Multi-omics atlas of combinatorial abiotic stress responses in wheat.

Field-grown crops rarely experience growth conditions in which yield can be maximized. Environmental stresses occur in combination, with advancements in crop tolerance further complicated by its polygenic nature. Strategic targeting of causal genes is required to meet future crop production needs. Here, we employed a systems biology approach in wheat (Triticum aestivum L.) to investigate physio-metabolic adjustments and transcriptome reprogramming involved in acclimations to heat, drought, salinity and all combinations therein. A significant shift in magnitude and complexity of plant response was evident across stress scenarios based on the agronomic losses, increased proline concentrations and 8.7-fold increase in unique differentially expressed transcripts (DETs) observed under the triple stress condition. Transcriptome data from all stress treatments were assembled into an online, open access eFP browser for visualizing gene expression during abiotic stress. Weighted gene co-expression network analysis revealed 152 hub genes of which 32% contained the ethylene-responsive element binding factor-associated amphiphilic repression (EAR) transcriptional repression motif. Cross-referencing against the 31 DETs common to all stress treatments isolated TaWRKY33 as a leading candidate for greater plant tolerance to combinatorial stresses. Integration of our findings with available literature on gene functional characterization allowed us to further suggest flexible gene combinations for future adaptive gene stacking in wheat. Our approach demonstrates the strength of robust multi-omics-based data resources for gene discovery in complex environmental conditions. Accessibility of such datasets will promote cross-validation of candidate genes across studies and aid in accelerating causal gene validation for crop resiliency.

Genome-wide identification of the Q-type C2H2 zinc finger protein gene family and expression analysis under abiotic stress in lotus (Nelumbo nucifera G.).

BACKGROUND: Lotus (Nelumbo nucifera G.) is an important aquatic plant with high ornamental, economic, cultural and ecological values, but abiotic stresses seriously affect its growth and distribution. Q-type C2H2 zinc finger proteins (ZFPs) play an important role in plant growth development and environmental stress responses. Although the Q-type C2H2 gene family has been identified in some plants, limited reports has been carried out it in lotus. RESULTS: In this study, we identified 45 Q-type NnZFP members in lotus. Based on the phylogenetic tree, these Q-type NnZFP gene family members were divided into 4 groups, including C1-1i, C1-2i, C1-3i and C1-4i. Promoter cis-acting elements analysis indicated that most Q-type NnZFP gene family members in lotus were associated with response to abiotic stresses. Through collinearity analyses, no tandem duplication gene pairs and 14 segmental duplication gene pairs were identified, which showed that duplication events might play a key role in the expansion of the Q-type NnZFP gene family. The synteny results suggested that 54 and 28 Q-type NnZFP genes were orthologous to Arabidopsis and rice, respectively. The expression patterns of these Q-type NnZFP genes revealed that 30 Q-type NnZFP genes were expressed in at least one lotus tissue. Nn5g30550 showed relatively higher expression levels in all tested tissues. 12 genes were randomly selected with at least one gene from each phylogenetic clade, and the expression of these selected genes were confirmed by qRT-PCR (quantitative real-time polymerase chain reaction). The results indicated that Q-type NnZFP genes were extensively involved in cadmium, drought, salt and cold stresses responses. Among them, 11 genes responded to at least three different stress treatments, especially Nn2g12894, which induced by all four treatments. CONCLUSIONS: These results could increase our understanding of the characterization of the Q-type NnZFP gene family and provide relevant information for further functional analysis of Q-type NnZFP genes in plant development, and abiotic stress tolerance in lotus.

Genome-Wide Analysis of VILLIN Gene Family Associated with Stress Responses in Cotton (Gossypium spp.).

The VILLIN (VLN) protein plays a crucial role in regulating the actin cytoskeleton, which is involved in numerous developmental processes, and is crucial for plant responses to both biotic and abiotic factors. Although various plants have been studied to understand the VLN gene family and its potential functions, there has been limited exploration of VLN genes in Gossypium and fiber crops. In the present study, we characterized 94 VLNs from Gossypium species and 101 VLNs from related higher plants such as Oryza sativa and Zea mays and some fungal, algal, and animal species. By combining these VLN sequences with other Gossypium spp., we classified the VLN gene family into three distinct groups, based on their phylogenetic relationships. A more in-depth examination of Gossypium hirsutum VLNs revealed that 14 GhVLNs were distributed across 12 of the 26 chromosomes. These genes exhibit specific structures and protein motifs corresponding to their respective groups. GhVLN promoters are enriched with cis-elements related to abiotic stress responses, hormonal signals, and developmental processes. Notably, a significant number of cis-elements were associated with the light responses. Additionally, our analysis of gene-expression patterns indicated that most GhVLNs were expressed in various tissues, with certain members exhibiting particularly high expression levels in sepals, stems, and tori, as well as in stress responses. The present study potentially provides fundamental insights into the VLN gene family and could serve as a valuable reference for further elucidating the diverse functions of VLN genes in cotton.

Genome-wide analysis of wheat xyloglucan endotransglucosylase/hydrolase (XTH) gene family revealed TaXTH17 involved in abiotic stress responses.

BACKGROUND: Environmental stresses, including high salinity and drought, severely diminish wheat yield and quality globally. The xyloglucan endotransglucosylase/hydrolase (XTH) family represents a class of cell wall-modifying enzymes and plays important roles in plants growth, development and stress adaptation. However, systematic analyses of XTH family genes and their functions under salt and drought stresses have not been undertaken in wheat. RESULTS: In this study, we identified a total of 135 XTH genes in wheat, which were clustered into three evolutionary groups. These TaXTHs were unevenly distributed on 21 chromosomes of wheat with a majority of TaXTHs located on homelogous groups 2, 3 and 7. Gene duplication analysis revealed that segmental and tandem duplication were the main reasons for the expansion of XTH family in wheat. Interaction network predictions indicated that TaXTHs could interact with multiple proteins, including three kinases, one methyltransferase and one gibberellin-regulated protein. The promoters of the TaXTH genes harbored various cis-acting elements related to stress and hormone responses. RNA-seq data analyses showed that some TaXTH genes were induced by salt and drought stresses. Furthermore, we verified that TaXTH17 was induced by abiotic stresses and phytohormone treatments, and demonstrated that TaXTH17 was localized in the secretory pathway and cell wall. Functional analyses conducted in heterologous expression systems and in wheat established that TaXTH17 plays a negative role in plant resistance to salt and drought. CONCLUSIONS: We identified 135 XTH genes in wheat and conducted comprehensive analyses of their phylogenetic relationships, gene structures, conserved motifs, gene duplication events, chromosome locations, interaction networks, cis-acting elements and gene expression patterns. Furthermore, we provided solid evidence supporting the notion that TaXTH17 plays a negative role in plant resistance to salt and drought stresses. Collectively, our results provide valuable insights into understanding wheat XTHs, particularly their involvement in plant stress responses, and establish a foundation for further functional and mechanistic studies of TaXTHs.

Exploring the antibiotic resistance of Listeria monocytogenes in food environments - a review.

Listeria monocytogenes, a resilient bacterium in diverse food conditions, such as refrigeration, reduced water activity and low pH, poses a significant threat to the food industry and public health. In recent years, it has been documented an increase in the antibiotic resistance of zoonotic pathogens, including L. monocytogenes. This review provides new insight into the molecular mechanisms involved in both intrinsic and acquired antibiotic resistance of L. monocytogenes with an emphasis on the effect of different environmental and food-related factors. It also explores the relationship of these resistance mechanisms with virulence factors. An analysis of literature data (2009-2021) was conducted to investigate statistically and graphically potential associations between specific antibiotic resistance patterns in the pathogen and food categories using an unbiased variance analysis. The results evidenced that food type had an influence on the antibiotic resistance profiles of L. monocytogenes, with meat and vegetables being the food categories exhibiting the most prevalent profiles. The frequent detection of resistance to ampicillin, penicillin, and tetracycline (non-intrinsic resistances) indicates that specific processing conditions along the food chain may induce them. Many questions remain about the impact of food chain factors (e.g. thermal treatments, cold chain, preservatives, etc.) and food type (low pH, reduced water activity, etc.) on the antibiotic resistance patterns of the pathogen, particularly concerning food-related sources, the resistance mechanisms involved (e.g. cross-protection, horizontal gene transfer, etc.), and the evolutionary processes of antibiotic-resistant microbial populations. Metagenomics, in addition to other -omics technologies (metabolomics and transcriptomics), allows a better understanding of the processes involved in the acquisition of resistance.

Insights into the evolutionary and ecological adaption strategies of nirS- and nirK-type denitrifying communities.

Denitrification is a crucial process in the global nitrogen cycle, in which two functionally equivalent genes, nirS and nirK, catalyse the critical reaction and are usually used as marker genes. The nirK gene can function independently, whereas nirS requires additional genes to encode nitrite reductase and is more sensitive to environmental factors than nirK. However, the ecological differentiation mechanisms of those denitrifying microbial communities and their adaptation strategies to environmental stresses remain unclear. Here, we conducted metagenomic analysis for sediments and bioreactor samples from Lake Donghu, China. We found that nirS-type denitrifying communities had a significantly lower horizontal gene transfer frequency than that of nirK-type denitrifying communities, and nirS gene phylogeny was more congruent with taxonomy than that of nirK gene. Metabolic reconstruction of metagenome-assembled genomes further revealed that nirS-type denitrifying communities have robust metabolic systems for energy conservation, enabling them to survive under environmental stresses. Nevertheless, nirK-type denitrifying communities seemed to adapt to oxygen-limited environments with the ability to utilize various carbon and nitrogen compounds. Thus, this study provides novel insights into the ecological differentiation mechanism of nirS and nirK-type denitrifying communities, as well as the regulation of the global nitrogen cycle and greenhouse gas emissions.

The CRZ1 transcription factor in plant fungi: regulation mechanism and impact on pathogenesis.

Calcium (Ca2+) is a universal signaling molecule that is tightly regulated, and a fleeting elevation in cytosolic concentration triggers a signal cascade within the cell, which is crucial for several processes such as growth, tolerance to stress conditions, and virulence in fungi. The link between calcium and calcium-dependent gene regulation in cells relies on the transcription factor Calcineurin-Responsive Zinc finger 1 (CRZ1). The direct regulation of approximately 300 genes in different stress pathways makes it a hot topic in host-pathogen interactions. Notably, CRZ1 can modulate several pathways and orchestrate cellular responses to different types of environmental insults such as osmotic stress, oxidative stress, and membrane disruptors. It is our belief that CRZ1 provides the means for tightly modulating and synchronizing several pathways allowing pathogenic fungi to install into the apoplast and eventually penetrate plant cells (i.e., ROS, antimicrobials, and quick pH variation). This review discusses the structure, function, regulation of CRZ1 in fungal physiology and its role in plant pathogen virulence.

Non-chemical stresses do not strongly induce male offspring in Daphnia magna ascertained using the short-term juvenile hormone activity screening assay.

Juvenile hormone (JH), together with ecdysone, regulates molting, metamorphosis, growth, and reproduction in arthropods. The effects of its analogs used as insecticides on nontarget species are of concern. Since JH and JH analogs (JHAs) induce male offspring in daphnids, which generally reproduce by parthenogenesis, short-term JH activity screening assay (JHASA) using the male offspring ratio as an endpoint has been developed as a detection method for JHA. However, the production of male offspring is also induced by environmental stresses such as temperature, short-day length, overcrowding, and food limitation. Thus, it is vital to prevent non-chemical stresses from inducing male offspring during the test to detect chemicals with potential JH activity accurately. Therefore, we investigated the effects of temperature (low and high), hardness, high density with low feeding, and day length on male production utilizing JHASA. Male offspring were not strongly induced by any stresses in JHASA, although the male ratios of 4-12% were observed in the preculture under high density (≥70 daphnid/L) and constant darkness. The Clone A strain was relatively more sensitive to high density and day length compared with the strain from National Institute for Environmental Studies (NIES). The selection of strains that rarely produce males under non-chemical stresses and finding the culturing conditions for each strain appropriate for not-inducing male offspring are recommended to control and prevent male offspring induction during JHASA.

AcrR1, a novel TetR/AcrR family repressor, mediates acid and antibiotic resistance and nisin biosynthesis in Lactococcus lactis F44.

Lactococcus lactis, widely used in the manufacture of dairy products, encounters various environmental stresses both in natural habitats and during industrial processes. It has evolved intricate machinery of stress sensing and defense to survive harsh stress conditions. Here, we identified a novel TetR/AcrR family transcription regulator, designated AcrR1, to be a repressor for acid and antibiotic tolerance that was derepressed in the presence of vancomycin or under acid stress. The survival rates of acrR1 deletion strain ΔAcrR1 under acid and vancomycin stresses were about 28.7-fold (pH 3.0, HCl), 8.57-fold (pH 4.0, lactic acid) and 2.73-fold (300 ng/mL vancomycin) greater than that of original strain F44. We also demonstrated that ΔAcrR1 was better able to maintain intracellular pH homeostasis and had a lower affinity to vancomycin. No evident effects of AcrR1 deletion on the growth and morphology of strain F44 were observed. Subsequently, we characterized that the transcription level of genes associated with amino acids biosynthesis, carbohydrate transport and metabolism, multidrug resistance, and DNA repair proteins significantly upregulated in ΔAcrR1 using transcriptome analysis and quantitative reverse transcription-PCR assays. Additionally, AcrR1 could repress the transcription of the nisin post-translational modification gene, nisC, leading to a 16.3% increase in nisin yield after AcrR1 deletion. Our results not only refined the knowledge of the regulatory mechanism of TetR/AcrR family regulator in L. lactis, but presented a potential strategy to enhance industrial production of nisin.

Monitoring calcium handling by the plant endoplasmic reticulum with a low-Ca2+ -affinity targeted aequorin reporter.

Precise measurements of dynamic changes in free Ca2+ concentration in the lumen of the plant endoplasmic reticulum (ER) have been lacking so far, despite increasing evidence for the contribution of this intracellular compartment to Ca2+ homeostasis and signalling in the plant cell. In the present study, we targeted an aequorin chimera with reduced Ca2+ affinity to the ER membrane and facing the ER lumen. To this aim, the cDNA for a low-Ca2+ -affinity aequorin variant (AEQmut) was fused to the nucleotide sequence encoding a non-cleavable N-terminal ER signal peptide (fl2). The correct targeting of fl2-AEQmut was confirmed by immunocytochemical analyses in transgenic Arabidopsis thaliana (Arabidopsis) seedlings. An experimental protocol well-established in animal cells - consisting of ER Ca2+ depletion during photoprotein reconstitution followed by ER Ca2+ refilling - was applied to carry out ER Ca2+ measurements in planta. Rapid and transient increases of the ER luminal Ca2+ concentration ([Ca2+ ]ER ) were recorded in response to different environmental stresses, displaying stimulus-specific Ca2+ signatures. The comparative analysis of ER and chloroplast Ca2+ dynamics indicates a complex interplay of these organelles in shaping cytosolic Ca2+ signals during signal transduction events. Our data highlight significant differences in basal [Ca2+ ]ER and Ca2+ handling by plant ER compared to the animal counterpart. The set-up of an ER-targeted aequorin chimera extends and complements the currently available toolkit of organelle-targeted Ca2+ indicators by adding a reporter that improves our quantitative understanding of Ca2+ homeostasis in the plant endomembrane system.

Insights into the Effects of Hydroxycinnamic Acid and Its Secondary Metabolites as Antioxidants for Oxidative Stress and Plant Growth under Environmental Stresses.

Plant immobility renders plants constantly susceptible to various abiotic and biotic stresses. Abiotic and biotic stresses are known to produce reactive oxygen species (ROS), which cause comparable cellular secondary reactions (osmotic or oxidative stress), leading to agricultural productivity constraints worldwide. To mitigate the challenges caused by these stresses, plants have evolved a variety of adaptive strategies. Phenolic acids form a key component of these strategies, as they are predominantly known to be secreted by plants in response to abiotic or biotic stresses. Phenolic acids can be divided into different subclasses based on their chemical structures, such as hydroxybenzoic acids and hydroxycinnamic acids. This review analyzes hydroxycinnamic acids and their derivatives as they increase under stressful conditions, so to withstand environmental stresses they regulate physiological processes through acting as signaling molecules that regulate gene expression and biochemical pathways. The mechanism of action used by hydroxycinnamic acid involves minimization of oxidative damage to maintain cellular homeostasis and protect vital cellular components from harm. The purpose of this review is to highlight the potential of hydroxycinnamic acid metabolites/derivatives as potential antioxidants. We review the uses of different secondary metabolites associated with hydroxycinnamic acid and their contributions to plant growth and development.

Apomixis: oh, what a tangled web we have!

MAIN CONCLUSION: Apomixis is a complex evolutionary trait with many possible origins. Here we discuss various clues and causes, ultimately proposing a model harmonizing the three working hypotheses on the topic. Asexual reproduction through seeds, i.e., apomixis, is the holy grail of plant biology. Its implementation in modern breeding could be a game-changer for agriculture. It has the potential to generate clonal crops and maintain valuable complex genotypes and their associated heterotic traits without inbreeding depression. The genetic basis and origins of apomixis are still unclear. There are three central hypothesis for the development of apomixis that could be: i) a deviation from the sexual developmental program caused by an asynchronous development, ii) environmentally triggered through epigenetic regulations (a polyphenism of sex), iii) relying on one or more genes/alleles. Because of the ever-increasing complexity of the topic, the path toward a detailed understanding of the mechanisms underlying apomixis remains unclear. Here, we discuss the most recent advances in the evolution perspective of this multifaceted trait. We incorporated our understanding of the effect of endogenous effectors, such as small RNAs, epigenetic regulation, hormonal pathways, protein turnover, and cell wall modification in response to an upside stress. This can be either endogenous (hybridization or polyploidization) or exogenous environmental stress, mainly due to oxidative stress and the corresponding ROS (Reacting Oxygen Species) effectors. Finally, we graphically represented this tangled web.

Prolonged ecological changes can affect morphometrics and gene expression profile? Focusing on Hsp-70 and NLHS-induced Hsp-70 of Artemia urmiana.

BACKGROUND: In recent years, many aquatic ecosystems, including Urmia Lake, have undergone severe ecological tensions. This lake, the largest natural habitat of the brine shrimp Artemia urmiana, has progressively desiccated and its salinity has dramatically increased over the last three decades. In the face of the long period environmental stresses, understanding the adaptation and ecological plasticity mechanisms is the most interesting challenges in genetic and applied ecology. These mechanisms may probably be driven by inducing expression of some genes involved in adaptation such as Hsp-70 and also adjusting morphological parameters. But they are yet to be understood. Hence, the present work aimed to study the mechanisms, along with testing the hypothesis that non-lethal heat shocked nauplii originating from drought period can evoke Hsp-70 expression more than those from rainy period. METHODS: This study measured and analyzed morphometrical characters of adult male and female Artemia urmiana over three decades. Then, the influence of three-decade ecological crisis on Hsp-70 and non-lethal heat shock (NLHS)-induced Hsp-70 expression levels of nauplii of Artemia urmiana habiting Urmia Lake using Real-time PCR technique, based on cyst collections in 1994 (rainy period) to 2020 (drought period), was evaluated. RESULTS: The morphometrics results showed that the morphological characters were significantly shrunk in 2020 compared to 1994 (CI 95%, p < 0.05). Furthermore, our results depicted that, Hsp-70 expression level was significantly upregulated in response to the prolonged ecological crisis, (CI 95%, P < 0.0001), and also interestingly, the nauplii exposed to longe-term ecological crisis (belong to 2020) were able to increase Hsp-70 expression more than other ones in response to environmental stressors including heat. CONCLUSIONS: The present results showed the involvement of Hsp-70 in the adaptation of Artemia urmiana to long term ecological alteration at the cost of shrinking morphometric parameters.

Unique and generic crossed metabolism in response to four sub-lethal environmental stresses in the oriental fruit fly, Bactrocera dorsalis Hendel.

Bactrocera dorsalis is a well-known invasive pest that causes considerable ecological and economic losses worldwild. Although it has a wide environmental tolerance, few studies have reported its mechanism of adaptation to multiple sub-lethal environmental stresses. In this study, 38, 41, 39 and 34 metabolites changed significantly in B. dorsalis under four sub-lethal stresses (heat, cold, desiccation and hypoxia), as found by the metabolomic method. Therein, lactic acid and pyruvic acid were induced, whereas metabolites in the tricarboxylic acid (TCA) cycle such as citric acid, α-ketoglutarate acid, malic acid and fumaric acid were reduced under at least one of the stresses. Enzyme activity and quantitative polymerase chain reaction (qPCR) analyses verified the repression of pyruvic acid proceeding into the TCA cycle. In addition, the levels of several cryoprotectants and membrane fatty acids in B. dorsalis were altered. The findings indicated that B. dorsalis has evolved shared metabolic pathways to adapt to heat, hypoxia and desiccation stresses, such as reducing energy consumption by activating the anaerobic glycolytic metabolism. Cryoprotectants and membrane fatty acids were produced to improve the efficiency of stress resistance. This study revealed the unique and generic crossed physiological mechanism of insects to adapt to various environmental stresses.

Identification of the cuticle protein AccCPR2 gene in Apis cerana cerana and its response to environmental stress.

Cuticular proteins (CPs) are known to play important roles in insect development and defence responses. The loss of CP genes can lead to changes in insect morphology and sensitivity to the external environment. In this study, we identified the AccCPR2 gene, which belongs to the CPR family (including the R&R consensus motif) of CPs, and explored its function in the response of Apis cerana cerana to adverse external stresses. Our results demonstrated that AccCPR2 was highly expressed in the late pupal stage and epidermis, and the expression of AccCPR2 may be induced or inhibited under different stressors. RNA interference experiments showed that knockdown of AccCPR2 reduced the activity of antioxidant enzymes, led to the accumulation of oxidative damage and suppressed the expression of several antioxidant genes. In addition, knockdown of AccCPR2 also reduced the pesticide resistance of A. cerana cerana. The overexpression of AccCPR2 in a prokaryotic system further confirmed its role in resistance to various stresses. In summary, AccCPR2 may play pivotal roles in the normal development and environmental stress response of A. cerana cerana. This study also enriched the theoretical knowledge of the resistance biology of bees.

Long-read RNA sequencing of Pacific abalone Haliotis discus hannai reveals innate immune system responses to environmental stress.

Haliotis discus hannai is a commercially important mollusk species, and the abalone aquaculture sector has been jeopardized by deteriorating environmental circumstances such as bacterial infection and thermal stress during the hot summers. However, due to a paucity of genetic information, such as transcriptome resources, our understanding of their stress adaptation is restricted. In this research, using single-molecule long-read (SMRT) sequencing technology, a library composed of ten tissues (i.e., haemocytes, gills, muscle, hepatopancreas, digestive tract, mantle, mucous gland, ovary, testis and head) was constructed and sequenced. In all, 41,855 high-quality unique transcripts, among which 24,778 were successfully annotated. Additionally, 13,463 SSRs, 1,169 transcription factors, and 18,124 lncRNAs were identified in H. discus hannai transcriptome. Furthermore, multiple immune-related transcripts were identified according to KEGG annotation, and a portion of these transcripts were mapped into several classical immune-related pathways, including the PI3K-AKT signaling pathway and Toll-like receptor signaling pathway. Additionally, 24 typical sequences related to the immunity pathway were detected by RT-PCR; the results showed that most of the immune-related genes showed significantly high expression at 72 h after bacterial challenges and thermal stress, especially the expression level of genes in gills was significantly higher than that in haemocytes under V. parahaemolyticus stress at 24 h. At the same time. The analysis of alternative splicing identified several innate immunity-related functions genes, including CD109 and caspase 2. These results suggest that the complex immune system, particularly the powerful innate immunity system, was crucial for H. discus hannai response to numerous environmental challenges.

Silver nanoparticles reduce the tolerance of Cronobacter sakazakii to environmental stress by inhibiting expression of related genes.

Cronobacter sakazakii is a food-borne pathogen that is resistant to a variety of environmental stress conditions. It can survive in harsh environments. We studied the effects of silver nanoparticles (AgNP) on the environmental tolerance and biofilm formation of C. sakazakii. First, we determined the minimum inhibitory concentration (MIC) of AgNP to C. sakazakii and determined the growth curve of C. sakazakii treated with different concentrations of AgNP by using the plate counting method. After determining the sub-inhibition concentrations (SIC) of AgNP on C. sakazakii, we studied the effects of AgNP on the resistance of C. sakazakii to heat, desiccation, osmotic pressure, and acid. The antibiofilm activity of AgNP was also studied. Finally, real-time quantitative PCR was used to analyze the transcription levels of 16 genes related to the environmental tolerance of C. sakazakii. The SIC of AgNP significantly reduced the survival rate of C. sakazakii under various environmental stress conditions. The results showed that AgNP at 0.625 and 1.25 µg/mL significantly inhibited the formation of C. sakazakii biofilms. The expression levels of most genes were significantly downregulated in C. sakazakii cells treated with 0.625 and 1.25 µg/mL AgNP. Therefore, AgNP may reduce the environmental tolerance of C. sakazakii by inhibiting the expression of genes related to stress tolerance. Moreover, AgNP inhibited the production of ATP in C. sakazakii cells and the formation of C. sakazakii biofilms. Our research provides a theoretical basis for the application of AgNP in food packaging, bactericidal coatings, and other fields.

Characterization of the Wheat Heat Shock Factor TaHsfA2e-5D Conferring Heat and Drought Tolerance in Arabidopsis.

Environmental stresses, especially heat and drought, severely limit plant growth and negatively affect wheat yield and quality worldwide. Heat shock factors (Hsfs) play a central role in regulating plant responses to various stresses. In this study, the wheat heat shock factor gene TaHsfA2e-5D on chromosome 5D was isolated and functionally characterized, with the goal of investigating its role in responses to heat and drought stresses. Gene expression profiling showed that TaHsfA2e-5D was expressed constitutively in various wheat tissues, most highly in roots at the reproductive stage. The expression of TaHsfA2e-5D was highly up-regulated in wheat seedlings by heat, cold, drought, high salinity, and multiple phytohormones. The TaHsfA2e-5D protein was localized in the nucleus and showed a transcriptional activation activity. Ectopic expression of the TaHsfA2e-5D in yeast exhibited improved thermotolerance. Overexpression of the TaHsfA2e-5D in Arabidopsis results in enhanced tolerance to heat and drought stresses. Furthermore, RT-qPCR analyses revealed that TaHsfA2e-5D functions through increasing the expression of Hsp genes and other stress-related genes, including APX2 and GolS1. Collectively, these results suggest that TaHsfA2e-5D functions as a positive regulator of plants' responses to heat and drought stresses, which may be of great significance for understanding and improving environmental stress tolerance in crops.

Biogenic Silver Nanoparticles as a Stress Alleviator in Plants: A Mechanistic Overview.

Currently, the growth and yield of crops are restrained due to an increase in the occurrence of ecological stresses globally. Biogenic generation of nanomaterials is an important step in the development of environmentally friendly procedures in the nanotechnology field. Silver-based nanomaterials are significant because of their physical, chemical, and biological features along with their plentiful applications. In addition to useful microbes, the green synthesized Ag nanomaterials are considered to be an ecologically friendly and environmentally biocompatible method for the enhancement of crop yield by easing stresses. In the recent decade, due to regular droughts, infrequent precipitation, salinity, and increased temperature, the climate alternation has changed certain ecological systems. As a result of these environmental changes, crop yield has decreased worldwide. The role of biogenic Ag nanomaterials in enhancing methylglyoxal detoxification, antioxidant defense mechanisms, and generating tolerance to stresses-induced ROS injury has been methodically explained in plants over the past ten years. However, certain studies regarding stress tolerance and metal-based nanomaterials have been directed, but the particulars of silver nanomaterials arbitrated stresses tolerance have not been well-reviewed. Henceforth, there is a need to have a good understanding of plant responses during stressful conditions and to practice the combined literature to enhance tolerance for crops by utilization of Ag nanoparticles. This review article illustrates the mechanistic approach that biogenic Ag nanomaterials in plants adopt to alleviate stresses. Moreover, we have appraised the most significant activities by exogenous use of Ag nanomaterials for improving plant tolerance to salt, low and high temperature, and drought stresses.

Adaptive evolution driving the young duplications in six Rosaceae species.

BACKGROUND: In plant genomes, high proportions of duplicate copies reveals that gene duplications play an important role in the evolutionary processes of plant species. A series of gene families under positive selection after recent duplication events in plant genomes indicated the evolution of duplicates driven by adaptive evolution. However, the genome-wide evolutionary features of young duplicate genes among closely related species are rarely reported. RESULTS: In this study, we conducted a systematic survey of young duplicate genes at genome-wide levels among six Rosaceae species, whose whole-genome sequencing data were successively released in recent years. A total of 35,936 gene families were detected among the six species, in which 60.25% were generated by young duplications. The 21,650 young duplicate gene families could be divided into two expansion types based on their duplication patterns, species-specific and lineage-specific expansions. Our results showed the species-specific expansions advantaging over the lineage-specific expansions. In the two types of expansions, high-frequency duplicate domains exhibited functional preference in response to environmental stresses. CONCLUSIONS: The functional preference of the young duplicate genes in both the expansion types showed that they were inclined to respond to abiotic or biotic stimuli. Moreover, young duplicate genes under positive selection in both species-specific and lineage-specific expansions suggested that they were generated to adapt to the environmental factors in Rosaceae species.