Methyl jasmonate treatment induces changes in fruit ripening by modifying the expression of several ripening genes in Fragaria chiloensis fruit

Increase of secondary metabolites in sweet basil (Ocimum basilicum L.) leaves by exposure to N2O5 with plasma technology

Exposure to N2O5 generated by plasma technology activates immunity in Arabidopsis through tryptophan metabolites. However, little is known about the effects of N2O5 exposure on other plant species. Sweet basil synthesizes many valuable secondary metabolites in its leaves. Therefore, metabolomic analyses were performed at three different exposure levels [9.7 (Ex1), 19.4 (Ex2) and 29.1 (Ex3) μmol] to assess the effects of N2O5 on basil leaves. As a result, cinnamaldehyde and phenolic acids increased with increasing doses. Certain flavonoids, columbianetin, and caryophyllene oxide increased with lower Ex1 exposure, cineole and methyl eugenol increased with moderate Ex2 exposure and L-glutathione GSH also increased with higher Ex3 exposure. Furthermore, gene expression analysis by quantitative RT-PCR showed that certain genes involved in the syntheses of secondary metabolites and jasmonic acid were significantly up-regulated early after N2O5 exposure. These results suggest that N2O5 exposure increases several valuable secondary metabolites in sweet basil leaves via plant defense responses in a controllable system.

A signaling cascade mediating fruit trait development via phosphorylation-modulated nuclear accumulation of JAZ repressor

It is generally accepted that jasmonate-ZIM domain (JAZ) repressors act to mediate jasmonate (JA) signaling via CORONATINE-INSENSITIVE1 (COI1)-mediated degradation. Here, we report a cryptic signaling cascade where a JAZ repressor, FvJAZ12, mediates multiple signaling inputs via phosphorylation-modulated subcellular translocation rather than the COI1-mediated degradation mechanism in strawberry (Fragaria vesca). FvJAZ12 acts to regulate flavor metabolism and defense response, and was found to be the target of FvMPK6, a mitogen-activated protein kinase that is capable of responding to multiple signal stimuli. FvMPK6 phosphorylates FvJAZ12 at the amino acid residues S179 and T183 adjacent to the PY residues, thereby attenuating its nuclear accumulation and relieving its repression for FvMYC2, which acts to control the expression of lipoxygenase 3 (FvLOX3), an important gene involved in JA biosynthesis and a diverse array of cellular metabolisms. Our data reveal a previously unreported mechanism for JA signaling and decipher a signaling cascade that links multiple signaling inputs with fruit trait development.

Application of Synephrine to Grape Increases Anthocyanin via Production of Hydrogen Peroxide, Not Phytohormones

Global warming has caused such problems as the poor coloration of grape skin and the decreased production of high-quality berries. We investigated the effect of synephrine (Syn) on anthocyanin accumulation. Anthocyanin accumulation in cultured grape cells treated with Syn at concentrations of 1 mM or higher showed no significant difference, indicating that the accumulation was concentration-independent. On the other hand, anthocyanin accumulation was dependent on the compound used for treatment. The sugar/acid ratio of the juice from berries treated with Syn did not differ from the control. The expression of anthocyanin-biosynthesis-related genes, but not phytohormones, was increased by the treatment with Syn at 24 h or later. The Syn treatment of cultured cells increased SOD3 expression and hydrogen peroxide (H2O2) production from 3 to 24 h after treatment. Subsequently, the expression of CAT and APX6 encoding H2O2-scavenging enzymes was also increased. Treatment of cultured cells with Syn and H2O2 increased the expression of the H2O2-responsive gene Chit4 and the anthocyanin-biosynthesis-related genes mybA1 and UFGT 4 days after the treatment and increased anthocyanin accumulation 7 days after the treatment. On the other hand, the treatment of berries with Syn and H2O2 increased anthocyanin accumulation after 9 days. These results suggest that Syn increases anthocyanin accumulation through H2O2 production without changing phytohormone biosynthesis. Syn is expected to improve grape skin coloration and contribute to high-quality berry production.

Ethylene biosynthesis and signal transduction during ripening and softening in non-climacteric fruits: an overview

In recent years, the ethylene-mediated ripening and softening of non-climacteric fruits have been widely mentioned. In this paper, recent research into the ethylene-mediated ripening and softening of non-climacteric fruits is summarized, including the involvement of ethylene biosynthesis and signal transduction. In addition, detailed studies on how ethylene interacts with other hormones to regulate the ripening and softening of non-climacteric fruits are also reviewed. These findings reveal that many regulators of ethylene biosynthesis and signal transduction are linked with the ripening and softening of non-climacteric fruits. Meanwhile, the perspectives of future research on the regulation of ethylene in non-climacteric fruit are also proposed. The overview of the progress of ethylene on the ripening and softening of non-climacteric fruit will aid in the identification and characterization of key genes associated with ethylene perception and signal transduction during non-climacteric fruit ripening and softening.

A tomato NAC transcription factor, SlNAP1, directly regulates gibberellin-dependent fruit ripening

In tomato (Solanum lycopersicum), the ripening of fruit is regulated by the selective expression of ripening-related genes, and this procedure is controlled by transcription factors (TFs). In the various plant-specific TF families, the no apical meristem (NAM), Arabidopsis thaliana activating factor 1/2 (ATAF1/2), and cup-shaped cotyledon 2 (CUC2; NAC) TF family stands out and plays a significant function in plant physiological activities, such as fruit ripening (FR). Despite the numerous genes of NAC found in the tomato genome, limited information is available on the effects of NAC members on FR, and there is also a lack of studies on their target genes. In this research, we focus on SlNAP1, which is a NAC TF that positively influences the FR of tomato. By employing CRISPR/Cas9 technology, compared with the wild type (WT), we generated slnap1 mutants and observed a delay in the ethylene production and color change of fruits. We employed the yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) assays to confirm that SlNAP1 directly binds to the promoters of two crucial genes involved in gibberellin (GA) degradation, namely SlGA2ox1 and SlGA2ox5, thus activating their expression. Furthermore, through a yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BIFC) and luciferase (LUC) assays, we established an interaction between SlNAP1 and SlGID1. Hence, our findings suggest that SlNAP1 regulates FR positively by activating the GA degradation genes directly. Additionally, the interaction between SlNAP1 and SlGID1 may play a role in SlNAP1-induced FR. Overall, our study provides important insights into the molecular mechanisms through which NAC TFs regulate tomato FR via the GA pathway.

Methyl jasmonate regulation of pectin polysaccharides in Cosmos bipinnatus roots: A mechanistic insight into alleviating cadmium toxicity

Methyl jasmonate (MeJA), a crucial phytohormone, which plays an important role in resistance to Cadmium (Cd) stress. The cell wall (CW) of root system is the main location of Cd and plays a key role in resistance to Cd toxicity. However, the mechanism effect of MeJA on the CW composition and Cd accumulation remain unclear. In this study, the contribution of MeJA in regulating CW structure, pectin composition and Cd accumulation was investigated in Cosmos bipinnatus. Phenotypic results affirm MeJA's significant role in reducing Cd-induced toxicity in C. bipinnatus. Notably, MeJA exerts a dual impact, reducing Cd uptake in roots while increasing Cd accumulation in the CW, particularly bound to pectin. The molecular structure of pectin, mainly uronic acid (UA), correlates positively with Cd content, consistent in HC1 and cellulose, emphasizing UA as pivotal for Cd binding. Furthermore, MeJA modulates pectin methylesterase (PME) activity under Cd stress, influencing pectin's molecular structure and homogalacturonan (HG) content affecting Cd-binding capacity. Chelate-soluble pectin (CSP) within soluble pectins accumulates a substantial Cd proportion, with MeJA regulating both UA content and the minor component 3-deoxy-oct-2-ulosonic acid (Kdo) in CSP. The study delves into the intricate regulation of pectin monosaccharide composition under Cd stress, revealing insights into the CW's physical defense and Cd binding. In summary, this research provides novel insights into MeJA-specific mechanisms alleviating Cd toxicity in C. bipinnatus, shedding light on complex interactions between MeJA, and Cd accumulation in CW pectin polysaccharide.

Hormonal Content and Gene Expression during Olive Fruit Growth and Ripening

The cultivated olive (Olea europaea L. subsp. europaea var. europaea) is one of the most valuable fruit trees worldwide. However, the hormonal mechanisms underlying the fruit growth and ripening in olives remain largely uncharacterized. In this study, we investigated the physiological and hormonal changes, by ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS), as well as the expression patterns of hormone-related genes, using quantitative real-time PCR (qRT-PCR) analysis, during fruit growth and ripening in two olive cultivars, 'Arbequina' and 'Picual', with contrasting fruit size and shape as well as fruit ripening duration. Hormonal profiling revealed that olive fruit growth involves a lowering of auxin (IAA), cytokinin (CKs), and jasmonic acid (JA) levels as well as a rise in salicylic acid (SA) levels from the endocarp lignification to the onset of fruit ripening in both cultivars. During olive fruit ripening, both abscisic acid (ABA) and anthocyanin levels rose, while JA levels fell, and SA levels showed no significant changes in either cultivar. By contrast, differential accumulation patterns of gibberellins (GAs) were found between the two cultivars during olive fruit growth and ripening. GA1 was not detected at either stage of fruit development in 'Arbequina', revealing a specific association between the GA1 and 'Picual', the cultivar with large sized, elongated, and fast-ripening fruit. Moreover, ABA may play a central role in regulating olive fruit ripening through transcriptional regulation of key ABA metabolism genes, whereas the IAA, CK, and GA levels and/or responsiveness differ between olive cultivars during olive fruit ripening. Taken together, the results indicate that the relative absence or presence of endogenous GA1 is associated with differences in fruit morphology and size as well as in the ripening duration in olives. Such detailed knowledge may be of help to design new strategies for effective manipulation of olive fruit size as well as ripening duration.

Safflower Flavonoid 3′5′Hydroxylase Promotes Methyl Jasmonate-induced Anthocyanin Accumulation in Transgenic Plants

Flavonoids are the most abundant class of secondary metabolites that are ubiquitously involved in plant development and resistance to biotic and abiotic stresses. Flavonoid biosynthesis involves multiple channels of orchestrated molecular regulatory factors. Methyl jasmonate (MeJA) has been demonstrated to enhance flavonoid accumulation in numerous plant species; however, the underlying molecular mechanism of MeJA-induced flavonoid biosynthesis in safflower is still not evident. In the present study, we revealed the underlying molecular basis of a putative F3′5′H gene from safflower imparting MeJA-induced flavonoid accumulation in transgenic plants. The constitutive expression of the CtF3′5′H1 gene was validated at different flowering stages, indicating their diverse transcriptional regulation through flower development in safflower. Similarly, the CtF3′5′H1-overexpressed Arabidopsis plants exhibit a higher expression level, with significantly increased anthocyanins and flavonoid content, but less proanthocyanidins than wild-type plants. In addition, transgenic plants treated with exogenous MeJA revealed the up-regulation of CtF3′5′H1 expression over different time points with significantly enhanced anthocyanin and flavonoid content as confirmed by HPLC analysis. Moreover, CtF3′5′H1- overexpressed Arabidopsis plants under methyl violet and UV-B irradiation also indicated significant increase in the expression level of CtF3′5′H1 with improved anthocyanin and flavonoid content, respectively. Noticeably, the virus-induced gene silencing (VIGS) assay of CtF3′5′H1 in safflower leaves also confirmed reduced anthocyanin accumulation. However, the CtF3′5′H1 suppression in safflower leaves under MeJA elicitation demonstrated significant increase in total flavonoid content. Together, our findings confirmed that CtF3′5′H1 is likely mediating methyl jasmonate-induced flavonoid biosynthesis in transgenic plants via enhanced anthocyanin accumulation.

Effect of Methyl Jasmonate on the Biosynthesis of Volatile Compounds Associated with the Ripening of Grape Tomato Fruits

The present work aims to evaluate the roles of methyl jasmonate (MeJA) in the formation of volatile organic compounds (VOC) from grape tomatoes during ripening. Fruits were treated with MeJA, ethylene, 1-MCP (1-methylcyclopropene), and MeJA+1-MCP, with analyses of the VOC and levels of the gene transcripts for the enzymes lipoxygenase (LOX), alcohol dehydrogenase (ADH), and hydroperoxide lyase (HPL). An intimate relationship between MeJA and ethylene in aroma formation was detected, mainly among the VOC from the carotenoid pathway. Expression of the fatty acid transcripts, LOXC, ADH, and HPL pathway genes, was reduced by 1-MCP, even when associated with MeJA. In ripe tomato, MeJA increased most of the volatile C6 compounds, except 1-hexanol. The MeJA+1-MCP treatment followed most of the increases in volatile C6 compounds that were increased by MeJA alone, which evidenced some ethylene-independent mechanism in the production of the volatile C6 compounds. In ripe tomato, MeJA and MeJA+1-MCP increased the levels of 6-methyl-5-hepten-2-one, which is derived from lycopene, evidencing an ethylene-independent biosynthetic process.

Genome-wide identification and expression analysis of the bHLH gene family in passion fruit (Passiflora edulis) and its response to abiotic stress

Passion fruit is a tropical fruit crop with significant agricultural, economic and ornamental values. The growth and development of passion fruit are greatly affected by climatic conditions. In plants, the basic helix-loop-helix (bHLH) gene family plays essential roles in the floral organ and fruit development, as well as stress response. However, the characteristics and functions of the bHLH genes of passion fruit remain unclear. Here, 138 passion fruit bHLH members were identified and classified into 20 subfamilies. The structural analysis illustrated that PebHLH proteins of the specific subfamily are relatively conserved. Collinearity analysis indicated that the expansion of the PebHLH gene family mainly took place by segmental duplication, and the structural diversity of duplicated genes might contribute to their functional diversity. PebHLHs, which potentially regulate different floral organ and fruit development, were further screened out, and many of these genes were differentially expressed under various stress treatments. The co-presence of different cis-regulatory elements involved in developmental regulation, hormone and stress responses in the promoter regions of PebHLHs might be closely related to their diverse regulatory roles. Overall, this study will be helpful for further functional investigation of PebHLHs and provides clues for improvement of the passion fruit breeding.

Transcriptome and Gene Regulatory Network Analyses Reveal New Transcription Factors in Mature Fruit Associated with Harvest Date in Prunus persica

Harvest date is a critical parameter for producers and consumers regarding agro-industrial performance. It involves a pleiotropic effect controlling the development of other fruit quality traits through finely controlling regulatory mechanisms. Fruit ripening is a process in which various signals and biological events co-occur and are regulated by hormone signaling that produces the accumulation/degradation of multiple compounds. However, the regulatory mechanisms that control the hormone signaling involved in fruit development and ripening are still unclear. To investigate the issue, we used individuals with early, middle and late harvest dates from a peach segregating population to identify regulatory candidate genes controlling fruit quality traits at the harvest stage and validate them in contrasting peach varieties for this trait. We identified 467 and 654 differentially expressed genes for early and late harvest through a transcriptomic approach. In addition, using the Arabidopsis DAP-seq database and network analysis, six transcription factors were selected. Our results suggest significant hormonal balance and cell wall composition/structure differences between early and late harvest samples. Thus, we propose that higher expression levels of the transcription factors HB7, ERF017 and WRKY70 in early harvest individuals would induce the expression of genes associated with the jasmonic acid pathway, photosynthesis and gibberellins inhibition. While on the other hand, the high expression levels of LHY, CDF3 and NAC083 in late harvest individuals would promote the induction of genes associated with abscisic acid biosynthesis, auxins and cell wall remodeling.

Genome-wide identification, comprehensive characterization of transcription factors, cis-regulatory elements, protein homology, and protein interaction network of DREB gene family in Solanum lycopersicum

Tomato is a drought-sensitive crop which has high susceptibility to adverse climatic changes. Dehydration-responsive element-binding (DREB) are significant plant transcription factors that have a vital role in regulating plant abiotic stress tolerance by networking with DRE/CRT cis-regulatory elements in response to stresses. In this study, bioinformatics analysis was performed to conduct the genome-wide identification and characterization of DREB genes and promoter elements in Solanum lycopersicum. In genome-wide coverage, 58 SlDREB genes were discovered on 12 chromosomes that justified the criteria of the presence of AP2 domain as conserved motifs. Intron-exon organization and motif analysis showed consistency with phylogenetic analysis and confirmed the absence of the A3 class, thus dividing the SlDREB genes into five categories. Gene expansion was observed through tandem duplication and segmental duplication gene events in SlDREB genes. Ka/Ks values were calculated in ortholog pairs that indicated divergence time and occurrence of purification selection during the evolutionary period. Synteny analysis demonstrated that 32 out of 58 and 47 out of 58 SlDREB genes were orthologs to Arabidopsis and Solanum tuberosum, respectively. Subcellular localization predicted that SlDREB genes were present in the nucleus and performed primary functions in DNA binding to regulate the transcriptional processes according to gene ontology. Cis-acting regulatory element analysis revealed the presence of 103 motifs in 2.5-kbp upstream promoter sequences of 58 SlDREB genes. Five representative SlDREB proteins were selected from the resultant DREB subgroups for 3D protein modeling through the Phyre2 server. All models confirmed about 90% residues in the favorable region through Ramachandran plot analysis. Moreover, active catalytic sites and occurrence in disorder regions indicated the structural and functional flexibility of SlDREB proteins. Protein association networks through STRING software suggested the potential interactors that belong to different gene families and are involved in regulating similar functional and biological processes. Transcriptome data analysis has revealed that the SlDREB gene family is engaged in defense response against drought and heat stress conditions in tomato. Overall, this comprehensive research reveals the identification and characterization of SlDREB genes that provide potential knowledge for improving abiotic stress tolerance in tomato.

Characterization of infected process and primary mechanism in rice Acuce defense against rice blast fungus, Magnaporthe oryzae

Identification of infection process and defense response during M. oryzae infecting Acuce. Magnaporthe oryzae is a destructive rice pathogen. Recent studies have focused on the initial infectious stage, with a few studies conducted to elucidate the characteristics of the late infectious stages. This study aims to decipher the characteristics at different stages (biotrophic, biotrophy-necrotrophy switch (BNS), and necrotrophic) between the interaction of two M. oryzae-rice combinations and investigate the resistance mechanisms of rice to M. oryzae using cytological and molecular methods. The biotrophic phase of M. oryzae-LTH compatible interaction was found to be longer than that of M. oryzae-Acuce incompatible interaction. We also found that jasmonic acid (JA) signaling plays an important role in defense by regulating antimicrobial compound accumulation in infected Acuce via a synergistic interaction of JA-salicylic acid (SA) and JA-ethylene (ET). In infected LTH, JA-ET/JA-SA showed antagonistic interaction. Ibuprofen (IBU) is a JA inhibitor. Despite the above findings, we found that exogenous JA-Ile and IBU significantly alleviated blast symptoms in infected LTH at 36 hpi (biotrophic) and 72 hpi (BNS), indicating these two-time points may be critical for managing blast disease in the compatible interaction. Conversely, IBU significantly increased blast symptoms on the infected Acuce at 36 hpi, confirming that the JA signal plays a central role in the defense response in infected Acuce. According to transcriptional analysis, the number of genes enriched in the plant hormone signal pathway was significantly higher than in other pathways. Our findings suggested that JA-mediated defense mechanism is essential in regulating Acuce resistance, particularly during the biotrophic and BNS phases.

Signal transduction in non-climacteric fruit ripening

Fleshy fruit ripening involves changes in numerous cellular processes and metabolic pathways, resulting from the coordinated actions of diverse classes of structural and regulatory proteins. These include enzymes, transporters and complex signal transduction systems. Many aspects of the signaling machinery that orchestrates the ripening of climacteric fruits, such as tomato (Solanum lycopersicum), have been elucidated, but less is known about analogous processes in non-climacteric fruits. The latter include strawberry (Fragaria x ananassa) and grape (Vitis vinifera), both of which are used as non-climacteric fruit experimental model systems, although they originate from different organs: the grape berry is a true fruit derived from the ovary, while strawberry is an accessory fruit that is derived from the floral receptacle. In this article, we summarize insights into the signal transduction events involved in strawberry and grape berry ripening. We highlight the mechanisms underlying non-climacteric fruit ripening, the multiple primary signals and their integrated action, individual signaling components, pathways and their crosstalk, as well as the associated transcription factors and their signaling output.

VviAGL11 self-regulates and targets hormone- and secondary metabolism-related genes during seed development

VviAGL11, the Arabidopsis SEEDSTICK homolog, has been proposed to have a causative role in grapevine stenospermocarpy. An association between a mutation in the coding sequence (CDS) and the seedless phenotype was reported, however, no working mechanisms have been demonstrated yet. We performed a deep investigation of the full VviAGL11 gene sequence in a collection of grapevine varieties belonging to several seedlessness classes that revealed three different promoter-CDS combinations. By investigating the expression of the three VviAGL11 alleles, and by evaluating their ability to activate the promoter region, we observed that VviAGL11 self-activates in a specific promoter-CDS combination manner. Furthermore, by transcriptomic analyses on ovule and developing seeds in seeded and seedless varieties and co-expression approaches, candidate VviAGL11 targets were identified and further validated through luciferase assay and in situ hybridization. We demonstrated that VviAGL11 Wild Type CDS activates Methyl jasmonate esterase and Indole-3-acetate beta-glucosyltransferase, both involved in hormone signaling and Isoflavone reductase, involved in secondary metabolism. The dominant-negative effect of the mutated CDS was also functionally ectopically validated in target induction. VviAGL11 was shown to co-localize with its targets in the outer seed coat integument, supporting its direct involvement in seed development, possibly by orchestrating the crosstalk among MeJA, auxin, and isoflavonoids synthesis. In conclusion, the VviAGL11 expression level depends on the promoter-CDS allelic combination, and this will likely affect its ability to activate important triggers of the seed coat development. The dominant-negative effect of the mutated VviAGL11 CDS on the target genes activation was molecularly validated. A new regulatory mechanism correlating VviAGL11 haplotype assortment and seedlessness class in grapevine is proposed.

Do Non-climacteric Fruits Share a Common Ripening Mechanism of Hormonal Regulation?

Fleshy fruits have been traditionally categorized into climacteric (CL) and non-climacteric (NC) groups. CL fruits share a common ripening mechanism of hormonal regulation, i.e., the ethylene regulation, whereas whether NC fruits share a common mechanism remains controversial. Abscisic acid (ABA) has been commonly thought to be a key regulator in NC fruit ripening; however, besides ABA, many other hormones have been increasingly suggested to play crucial roles in NC fruit ripening. NC fruits vary greatly in their organ origin, constitution, and structure. Development of different organs may be different in the pattern of hormonal regulation. It has been well demonstrated that the growth and development of strawberry, the model of NC fruits, is largely controlled by a hormonal communication between the achenes and receptacle; however, not all NC fruits contain achenes. Accordingly, it is particularly important to understand whether strawberry is indeed able to represent a universal mechanism for the hormonal regulation of NC fruit ripening. In this mini-review, we summarized the recent research advance on the hormone regulation of NC ripening in relation to fruit organ origination, constitution, and structure, whereby analyzing and discussing whether NC fruits may share a common mechanism of hormonal regulation.

FvWRKY48 binds to the pectate lyase FvPLA promoter to control fruit softening in Fragaria vesca

The regulatory mechanisms that link WRKY gene expression to fruit ripening are largely unknown. Using transgenic approaches, we showed that a WRKY gene from wild strawberry (Fragaria vesca), FvWRKY48, may be involved in fruit softening and ripening. We showed that FvWRKY48 is localized to the nucleus and that degradation of the pectin cell wall polymer homogalacturonan, which is present in the middle lamella and tricellular junction zones of the fruit, was greater in FvWRKY48-OE (overexpressing) fruits than in empty vector (EV)-transformed fruits and less substantial in FvWRKY48-RNAi (RNA interference) fruits. Transcriptomic analysis indicated that the expression of pectate lyase A (FvPLA) was significantly downregulated in the FvWRKY48-RNAi receptacle. We determined that FvWRKY48 bound to the FvPLA promoter via a W-box element through yeast one-hybrid, electrophoretic mobility shift, and chromatin immunoprecipitation quantitative polymerase chain reaction experiments, and β-glucosidase activity assays suggested that this binding promotes pectate lyase activity. In addition, softening and pectin degradation were more intense in FvPLA-OE fruit than in EV fruit, and the middle lamella and tricellular junction zones were denser in FvPLA-RNAi fruit than in EV fruit. We speculated that FvWRKY48 maybe increase the expression of FvPLA, resulting in pectin degradation and fruit softening.

Impact of hormone applications on ripening-related metabolites in Gewürztraminer grapes (Vitis vinifera L.): The key role of jasmonates in terpene modulation

Terpenes play a formative role in grape and wine flavor, particularly for high-terpenic cultivars. Differences in terpene profiles influence grape varietal character and vintage quality. Little is known about the endogenous factors controlling terpene biosynthesis in grape. Through multiple experiments, six hormones (abscisic acid, ABA; ethylene, ETH; jasmonic acid, JA; methyl jasmonate, MeJA; indole-3-acetic acid, IAA; 1-naphthaleneacetic acid, NAA) that either promote or repress ripening were applied to Gewürztraminer clusters near veraison to gauge their effect on ripening and terpene biosynthesis. Jasmonates (JA, MeJA) increased terpene concentrations and the expression of terpene genes in grapes. Such increases were not associated to increases of other ripening-related metabolites such as sugars or anthocyanins. MeJA also affected the expression of several hormone related genes, increased IAA levels, and reduced sugar and anthocyanin concentration in grapes. This research provides novel insights into terpene regulation by ripening-related hormones and jasmonates in grapes.

Induction of Metabolic Changes in Amino Acid, Fatty Acid, Tocopherol, and Phytosterol Profiles by Exogenous Methyl Jasmonate Application in Tomato Fruits

Methyl jasmonate hormone can stimulate the production of several metabolites responsible for improving fruit quality and nutritional attributes related to human health. In this context, efforts to manipulate tomatoes, such as using hormonal treatment to increase metabolite levels essential to plant growth and human nutrition, have received considerable attention. The aim of this study was to show the impact of metabolic profile on fruit quality and nutritional properties under exogenous methyl jasmonate during fruit ripening. The treatments were performed using 100 ppm of methyl jasmonate and 100 ppm of gaseous ethylene over 24 h. Ethylene emission, fruit surface color and metabolomics analysis were measured at 4, 10, and 21 days after harvest, considering the untreated fruits as control group. Methyl jasmonate induced the production of amino acids—mainly glutamine, glutamic acid and γ-aminobutyric acid (at least 14-fold higher)—and fatty acids—mainly oleic, linoleic, and linolenic acids (at least three-fold higher than untreated fruits); while exogenous ethylene predominantly affected sugar metabolism, increasing the levels of fructose, mannose and glucose to at least two-fold that levels in the untreated fruits. Additionally, methyl jasmonate significantly affected secondary metabolites, inducing by at least 80% the accumulation of α-tocopherol and β-sitosterol in fully ripe fruits. Our results suggest that the postharvest application of the hormone methyl jasmonate can contribute to the sensory characteristics and increase the nutritional value of the fruits since important changes related to the tomato metabolome were associated with compounds responsible for the fruit quality and health benefits.

Roles of abscisic acid in regulating ripening and quality of strawberry, a model non-climacteric fruit

Abscisic acid (ABA) is a dominant regulator of ripening and quality in non-climacteric fruits. Strawberry is regarded as a model non-climacteric fruit due to its extensive genetic studies and proven suitability for transgenic approaches to understanding gene function. Strawberry research has contributed to studies on color, flavor development, and fruit softening, and in recent years ABA has been established as a core regulator of strawberry fruit ripening, whereas ethylene plays this role in climacteric fruits. Despite this major difference, several components of the interacting genetic regulatory network in strawberry, such as MADS-box and NAC transcription factors, are similar to those that operate in climacteric fruit. In this review, we summarize recent advances in understanding the role of ABA biosynthesis and signaling and the regulatory network of transcription factors and other phytohormones in strawberry fruit ripening. In addition to providing an update on its ripening, we discuss how strawberry research has helped generate a broader and more comprehensive understanding of the mechanism of non-climacteric fruit ripening and focus attention on the use of strawberry as a model platform for ripening studies.

Genome-wide promoter analysis, homology modeling and protein interaction network of Dehydration Responsive Element Binding (DREB) gene family in Solanum tuberosum

Dehydration Responsive Element Binding (DREB) regulates the expression of numerous stress-responsive genes, and hence plays a pivotal role in abiotic stress responses and tolerance in plants. The study aimed to develop a complete overview of the cis-acting regulatory elements (CAREs) present in S. tuberosum DREB gene promoters. A total of one hundred and four (104) cis-regulatory elements (CREs) were identified from 2.5kbp upstream of the start codon (ATG). The in-silico promoter analysis revealed variable sets of cis-elements and functional diversity with the predominance of light-responsive (30%), development-related (20%), abiotic stress-responsive (14%), and hormone-responsive (12%) elements in StDREBs. Among them, two light-responsive elements (Box-4 and G-box) were predicted in 64 and 61 StDREB genes, respectively. Two development-related motifs (AAGAA-motif and as-1) were abundant in StDREB gene promoters. Most of the DREB genes contained one or more Myeloblastosis (MYB) and Myelocytometosis (MYC) elements associated with abiotic stress responses. Hormone-responsive element i.e. ABRE was found in 59 out of 66 StDREB genes, which implied their role in dehydration and salinity stress. Moreover, six proteins were chosen corresponding to A1-A6 StDREB subgroups for secondary structure analysis and three-dimensional protein modeling followed by model validation through PROCHECK server by Ramachandran Plot. The predicted models demonstrated >90% of the residues in the favorable region, which further ensured their reliability. The present study also anticipated pocket binding sites and disordered regions (DRs) to gain insights into the structural flexibility and functional annotation of StDREB proteins. The protein association network determined the interaction of six selected StDREB proteins with potato proteins encoded by other gene families such as MYB and NAC, suggesting their similar functional roles in biological and molecular pathways. Overall, our results provide fundamental information for future functional analysis to understand the precise molecular mechanisms of the DREB gene family in S. tuberosum.

Pre-Harvest Application of Salicylic Acid, Abscisic Acid, and Methyl Jasmonate Conserve Bioactive Compounds of Strawberry Fruits during Refrigerated Storage

The short shelf-life and loss of bioactive compounds of strawberry fruit are the most important problems during strawberry refrigerated storage. This study was carried out to evaluate the effect of the pre-harvest foliar application of salicylic acid (SA) (2 and 4 mM), abscisic acid (ABA) (0.25 and 0.50 mM), and methyl jasmonate (MeJA) (0.25 and 0.50 mM) three times, 10 d apart, at fruit development and ripening stages on storage ability and bioactive compounds of strawberry fruit (cv. Festival) stored at 4 °C for 12 d. Our results showed that fruit obtained from both concentrations of ABA and 0.25 mM MeJA was firmer and had higher total soluble solids (TSS) than fruit from non-treated plants. However, all previous applications had no significant effect on weight loss, pH, or color. Applications of 4 mM SA and 0.25 mM MeJA conserved fruit from ascorbic acid (AsA) loss compared to control at the end of the storage period. In addition, all pre-harvest applications remained higher in total phenolic compounds (TPC) and anthocyanin contents compared to controls at the last storage period. Hence, the pre-harvest application of SA, ABA, and MeJA could be used to conserve TPC and anthocyanin as well as the quality of strawberry fruits during refrigerated storage.

A Method for Assaying of Protein Kinase Activity In Vivo and Its Use in Studies of Signal Transduction in Strawberry Fruit Ripening

Strawberry (Fragaria × ananassa) fruit ripening is regulated by a complex of cellular signal transduction networks, in which protein kinases are key components. Here, we report a relatively simple method for assaying protein kinase activity in vivo and specifically its application to study the kinase, FaMPK6, signaling in strawberry fruit. Green fluorescent protein (GFP)-tagged FaMPK6 was transiently expressed in strawberry fruit and after stimuli were applied to the fruit it was precipitated using an anti-GFP antibody. The precipitated kinase activity was measured in vitro using ³²P-ATP and myelin basic protein (MBP) as substrates. We also report that FaMPK6 is not involved in the abscisic acid (ABA) signaling cascade, which is closely associated with FaMPK6 signaling in other plant species. However, methyl jasmonate (MeJA), low temperature, and high salt treatments were all found to activate FaMPK6. Transient manipulation of FaMPK6 expression was observed to cause significant changes in the expression patterns of 2749 genes, of which 264 were associated with MeJA signaling. The data also suggest a role for FaMPK6 in modulating cell wall metabolism during fruit ripening. Taken together, the presented method is powerful and its use will contribute to a profound exploration to the signaling mechanism of strawberry fruit ripening.

Therapeutic Potential of Jasmonic Acid and Its Derivatives

A modern method of therapeutic use of natural compounds that would protect the body are jasmonates. The main representatives of jasmonate compounds include jasmonic acid and its derivatives, mainly methyl jasmonate. Extracts from plants rich in jasmonic compounds show a broad spectrum of activity, i.e., anti-cancer, anti-inflammatory and cosmetic. Studies of the biological activity of jasmonic acid and its derivatives in mammals are based on their structural similarity to prostaglandins and the compounds can be used as natural therapeutics for inflammation. Jasmonates also constitute a potential group of anti-cancer drugs that can be used alone or in combination with other known chemotherapeutic agents. Moreover, due to their ability to stimulate exfoliation of the epidermis, remove discoloration, regulate the function of the sebaceous glands and reduce the visible signs of aging, they are considered for possible use in cosmetics and dermatology. The paper presents a review of literature data on the biological activity of jasmonates that may be helpful in treatment and prevention.

The NAC transcription factor FaRIF controls fruit ripening in strawberry

In contrast to climacteric fruits such as tomato, the knowledge on key regulatory genes controlling the ripening of strawberry, a nonclimacteric fruit, is still limited. NAC transcription factors (TFs) mediate different developmental processes in plants. Here, we identified and characterized Ripening Inducing Factor (FaRIF), a NAC TF that is highly expressed and induced in strawberry receptacles during ripening. Functional analyses based on stable transgenic lines aimed at silencing FaRIF by RNA interference, either from a constitutive promoter or the ripe receptacle-specific EXP2 promoter, as well as overexpression lines showed that FaRIF controls critical ripening-related processes such as fruit softening and pigment and sugar accumulation. Physiological, metabolome, and transcriptome analyses of receptacles of FaRIF-silenced and overexpression lines point to FaRIF as a key regulator of strawberry fruit ripening from early developmental stages, controlling abscisic acid biosynthesis and signaling, cell-wall degradation, and modification, the phenylpropanoid pathway, volatiles production, and the balance of the aerobic/anaerobic metabolism. FaRIF is therefore a target to be modified/edited to control the quality of strawberry fruits.

Ethylene application at the immature stage of Fragaria chiloensis fruit represses the anthocyanin biosynthesis with a concomitant accumulation of lignin

Ethylene seems to play a secondary role in non-climacteric strawberry ripening compared to abscisic acid. However, this does not exclude that ethylene can regulate some specific events related to the ripening process. Preliminary experiments of applications of ethylene or its inhibitor 1-MCP to strawberry fruits have reinforced this hypothesis. Here, we reveal some previously non-covered physiological effects of ethylene using an in vitro strawberry ripening system. Fruits of Fragaria chiloensis treated with ethephon at the large green developmental stage showed inhibition of anthocyanin biosynthesis and downregulation of essential anthocyanin biosynthesis genes during the ripening. At the same time, ethylene stimulated lignin biosynthesis and remarkably upregulated the expression of FcPOD27. Since contrasting results have been reported when ethylene was applied at late ripening developmental stages, our findings support the hypothesis of a temporal-specific ethylene role in the ripening of strawberry fruits.

Transcriptome analysis of strawberry fruit in response to exogenous arginine

Transcriptome and physiological analysis showed that exogenous arginine can delay the ripening process of postharvest strawberry fruit. Arginine (Arg) plays an important role in the growth and development of plants, but its growth and development regulatory mechanisms in strawberry fruit are unknown. In this study, we found that the content of Arg decreased after the onset of fruit coloration and exogenous Arg inhibited fruit coloration. We comprehensively analyzed the transcriptome of 'Sweet Charlie' strawberry fruit with or without Arg treatment and identified a large number of differential genes and metabolites. Based on the transcriptome data, we also found that Arg inhibited ripening, which coincided with changes in several physiological parameters and their corresponding gene transcripts, including firmness, anthocyanin content, sugar content, Arg content, indole-acetic acid (IAA) content, abscisic acid (ABA) content, and ethylene emissions. We also found that Arg induced the expression of heat-shock proteins (HSPs) and antioxidant enzyme genes, which improved strawberry stress resistance. This study elucidated the molecular mechanism by which exogenous Arg delays strawberry fruit ripening, providing some genetic information to help guide the future improvement and cultivation of strawberry.

Low temperature modulates natural peel degreening in lemon fruit independently of endogenous ethylene

Peel degreening is an important aspect of fruit ripening in many citrus fruit, and previous studies have shown that it can be advanced by ethylene treatment or by low-temperature storage. However, the important regulators and pathways involved in natural peel degreening remain largely unknown. To determine how natural peel degreening is regulated in lemon fruit (Citrus limon), we studied transcriptome and physiochemical changes in the flavedo in response to ethylene treatment and low temperatures. Treatment with ethylene induced rapid peel degreening, which was strongly inhibited by the ethylene antagonist, 1-methylcyclopropene (1-MCP). Compared with 25 ºC, moderately low storage temperatures of 5-20 °C also triggered peel degreening. Surprisingly, repeated 1-MCP treatments failed to inhibit the peel degreening induced by low temperature. Transcriptome analysis revealed that low temperature and ethylene independently regulated genes associated with chlorophyll degradation, carotenoid metabolism, photosystem proteins, phytohormone biosynthesis and signalling, and transcription factors. Peel degreening of fruit on trees occurred in association with drops in ambient temperature, and it coincided with the differential expression of low temperature-regulated genes. In contrast, genes that were uniquely regulated by ethylene showed no significant expression changes during on-tree peel degreening. Based on these findings, we hypothesize that low temperature plays a prominent role in regulating natural peel degreening independently of ethylene in citrus fruit.

Methyl Jasmonate Applications From Flowering to Ripe Fruit Stages of Strawberry (Fragaria × ananassa 'Camarosa') Reinforce the Fruit Antioxidant Response at Post-harvest

Preharvest applications of methyl jasmonate (MeJA) have been shown to improve post-harvest fruit quality in strawberry fruit. However, the effectiveness of consecutive field applications at different phenological stages on the reinforcement of the antioxidant capacity remains to be analyzed. To determine the best antioxidant response of strawberry (Fragaria × ananassa 'Camarosa') fruit to different numbers and timing of MeJA applications, we performed three differential preharvest treatments (M1, M2, and M3) consisted of successive field applications of 250 μmol L^-1 MeJA at flowering (M3), large green (M2 and M3), and ripe fruit stages (M1, M2, and M3). Then, we analyzed their effects on fruit quality parameters [firmness, skin color, soluble solids content/titratable acidity (SSC/TA) ratio, fruit weight at harvest, and weight loss] along with anthocyanin and proanthocyanidin (PA) accumulation; the antioxidant-related enzymatic activity of catalase (CAT), guaiacol peroxidase (POX), and ascorbate peroxidase (APX); the total flavonoid and phenolic contents, antioxidant capacity, and ascorbic acid content (AAC) during post-harvest storage (0, 24, 48, and 72 h). We also evaluated the effect on lignin, total carbon and nitrogen (%C and N), lipid peroxidation, and C and N isotopes signatures on fruits. Remarkably, the results indicated that MeJA treatment increases anthocyanin and PA contents as well as CAT activity in post-harvest storage, depending on the number of preharvest MeJA applications. Also, M3 fruit showed a higher AAC compared to control at 48 and 72 h. Noticeably, the anthocyanin content and CAT activity were more elevated in M3 treatment comparing with control at all post-harvest times. In turn, APX activity was found higher on all MeJA-treated fruit independent of the number of applications. Unlike, MeJA applications did not generate variations on fruit firmness and weight, lignin contents,% C and N, and in lipid peroxidation and water/nitrogen use efficiency according to C and N isotope discrimination. Finally, we concluded that an increasing number of MeJA applications (M3 treatment) improve anthocyanin, PA, AAC, and CAT activity that could play an essential role against reactive oxygen species, which cause stress that affects fruits during post-harvest storage.

Priming of Defense Systems and Upregulation of MYC2 and JAZ1 Genes after Botrytis cinerea Inoculation in Methyl Jasmonate-Treated Strawberry Fruits

Several attempts have been made to study the effects of methyl jasmonate (MeJA) on plants in the past years. However, the comparative effects of the number and phenological time of MeJA applications on the activation of defense systems is currently unknown in strawberries. In the present research, we performed three field treatments during strawberry (Fragaria× ananassa 'Camarosa') fruit development and ripening which consisted of differential MeJA applications at flowering (M3), and the large green (M2 and M3) and red ripe (M1, M2, and M3) fruit stages. We also checked changes in gene expression related to plant defense against Botrytis cinerea inoculation post-harvest. In M3 treatment, we observed an upregulation of the anthocyanin and lignin contents and the defense-related genes, encoding for chitinases, β-1,3-glucanases and polygalacturonase-inhibiting proteins, after harvest (0 hpi), along with the jasmonate signaling-related genes FaMYC2 and FaJAZ1 at 48 h after B. cinerea inoculation (48 hpi) during postharvest storage. Although we did not find differences in gray mold incidence between the MeJA treatments and control, these results suggest that preharvest MeJA treatment from the flowering stage onwards (M3) primes defense responses mediated by the upregulation of different defense-related genes and retains the upregulation of MYC2 and JAZ1 at 48 hpi.

Characterizing the involvement of FaMADS9 in the regulation of strawberry fruit receptacle development

FaMADS9 is the strawberry (Fragaria x ananassa) gene that exhibits the highest homology to the tomato (Solanum lycopersicum) RIN gene. Transgenic lines were obtained in which FaMADS9 was silenced. The fruits of these lines did not show differences in basic parameters, such as fruit firmness or colour, but exhibited lower Brix values in three of the four independent lines. The gene ontology MapMan category that was most enriched among the differentially expressed genes in the receptacles at the white stage corresponded to the regulation of transcription, including a high percentage of transcription factors and regulatory proteins associated with auxin action. In contrast, the most enriched categories at the red stage were transport, lipid metabolism and cell wall. Metabolomic analysis of the receptacles of the transformed fruits identified significant changes in the content of maltose, galactonic acid-1,4-lactone, proanthocyanidins and flavonols at the green/white stage, while isomaltose, anthocyanins and cuticular wax metabolism were the most affected at the red stage. Among the regulatory genes that were differentially expressed in the transgenic receptacles were several genes previously linked to flavonoid metabolism, such as MYB10, DIV, ZFN1, ZFN2, GT2, and GT5, or associated with the action of hormones, such as abscisic acid, SHP, ASR, GTE7 and SnRK2.7. The inference of a gene regulatory network, based on a dynamic Bayesian approach, among the genes differentially expressed in the transgenic receptacles at the white and red stages, identified the genes KAN1, DIV, ZFN2 and GTE7 as putative targets of FaMADS9. A MADS9-specific CArG box was identified in the promoters of these genes.

Methyl Jasmonate Enhances Ethylene Synthesis in Kiwifruit by Inducing NAC Genes That Activate ACS1

Cross-talk between various hormones is important in regulating many aspects of plant growth, development, and senescence, including fruit ripening. Here, exogenous ethylene (ETH, 100 μL/L, 12 h) rapidly accelerated 'Hayward' kiwifruit (Actinidia deliciosa) softening and ethylene production and was enhanced by supplementing with continuous treatment with methyl jasmonate (MeJA, 100 μM/L, 12 h) (ETH+MeJA). ETH+MeJA enhanced ACC synthase (ACS) activities and 1-aminocyclopropane-1-carboxylic acid (ACC) accumulation but not ACC oxidase (ACO) activity. Increased transcripts of ACS genes AdACS1 and AdACS2, ACS activity, and ethylene production were positively correlated. The abundance of AdACS1 was about 6-fold higher than AdACS2. RNA-seq identified 6 transcription factors among the 87 differentially expressed unigenes induced by ETH+MeJA. Dual-luciferase and electrophoretic mobility shift assays (EMSA) indicated that AdNAC2/3 physically interacted with and trans-activated the AdACS1 promoter 2.2- and 3.5-fold, respectively. Collectively, our results indicate that MeJA accelerates ethylene production in kiwifruit induced by exogenous ethylene, via a preferential activation of AdACS1 and AdACS2.

A Development-Associated Decrease in Osmotic Potential Contributes to Fruit Ripening Initiation in Strawberry (Fragaria ananassa)

Fruit development and ripening are accompanied by a large increase in cellular soluble solid contents, which results in a significant decrease in osmotic potential (DOP). Here, we report that this development-associated DOP contributes to the initiation of ripening in strawberry (Fragaria ananassa Duch., Benihoppe) fruit. We show that fruit water potential significantly decreases at the onset of ripening as a result of the DOP. Further analysis using nuclear magnetic resonance spectroscopy (NMR) indicated that the change in fruit water potential was likely caused by catabolism of large molecules in receptacle cells, and bioinformatic analysis identified a family of osmotin-like proteins (OLP) that have a potential role in osmolyte accommodation. The gene expression of more than half of the OLP members increased substantially at the onset of fruit ripening, and specifically responded to DOP treatment, consistent with a close relationship between DOP and fruit ripening. We report that the DOP induced either by mannitol or water loss, triggered fruit ripening, as indicated by the elevated expression of multiple ripening genes and diverse ripening-associated physiological parameters. Collectively, these results suggest that the DOP contributes to strawberry fruit ripening initiation.

Regulation of color transition in purple tea (Camellia sinensis)

Comparative proteomics and metabolomics study of juvenile green, light purple and dark purple leaf to identify key proteins and metabolites that putatively govern color transition in Camellia sinensis. Color transition from juvenile green to dark purple leaf in Camellia sinensis is a complex process and thought to be regulated by an intricate balance of genes, proteins and metabolites expression. A molecular-level understanding of proteins and metabolites expression is needed to define metabolic process underpinning color transition in C. sinensis. Here, purple leaf growth of C. sinensis cultivar was divided into three developmental stages viz. juvenile green (JG), light purple (LP) and dark purple (DP) leaf. Scanning electron microscope (SEM) analysis revealed a clear morphological variation such as cell size, shape and texture as tea leaf undergoing color transition. Proteomic and metabolomic analyses displayed the temporal changes in proteins and metabolites that occur in color transition process. In total, 211 differentially expressed proteins (DEPs) were identified presumably involved in secondary metabolic processes particularly, flavonoids/anthocyanin biosynthesis, phytohormone regulation, carbon and nitrogen assimilation and photosynthesis, among others. Subcellular localization of three candidate proteins was further evaluated by their transient expression in planta. Interactome study revealed that proteins involved in primary metabolism, precursor metabolite, photosynthesis, phytohormones, transcription factor and anthocyanin biosynthesis were found to be interact directly or indirectly and thus, regulate color transition from JG to DP leaf. The present study not only corroborated earlier findings but also identified novel proteins and metabolites that putatively govern color transition in C. sinensis. These findings provide a platform for future studies that may be utilized for metabolic engineering/molecular breeding in an effort to develop more desirable traits.

ABA and sucrose co-regulate strawberry fruit ripening and show inhibition of glycolysis

Abscisic acid (ABA) and sucrose play an important role in strawberry fruit ripening, but how ABA and sucrose co-regulate this ripening progress remains unclear. The intention of this study was to examine the effect of ABA and sucrose on strawberry fruit ripening and to evaluate the ABA/sucrose interaction mechanism on the strawberry fruit ripening process. Here, we report that there is an acute synergistic effect between ABA and sucrose in accelerating strawberry fruit ripening. The time frame of fruit development and ripening was shortened after the application of ABA, sucrose, and ABA + sucrose, but most of the major quality parameters in treated-ripe fruit, including fruit weight, total soluble solids, anthocyanin, ascorbic acid, the total phenolic content, lightness (L*), chroma (C*), and hue angle (h°) values were not affected. Meanwhile, the endogenous ABA and sucrose levels, and the expression of ABA and sucrose signaling genes and ripening-related genes, such as NCED1, NCED2, SnRK2.2, SuSy, MYB5, CEL1, and CEL2, was all significantly enhanced by ABA or sucrose treatment alone, but in particular, by the ABA + sucrose treatment. Therefore, improving the ripening regulation efficiency is one synergetic action of ABA/sucrose. Another synergetic action of ABA/sucrose shows that a short inhibition of glycolysis occurs during accelerated strawberry ripening. ABA and sucrose can induce higher accumulation of H₂O₂, leading to a transient decrease in glycolysis. Conversely, lower endogenous H₂O₂ levels caused by reduced glutathione (GSH) treatment resulted in a transient increase in glycolysis while delaying strawberry fruit ripening. Collectively, this study demonstrates that the ABA/sucrose interaction affects the ripening regulation efficiency and shows inhibition of glycolysis.

Uptake of pharmaceuticals acts as an abiotic stress and triggers variation of jasmonates in Malabar spinach (Basella alba. L)

In recent years, pharmaceuticals have received increasing attentions because of their potential risks to the environment, but researches focusing on their impacts on defense system of living plants are still lacking. As an important class of phytohormones, jasmonates play crucial roles in plant defense system against environmental stress. In order to investigate the effect of pharmaceuticals uptake on endogenous jasmonates, an in vivo solid phase microextraction (SPME) method was established to simultaneously detect and monitor both pharmaceuticals and jasmonates in living plants. The proposed method exhibited wide linear ranges, high sensitivity (limits of detection ranging 0.0043-0.035 ng g^-1 for pharmaceuticals and 0.091-0.22 ng g^-1 for jasmonates, respectively), and satisfactory reproducibility (relative standard deviation of intrafiber ranging 4.2%-8.6% and interfiber ranging 5.2%-8.2%, respectively). Subsequently, this method was successfully applied to track the concentrations of each pharmaceutical and corresponding jasmonates in living Malabar spinach plants (Basella alba. L) exposed to three common pharmaceuticals (i.e. gemfibrozil, mefenamic acid and tolfenamic acid) over 15 days. In result, all pharmaceuticals appeared to trigger intensive biosynthesis of jasmonic acid (JA) (3.1-9.4 times of control) while reduced the concentration of methyl jasmonate (MeJA) (18.3%-38.1% of control). We inferred that uptake of pharmaceuticals acted as an abiotic stress and stimulated the plant defense response because of the variation of jasmonates. To the best of our knowledge, this is the first study applying SPME to detect and track both pharmaceuticals and phytohormones in living plants, which not only provided a glimpse to the adverse effect of pharmaceuticals on plants as well as the regulation of endogenous jasmonates, but also set a promising template for future in vivo analysis of xenobiotics and plant endogenous substances.

Analysis of eight phytohormone concentrations, expression levels of ABA biosynthesis genes, and ripening-related transcription factors during fruit development in strawberry

The contents of eight phytohormones and the expression levels of genes encoding enzymes related to abscisic acid (ABA) biosynthesis and deactivation/degradation and transcription factors (TFs) related to fruit ripening were studied in the non-climacteric strawberry fruit (Fragaria × ananassa Duch., cv. 'Seolhyang') at six developmental stages. The hormones tested were ABA, indole-3-acetic acid (IAA), gibberellic acid 4 (GA₄), jasmonic acid (JA), methyljasmonate (MJ), jasmonoyl isoleucine (JA-Ile), salicylic acid (SA), and ethylene (ET). The developmental and ripening stages studied were small green (S1, 11 days post-anthesis, DPA), green (S2, 20 DPA), breaker (S3, 24 DPA), pink (S4, 27 DPA), red (S5, 31 DPA), and fully red (S6, 40 DPA). IAA and GA₄ contents were highest at S1 and gradually decreased after this stage. ABA content was low at S1-S3 and then increased rapidly until peaking at S6. By contrast, MJ content showed no significant changes over time, while SA content gradually increased. JA, JA-Ile, and ET contents were either insufficient for quantification or undetectable. Expression of the ABA biosynthesis genes FaNCED1 and FaABA2 increased during fruit ripening, whereas expression of the ABA deactivation/degradation genes FaUGT75C1 and FaCYP707A1 was high early in development, when ABA content was low, and then decreased. Among four ripening-related TF genes, FaMYB1, FaMYB5, FaMYB10, and FaASR, only the expression of FaMYB10 seemed to be closely related to strawberry fruit ripening. Our study supports the idea that ABA and FaMYB10 appear to be the key hormone and TF regulating strawberry ripening.

Patagonian Berries: Healthy Potential and the Path to Becoming Functional Foods

In recent years, there has been an increasing interest in studying food and its derived ingredients that can provide beneficial effects for human health. These studies are helping to understand the bases of the ancestral use of several natural products, including native fruits as functional foods. As a result, the polyphenol profile and the antioxidant capacity of the extracts obtained from different Patagonian native berries have been described. This review aims to provide valuable information regarding fruit quality, its particular compound profile, and the feasibility of producing functional foods for human consumption to prevent disorders such as metabolic syndrome and cardiovascular diseases. We also discuss attempts concerning the domestication of these species and generating knowledge that strengthens their potential as traditional fruits in the food market and as a natural heritage for future generations. Finally, additional efforts are still necessary to fully understand the potential beneficial effects of the consumption of these berries on human health, the application of suitable technology for postharvest improvement, and the generation of successfully processed foods derived from Patagonian berries.

Identification of Jasmonic Acid Biosynthetic Genes in Sweet Cherry and Expression Analysis in Four Ancient Varieties from Tuscany

Sweet cherries are non-climacteric fruits whose early development is characterized by high levels of the phytohormone jasmonic acid (JA). Important parameters, such as firmness and susceptibility to cracking, can be affected by pre- and postharvest treatments of sweet cherries with JA. Despite the impact of JA on sweet cherry development and fruit characteristics, there are no studies (to the best of our knowledge) identifying the genes involved in the JA biosynthetic pathway in this species. We herein identify the sweet cherry members of the lipoxygenase family (13-LOX); allene oxide synthase, allene oxide cyclase and 12-oxo-phytodienoic acid reductase 3, as well as genes encoding the transcriptional master regulator MYC2. We analyze their expression pattern in four non-commercial Tuscan varieties ('Carlotta', 'Maggiola', 'Morellona', 'Crognola') having different levels of bioactives (namely phenolics). The highest differences are found in two genes encoding 13-LOX in the variety 'Maggiola' and one MYC2 isoform in 'Morellona'. No statistically-significant variations are instead present in the allene oxide synthase, allene oxide cyclase and 12-oxo-phytodienoic acid reductase 3. Our data pave the way to follow-up studies on the JA signaling pathway in these ancient varieties, for example in relation to development and post-harvest storage.

Transcriptome and hormone analyses provide insights into hormonal regulation in strawberry ripening

The possible molecular mechanisms regulating strawberry fruit ripening were revealed by plant hormone quantification, exogenous hormone application, and RNA-sequencing. Fruit ripening involves a complex interplay among plant hormones. Strawberry is a model for studies on non-climacteric fruit ripening. However, the knowledge on how plant hormones are involved in strawberry ripening is still limited. To understand hormonal actions in the ripening process, we performed genome-wide transcriptome and hormonal analysis for the five major hormones (abscisic acid and catabolites, auxins, cytokinins, gibberellins, and ethylene) in achenes and receptacles (flesh) at different ripening stages of the woodland strawberry Fragaria vesca. Our results demonstrate that the pre-turning stage (a stage with white flesh and red achenes defined in this study) is the transition stage from immature to ripe fruits. The combinatorial analyses of hormone content, transcriptome data, and exogenous hormone treatment indicate that auxin is synthesized predominantly in achenes, while abscisic acid (ABA), bioactive free base cytokinins, gibberellins, and ethylene are mainly produced in receptacles. Furthermore, gibberellin may delay ripening, while ethylene and cytokinin are likely involved at later stages of the ripening process. Our results also provide additional evidence that ABA promotes ripening, while auxin delays it. Although our hormone analysis demonstrates that the total auxin in receptacles remains relatively low and unchanged during ripening, our experimental evidence further indicates that ABA likely enhances expression of the endoplasmic reticulum-localized auxin efflux carrier PIN-LIKES, which may subsequently reduce the auxin level in nucleus. This study provides a global picture for hormonal regulation of non-climacteric strawberry fruit ripening and also evidence for a possible mechanism of ABA and auxin interaction in the ripening process.

Recent Advances in Hormonal Regulation and Cross-Talk during Non-Climacteric Fruit Development and Ripening

Fleshy fruits are characterized by having a developmentally and genetically controlled, highly intricate ripening process, leading to dramatic modifications in fruit size, texture, color, flavor, and aroma. Climacteric fruits such as tomato, pear, banana, and melon show a ripening-associated increase in respiration and ethylene production and these processes are well-documented. In contrast, the hormonal mechanism of fruit development and ripening in non-climacteric fruit, such as strawberry, grape, raspberry, and citrus, is not well characterized. However, recent studies have shown that non-climacteric fruit development and ripening, involves the coordinated action of different hormones, such as abscisic acid (ABA), auxin, gibberellins, ethylene, and others. In this review, we discuss and evaluate the recent research findings concerning the hormonal regulation of non-climacteric fruit development and ripening and their cross-talk by taking grape, strawberry, and raspberry as reference fruit species.

Molecular Events Occurring During Softening of Strawberry Fruit

Changes in fruit texture taking place during ripening, described as softening, are mainly due to alterations in structure and/or composition of the cell wall. Several non-covalent interactions between the three carbohydrate polymers of the cell wall, cellulose, pectins and hemicellulose, and many structural proteins and ions, enable a complex structure. During softening, the disassembly of the cell wall structure takes place, mediated by a complete set of cell wall degrading enzymes or proteins. Softening is a coordinated event that requires the orchestrated participation of a wide variety of proteins. Plant hormones and a set of transcription factors are the organizers of this multi-protein effort. Strawberry is a non climacteric fruit that softens intensively during the last stages of development. The Chilean strawberry fruit (Fragaria chiloensis), the maternal relative of the commercial strawberry (F. × ananassa), softens even faster than commercial strawberry. Softening of the Chilean strawberry fruit has been studied at different levels: changes in cell wall polymers, activity of cell wall degrading enzymes and transcriptional changes of their genes, providing a general view of the complex process. The search for the 'orchestra director' that could coordinate softening events in strawberry fruit has been focussed on hormones like ABA and auxins, and more precisely the relation ABA/AUX. These hormones regulate the expression of many cell wall degrading enzyme genes, and this massive transcriptional change that takes place involves the participation of key transcriptional factors (TF). This review provides an update of the present knowledge regarding the softening of strawberry fruit. Nevertheless, the entire softening process is still under active research especially for the great influence of texture on fruit quality and its high impact on fruit shelf life, and therefore it is expected that new and promising information will illuminate the field in the near future.

The Research Progress of Chalcone Isomerase (CHI) in Plants

Chalcone isomerase (CHI) is the second rate-limiting and the first reported enzyme involved in the biosynthetic pathway of flavonoids. It catalyzes the intramolecular cyclization reaction, converting the bicyclic chalcone into tricyclic (2S)-flavanone. In this paper, we obtained and analyzed 916 DNA sequences, 1310 mRNA sequences, and 2403 amino acid sequences of CHI registered in NCBI by Jan 2018. The full length of CHI DNA sequences ranges from 218 to 3758 bp, CHI mRNA sequences ranges from 265 to 1436 bp, and CHI amino acid sequences ranges from 35 to 465 amino acid residues. Forty representative species were selected from each family to construct the maximum likelihood tree and analyze the evolutionary relationship. According to the medicinal and agricultural use, 13 specific species were selected, and their physicochemical properties were analyzed. The molecular weight of CHI ranges from 23 to 26 kD, and the isoelectric point of CHI ranges from 4.93 to 5.85. All the half-life periods of CHI are 30 h in mammalian reticulocytes in vitro, 20 h in yeast, and 10 h in E. coli in vivo, theoretically. The consistency of the 13 CHI amino acid sequences is 63.55%. According to the similarity between each sequence, we selected four CHI sequences of Paeonia suffruticosa, Paeonia lactiflora, Taxus wallichiana, and Tradescantia hirsutiflora for secondary structure, three-dimensional protein models, conserved domains, transmembrane structure, and signal peptide prediction analysis. It was found that CHI sequences of Paeonia suffruticosa and Paeonia lactiflora owned a higher similarity; they both share the template 4doi.1.A. The four CHI all have no signal peptides, and they exert their activities in cytoplasm. Then, PubMed, Web of Science, Science Direct, and Research Gate were used as information sources through the search terms 'chalcone isomerase', 'biosynthesis', 'expression', and their combinations to get the latest and comprehensive information of CHI, mainly from the year 2010 to 2018. More than 300 papers were searched and 116 papers were reviewed in the present work. We summarized the classification of CHI, catalytic reaction mechanism of CHI, and progress of genetic engineering regarding CHI clone, expression, and exogenous stimulator regulation. This paper will lay a foundation for further studies of CHI and other functional genes involved in flavonoids biosynthetic pathway.

Stepwise response of MeJA-induced genes and pathways in leaves of C. roseus

Catharanthus roseus is a perennial herb known for the production of important terpenoid indole alkaloids (TIAs) in addition to a variety of phenolic compounds. The goal of the present work was to detect the prolonged effects of MeJA (6 uM) treatment across time (up to 24 days) in order to detect the stepwise response of MeJA-induced genes and pathways in leaves of C. rouses. Prolonged exposure of plants to MeJA (6 uM) treatment for different time points (6, 12 and 24 days) indicated that genes in the indole alkaloid biosynthesis pathway and upstream pathways were triggered earlier (e.g., 6 days) than those in the anthocyanin biosynthesis pathway and its upstream pathways (e.g., 12 days). Three enzymes, e.g., T16H, OMT, and D4H, in the six-step vindoline biosynthesis and two enzymes, e.g., TDC and STR, acting consecutively in the conversion of tryptophan to strictosidine, were activated after 6 days of MeJA treatment. Two other key enzymes, e.g., TRP and CYP72A1, acting concurrently upstream of the TIA biosynthesis pathway were upregulated after 6 days. The genes encoding TDC and STR might concurrently act as a master switch of the TIA pathway towards the production of the indole alkaloids. On the other hand, we speculate that the gene encoding PAL enzyme also acts as the master switch of phenylpropanoid biosynthesis and the downstream flavonoid biosynthesis and anthocyanin biosynthesis pathways towards the production of several phenolic compounds. PAL and the downstream enzymes were activated 12 days after treatment. Cluster analysis confirmed the concordant activities of the flower- and silique-specific bHLH25 transcription factor and the key enzyme in the TIA biosynthesis pathway, e.g., STR. Due to the stepwise response of the two sets of pathways, we speculate that enzymes activated earlier likely make TIA biosynthesis pathway a more favourable target in C. roseus than anthocyanin biosynthesis pathway.