important cereal crop and a staple food source globally. Enhanced drought tolerance in wheat is critical for sustainable food production and global food security. Recent advances in drought tolerance research have uncovered many key genes and transcription regulators governing morpho-physiological traits. Genes controlling root architecture and stomatal development play an important role in soil moisture extraction and its retention, and therefore have been targets of molecular breeding strategies for improving drought tolerance. In this systematic review, we have summarized evidence of beneficial contributions of root and stomatal traits to plant adaptation to drought stress. Specifically, we discuss a few key genes such as, DRO1 in rice and ERECTA in Arabidopsis and rice that were identified to be the enhancers of drought tolerance via regulation of root traits and transpiration efficiency. Additionally, we highlight several transcription factor families, such as, ERF (ethylene response factors), DREB (dehydration responsive element binding), ZFP (zinc finger proteins), WRKY, and MYB that were identified to be both positive and negative regulators of drought responses in wheat, rice, maize, and/or Arabidopsis. The overall aim of this review is to provide an overview of candidate genes that have been identified as regulators of drought response in plants. The lack of a reference genome sequence for wheat and non-transgenic approaches for manipulation of gene functions in wheat in the past had impeded high-resolution interrogation of functional elements, including genes and QTLs, and their application in cultivar improvement. The recent developments in wheat genomics and reverse genetics, including the availability of a gold-standard reference genome sequence and advent of genome editing technologies, are expected to aid in deciphering of the functional roles of genes and regulatory networks underlying adaptive phenological traits, and utilizing the outcomes of such studies in developing drought tolerant cultivars.

Estimation of Stomatal Aperture in Arabidopsis thaliana Using Silicone Rubber Imprints

Estimation of stomatal aperture using low viscosity silicone-base impression material has the advantage of working with the whole leaf. The developmental stage and the environment strongly affect the stomatal aperture. Therefore, it is mandatory to have accurate estimations of the stomatal aperture of intact leaves under different situations. With this technique, it is possible to get the real picture at any moment. The outputs of the data include studies on cell area and morphology, epidermis cell and stomata lineages, among others. This protocol is useful for the accurate estimation of stomatal aperture in many samples of intact leaves in Arabidopsis thaliana.

Regulation of Apetala2/Ethylene Response Factors in Plants

Multiple environmental stresses affect growth and development of plants. Plants try to adapt under these unfavorable condition through various evolutionary mechanisms like physiological and biochemical alterations connecting various network of regulatory processes. Transcription factors (TFs) like APETALA2/ETHYLENE RESPONSE FACTORS (AP2/ERFs) are an integral component of these signaling cascades because they regulate expression of a wide variety of down stream target genes related to stress response and development through different mechanism. This downstream regulation of transcript does not always positively or beneficially affect the plant but also they display some developmental defects like senescence and reduced growth under normal condition or sensitivity to stress condition. Therefore, tight auto/cross regulation of these TFs at transcriptional, translational and domain level is crucial to understand. The present manuscript discuss the multiple regulation and advantage of plasticity and specificity of these family of TFs to a wide or single downstream target(s) respectively. We have also discussed the concern which comes with the unwanted associated traits, which could only be averted by further study and exploration of these AP2/ERFs.