Sound Waves Promote Arabidopsis thaliana Root Growth by Regulating Root Phytohormone Content.

Sound waves affect plants at the biochemical, physical, and genetic levels. However, the mechanisms by which plants respond to sound waves are largely unknown. Therefore, the aim of this study was to examine the effect of sound waves on Arabidopsis thaliana growth. The results of the study showed that Arabidopsis seeds exposed to sound waves (100 and 100 + 9k Hz) for 15 h per day for 3 day had significantly longer root growth than that in the control group. The root length and cell number in the root apical meristem were significantly affected by sound waves. Furthermore, genes involved in cell division were upregulated in seedlings exposed to sound waves. Root development was affected by the concentration and activity of some phytohormones, including cytokinin and auxin. Analysis of the expression levels of genes regulating cytokinin and auxin biosynthesis and signaling showed that cytokinin and ethylene signaling genes were downregulated, while auxin signaling and biosynthesis genes were upregulated in Arabidopsis exposed to sound waves. Additionally, the cytokinin and auxin concentrations of the roots of Arabidopsis plants increased and decreased, respectively, after exposure to sound waves. Our findings suggest that sound waves are potential agricultural tools for improving crop growth performance.

Sound waves affect the total flavonoid contents in Medicago sativa, Brassica oleracea and Raphanus sativus sprouts.

BACKGROUND: Sound waves are emerging as a potential biophysical alternative to traditional methods for enhancing plant growth and phytochemical contents. However, little information is available on the improvement of the concentration of functional metabolites like flavonoids in sprouts using sound waves. In this study, different frequencies of sound waves with short and long exposure times were applied to three important varieties to improve flavonoid content. The aim of this study was to investigate the effect of sound waves on flavonoid content on the basis of biochemical and molecular characteristics. RESULTS: We examined the effects of various sound wave treatments (250 Hz to 1.5 kHz) on flavonoid production in alfalfa (Medicago sativa), broccoli (Brassica oleracea) and red young radish (Raphanus sativus). The results showed that sound wave treatments differentially altered the total flavonoid contents depending upon the growth stages, species and frequency of and exposure time to sound waves. Sound wave treatments of alfalfa (250 Hz), broccoli sprouts (800 Hz) and red young radish sprouts (1 kHz) increased the total flavonoid content by 200%, 35% and 85%, respectively, in comparison with untreated control. Molecular analysis showed that sound waves induce the expression of genes of the flavonoid biosynthesis pathway, which positively corresponds to the flavonoid content. Moreover, the sound wave treatment significantly improves the antioxidant efficiency of sprouts. CONCLUSIONS: The significant improvement of flavonoid content in sprouts with sound waves makes their use a potential and promising technology for the production of agriculture-based functional foods. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Genome-wide analysis of spatiotemporal gene expression patterns during floral organ development in Brassica rapa.

Flowering is a key agronomic trait that directly influences crop yield and quality and serves as a model system for elucidating the molecular basis that controls successful reproduction, adaptation, and diversification of flowering plants. Adequate knowledge of continuous series of expression data from the floral transition to maturation is lacking in Brassica rapa. To unravel the genome expression associated with the development of early small floral buds (< 2 mm; FB2), early large floral buds (2-4 mm; FB4), stamens (STs) and carpels (CPs), transcriptome profiling was carried out with a Br300K oligo microarray. The results showed that at least 6848 known nonredundant genes (30% of the genes of the Br300K) were differentially expressed during the floral transition from vegetative tissues to maturation. Functional annotation of the differentially expressed genes (DEGs) (fold change ≥ 5) by comparison with a close relative, Arabidopsis thaliana, revealed 6552 unigenes (4579 upregulated; 1973 downregulated), including 131 Brassica-specific and 116 functionally known floral Arabidopsis homologs. Additionally, 1723, 236 and 232 DEGs were preferentially expressed in the tissues of STs, FB2, and CPs. These DEGs also included 43 transcription factors, mainly AP2/ERF-ERF, NAC, MADS-MIKC, C2H2, bHLH, and WRKY members. The differential gene expression during flower development induced dramatic changes in activities related to metabolic processes (23.7%), cellular (22.7%) processes, responses to the stimuli (7.5%) and reproduction (1%). A relatively large number of DEGs were observed in STs and were overrepresented by photosynthesis-related activities. Subsequent analysis via semiquantitative RT-PCR, histological analysis performed with in situ hybridization of BrLTP1 and transgenic reporter lines (BrLTP promoter::GUS) of B. rapa ssp. pekinensis supported the spatiotemporal expression patterns. Together, these results suggest that a temporally and spatially regulated process of the selective expression of distinct fractions of the same genome leads to the development of floral organs. Interestingly, most of the differentially expressed floral transcripts were located on chromosomes 3 and 9. This study generated a genome expression atlas of the early floral transition to maturation that represented the flowering regulatory elements of Brassica rapa.

Exploring the sound-modulated delay in tomato ripening through expression analysis of coding and non-coding RNAs.

Background and Aims: Sound is omnipresent in nature. Recent evidence supports the notion that naturally occurring and artificially generated sound waves induce inter- and intracellular changes in plants. These changes, in turn, lead to diverse physiological changes, such as enhanced biotic and abiotic stress responses, in both crops and model plants. Methods: We previously observed delayed ripening in tomato fruits exposed to 1 kHz sound vibrations for 6 h. Here, we evaluated the molecular mechanism underlying this delaying fruit ripening by performing RNA-sequencing analysis of tomato fruits at 6 h, 2 d, 5 d and 7 d after 1 kHz sound vibration treatment. Key Results: Bioinformatic analysis of differentially expressed genes and non-coding small RNAs revealed that some of these genes are involved in plant hormone and cell wall modification processes. Ethylene and cytokinin biosynthesis and signalling-related genes were downregulated by sound vibration treatment, whereas genes involved in flavonoid, phenylpropanoid and glucan biosynthesis were upregulated. Furthermore, we identified two sound-specific microRNAs and validated the expression of the pre-microRNAs and the mRNAs of their target genes. Conclusions: Our results indicate that sound vibration helps to delay fruit ripening through the sophisticated regulation of coding and non-coding RNAs and transcription factor genes.

The Importance of the Circadian Clock in Regulating Plant Metabolism.

Carbohydrates are the primary energy source for plant development. Plants synthesize sucrose in source organs and transport them to sink organs during plant growth. This metabolism is sensitive to environmental changes in light quantity, quality, and photoperiod. In the daytime, the synthesis of sucrose and starch accumulates, and starch is degraded at nighttime. The circadian clock genes provide plants with information on the daily environmental changes and directly control many developmental processes, which are related to the path of primary metabolites throughout the life cycle. The circadian clock mechanism and processes of metabolism controlled by the circadian rhythm were studied in the model plant Arabidopsis and in the crops potato and rice. However, the translation of molecular mechanisms obtained from studies of model plants to crop plants is still difficult. Crop plants have specific organs such as edible seed and tuber that increase the size or accumulate valuable metabolites by harvestable metabolic components. Human consumers are interested in the regulation and promotion of these agriculturally significant crops. Circadian clock manipulation may suggest various strategies for the increased productivity of food crops through using environmental signal or overcoming environmental stress.

Reduction of GIGANTEA expression in transgenic Brassica rapa enhances salt tolerance.

KEY MESSAGE: Here we report the enhancement of tolerance to salt stress in Brassica rapa (Chinese cabbage) through the RNAi-mediated reduction of GIGANTEA ( GI ) expression. Circadian clocks integrate environmental signals with internal cues to coordinate diverse physiological outputs. The GIGANTEA (GI) gene was first discovered due to its important contribution to photoperiodic flowering and has since been shown to be a critical component of the plant circadian clock and to contribute to multiple environmental stress responses. We show that the GI gene in Brassica rapa (BrGI) is similar to Arabidopsis GI in terms of both expression pattern and function. BrGI functionally rescued the late-flowering phenotype of the Arabidopsis gi-201 loss-of-function mutant. RNAi-mediated suppression of GI expression in Arabidopsis Col-0 and in the Chinese cabbage, B. rapa DH03, increased tolerance to salt stress. Our results demonstrate that the molecular functions of GI described in Arabidopsis are conserved in B. rapa and suggest that manipulation of gene expression through RNAi and transgenic overexpression could enhance tolerance to abiotic stresses and thus improve agricultural crop production.

Genome-wide analysis of the expansin gene superfamily reveals Brassica rapa-specific evolutionary dynamics upon whole genome triplication.

Chinese cabbage (Brassica rapa subsp. pekinensis) is an economically important vegetable that has encountered four rounds of polyploidization. The fourth event, whole genome triplication (WGT), occurred after its divergence from Arabidopsis. Expansins (EXPs) are cell wall loosening proteins that participate in cell wall modification processes. In this study, the impacts of WGT on the B. rapa expansin (BrEXP) superfamily were evaluated. Whole genome screening of B. rapa identified 32 loci coding 53 expansin genes. Fifteen of the loci maintained a single gene copy, 15 maintained two gene copies and 2 maintained three gene copies. Six loci had no synteny to any Arabidopsis thaliana orthologs. Two loci were involved in tandem duplication. Segmental duplication and fragment recombination were dominant in accelerating BrEXP evolution. Three genes (BrEXPA7, BrEXLA1 and BrEXLA2) lost one of their ancestral introns, two genes (BrEXPA18 and BrEXPB6) gained new introns, and a domain tandem repeat (BrEXPA18) and domain recombination (Bra016981; not considered as expansin) were observed in one gene each. Further, domain deletion was observed in an additional five genes (Bra033068, Bra000142, Bra025800, Bra016473 and Bra004891, not considered as expansins) that lost one of their expansin-specific domains evolutionarily. These findings provide a basis for the evolution and modification of the BrEXP superfamily after a WGT event, which will help in determining the functional characteristics of BrEXPs.

Defining the RNA-binding glycine-rich (RBG) gene superfamily: new insights into nomenclature, phylogeny, and evolutionary trends obtained by genome-wide comparative analysis of Arabidopsis, Chinese cabbage, rice and maize genomes.

RNA-binding glycine-rich (RBG) proteins play diverse roles in plant growth, development, protection and genome organization. An overly broad definition for class IV glycine-rich proteins (GRPs), namely RNA-binding activity and a glycine-rich C-terminus, has resulted in many distantly related and/or non-related proteins being grouped into this class of RBGs. This definition has hampered the study of RBG evolution. In this study, we used a comparative genomic approach consisting of ortholog, homolog, synteny and phylogenetic analyses to legitimately exclude all distantly/non-related proteins from class IV GRPs and to identify 15, 22, 12 and 18 RBG proteins in Arabidopsis, Chinese cabbage, rice and maize genomes, respectively. All identified RBGs could be divided into three subclasses, namely RBGA, RBGB and RBGD, which may be derived from a common ancestor. We assigned RBGs excluded from class IV GRPs to a separate RBG superfamily. RBGs have evolved and diversified in different species via different mechanisms; segmental duplication and recombination have had major effects, with tandem duplication, intron addition/deletion and domain recombination/deletion playing minor roles. Loss and retention of duplicated RBGs after polyploidization has been species and subclass specific. For example, following recent whole-genome duplication and triplication in maize and Chinese cabbage, respectively, most duplicated copies of RBGA have been lost in maize while RBGD duplicates have been retained; in Chinese cabbage, in contrast, RBGA duplicates have been retained while RBGD duplicates have been lost. Our findings reveal fundamental information and shed new light on the structural characteristics and evolutionary dynamics of RBGs.

Over-expression of PsGPD, a mushroom glyceraldehyde-3-phosphate dehydrogenase gene, enhances salt tolerance in rice plants.

Transgenic potatoes expressing glyceraldehyde-3-phosphate dehydrogenase (GPD), isolated from the oyster mushroom, Pleurotus sajor-caju, had increased tolerance to salt stress (Jeong et al. Biochem Biophys Res Commun 278:192-196, 2000). To examine the physiological mechanisms enhancing salt tolerance in GPD-transgenic rice plants, the salt tolerance of five GPD transgenic rice lines (T1-T5) derived from Dongjin rice cultivar were evaluated in a fixed 150 mM saline environment in comparison to two known wild-type rice cultivars, Dongjin (salt sensitive) and Pokali (salt tolerant). Transgenic lines, T2, T3, and T5, had a substantial increase in biomass and relative water content compared to Dongjin. Stomatal conductance and osmotic potential were higher in the GPD transgenic lines and were similar to those in Pokali. The results are discussed based on the comparative physiological response of GPD transgenic lines with those of the salt-sensitive and salt-tolerant rice cultivars.

Determination of the variations in levels of phenolic compounds in soybean (Glycine max Merr.) sprouts infected by anthracnose (Colletotrichum gloeosporioides).

BACKGROUND: Soybean sprouts (Kongnamool) are one of the most popular and nutritive traditional vegetables in East Asia. Anthracnose caused by Colletotrichum gloeosporioides is one of the most serious diseases of soybean sprouts. In order to obtain basic information for breeding and/or selecting soybean genotypes with increased natural defense against anthracnose, phenolic compounds were profiled for healthy and infected soybean (Glycine max Merr.) sprouts by using high-performance liquid chromatography coupled with tandem mass spectrometry. RESULTS: Tryptophan and eight phenolic compounds (daidzin, genistin, malonyldaidzin, malonylgenistin, daidzein, glycitein, genistein and coumestrol) were determined from healthy and inoculated sprouts. Total identified phenolic content was 40.02 ± 0.03 mg kg⁻¹, 99.4% of which was isoflavones. CONCLUSION: The monitoring suggested that de novo induced glycitein appeared to act as a phytoalexin in the defence mechanism of the soybean sprouts against C. gloeosporioides, and constitutively formed seven phenolic components that functioned as phytoanticipins in the diseased soybean sprouts.

Source identification of atmospheric polycyclic aromatic hydrocarbons in industrial complex using diagnostic ratios and multivariate factor analysis.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants worldwide; currently, they are being described as potential persistent organic pollutants (POPs). This study is aimed to identify sources of PAHs in the atmosphere around the Sihwa and Banwol industrial area by using diagnostic ratios and multivariate factor analysis such as principal component analysis/absolute principal component score (PCA/APCS) and positive matrix factorization (PMF). The atmospheric PAHs level was 8.07-177 ng/m(3) (gaseous phase: 5.93-68.4 ng/m(3); particulate phase: 1.85-128 ng/m(3)) and PAHs concentration in the warm period was lower than the cold period. As a result of the examination of relative BaP concentration, photodecomposition was found not to be an important factor in the seasonal difference of PAHs concentration in this study. Source identification was first carried out through a double ratio plot. As a result of double ratio plots, atmospheric PAHs in this study were found to stem from the combination of vehicular emission, combustion (coal or biomass-wood or grass), and petroleum. Moreover, PCA/APCS and PMF showed that the main sources were vehicular emission and coal combustion and and incineration-related source with a summed contribution of about 72.6-86.7%. Finally, the fitness of the two models was very good; the estimated values were highly correlated with the measured values (R(2) = 0.991-0.999, p < 0.05).

Physiological Aspects of Germination and Early Seedling Establishment of Pleurotus sajor-caju Glyceraldehyde-3-Phosphate Dehydrogenase Expressing Transgenic Rice in Saline Environment.

GPD encodes glyceraldehyde-3-phosphate dehydrogenase enzyme involved in sugar mobilization, particularly glycolysis and gluconeogenesis. The objective of this study was to determine physiological aspects of germination and early seedling establishment of PsGPD (Pleurotus sajor-caju glyceraldehyde-3-phosphate dehydrogenase) expressing transgenic rice (T5) against different salt concentrations. The T5 line that carried 2 copies of T-DNA and had the highest level of PsGPD expression was used in the investigation. Final germination percentage, amylase activity, reducing sugar accumulation, and chlorophyll biosynthesis were comparatively higher in PsGPD expressing transgenic rice against elevating saline conditions. A slow-paced conversion of porphyrin's precursors was seen through the matrix model and further elaborated by a graphical model. A sustained level of porphyrin was observed in PsGPD expressing transgenic rice. These data were concurrent with the relative gene expression and thermal imaging (thermography) of PsGPD expressing transgenic rice against salt stress. Morphological attributes also favored the salt tolerance exhibited by PsGPD-transformed rice.

Proteome analysis of Arabidopsis seedlings exposed to bacterial volatiles.

Plant root-associated bacteria (rhizobacteria) elicit plant basal immunity referred to as induced systemic resistance (ISR) against multiple pathogens. Among multi-bacterial determinants involving such ISR, the induction of ISR and promotion of growth by bacterial volatile compounds was previously reported. To exploit global de novo expression of plant proteins by bacterial volatiles, proteomic analysis was performed after exposure of Arabidopsis plants to the rhizobacterium Bacillus subtilis GB03. Ethylene biosynthesis enzymes were significantly up-regulated. Analysis by quantitative reverse transcriptase polymerase chain reaction confirmed that ethylene biosynthesis-related genes SAM-2, ACS4, ACS12, and ACO2 as well as ethylene response genes, ERF1, GST2, and CHIB were up-regulated by the exposure to bacterial volatiles. More interestingly, the emission of bacterial volatiles significantly up-regulated both key defense mechanisms mediated by jasmonic acid and salicylic acid signaling pathways. In addition, high accumulation of antioxidant proteins also provided evidence of decreased sensitivity to reactive oxygen species during the elicitation of ISR by bacterial volatiles. The present results suggest that the proteomic analysis of plant defense responses in bacterial volatile-mediated ISR can reveal the mechanisms of plant basal defenses orchestrated by endogenous ethylene production pathways and the generation of reactive oxygen species.

Sound Vibration-Triggered Epigenetic Modulation Induces Plant Root Immunity Against Ralstonia solanacearum.

Sound vibration (SV) is one of the several environmental stimuli that induce physiological changes in plants including changes in plant immunity. Immune activation is a complicated process involving epigenetic modifications, however, SV-induced epigenetic modifications remain unexplored. Here, we performed an integrative analysis comprising chromatin immunoprecipitation (ChIP) and microRNA sequencing (miRNA-seq) to understand the role of SV-mediated epigenetic modifications in immune activation in Arabidopsis thaliana against the root pathogen Ralstonia solanacearum. Plants exposed to SV (10 kHz) showed abundant H3K27me3 modification in the promoter regions of aliphatic glucosinolate biosynthesis and cytokinin signaling genes, leading to transcriptional changes that promote immunity. Additionally, 10 kHz SV down-regulated miR397b expression, thus activating three target LACCASE transcripts that mediate cell wall reinforcement via lignin accumulation. Taken together, SV triggers epigenetic modification of genes involved in secondary metabolite biosynthesis, defense hormone signaling, and pre-formed defense in A. thaliana, leading to the activation of plant immunity against R. solanacearum.

Brassica Rapa SR45a Regulates Drought Tolerance via the Alternative Splicing of Target Genes.

The emerging evidence has shown that plant serine/arginine-rich (SR) proteins play a crucial role in abiotic stress responses by regulating the alternative splicing (AS) of key genes. Recently, we have shown that drought stress enhances the expression of SR45a (also known as SR-like 3) in Brassica rapa. Herein, we unraveled the hitherto unknown functions of BrSR45a in drought stress response by comparing the phenotypes, chlorophyll a fluorescence and splicing patterns of the drought-responsive genes of Arabidopsis BrSR45a overexpressors (OEs), homozygous mutants (SALK_052345), and controls (Col-0). Overexpression and loss of function did not result in aberrant phenotypes; however, the overexpression of BrSR45a was positively correlated with drought tolerance and the stress recovery rate in an expression-dependent manner. Moreover, OEs showed a higher drought tolerance index during seed germination (38.16%) than the control lines. Additionally, the overexpression of BrSR45a induced the expression of the drought stress-inducible genes RD29A, NCED3, and DREB2A under normal conditions. To further illustrate the molecular linkages between BrSR45a and drought tolerance, we investigated the AS patterns of key drought-tolerance and BrSR45a interacting genes in OEs, mutants, and controls under both normal and drought conditions. The splicing patterns of DCP5, RD29A, GOLS1, AKR, U2AF, and SDR were different between overexpressors and mutants under normal conditions. Furthermore, drought stress altered the splicing patterns of NCED2, SQE, UPF1, U4/U6-U5 tri-snRNP-associated protein, and UPF1 between OEs and mutants, indicating that both overexpression and loss of function differently influenced the splicing patterns of target genes. This study revealed that BrSR45a regulates the drought stress response via the alternative splicing of target genes in a concentration-dependent manner.

Comparative evaluation of QuantiFERON-TB Gold Plus for diagnosis of latent tuberculosis infection during solid organ transplantation.

Background: The diagnosis of latent tuberculosis infection (LTBI) in solid organ transplantation (SOT) patients under lifelong immunosuppression has profound effects on preoperative and postoperative management. Interferon-gamma release assay (IGRA) is widely used to screen LTBI before or after transplantation. Methods: We evaluated the effect of posttransplantation immunosuppression on IGRA and influencing factors by measuring interval change of QuantiFERON-TB Gold Plus (QFT-Plus) between pretransplantation (pre-QFT-Plus) and posttransplantation (post-QFT-Plus) state in 20 patients who previously had reactive IGRA but not taken LTBI treatment. Results: Eleven (55%) out of 20 pre-QFT-Plus reactive patients became nonreactive state in repeated QFT-Plus (post-QFT-Plus) at 194-413 days (median, 257 days) after transplantation (discordant group). Even in persistently reactive group (concordant group), interferon-gamma (IFN-γ) levels after transplantation were decreased about 34% and 36% of their pretransplantation levels for TB1 and TB2, respectively. The only significant factors that affect interval change of QFT-Plus between pre- and post-SOT status were the concentrations of IFN-γ in pre-QFT-Plus (6.93 vs. 0.44 IU/mL in TB1 and 7.33 vs. 0.71 IU/mL in TB2). Conclusions: The reactivity of QFT-Plus is significantly compromised by immunosuppressive therapy, which increase the risk of false negative, particularly in patients with low level of IGRA reactivity. Therefore, interpretation of IGRA under immunosuppressive treatment require a caution and eventually, more sensitive tuberculosis-specific cytokine markers might be needed.

Proteomic analysis of Caenorhabditis elegans.

Proteomic studies of the free-living nematode Caenorhabditis elegans have recently received great attention because this animal model is a useful platform for the in vivo study of various biological problems relevant to human disease. In general, proteomic analysis is carried out in order to address a specific question with respect to differential changes in proteome expression under certain perturbed conditions. In this chapter, we focus on gel-based proteomic analysis of C. elegans subjected to two specific stress conditions during development: induction of the dauer state for whole body protein expression and a temperature shift for egg protein expression. Utilizing these differently perturbed C. elegans protein samples, two-dimensional electrophoresis and differential in-gel electrophoresis methods have led to the discovery of remarkable aspects of the worm's biology. We also provide numerous details about the technical points and protocols necessary for successful experimentation.

Transcriptome Analysis of Diurnal Gene Expression in Chinese Cabbage.

Plants have developed timing mechanisms that enable them to maintain synchrony with daily environmental events. These timing mechanisms, i.e., circadian clocks, include transcriptional/translational feedback loops that drive 24 h transcriptional rhythms, which underlie oscillations in protein abundance, thus mediating circadian rhythms of behavior, physiology, and metabolism. Circadian clock genes have been investigated in the diploid model plant Arabidopsis thaliana. Crop plants with polyploid genomes-such as Brassica species-have multiple copies of some clock-related genes. Over the last decade, numerous studies have been aimed at identifying and understanding the function of paralogous genes with conserved sequences, or those that diverged during evolution. Brassicarapa's triplicate genomes retain sequence-level collinearity with Arabidopsis. In this study, we used RNA sequencing (RNAseq) to profile the diurnal transcriptome of Brassicarapa seedlings. We identified candidate paralogs of circadian clock-related genes and assessed their expression levels. These genes and their related traits that modulate the diurnal rhythm of gene expression contribute to the adaptation of crop cultivars. Our findings will contribute to the mechanistic study of circadian clock regulation inherent in polyploidy genome crops, which differ from those of model plants, and thus will be useful for future breeding studies using clock genes.

How do we know that plants listen: Advancements and limitations of transcriptomic profiling for the identification of sound-specific biomarkers in tomato.

Sound vibration has been recently identified as an important physical trigger to elicit plant responses. Naturally occurring sound waves modulate diverse aspects of plant physiology, such as root growth, stress responses, and seed germination. However, it has been debated whether plants perceive artificially generated sound vibration and exhibit similar phenotypic changes to those exhibited after perception of natural sound waves. Recently, analysis of RNA-Seq and microRNA-Seq using tomato fruits treated with optimized sound waves to attenuate fruit ripening revealed sound-specific microRNAs, which could be used as sound-specific biomarkers in tomato. These data provide solid molecular evidence of sound perception in plants. Despite these results, there are obvious limitations of biomarkers' specificity and selectivity that need be addressed to facilitate the application of sound treatment in agriculture. Here, the pros and cons of sequencing technologies used to identify sound-associated molecules suggest recommendations for the effective identification of biomarkers responsive to sound treatment in plants.

Beyond Chemical Triggers: Evidence for Sound-Evoked Physiological Reactions in Plants.

Sound is ubiquitous in nature. Recent evidence supports the notion that naturally occurring and artificially generated sound waves contribute to plant robustness. New information is emerging about the responses of plants to sound and the associated downstream signaling pathways. Here, beyond chemical triggers which can improve plant health by enhancing plant growth and resistance, we provide an overview of the latest findings, limitations, and potential applications of sound wave treatment as a physical trigger to modulate physiological traits and to confer an adaptive advantage in plants. We believe that sound wave treatment is a new trigger to help protect plants against unfavorable conditions and to maintain plant fitness.