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Ethylene emission and expression of ethylene synthesis genes in OE and WT fruits. (A) Ethylene production of OE and WT fruits was detected at the indicated stage. (B) to (D) qRT-PCR analysis of genes related to ethylene synthesis. The expression of SlACS2 (B), SlACS4 (C) and SlACO1 (D) were detected between OE and WT fruits. (E) Changes in the phenotypes of OE-8 fruits after these fruits were treated with ethephon. MG, mature green; Br, breaker; B3, 3 d after breaker; B7, 7 d after breaker. Data are the means ± SD of three independent experiments. The asterisks indicate statistically significant differences between OE and WT fruits (*P < 0.05, **P < 0.01).
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Background
Fruit maturation and ripening are genetically regulated processes that involve a complex interplay of plant hormones, growth regulators and multiple biological and environmental factors. Tomato (Solanum lycopersicum) has been used as a model of biological and genetic studies on the regulation of specific ripening pathways, including ethy...
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... released ethylene after Br was measured to determine whether or not the phenotype observed is caused by the change in ethylene contents. Ethylene production of OE and WT fruits had the similar pattern and the climac- teric peak of both OE and WT fruits emerged at B3, but the climacteric peaks of the OE fruits were clearly lower than those of the WT fruits; these peaks were reduced by 54% to 79% ( Figure 4A). We then detected the relative mRNA levels of the genes related to ethylene biosynthesis. ...
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... expressions of SlACS2, SlACS4 and SlACO1 in the OE fruits exhibited varying degrees of repression compared with those of WT fruits; this result is consistent with the production of ethylene (Figures 4B to 4D). After the fruits of the OE-8 line at the breaker stage were treated with ethephon for 7 d, the phe- notypes of the treated fruit could be partly resumed ( Figure 4E). These results illustrated that the pigmen- tation of SlNAC1 overexpresion tomato fruits is partly dependent on ethylene. ...
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... functions as a key regulatory hormone in fruit ripening [55]. Ethylene emission of SlNAC1 overexpression lines was reduced ( Figure 4A), suggesting that SlNAC1 is a negative re- gulator of ethylene biosynthesis in maturing OE fruit. Ethylene synthesis in ripening tomato fruit is regulated by ACS and ACO gene families [12]. ...
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... upregulation of ACS2 [12] and ACO1 [57] resulted in ethylene and carotenoid accumulation. In agreement with the reduced ethylene production in the OE fruits, the transcript level of crucial genes involved in ethylene synthesis (SlACS2, SlACS4 and SlACO1) were suppressed to varying degrees ( Figures 4B to 4D). Moreover, exogenous ethephon treatment partially recovered the phenotype of OE fruits ( Figure 4E). ...
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... agreement with the reduced ethylene production in the OE fruits, the transcript level of crucial genes involved in ethylene synthesis (SlACS2, SlACS4 and SlACO1) were suppressed to varying degrees ( Figures 4B to 4D). Moreover, exogenous ethephon treatment partially recovered the phenotype of OE fruits ( Figure 4E). These results suggested that SlNAC1 is im- plicated in OE fruit ripening probably by interacting with ethylene pathway. ...
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... climacteric fruits, the degradation of pectin and cellulose depends on ethylene during softening [61][62][63]. The results of fruit firmness analysis showed that the softening rate of OE fruits was inconsistent with ethylene production ( Figures 4A and 6A), suggesting there may be an ethylene-independent softening pathway in tomato fruit. It has been reported that SlNCED1 suppression by RNA interference reduced ABA accumulation in the transgenic fruits, downregulated the genes encoding for major cell wall catabolic enzymes, and then increased the firmness of the transgenic fruits [51]. ...
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Citations
... defensin alpha (DEFA), and serum response factor (SRF)], Cys2-His2 (C2H2) zinc finger proteins (ZFPs), and basic helix-loop-helix (bHLH) [1][2][3][4]. These TFs oversee the maturation of tomato FR by binding to the promoters of specific genes linked to ethylene (ETH) biosynthesis (SlACS2 and SlACS4), abscisic acid (ABA) synthesis (SlNECD), color pigmentation regulated by SlSGR1, and the metabolism of the cell wall (SlPG2a, SlPL, SlCEL2, and SlEXP1) [5]. ...
... In the genome of the tomato, a total of 101 NACs have been identified [6]. The regulation of tomato FR is specifically linked to NAC TFs, such as NOR, NOR-like, SlNAC1, SlNAC4, SlNAC9, and SlNAM1 [1,[7][8][9][10][11]. Studies on the involvement of NAC TFs in the process of tomato FR originated from the identification of the spontaneous nonripening (nor) mutant [12,13]. ...
... Similarly, in citrus, CrNCED5 expression is inhibited by the CrNAC036 TF in collaboration with CrMYB68, which suppresses ABA biosynthesis during citrus ripening [20]. The primary focus of scientific research on plant hormone biosynthesis and signaling during FR has been the investigation of the influence of TFs, such as ripening inhibitor (RIN), colorless non-ripening (CNR), signal-responsive/calmodulin-binding transcription activators (SR/CAMTA), ZFPs, FRUITFULL1/2 (FUL1/2), forever young flower (FYFL), and NAC [1,3,10,[21][22][23][24]. Although a large number of TFs are involved in the regulation of phytohormones during FR, there are only a few reports that focus on the regulation of GA in this process. ...
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.
Supplementary Information
The online version contains supplementary material available at 10.1186/s11658-024-00577-7.
... Ethylene has been widely studied as an important hormone affecting fruit ripening, especially climacteric fruits (Adams-Phillips et al. 2004;Klee and Giovannoni 2011;Zhang et al. 2009). At present, many transcription factors have been reported to be involved in the ethylene biosynthesis and fruit ripening (Giovannoni 2004;Liu et al. 2014), including ERF (Han et al. 2016), HB , ARF (Yue et al. 2020); NAC (Ma et al. 2014), SBPbox (CNR; Manning et al. 2006), and MADS-box (Itkin et al. 2009;Vrebalov et al. 2002) transcription families. In this study, based on the transcriptome analysis of developing and ripening fruits, we found that the expression pattern of the Aux/IAA TF, PbIAA.C3 was positively correlated to pear fruit ripening (Fig. 2). ...
Phytohormone ethylene is one of the important plant hormones that regulate fruit development and ripening. The transcription regulation of ethylene biosynthesis has been extensively studied in fleshy fruit, but the role of auxin/indole-3-acetic acid (Aux/IAA) in ethylene biosynthesis is still unknown. In this study, based on the genome-wide expression analyses of pear Aux/IAA genes, we found that PbIAA.C3 had a higher expression level in ripening fruits than in developing fruits in all 13 tested pear cultivars. Over-expression of PbIAA.C3 increased ethylene production, while silencing of PbIAA.C3 decreased ethylene production in pear fruit. This result indicates that PbIAA.C3 positively regulates ethylene biosynthesis during fruit ripening. Dual-luciferase assay showed that PbIAA.C3 could enhance the activity of the 1-aminocyclopropane1-carboxylate synthase PbACS1b expression by binding to the upstream region from − 2000 to − 1500 bp of the initiation codon of PbACS1b to increase the expression level. However, the transcription activation of PbIAA.C3 was repressed by the auxin-responsive factor PbARF32 which physically interacted with PbIAA.C3. Therefore, PbARF32 may be also involved in ethylene biosynthesis in pear fruit via the PbIAA.C3–PbARF32 interaction. The information provided new insights into the molecular regulation of ethylene biosynthesis during fruit ripening.
... NOR, a member of the NAC domain family, could positively regulate tomato ripening by binding to SlACO1, SlACS1, and SlACS2 promoter [11]. On the contrary, NAC domain family transcription factor SlNAC1 could decrease ETH production in tomato by inhibiting SlACO1, SlACS2, and SlPSY1 expression; the tomato fruit with overexpressing SlNAC1 could be softened while still becoming orange when fully ripened [12]. ...
... RIN (ripening inhibitor) and NOR (non-ripening) are known to be important transcription factors that can regulate tomato fruit ripening by binding to the ACOs and ACSs promoters [10,11]. Besides RIN and NOR, many more transcription factors have been studied and are reported to be involved in the regulation of the fruit ripening process, including NACs, WRKYs, and ERFs etc. [12,[17][18][19]22,23]. ...
... A previously study showed that SlNAC1 acted as a negative regulator inhibiting the tomato fruit ripening process by down-regulating SlACO1 expression and decreasing ETH production [12]. The phenotype of tomato fruit infected by TRV-SlNAC1 also showed that the ripening process was accelerated, and the chlorophyll degradation and carotenoids accumulation increased ( Figure 5), but pSAK277-SlNAC1 showed the opposite phenotype ( Figure 7). ...
As a typical climacteric fruit, tomato (Solanum lycopersicum) is widely used for studying the ripening process. The negative regulation of tomato fruits by transcription factor SlNAC1 has been reported, but its regulatory network was unclear. In the present study, we screened a transcription factor, SlERF109-like, and found it had a stronger relationship with SlNAC1 at the early stage of tomato fruit development through the use of transcriptome data, RT-qPCR, and correlation analysis. We inferred that SlERF109-like could interact with SlNAC1 to become a regulatory complex that co-regulates the tomato fruit ripening process. Results of transient silencing (VIGS) and transient overexpression showed that SlERF109-like and SlNAC1 could regulate chlorophyll degradation-related genes (NYC1, PAO, PPH, SGR1), carotenoids accumulation-related genes (PSY1, PDS, ZDS), ETH-related genes (ACO1, E4, E8), and cell wall metabolism-related genes expression levels (CEL2, EXP, PG, TBG4, XTH5) to inhibit tomato fruit ripening. A dual-luciferase reporter and yeast one-hybrid (Y1H) showed that SlNAC1 could bind to the SlACO1 promoter, but SlERF109-like could not. Furthermore, SlERF109-like could interact with SlNAC1 to increase the transcription for ACO1 by a yeast two-hybrid (Y2H) assay, a luciferase complementation assay, and a dual-luciferase reporter. A correlation analysis showed that SlERF109-like and SlNAC1 were positively correlated with chlorophyll contents, and negatively correlated with carotenoid content and ripening-related genes. Thus, we provide a model in which SlERF109-like could interact with SlNAC1 to become a regulatory complex that negatively regulates the tomato ripening process by inhibiting SlACO1 expression. Our study provided a new regulatory network of tomato fruit ripening and effectively reduced the waste of resources.
... For example, GmNAC109 is involved in lateral root formation in soybean [11]. SlNAC1 controls the biosynthesis of lycopene and ethylene in tomato [12]. CmNAC-NOR directly activates the genes that are involved in the biosynthesis of carotenoids, ethylene and abscisic acid, thereby promoting fruit coloration and ripening in melons [13]. ...
NAC is a class of plant-specific transcription factors that are widely involved in the growth, development and (a)biotic stress response of plants. However, their molecular evolution has not been extensively studied in Malvales, especially in Aquilaria sinensis, a commercial and horticultural crop that produces an aromatic resin named agarwood. In this study, 1502 members of the NAC gene family were identified from the genomes of nine species from Malvales and three model plants. The macroevolutionary analysis revealed that whole genome duplication (WGD) and dispersed duplication (DSD) have shaped the current architectural structure of NAC gene families in Malvales plants. Then, 111 NAC genes were systemically characterized in A. sinensis. The phylogenetic analysis suggests that NAC genes in A. sinensis can be classified into 16 known clusters and four new subfamilies, with each subfamily presenting similar gene structures and conserved motifs. RNA-seq analysis showed that AsNACs presents a broad transcriptional response to the agarwood inducer. The expression patterns of 15 AsNACs in A. sinensis after injury treatment indicated that AsNAC019 and AsNAC098 were positively correlated with the expression patterns of four polyketide synthase (PKS) genes. Additionally, AsNAC019 and AsNAC098 were also found to bind with the AsPKS07 promoter and activate its transcription. This comprehensive analysis provides valuable insights into the molecular evolution of the NAC gene family in Malvales plants and highlights the potential mechanisms of AsNACs for regulating secondary metabolite biosynthesis in A. sinensis, especially for the biosynthesis of 2-(2-phenyl) chromones in agarwood.
... In addition, a large number of studies have found that the transcription factors (TFs) such as the NAC, MADS-box, ERF, and bHLH families can regulate fruit softening by changing fruit texture [32,33,34,35]. The NAC TF NOR-like1 has been found that positively regulate the fruit softening by changing the expressions of SlPG2a, SlPL, SlCEL2 and SlEXP1 [36], and overexpressed or repressed the expression of SlNAC1 displayed earlier or delayed softening [37,34], and the NAC-MYB module has been proven to regulate secondary cell wall biosynthesis in peach fruit [38]. Moreover, the SlERF.F12 was shown to negatively regulate the fruit softening by repressing the expression of cell wall genes SlPG2a and SlPL [39]. ...
Berry texture is a noteworthy economic trait for grape; however, the genetic bases and the complex gene expression and regulatory mechanism for the diverse changes in berry texture are still poorly understood. In this study, the results suggest that it is difficult to obtain high-mesocarp firmness (MesF) and high-pericarp puncture hardness (PPH) grape cultivars with high pericarp brittleness (PerB). The high-density linkage map was constructed using whole-genome resequencing based on 151 F1 individuals originating from intraspecific hybridization between the firm-flesh cultivar ‘Red Globe’ and soft-flesh cultivar ‘Muscat Hamburg’. The total length of the consensus map was 1613.17 cM, with a mean genetic distance between adjacent bin markers of 0.59 cM. Twenty-seven quantitative trait loci (QTLs) for berry MesF, PPH, and PerB were identified in linkage groups (LGs) 1, 3, 4, 6, 8, 9, 10, 11, 14, 16, and 17, including twelve QTLs that were firstly detected in LGs 6, 11, and 14. Fourteen promising candidate genes were identified from the stable QTL regions in LGs 10, 11, 14, and 17. In particular, VvWARK2 and VvWARK8 refer to chromosome 17 and are two promising candidate genes for MesF and PPH, as the VvWARK8 gene may increase pectin residue binding with WARK for high berry firmness maintenance and the allele for VvWARK2 carrying the ‘CC’ and ‘GA’ genotypes at Chr17:1836764 and Chr17:1836770 may be associated with non-hard texture grape cultivars. In addition, real-time quantitative polymerase chain reaction (RT–qPCR) verification revealed that the promising candidate transcription factor genes VvMYB4-like, VvERF113, VvWRKY31, VvWRKY1, and VvNAC83 may regulate cell wall metabolism candidate gene expression for grape berry texture changes.
... Transcription factors (TFs) have been reported to regulate softening in various fruits. For instance, in tomatoes, SlNAC1 (Ma et al., 2014), SlAN2 (an R2R3-MYB TF; Meng et al., 2015), and SlLOB1 (a Lateral Organ Boundaries TF; Shi et al., 2021b) have been characterized as positive regulators of fruit softening. In kiwifruit, a zinc finger TF, AdZAT5, has been reported to positively regulate the promoters of pectin degradation related genes including Adβ-Gal5 and AdPL5 (Zhang et al., 2022). ...
Fruit ripening and the associated softening are major determinants of fruit quality and post-harvest shelf life. Although the mechanisms underlying fruit softening have been intensively studied, there are limited reports on the regulation of fruit softening in apples (Malus domestica). Here, we identified a zinc finger homeodomain transcription factor, MdZF-HD11, trans-activates the promoter of Mdβ-GAL18, which encodes a pectin-degradation enzyme associated with cell wall metabolism. Both of the genes were upregulated by exogenous ethylene treatment and repressed by 1-methylcyclopropene treatment. Further experiments revealed that MdZF-HD11 binds directly to the Mdβ-GAL18 promoter and upregulates its transcription. Moreover, using transgenic apple fruit calli, we found that overexpression of Mdβ-GAL18 or MdZF-HD11 significantly enhanced β-Galactosidase activity, and overexpression of MdZF-HD11 induced the expression of Mdβ-GAL18. We also discovered that transient overexpression of Mdβ-GAL18 or MdZF-HD11 in ‘Golden Delicious’ apples significantly increased the release of ethylene, reduced fruit firmness, promoted the transformation of skin color from green to yellow, and accelerated ripening and softening of the fruit. Finally, the overexpression of MdZF-HD11 in tomatoes also promoted fruit softening. Collectively, these results indicate that ethylene-induced MdZF-HD11 interacts with Mdβ-GAL18 to promote the post-harvest softening of apples.
... Understanding the pathway and regulatory mechanisms of carotenoid synthesis holds immense significance, as it could pave the way for leveraging genetic engineering to effectively enhance carotenoid content in peaches. Presently, the regulatory mechanisms governing carotenoid synthesis have been extensively investigated across a range of plant species, including Solanum lycopersicum (Kachanovsky et al. 2012;Ma et al. 2014;Zhu et al. 2014;Endo et al. 2016), Capsicum annuum (Rodriguez-Uribe et al. 2012;Liu et al. 2020), Citrus sinensis (Butelli et al. 2012), Vitis vinifera (Kobayashi et al. 2004;Mathieu et al. 2005), Camellia sinensis , orchids (Li et al. 2020a, b), Mimulus lewisii (Sagawa et al. 2016), Actinidia deliciosa (Ampomah-Dwamena et al. 2019), and Medicago truncatula (Meng et al. 2019). Within these studies, TFs such as bHLH, MYB110, MlRCP, MYB, MtWP1, NAC, NAC and the MBW complex have been identified as key players in carotenoid synthesis. ...
... For instance, in citrus, CubHLH1 plays a role in carotenoid accumulation in fruits (Endo et al. 2016). Tomato SlNAC4 positively impacts carotenoid accumulation (Ma et al. 2014;Zhu et al. 2014). Osmanthus fragrans, OfWRKY3 positively regulates OfCCD4, a carotenoid cleavage dioxygenase gene, governing carotenoid catabolism (Han et al. 2016). ...
Carotenoids, as natural tetraterpenes, play a pivotal role in the yellow coloration of peaches and contribute to human dietary health. Despite a relatively clear understanding of the carotenoid biosynthesis pathway, the regulatory mechanism of miRNAs involved in carotenoid synthesis in yellow peaches remain poorly elucidated. This study investigated a total of 14 carotenoids and 40 xanthophyll lipids, including six differentially accumulated carotenoids: violaxanthin, neoxanthin, lutein, zeaxanthin, cryptoxanthin, and (E/Z)-phytoene. An integrated analysis of RNA-seq, miRNA-seq and degradome sequencing revealed that miRNAs could modulate structural genes such as PSY2, CRTISO, ZDS1, CHYB, VDE, ZEP, NCED1, NCED3 and the transcription factors NAC, ARF, WRKY, MYB, and bZIP, thereby participating in carotenoid biosynthesis and metabolism. The authenticity of miRNAs and target gene was corroborated through quantitative real-time PCR. Moreover, through weighted gene coexpression network analysis and a phylogenetic evolutionary study, coexpressed genes and MYB transcription factors potentially implicated in carotenoid synthesis were identified. The results of transient expression experiments indicated that mdm-miR858 inhibited the expression of PpMYB9 through targeted cleavage. Building upon these findings, a regulatory network governing miRNA-mediated carotenoid synthesis was proposed. In summary, this study comprehensively identified miRNAs engaged in carotenoid biosynthesis and their putative target genes, thus enhancing the understanding of carotenoid accumulation and regulatory mechanism in yellow peach peel and expanding the gene regulatory network of carotenoid synthesis.
Graphical Abstract
Supplementary Information
The online version contains supplementary material available at 10.1186/s43897-023-00070-3.
... Carotenoid biosynthesis is strictly regulated in plants, and transcription factors play an important role. Previous reports showed that CsMADS5, CsMADS6 and CsERF061 in citrus [61][62][63], UpMYB44 in Ulva prolifera [64], MdAP2-34 in M. domestica [65] and SlNAC1, SlNAC4, SlAP2a, and SlBBX20 in Solanum lycopersicum [66][67][68][69] could directly interact with the carotenoid synthesis gene to regulate carotenoid accumulation. In P. mume, the transcriptional regulation mechanism of carotenoids is unclear, hindering the germplasm innovation of flower color. ...
Prunus mume is a famous ornamental woody tree with colorful flowers. P. mume with yellow flowers is one of the most precious varieties. Regretfully, metabolites and regulatory mechanisms of yellow flowers in P. mume are still unclear. This hinders innovation of flower color breeding in P. mume. To elucidate the metabolic components and molecular mechanisms of yellow flowers, we analyzed transcriptome and metabolome between ‘HJH’ with yellow flowers and ‘ZLE’ with white flowers. Comparing the metabolome of the two varieties, we determined that carotenoids made contributions to the yellow flowers rather than flavonoids. Lutein was the key differential metabolite to cause yellow coloration of ‘HJH’. Transcriptome analysis revealed significant differences in the expression of carotenoid cleavage dioxygenase (CCD) between the two varieties. Specifically, the expression level of PmCCD4 was higher in ‘ZLE’ than that in ‘HJH’. Moreover, we identified six major transcription factors that probably regulated PmCCD4 to affect lutein accumulation. We speculated that carotenoid cleavage genes might be closely related to the yellow flower phenotype in P. mume. Further, the coding sequence of PmCCD4 has been cloned from the ‘HJH’ petals, and bioinformatics analysis revealed that PmCCD4 possessed conserved histidine residues, ensuring its enzymatic activity. PmCCD4 was closely related to PpCCD4, with a homology of 98.16%. Instantaneous transformation analysis in petal protoplasts of P. mume revealed PmCCD4 localization in the plastid. The overexpression of PmCCD4 significantly reduced the carotenoid content in tobacco plants, especially the lutein content, indicating that lutein might be the primary substrate for PmCCD4. We speculated that PmCCD4 might be involved in the cleavage of lutein in plastids, thereby affecting the formation of yellow flowers in P. mume. This work could establish a material and molecular basis of molecular breeding in P. mume for improving the flower color.
... Table S1: Primer list of used primers in this study; Figure S1: Expressions of ODC1 gene of control and AG-treated tomato roots with and without NaCl treatment (100 and 250 mM); Figure S2: Expressions of PAO4 and PAO5 genes of control and AG-treated tomato roots with and without NaCl treatment (100 and 250 mM); Figure S3: Heat map of some important TCA cycle metabolite contents of control and AG-treated tomato roots with and without NaCl treatment (100 and 250 mM); Table S2: Levels of some important TCA cycle metabolite contents of control and AG-treated tomato roots with and without NaCl treatment (100 and 250 mM); Table S3: P values for AG and NaCl treatments in case of different parameters; Figure S4: Representative summary of AG treatment and salt stress on tomato roots exposed to NaCl at 100 and 250 mM concentration. References [21,[73][74][75][76] are cited in the supplementary materials. Author Contributions: Conceptualization, Á.S. and L.Z.; methodology, Á.S.; software, L.B.; validation, T.J., G.S. and O.K.G.; investigation, Á.S., L.Z., P.P. (Péter Pálfi) and H.K.; microscopy, P.P. (Péter Poór) and R.S.; molecular studies, L.S. and L.Z.; statistical analysis, Á.S. and L.B.; writing-original draft preparation, Á.S. and L.Z.; writing-review and editing, A.F., L.S. and L.Z.; nitrosothiol measurement, C.L.; funding acquisition, Á.S. and L.Z. ...
Polyamine (PA) catabolism mediated by amine oxidases is an important process involved in fine-tuning PA homeostasis and related mechanisms during salt stress. The significance of these amine oxidases in short-term responses to salt stress is, however, not well understood. In the present study, the effects of L-aminoguanidine (AG) on tomato roots treated with short-term salt stress induced by NaCl were studied. AG is usually used as a copper amine oxidase (CuAO or DAO) inhibitor. In our study, other alterations of PA catabolism, such as reduced polyamine oxidase (PAO), were also observed in AG-treated plants. Salt stress led to an increase in the reactive oxygen and nitrogen species in tomato root apices, evidenced by in situ fluorescent staining and an increase in free PA levels. Such alterations were alleviated by AG treatment, showing the possible antioxidant effect of AG in tomato roots exposed to salt stress. PA catabolic enzyme activities decreased, while the imbalance of hydrogen peroxide (H2O2), nitric oxide (NO), and hydrogen sulfide (H2S) concentrations displayed a dependence on stress intensity. These changes suggest that AG-mediated inhibition could dramatically rearrange PA catabolism and related reactive species backgrounds, especially the NO-related mechanisms. More studies are, however, needed to decipher the precise mode of action of AG in plants exposed to stress treatments.
... The NAC TF family is a major plant-specific TF family with a variety of roles (Olsen et al., 2005). In tomato, the expression of SlNAC1 increases as the fruit ripens, but its inhibition slows the ET release burst and act as a negative regulator of ripening (Meng et al., 2016), on the other hand, overexpression of SlNAC1 reduces ET synthesis, owing to decreased transcription of system II ET biosynthetic genes, resulting in yellow/orange fruit at the ripe stage (Ma et al., 2014). A mutation in the gene NOR, which is part of the NAC family of transcription factors, causes tomato to mature later than usual. ...
Crop production is significantly influenced by climate, and even minor climate changes can have a substantial impact on crop yields. Rising temperature due to climate change can lead to heat stress (HS) in plants, which not only hinders plant growth and development but also result in significant losses in crop yields. To cope with the different stresses including HS, plants have evolved a variety of adaptive mechanisms. In response to these stresses, phytohormones play a crucial role by generating endogenous signals that regulate the plant’s defensive response. Among these, Ethylene (ET), a key phytohormone, stands out as a major regulator of stress responses in plants and regulates many plant traits, which are critical for crop productivity and nutritional quality. ET is also known as a ripening hormone for decades in climacteric fruit and many studies are available deciphering the function of different ET biosynthesis and signaling components in the ripening process. Recent studies suggest that HS significantly affects fruit quality traits and perturbs fruit ripening by altering the regulation of many ethylene biosynthesis and signaling genes resulting in substantial loss of fruit yield, quality, and postharvest stability. Despite the significant progress in this field in recent years the interplay between ET, ripening, and HS is elusive. In this review, we summarized the recent advances and current understanding of ET in regulating the ripening process under HS and explored their crosstalk at physiological and molecular levels to shed light on intricate relationships
