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SUMMARY Vascular plant one‐zinc finger (VOZ) transcription factors (TFs) play crucial roles in plant immunity. Nevertheless, how VOZs modulate defense signaling in response to elicitor‐induced resistance is not fully understood. Here, the defense elicitor β‐aminobutyric acid (BABA) resulted in the visible suppression of Rhizopus rot disease of peach fruit caused by Rhizopus stolonifer. Defense priming by BABA was notably associated with increased levels of salicylic acid (SA) and SA‐dependent gene expression. Data‐independent acquisition proteomic analysis revealed that two VOZ proteins (PpVOZ1 and PpVOZ2) were substantially upregulated in BABA‐induced resistance (BABA‐IR). Furthermore, the interaction of PpVOZ1 and PpVOZ2 and their potential target of the TEOSINTE‐BRANCHED1/CYCLOIDEA/PCF (TCP)‐family protein PpTCP2 screened from protein–protein interaction networks was confirmed by yeast two‐hybrid (Y2H), luciferase complementation imaging and glutathione S‐transferase pull‐down assays. Furthermore, subcellular localization, yeast one‐hybrid, electrophoretic mobility shift assay and dual‐luciferase reporter assays demonstrated that nuclear localization of both PpVOZ1 and PpVOZ2 was critical for their contribution to BABA‐IR, as these proteins potentiated the PpTCP2‐mediated transcriptional activation of isochorismate synthase genes (ICS1/2). The overexpression of both PpVOZ1 and PpVOZ2 could activate the transcription of SA‐dependent genes and provide disease resistance in transgenic Arabidopsis. In contrast, the ppvoz1cas9 and ppvoz2cas9 loss‐of‐function mutations and the voz1cas9 voz2cas9 double mutation attenuated BABA‐IR against R. stolonifer. Therefore, the three identified positive TFs, PpVOZ1, PpVOZ2, and PpTCP2, synergistically contribute to the BABA‐activated priming of systemic acquired resistance in postharvest peach fruit by a VOZ‐TCP‐ICS regulatory module. [ABSTRACT FROM AUTHOR]

Summary Tomato is a major global crop. However, its production is limited by Botrytis cinerea. Due to the toxicity of postharvest pesticide application, alternative control methods such as priming are being investigated. Plants were treated with β‐aminobutyric acid (BABA) at two developmental stages and resistance against B. cinerea was tested in fruit tissue and in progenies. DNA methylation and RNA sequencing were conducted to characterise the (epi)genetic changes associated with long‐lasting resistance. Grafting experiments were done to assess the systemic nature of this signal, which was further characterised by small RNA (sRNA) sequencing of scions. Only BABA‐treated seedlings displayed induced resistance (IR). DNA methylation analysis revealed seedling‐specific changes, which occurred in the context of lower basal methylation. BABA‐IR was found to be transmissible from primed rootstock to grafted unprimed scions. In these scions, we identified a subset of mobile 24 nt sRNAs associated with genes showing primed expression during infection in fruit. Our results demonstrate the functional association of a systemic signal with long‐lasting IR and priming. Through integrated omics approaches, we have identified markers of long‐lasting priming in tomato fruit which could also serve as targets for durable resistance in other crops. [ABSTRACT FROM AUTHOR]

Abstract Background β-Aminobutyric acid (BABA) has been successfully used to prime stress resistance in numerous plant species; however, its effectiveness in forest trees has been poorly explored thus far. This study aimed to investigate the influence of BABA on morphological, physiological, and epigenetic parameters in field elms under various growth conditions. Epigenetic changes were assessed in both DNA and RNA through the use of reversed-phase ultra-performance liquid chromatography (UPLC) coupled with sensitive mass spectrometry. Results The presented results confirm the influence of BABA on the development, physiology, and stress tolerance in field elms. However, the most important findings are related to the broad epigenetic changes promoted by this amino acid, which involve both DNA and RNA. Our findings confirm, for the first time, that BABA influences not only well-known epigenetic markers in plants, such as 5-methylcytosine, but also several other non-canonical nucleobases, such as 5-hydroxymethyluracil, 5-formylcytosine, 5-hydroxymethylcytosine, N6-methyladenine, uracil (in DNA) and thymine (in RNA). The significant effect on the levels of N6-methyladenine, the main bacterial epigenetic marker, is particularly noteworthy. In this case, the question arises as to whether this effect is due to epigenetic changes in the microbiome, the plant genome, or both. Conclusions The plant phenotype is the result of complex interactions between the plant’s DNA, the microbiome, and the environment. We propose that different types of epigenetic changes in the plant and microbiome may play important roles in the largely unknown memory process that enables plants to adapt faster to changing environmental conditions.

Background: β-Aminobutyric acid (BABA) has been successfully used to prime stress resistance in numerous plant species; however, its effectiveness in forest trees has been poorly explored thus far. This study aimed to investigate the influence of BABA on morphological, physiological, and epigenetic parameters in field elms under various growth conditions. Epigenetic changes were assessed in both DNA and RNA through the use of reversed-phase ultra-performance liquid chromatography (UPLC) coupled with sensitive mass spectrometry. Results: The presented results confirm the influence of BABA on the development, physiology, and stress tolerance in field elms. However, the most important findings are related to the broad epigenetic changes promoted by this amino acid, which involve both DNA and RNA. Our findings confirm, for the first time, that BABA influences not only well-known epigenetic markers in plants, such as 5-methylcytosine, but also several other non-canonical nucleobases, such as 5-hydroxymethyluracil, 5-formylcytosine, 5-hydroxymethylcytosine, N6-methyladenine, uracil (in DNA) and thymine (in RNA). The significant effect on the levels of N6-methyladenine, the main bacterial epigenetic marker, is particularly noteworthy. In this case, the question arises as to whether this effect is due to epigenetic changes in the microbiome, the plant genome, or both. Conclusions: The plant phenotype is the result of complex interactions between the plant's DNA, the microbiome, and the environment. We propose that different types of epigenetic changes in the plant and microbiome may play important roles in the largely unknown memory process that enables plants to adapt faster to changing environmental conditions. [ABSTRACT FROM AUTHOR]

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Summary: In this study, the accumulation of hydrogen peroxide (H2O2) in different parts (healthy root, gall, root attached to gall, aerial parts) of healthy tomato plants and plants infected by the root-knot nematode, Meloidogyne javanica , was investigated after treating the roots with β -aminobutyric acid (BABA). In addition, the effects of different concentrations of H2O2 (0-2 mM) on mortality, body structures and the digestive system of second-stage juveniles (J2) were also investigated in in vitro experiments. Results showed that exposure to concentrations of more than 1 mM H2O2 is lethal for J2, while the digestive system is not able to tolerate concentrations of more than 0.2 mM. Evaluating the activity level of enzymes related to biosynthesis and removing H2O2 in treated plants also showed that the nematode has significant suppressive effects on the biosynthesis enzymes of this compound, and this effect is greater in the site of nematode activity than in other parts of the plant. By contrast, the activity of catalase enzyme, as one of the H2O2-removing enzymes, shows a significant increase in all parts of nematode infected plants (especially in galls). [ABSTRACT FROM AUTHOR]

Tobacco black shank (TBS), caused by Phytophthora nicotianae, is one of the most harmful diseases of tobacco. There are many studies have examined the mechanism underlying the induction of disease resistance by arbuscular mycorrhizal fungi (AMF) and β-aminobutyric acid (BABA) alone, but the synergistic effects of AMF and BABA on disease resistance have not yet been studied. This study examined the synergistic effects of BABA application and AMF inoculation on the immune response to TBS in tobacco. The results showed that spraying BABA on leaves could increase the colonization rate of AMF, the disease index of tobacco infected by P.nicotianae treated with AMF and BABA was lower than that of P.nicotianae alone. The control effect of AMF and BABA on tobacco infected by P.nicotianae was higher than that of AMF or BABA and P.nicotianae alone. Joint application of AMF and BABA significantly increased the content of N, P, and K in the leaves and roots, in the joint AMF and BABA treatment than in the sole P. nicotianae treatment. The dry weight of plants treated with AMF and BABA was 22.3% higher than that treated with P.nicotianae alone. In comparison to P. nicotianae alone, the combination treatment with AMF and BABA had increased Pn, Gs, Tr, and root activity, while P. nicotianae alone had reduced Ci, H2O2 content, and MDA levels. SOD, POD, CAT, APX, and Ph activity and expression levels were increased under the combined treatment of AMF and BABA than in P.nicotianae alone. In comparison to the treatment of P.nicotianae alone, the combined use of AMF and BABA increased the accumulation of GSH, proline, total phenols, and flavonoids. Therefore, the joint application of AMF and BABA can enhance the TBS resistance of tobacco plants to a greater degree than the application of either AMF or BABA alone. In summary, the application of defense-related amino acids, combined with inoculation with AMF, significantly promoted immune responses in tobacco. Our findings provide new insights that will aid the development and use of green disease control agents.

In plants, the establishment of broad and long-lasting immunity is based on programs that control systemic resistance and immunological memory or “priming”. Despite not showing activated defenses, a primed plant induces a more efficient response to recurrent infections. Priming might involve chromatin modifications that allow a faster/stronger activation of defense genes. The Arabidopsis chromatin regulator “Morpheus Molecule 1” (MOM1) has been recently suggested as a priming factor affecting the expression of immune receptor genes. Here, we show that mom1 mutants exacerbate the root growth inhibition response triggered by the key defense priming inducers azelaic acid (AZA), β-aminobutyric acid (BABA) and pipecolic acid (PIP). Conversely, mom1 mutants complemented with a minimal version of MOM1 (miniMOM1 plants) are insensitive. Moreover, miniMOM1 is unable to induce systemic resistance against Pseudomonas sp. in response to these inducers. Importantly, AZA, BABA and PIP treatments reduce the MOM1 expression, but not miniMOM1 transcript levels, in systemic tissues. Consistently, several MOM1-regulated immune receptor genes are upregulated during the activation of systemic resistance in WT plants, while this effect is not observed in miniMOM1. Taken together, our results position MOM1 as a chromatin factor that negatively regulates the defense priming induced by AZA, BABA and PIP.

Grapefruit mint, Mentha suaveolens × M. piperita, belonging to the Lamiaceae family, is an important medicinal plant with applications in the cosmetic, pharmaceutical, food, and nutraceutical industries. Environmental factors such as cold, salinity, and water deficit significantly impact the quantity and quality of the active compounds of medicinal plants. To examine the effects of drought stress and β-aminobutyric acid (BABA) as an elicitor on the biochemical characteristics and essential oil (EO) profile of grapefruit mint, a factorial experiment was conducted in a completely randomized design (CRD) with two factor and three replications under greenhouse conditions. The first factor included field moisture capacity (FC) as the control (100% FC), mild (75% FC), moderate (55% FC), and severe water deficit stress (35% FC), while the second factor consisted of 0 (control plants without BABA), 0.8, 1.6, and 2.4 mM of BABA foliar application. Water stress and BABA application significantly affected the EO content and composition of grapefruit mint. The highest content of EO was observed in mild drought stress and BABA spraying at 1.6 to 2.4 mM, which increased by about 140% compared with the control condition. The EO components were identified using GC-FID and GC-MS analysis. Linalool (33.7–47.3%) and linalool acetate (31.2–52%) were the most abundant compounds. The highest content of linalool acetate was observed in severe drought stress (35% FC) with foliar application of BABA (1.6 mM), which increased by 33.86% compared with the control condition. However, the highest content of linalool was observed under normal irrigation with foliar application of 0.8 to 1.6 mM BABA. Based on the results, severe drought stress reduced the total chlorophyll and carotenoids by 81.76 and 64.6% compared with the control condition, respectively. Water stress and the foliar application of BABA significantly affected the activity of antioxidant enzymes (ascorbate peroxidase, APX; guaiacol peroxides, GPX; and superoxide dismutase, SOD). The application of 1.6 mM BABA significantly increased the activity of antioxidant enzymes under water stress conditions. Finally, our results showed that the application of BABA (mainly at 1.6 mM) can improve the grapefruit mint yield and EO profile under water stress conditions. [ABSTRACT FROM AUTHOR]

A new ammonolysis technology is developed for producing targeted functional C4 acids from a renewable feedstock, i.e., poly(3-hydroxybutyrate) (PHB). β-Aminobutyric acid (BABA) and β-hydroxybutyric acid (BHBA) are produced from PHB with an aggregate selectivity of 99% under a one-pot catalyst-free reaction at 140 °C. The product distribution can be controlled by ammonia concentration, and the reaction mechanism is investigated based on quantum chemical calculation. This work establishes a promising route for the production of β-substituted C4 acids via a green and sustainable pathway. [ABSTRACT FROM AUTHOR]

Purpose: Apple fruit widely suffers from different damages every year including post-harvest diseases such as blue mold (caused by Penicillium expansum). Recent studies have shown the role of hormones in different signaling pathways after a pathogen attack. Hormones may trigger different the expression of genes involved in the resistance mechanism and thus activating the immune system in plants. Findings: qRT-PCR results showed an increase in the expression of PR5, ERF1 and CHIB genes after treatment with BABA in both Golden Delicious and Fuji cultivars. ACC treatment also significantly increased the expression of ERF1 and CHIB genes after challenged with fungal spores. The expression of PR5 and ERF1 was relatively very similar in both cultivars after treatment with BABA and ACC, respectively. In contrast, the expression of CHIB was different in two cultivars, thus showing a 4 times higher expression in Golden delicious in compared to Fuji. Originality/Value: Using of new insecticides with new and widespread mode of action can be recommended against postharvest pest in the practical entomology. Research limitations: No limitations were found. Originality/value: The results of this study can be important in breeding studies and to select genes involved in the resistance mechanism. In addition, hormones with a positive impact to provide resistance to fungal diseases can be considered as a possible alternative to fungicides.

Induced resistance (IR), a phenotypic state induced by an exogenous stimulus and characterized by enhanced resistance to future (a)biotic challenge, is an important component of plant immunity. Numerous IR-inducing stimuli have been described in various plant species, but relatively little is known about 'core' systemic responses shared by these distinct IR stimuli and the effects of IR on plant-associated microbiota. In this study, rice (Oryza sativa) leaves were treated with four distinct IR stimuli (β-aminobutyric acid, acibenzolar-S-methyl, dehydroascorbic acid, and piperonylic acid) capable of inducing systemic IR against the root-knot nematode Meloidogyne graminicola and evaluated their effect on the root transcriptome and exudome, and root-associated nematode communities. Our results reveal shared transcriptional responses—notably induction of jasmonic acid and phenylpropanoid metabolism—and shared alterations to the exudome that include increased amino acid, benzoate, and fatty acid exudation. In rice plants grown in soil from a rice field, IR stimuli significantly affected the composition of rhizosphere nematode communities 3 d after treatment, but by 14 d after treatment these changes had largely reverted. Notably, IR stimuli did not reduce nematode diversity, which suggests that IR might offer a sustainable option for managing plant-parasitic nematodes. [ABSTRACT FROM AUTHOR]

Grey mold caused by the necrotrophic fungal pathogen Botrytis cinerea can affect leaves, flowers, and berries of strawberry, causing severe pre- and postharvest damage. The defense elicitor β-aminobutyric acid (BABA) is reported to induce resistance against B. cinerea and many other pathogens in several crop plants. Surprisingly, BABA soil drench of woodland strawberry (Fragaria vesca) plants two days before B. cinerea inoculation caused increased infection in leaf tissues, suggesting that BABA induce systemic susceptibility in F. vesca. To understand the molecular mechanisms involved in B. cinerea susceptibility in leaves of F. vesca plants soil drenched with BABA, we used RNA sequencing to characterize the transcriptional reprogramming 24 h post-inoculation. The number of differentially expressed genes (DEGs) in infected vs. uninfected leaf tissue in BABA-treated plants was 5205 (2237 upregulated and 2968 downregulated). Upregulated genes were involved in pathogen recognition, defense response signaling, and biosynthesis of secondary metabolites (terpenoid and phenylpropanoid pathways), while downregulated genes were involved in photosynthesis and response to auxin. In control plants not treated with BABA, we found a total of 5300 DEGs (2461 upregulated and 2839 downregulated) after infection. Most of these corresponded to those in infected leaves of BABA-treated plants but a small subset of DEGs, including genes involved in ‘response to biologic stimulus‘, ‘photosynthesis‘ and ‘chlorophyll biosynthesis and metabolism’, differed significantly between treatments and could play a role in the induced susceptibility of BABAtreated plants. [ABSTRACT FROM AUTHOR]

Plant diseases caused by pathogens lead to economic and agricultural losses, while plant resistance is defined by robustness and timing of defence response. Exposure to microbial-associated molecular patterns or specific chemical compounds can promote plants into a primed state with more robust defence responses. β-aminobutyric acid (BABA) is an endogenous stress metabolite that induces resistance, thereby protecting various plants' diverse stresses by induction of non-canonical activity after binding into aspartyl-tRNA synthetase (AspRS). In this study, by integrating BABA-induced changes in selected metabolites and transcript data, we describe the molecular processes involved in BABA-induced resistance (BABA-IR) in tomatoes. BABA significantly restricted the growth of the pathogens P. syringae pv. tomato DC3000 and was related to the accumulation of transcripts for pathogenesis-related proteins and jasmonic acid signalling but not salicylic acid signalling in Arabidopsis. The resistance was considerably reduced by applying amino acids L-Asp and L-Gln when L-Gln prevents general amino acid inhibition in plants. Analysis of amino acid changes suggests that BABA-IR inhibition by L-Asp is due to its rapid metabolisation to L-Gln and not its competition with BABA for the aspartyl-tRNA synthetase (AspRS) binding site. Our results showed differences between the effect of BABA on tomatoes and other model plants. They highlighted the importance of comparative studies between plants of agronomic interest subjected to treatment with BABA. [ABSTRACT FROM AUTHOR]

Vascular plant one-zinc finger (VOZ) transcription factors (TFs) play crucial roles in plant immunity. Nevertheless, how VOZs modulate defense signaling in response to elicitor-induced resistance is not fully understood. Here, the defense elicitor β-aminobutyric acid (BABA) resulted in the visible suppression of Rhizopus rot disease of peach fruit caused by Rhizopus stolonifer. Defense priming by BABA was notably associated with increased levels of salicylic acid (SA) and SA-dependent gene expression. Data-independent acquisition proteomic analysis revealed that two VOZ proteins (PpVOZ1 and PpVOZ2) were substantially upregulated in BABA-induced resistance (BABA-IR). Furthermore, the interaction of PpVOZ1 and PpVOZ2 and their potential target of the TEOSINTE-BRANCHED1/CYCLOIDEA/PCF (TCP)-family protein PpTCP2 screened from protein-protein interaction networks was confirmed by yeast two-hybrid (Y2H), luciferase complementation imaging and glutathione S-transferase pull-down assays. Furthermore, subcellular localization, yeast one-hybrid, electrophoretic mobility shift assay and dual-luciferase reporter assays demonstrated that nuclear localization of both PpVOZ1 and PpVOZ2 was critical for their contribution to BABA-IR, as these proteins potentiated the PpTCP2-mediated transcriptional activation of isochorismate synthase genes (ICS1/2). The overexpression of both PpVOZ1 and PpVOZ2 could activate the transcription of SA-dependent genes and provide disease resistance in transgenic Arabidopsis. In contrast, the ppvoz1 cas9 and ppvoz2 cas9 loss-of-function mutations and the voz1 cas9 voz2 cas9 double mutation attenuated BABA-IR against R. stolonifer. Therefore, the three identified positive TFs, PpVOZ1, PpVOZ2, and PpTCP2, synergistically contribute to the BABA-activated priming of systemic acquired resistance in postharvest peach fruit by a VOZ-TCP-ICS regulatory module., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

The inducer β-aminobutyric acid (BABA) is capable of immune response in various plants. However, the specific mitogen-activated protein kinase (MAPK) cascade involved in BABA-induced resistance (BABA-IR) has not yet been elucidated. Here, peach fruits treated with the BABA exhibited a pattern-triggered immunity (PTI) defense against Rhizopus stolonifer, accompanied by the generation of reactive oxygen species (ROS) and activation of MAPK cascade. Transcriptome sequencing suggested a total of fifteen PpMAPKKK/PpMAPKK/PpMAPK genes involved in BABA-IR in peach fruit. Further qRT-PCR analysis showed that the transcript profiles of PpMAPKKK3, PpMAPKK5 and PpMAPK1 were obviously potentiated. Subsequently, yeast two-hybrid (Y2H), luciferase complementation imaging (LCI), pull-down and in vitro phosphorylation assays were conducted to characterize the complete MAPK cascade (PpMAPKKK3-PpMAPKK5-PpMAPK1) involved in peach fruit. Moreover, the downstream events of MAPK1 include the involvement of SNARE13 and the corresponding NPR1-responsive defense. Single silencing of MAPKKK3, MAPKK5 or MAPK1 and double silencing of MAPKKK3/MAPKK5 or MAPKK5/MAPK1 resulted in enhanced susceptibility to the fungus R. stolonifer in mutants and attenuated salicylic acid (SA)-dependent defense gene expression; in contrast, the homologous or heterologous overexpression of PpSNARE13 in peach fruit or Arabidopsis led to an enhanced SA pool and elevated expression of PR genes. Reciprocally, the ppsnare13cas9 mutants are generally compromised in the priming of SA-dependent resistance. Therefore, the MAPKKK3-MAPKK5-MAPK1 cascade contributes to PTI signal transduction in BABA-elicited peach fruit, by combination with downstream events such as SNARE13, NPR1, and SA-dependent signaling., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Defense elicitors can induce fruit disease resistance to control postharvest decay but may incur quality impairment. Our present work aimed to investigate the resistance against Botrytis cinerea induced by the elicitor β-aminobutyric acid (BABA) and to elucidate the specific transcriptional mechanism implicated in defense-related metabolic regulations. The functional dissection results demonstrated that, after inoculation with the fungal necrotroph B. cinerea, a suite of critical genes encoding enzymes related to the sucrose metabolism and phenylpropanoid pathway in priming defense in grapes were transcriptionally induced by treatment with 10 mM BABA. In contrast, more UDP-glucose, a shared precursor of phenylpropanoid and sucrose metabolism, may be redirected to the phenylpropanoid pathway for the synthesis of phytoalexins, including trans-resveratrol and ɛ-viniferin, in 100 mM BABA–treated grapes, resulting in direct resistance but compromised soluble sugar contents. An R2R3-type MYB protein from Vitis vinifera, VvMYB44, was isolated and characterized. VvMYB44 expression was significantly induced upon the grapes expressed defensive reaction. Subcellular localization, yeast two-hybrid, and coimmunoprecipitation assays revealed that the nuclear-localized VvMYB44 physically interacted with the salicylic acid–responsive transcription coactivator NPR1 in vivo for defense expression. In addition, VvMYB44 directly bound to the promoter regions of sucrose and phenylpropanoid metabolism-related genes and transactivated their expression, thus tipping the balance of antifungal compound accumulation and soluble sugar maintenance. Hence, these results suggest that 2R-type VvMYB44 might be a potential positive participant in BABA-induced priming defense in grape berries that contributes to avoiding the excessive consumption of soluble sugars during the postharvest storage.[Graphic: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Grey mold caused by the necrotrophic fungal pathogen Botrytis cinerea can affect leaves, flowers, and berries of strawberry, causing severe pre- and postharvest damage. The defense elicitor β-aminobutyric acid (BABA) is reported to induce resistance against B. cinerea and many other pathogens in several crop plants. Surprisingly, BABA soil drench of woodland strawberry (Fragaria vesca) plants two days before B. cinerea inoculation caused increased infection in leaf tissues, suggesting that BABA induce systemic susceptibility in F. vesca. To understand the molecular mechanisms involved in B. cinerea susceptibility in leaves of F. vesca plants soil drenched with BABA, we used RNA sequencing to characterize the transcriptional reprogramming 24 h post-inoculation. The number of differentially expressed genes (DEGs) in infected vs. uninfected leaf tissue in BABA-treated plants was 5205 (2237 upregulated and 2968 downregulated). Upregulated genes were involved in pathogen recognition, defense response signaling, and biosynthesis of secondary metabolites (terpenoid and phenylpropanoid pathways), while downregulated genes were involved in photosynthesis and response to auxin. In control plants not treated with BABA, we found a total of 5300 DEGs (2461 upregulated and 2839 downregulated) after infection. Most of these corresponded to those in infected leaves of BABA-treated plants but a small subset of DEGs, including genes involved in ‘response to biologic stimulus‘, ‘photosynthesis‘ and ‘chlorophyll biosynthesis and metabolism’, differed significantly between treatments and could play a role in the induced susceptibility of BABA-treated plants.

The study was conducted to evaluate the effect of beta-aminobutyric acid (BABA) on negative intestinal bacteria and gastrointestinal tissues (stomach, small intestine and large intestine) of male rats. The rats were dosed with BABA orally four times a week. The results showed that the histological structure of the digestive system of the control treatment was normal. Also, the histological structure of the stomach was normal for all concentrations of acid. As for the small intestine and large intestine, its histological structure was affected with the increase in concentration. As for the studied negative enterococcus bacteria, it was also affected by the addition of (BABA), it decreased with increasing concentration. [ABSTRACT FROM AUTHOR]

Despite huge progress in biotechnological approaches to paclitaxel production, Taxus spp. in vitro culture productivity still remains a challenge. This could be solved by developing a new strategy engaging mechanisms of the primed defence response joined with subsequent elicitation treatment to circumvent limitations in paclitaxel biosynthesis. The hairy roots were primed by preincubation with β-aminobutyric acid (BABA) for 24 h or 1 week, and then elicited with methyl jasmonate (MeJA) or a mixture of MeJA, sodium nitroprusside and L-phenylalanine (MIX). The effect of priming was evaluated on a molecular level by examination of the expression profiles of the four genes involved in paclitaxel biosynthesis, i.e., TXS (taxadiene synthase), BAPT (baccatin III: 3-amino, 3-phenylpropanoyltransferase), DBTNBT (3′-N-debenzoyl-2-deoxytaxol-N-benzoyltransferase) and PAM (phenylalanine aminomutase), as well as rolC (cytokinin-β-glucosidase), originated from the T-DNA of Agrobacterium rhizogenes. The maximum paclitaxel yield was achieved in cultures primed with BABA for 1 week and elicited with MIX (3179.9 ± 212 µg/g dry weight), which corresponded to the highest expression levels of TXS and BAPT genes. Although BABA itself induced the investigated gene expression over control level, it was not translated into paclitaxel production. Nevertheless, preincubation with BABA essentially affected paclitaxel yield, and the duration of BABA pretreatment seemed to have the most pronounced impact on its productivity. [ABSTRACT FROM AUTHOR]

Salinity stress is one of the most prevalent environmental factors that severely affect seed germination, early growth stages, and crop production. The present study was carried out to evaluate the protective role of β-aminobutyric acid (BABA) in alleviating salt stress in chickpea (Cicer arietinum L.) varieties (Jabel Marra, Porgeg and Shendi) under four concentrations of NaCl solutions (0, 50, 100, and 150 mM NaCl). Three levels of β-aminobutyric acid (0, 0.25, and 0.50 mM) were applied. Germination and seedling attributes were measured. A high level of salinity (150 mM NaCl) increased mean germination time by 10.0% and decreased the coefficient velocity of germination and root dry weight by 12.1% and 96.2%, respectively, compared with the control. 'Jabel Marra' significantly surpassed other studied varieties in germination characters, while at seedling growth, 'Shendi' outperformed other varieties in root and shoot length, fresh, and dry weights. Seeds treated with 0.25 mM BABA caused increment on water uptake by 18.1% compared with 0.0 mM BABA. At 150 mM NaCl, seeds primed with 0.50 mM BABA increased the germination percentage of 'Jabel Marra' and 'Porgeg' by 6.3% and 11.9% as compared with 0.0 mM BABA. Under 50 mM NaCl and 0.50 mM BABA, root length, shoot length, shoot fresh weight, and root dry weight were increased by 170.6%, 44.8%, 80%, and 49.3%, respectively, relative to 0.0 mM BABA. The present study results suggested that seed priming by BABA could be useful to alleviate the salinity stress of chickpea at germination and early seedling growth. [ABSTRACT FROM AUTHOR]

MADS-box genes play well-documented roles in plant development, but relatively little is known regarding their involvement in defence responses. In this study, pre-treatment of peach (Prunus persica) fruit with β-aminobutyric acid (BABA) activated resistance against Rhizopus stolonifer , leading to a significant delay in the symptomatic appearance of disease. This was associated with an integrated defence response that included a H2O2 burst, ABA accumulation, and callose deposition. cDNA library screening identified nucleus-localized MADS2 as an interacting partner with NPR1, and this was further confirmed by yeast two-hybrid, luciferase complementation imaging, and co-immunoprecipitation assays. The DNA-binding activity of NPR1 conferred by the NPR1–MADS2 complex was required for the transcription of SA-dependent pathogenesis-related (PR) and ABA-inducible CalS genes in order to gain the BABA-induced resistance, in which MAPK1-induced post-translational modification of MADS2 was also involved. In accordance with this, overexpression of PpMADS2 in Arabidopsis potentiated the transcription of a group of PR genes and conferred fungal resistance in the transgenic plants. Conversely, Arabidopsis mads2 -knockout lines showed high sensitivity to the fungal pathogen. Our results indicate that MADS2 positively participates in BABA-elicited defence in peach through a combination of SA-dependent NPR1 activation and ABA signaling-induced callose accumulation, and that this defence is also related to the post-translational modification of MADS2 by MAPK1 for signal amplification. [ABSTRACT FROM AUTHOR]

Heat stress is one of the major abiotic factors that limit the growth, development, and productivity of plants. Both glycine betaine (GB) and β-aminobutyric acid (BABA) have received considerable attention due to their roles in stimulating tolerance to diverse abiotic stresses. In order to understand how GB and BABA biostimulants alleviate heat stress in a cool-weather Chinese cabbage (Brassica rapa L. ssp. pekinensis) plant, we investigated the GB- and BABA-primed heat-stressed plants in terms of their morpho-physiological and biochemical traits. Priming with GB (15 mM) and BABA (0.2 mM) was conducted at the third leaf stage by applying foliar sprays daily for 5 days before 5 days of heat stress (45 °C in 16 h light/35 °C in 8 h dark) on Chinese cabbage seedlings. The results indicate that GB and BABA significantly increased chlorophyll content, and the parameters of both gas exchange and chlorophyll fluorescence, of Chinese cabbage under heat stress. Compared with the unprimed heat-stressed control, the dry weights of GB- and BABA-primed plants were significantly increased by 36.36% and 45.45%, respectively. GB and BABA priming also greatly mitigated membrane damage, as indicated by the reduction in malondialdehyde (MDA) and electrolyte leakage through the elevation of proline content, and increased activity levels of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). Taken together, GB and BABA have great potential to enhance the thermotolerance of Chinese cabbage through higher photosynthesis performance, osmoprotection, and antioxidant enzyme activity. [ABSTRACT FROM AUTHOR]

Tomato is a major global crop. However, its production is limited by Botrytis cinerea. Due to the toxicity of postharvest pesticide application, alternative control methods such as priming are being investigated. Plants were treated with β-aminobutyric acid (BABA) at two developmental stages and resistance against B. cinerea was tested in fruit tissue and in progenies. DNA methylation and RNA sequencing were conducted to characterise the (epi)genetic changes associated with long-lasting resistance. Grafting experiments were done to assess the systemic nature of this signal, which was further characterised by small RNA (sRNA) sequencing of scions. Only BABA-treated seedlings displayed induced resistance (IR). DNA methylation analysis revealed seedling-specific changes, which occurred in the context of lower basal methylation. BABA-IR was found to be transmissible from primed rootstock to grafted unprimed scions. In these scions, we identified a subset of mobile 24 nt sRNAs associated with genes showing primed expression during infection in fruit. Our results demonstrate the functional association of a systemic signal with long-lasting IR and priming. Through integrated omics approaches, we have identified markers of long-lasting priming in tomato fruit which could also serve as targets for durable resistance in other crops., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

β-Aminobutyric acid (BABA) has consistently been reported to enhance plant immunity. However, the specific mechanisms and downstream components that mediate this resistance are not yet agreed upon. Nitric oxide (NO) is an important signal molecule involved in a diverse range of physiological processes, and whether NO is involved in BABA-induced resistance is interesting. In this study, treatment with BABA significantly increased NO accumulation and reduced the sensitivity to Botrytis cinerea in tomato plants. BABA treatment reduced physical signs of infection and increased both the transcription of key defense marker genes and the activity of defensive enzymes. Interestingly, compared to treatment with BABA alone, treatment with BABA plus cPTIO (NO specific scavenger) not only significantly reduced NO accumulation, but also increased disease incidence and lesion area. These results suggest that NO accumulation plays an important role in BABA-induced resistance against B. cinerea in tomato plants.

The non-protein amino acid β-Aminobutyric acid (BABA) may trigger the immune responses of plants to various biotic and abiotic stresses leading to a long-term resistance (primed state). We present RNA-seq datasets of BABA - primed mono- and dicotyledonous plants, such as Arabidopsis thaliana and Hordeum vulgare. Illumina NextSeq550 sequencing were carried out after 72 h of BABA exposure. 87 bp long sequence reads were preprocessed of treated and control samples and deposited in the NCBI SRA database. Transcriptome datasets were de novo assembled of each species and deposited in the NCBI TSA database. These SRA and TSA depositions are under the Bioproject accession: PRJNA791573. Pairwise differential expression with enrichment analyses were performed and the most specific DEGs were determined and annotated in both plants.

Grapefruit mint, Mentha suaveolens × M. piperita, belonging to the Lamiaceae family, is an important medicinal plant with applications in the cosmetic, pharmaceutical, food, and nutraceutical industries. Environmental factors such as cold, salinity, and water deficit significantly impact the quantity and quality of the active compounds of medicinal plants. To examine the effects of drought stress and β-aminobutyric acid (BABA) as an elicitor on the biochemical characteristics and essential oil (EO) profile of grapefruit mint, a factorial experiment was conducted in a completely randomized design (CRD) with two factor and three replications under greenhouse conditions. The first factor included field moisture capacity (FC) as the control (100% FC), mild (75% FC), moderate (55% FC), and severe water deficit stress (35% FC), while the second factor consisted of 0 (control plants without BABA), 0.8, 1.6, and 2.4 mM of BABA foliar application. Water stress and BABA application significantly affected the EO content and composition of grapefruit mint. The highest content of EO was observed in mild drought stress and BABA spraying at 1.6 to 2.4 mM, which increased by about 140% compared with the control condition. The EO components were identified using GC-FID and GC-MS analysis. Linalool (33.7–47.3%) and linalool acetate (31.2–52%) were the most abundant compounds. The highest content of linalool acetate was observed in severe drought stress (35% FC) with foliar application of BABA (1.6 mM), which increased by 33.86% compared with the control condition. However, the highest content of linalool was observed under normal irrigation with foliar application of 0.8 to 1.6 mM BABA. Based on the results, severe drought stress reduced the total chlorophyll and carotenoids by 81.76 and 64.6% compared with the control condition, respectively. Water stress and the foliar application of BABA significantly affected the activity of antioxidant enzymes (ascorbate peroxidase, APX; guaiacol peroxides, GPX; and superoxide dismutase, SOD). The application of 1.6 mM BABA significantly increased the activity of antioxidant enzymes under water stress conditions. Finally, our results showed that the application of BABA (mainly at 1.6 mM) can improve the grapefruit mint yield and EO profile under water stress conditions.

The priming of defence responses in pathogen‐challenged model plants undergoes a preparation phase and an expression phase for defence function. However, the priming response in postharvest fruits has not been elucidated. Here, we found that 50 mM β‐aminobutyric acid (BABA) treatment could induce two distinct pathways linked with TGA1‐related systemic acquired resistance (SAR), resulting in the alleviation of Rhizopus rot in postharvest peach fruit. The first priming phase was elicited by BABA alone, leading to the enhanced transcription of redox‐regulated genes and posttranslational modification of PpTGA1. The second phase was activated by an H2O2 burst via up‐regulation of PpRBOH genes and stimulation of the MAPK cascade on pathogen invasion, resulting in a robust defence. In the MAPK cascade, PpMAPKK5 was identified as a shortcut interacting protein of PpTGA1 and increased the DNA binding activity of PpTGA1 for the activation of salicylic acid (SA)‐responsive PR genes. The overexpression of PpMAPKK5 in Arabidopsis caused the constitutive transcription of SA‐dependent PR genes and as a result conferred resistance against the fungus Rhizopus stolonifer. Hence, we suggest that the BABA‐induced priming defence in peaches is activated by redox homeostasis with an elicitor‐induced reductive signalling and a pathogen‐stimulated H2O2 burst, which is accompanied by the possible phosphorylation of PpTGA1 by PpMAPKK5 for signal amplification. [ABSTRACT FROM AUTHOR]

Salicylic acid (SA) and β-aminobutyric acid (BABA) are signaling compounds that regulate a large number of defense responses in plants after exposure to the biotic and abiotic stresses. The antagonistic fungus Trichoderma harzianum is well-known as a potential biocontrol agent that also induces defensive responses. In the present study, we tested the up- and down-regulation of defense responses of eggplant and tomato mediated by root application of SA and BABA as well as T. harzianum. Especially, we analyzed and compared the expression of ASR1, PIN2, and PAL in 4, 10, and 14 d post treatment. In all time courses, the root Trichoderma application + root β-aminobutyric acid application (RT + RBABA)- and root Trichoderma application + root salicylic acid application (RT + RSA)-treated plants had a much higher expression of genes than those on RT-treated plants and controls. Also, control and treated plants had significantly higher expression of ASR1 and PIN2 on the 4th day compared to other time courses. The PAL gene expression reached the maximum level at 10 days after treatment and it increased to about twofold level than 4 days after treatment. Information on expression profiles of the genes in different plants and under various inducers helps to identify candidates to the increase of resistance to environmental stress conditions. [ABSTRACT FROM AUTHOR]

Plant diseases caused by pathogens lead to economic and agricultural losses, while plant resistance is defined by robustness and timing of defence response. Exposure to microbial-associated molecular patterns or specific chemical compounds can promote plants into a primed state with more robust defence responses. β-aminobutyric acid (BABA) is an endogenous stress metabolite that induces resistance, thereby protecting various plants’ diverse stresses by induction of non-canonical activity after binding into aspartyl-tRNA synthetase (AspRS). In this study, by integrating BABA-induced changes in selected metabolites and transcript data, we describe the molecular processes involved in BABA-induced resistance (BABA-IR) in tomatoes. BABA significantly restricted the growth of the pathogens P. syringae pv. tomato DC3000 and was related to the accumulation of transcripts for pathogenesis-related proteins and jasmonic acid signalling but not salicylic acid signalling in Arabidopsis. The resistance was considerably reduced by applying amino acids L-Asp and L-Gln when L-Gln prevents general amino acid inhibition in plants. Analysis of amino acid changes suggests that BABA-IR inhibition by L-Asp is due to its rapid metabolisation to L-Gln and not its competition with BABA for the aspartyl-tRNA synthetase (AspRS) binding site. Our results showed differences between the effect of BABA on tomatoes and other model plants. They highlighted the importance of comparative studies between plants of agronomic interest subjected to treatment with BABA.

Although heat shock proteins (HSPs), a family of ubiquitous molecular chaperones, are well characterized in heat stress-related responses, their function in plant defense remains largely unclear. Here, we report the role of VvHSP24, a class B HSP from Vitis vinifera, in β-aminobutyric acid (BABA)-induced priming defense against the necrotrophic fungus Botrytis cinerea in grapes. Grapes treated with 10 mmol L–1 BABA exhibited transiently increased transcript levels of VvNPR1 and several SA-inducible genes, including PR1, PR2, and PR5. Additionally, phytoalexins accumulated upon inoculation with the gray mold fungus B. cinerea, which coincided with the action of a priming mode implicated in pathogen-driven resistance. Intriguingly, electrophoretic mobility shift (EMSA), yeast two-hybrid (Y2H) and His pull-down assays demonstrated that the nuclear chaperone VvHSP24 cannot modulate the transcript of PR genes but does directly interact with VvNPR1 in vivo or in vitro. Furthermore, we found that VvHSP24 overexpression enhanced the transcript levels of NPR1 and SA-responsive genes (PR1, PR2, and PR5) and increased the resistance of transgenic Arabidopsis thaliana to B. cinerea compared with wildtype Col-0. An opposite trend between CRISPR mutants of AtHSFB1 (the orthologous gene of VvHSP24 in Arabidopsis) and wildtype plants was observed. Hence, our results suggest that VvHSP24 has a potential role in NPR1-dependent plant resistance to fungal pathogen. BABA-induced priming defense in grapes may require posttranslational modification of the chaperone VvHSP24 to activate VvNPR1 transcript, leading to PR gene expressions and resistance phenotypes.

Despite huge progress in biotechnological approaches to paclitaxel production, Taxus spp. in vitro culture productivity still remains a challenge. This could be solved by developing a new strategy engaging mechanisms of the primed defence response joined with subsequent elicitation treatment to circumvent limitations in paclitaxel biosynthesis. The hairy roots were primed by preincubation with β-aminobutyric acid (BABA) for 24 h or 1 week, and then elicited with methyl jasmonate (MeJA) or a mixture of MeJA, sodium nitroprusside and L-phenylalanine (MIX). The effect of priming was evaluated on a molecular level by examination of the expression profiles of the four genes involved in paclitaxel biosynthesis, i.e., TXS (taxadiene synthase), BAPT (baccatin III: 3-amino, 3-phenylpropanoyltransferase), DBTNBT (3′-N-debenzoyl-2-deoxytaxol-N-benzoyltransferase) and PAM (phenylalanine aminomutase), as well as rolC (cytokinin-β-glucosidase), originated from the T-DNA of Agrobacterium rhizogenes. The maximum paclitaxel yield was achieved in cultures primed with BABA for 1 week and elicited with MIX (3179.9 ± 212 µg/g dry weight), which corresponded to the highest expression levels of TXS and BAPT genes. Although BABA itself induced the investigated gene expression over control level, it was not translated into paclitaxel production. Nevertheless, preincubation with BABA essentially affected paclitaxel yield, and the duration of BABA pretreatment seemed to have the most pronounced impact on its productivity.

Although heat shock proteins (HSPs), a family of ubiquitous molecular chaperones, are well characterized in heat stress-related responses, their function in plant defense remains largely unclear. Here, we report the role of VvHSP24 , a class B HSP from Vitis vinifera , in β-aminobutyric acid (BABA)-induced priming defense against the necrotrophic fungus Botrytis cinerea in grapes. Grapes treated with 10 mmol L–1 BABA exhibited transiently increased transcript levels of VvNPR1 and several SA-inducible genes, including PR1 , PR2 , and PR5. Additionally, phytoalexins accumulated upon inoculation with the gray mold fungus B. cinerea , which coincided with the action of a priming mode implicated in pathogen-driven resistance. Intriguingly, electrophoretic mobility shift (EMSA), yeast two-hybrid (Y2H) and His pull-down assays demonstrated that the nuclear chaperone VvHSP24 cannot modulate the transcript of PR genes but does directly interact with VvNPR1 in vivo or in vitro. Furthermore, we found that VvHSP24 overexpression enhanced the transcript levels of NPR1 and SA-responsive genes (PR1 , PR2 , and PR5) and increased the resistance of transgenic Arabidopsis thaliana to B. cinerea compared with wildtype Col-0. An opposite trend between CRISPR mutants of AtHSFB1 (the orthologous gene of VvHSP24 in Arabidopsis) and wildtype plants was observed. Hence, our results suggest that VvHSP24 has a potential role in NPR1-dependent plant resistance to fungal pathogen. BABA-induced priming defense in grapes may require posttranslational modification of the chaperone VvHSP24 to activate VvNPR1 transcript, leading to PR gene expressions and resistance phenotypes. [ABSTRACT FROM AUTHOR]

Chilling is a major abiotic factor limiting the growth, development, and productivity of plants. β-aminobutyric acid (BABA), a new environmentally friendly agent, is widely used to induce plant resistance to biotic and abiotic stress. Calcium, as a signaling substance, participates in various physiological activities in cells and plays a positive role in plant defense against cold conditions. In this study, we used tobacco as a model plant to determine whether BABA could alleviate chilling stress and further to explore the relationship between BABA and Ca2+. The results showed that 0.2 mM BABA significantly reduced the damage to tobacco seedlings from chilling stress, as evidenced by an increase in photosynthetic pigments, the maintenance of cell structure, and upregulated expression of NtLDC1, NtERD10B, and NtERD10D. Furthermore, 0.2 mM BABA combined with 10 mM Ca2+ increased the fresh and dry weights of both roots and shoots markedly. Compared to that with single BABA treatment, adding Ca2+ reduced cold injury to the plant cell membrane, decreased ROS production, and increased antioxidant enzyme activities and antioxidant contents. The combination of BABA and Ca2+ also improved abscisic acid and auxin contents in tobacco seedlings under chilling stress, whereas ethylene glycol-bis (β-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA) reversed the effects of BABA. These findings suggested that BABA enhances the cold tolerance of tobacco and is closely related to the state of Ca2+ signaling.

Heat stress is one of the major abiotic factors that limit the growth, development, and productivity of plants. Both glycine betaine (GB) and β-aminobutyric acid (BABA) have received considerable attention due to their roles in stimulating tolerance to diverse abiotic stresses. In order to understand how GB and BABA biostimulants alleviate heat stress in a cool-weather Chinese cabbage (Brassica rapa L. ssp. pekinensis) plant, we investigated the GB- and BABA-primed heat-stressed plants in terms of their morpho-physiological and biochemical traits. Priming with GB (15 mM) and BABA (0.2 mM) was conducted at the third leaf stage by applying foliar sprays daily for 5 days before 5 days of heat stress (45 °C in 16 h light/35 °C in 8 h dark) on Chinese cabbage seedlings. The results indicate that GB and BABA significantly increased chlorophyll content, and the parameters of both gas exchange and chlorophyll fluorescence, of Chinese cabbage under heat stress. Compared with the unprimed heat-stressed control, the dry weights of GB- and BABA-primed plants were significantly increased by 36.36% and 45.45%, respectively. GB and BABA priming also greatly mitigated membrane damage, as indicated by the reduction in malondialdehyde (MDA) and electrolyte leakage through the elevation of proline content, and increased activity levels of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). Taken together, GB and BABA have great potential to enhance the thermotolerance of Chinese cabbage through higher photosynthesis performance, osmoprotection, and antioxidant enzyme activity.

Either NPR1 or TGA1 serve as master redox-sensitive transcriptional regulators for the transcription of PR genes in plants. The redox modification of the two co-activators involved in BABA-induced priming resistance against Botrytis cinerea in grapes was examined in this study. The results showed that 10 mmol L−1 BABA could effectively trigger a priming defense in grapes as manifested by augmented expression levels of PR genes upon inoculation with B. cinerea. Moreover, transcriptome profiling analysis revealed that all of the sets of key genes in the enzymatic ROS scavenging system, the PPP and AsA-GSH cycle were in harmony and were transcriptionally induced in BABA-primed grapes with pathogenic infection; in addition, this enhanced expression caused the accelerated accumulation of reductive substances, namely, AsA, GSH and NADPH, resulting in reduced intercellular conditions. Under reduced conditions, the interaction of VvTGA1 and VvNPR1 in the Y2H assay implied that VvTGA1 can provide the DNA binding capacity required by VvNPR1 for activation of VvPR genes. Consequently, the transactivation of VvNPR1 by the promoters of VvPR1 , VvPR2 and VvPR5 was determined via a DLR assay, and it induced the transcription of the VvPR genes. In parallel, the redox-modified reducing condition achieved with an abundant supply of reductive substances was closely associated with the translocation of NPR1 for interaction with TGA in the nucleus. Thus, the posttranslational modification and subsequent interaction of the two redox-sensitive co-activators of VvNPR1 and VvTGA1 under reduced conditions may be responsible for BABA-induced priming for effective disease resistance in grapes. Image 1 • BABA-triggered resistance against B. cinerea in grapes contributed to a priming defence. • Maintenance of redox homeostasis by BABA is a backup mechanism for priming defense. • Interaction between NPR1 and TGA1 was essential for defence activation. • Assembling NPR1-TGA1 regulator depended on intercellular reduced status. [ABSTRACT FROM AUTHOR]

External and internal signals can prime the plant immune system for a faster and/or stronger response to pathogen attack. β-aminobutyric acid (BABA) is an endogenous stress metabolite that induces broad-spectrum disease resistance in plants. BABA perception in Arabidopsis is mediated by the aspartyl tRNA synthetase IBI1, which activates priming of multiple immune responses, including callose-associated cell wall defenses that are under control by abscisic acid (ABA). However, the immediate signaling components after BABA perception by IBI1, as well as the regulatory role of ABA therein, remain unknown. Here, we have studied the early signaling events controlling IBI1-dependent BABA-induced resistance (BABA-IR), using untargeted transcriptome and protein interaction analyses. Transcriptome analysis revealed that IBI1-dependent expression of BABA-IR against the biotrophic oomycete Hyaloperonospora arabidopsidis is associated with suppression of ABA-inducible abiotic stress genes. Protein interaction studies identified the VOZ1 and VOZ2 transcription factors (TFs) as IBI1-interacting partners, which are transcriptionally induced by ABA but suppress pathogen-induced expression of ABA-dependent genes. Furthermore, we show that VOZ TFs require nuclear localization for their contribution to BABA-IR by mediating augmented expression of callose-associated defense. Collectively, our study indicates that the IBI1-VOZ signaling module channels pathogen-induced ABA signaling toward cell wall defense while simultaneously suppressing abiotic stress-responsive genes. Perception of the plant stress metabolite β-aminobutyric acid (BABA) by the aspartyl tRNA synthetase IBI1 primes callose-associated cell wall defenses that are controlled by the plant hormone abscisic acid (ABA). This study investigated the early signaling events controlling IBI1-dependent BABA-induced resistance against downy mildew and identified the ABA-inducible VOZ transcription factors as downstream regulators of BABA-primed callose defense. The interaction between VOZ and IBI1 after downy mildew infection channels pathogenesis-related ABA signaling toward callose defense, while simultaneously suppressing abiotic stress-responsive genes. [ABSTRACT FROM AUTHOR]

The hemibiotrophic fungus Zymoseptoria tritici is the causative agent of Septoria tritici leaf blotch (STB) disease of wheat (Triticum aestivum L.), the economically most damaging disease of wheat in Europe. Today, ecofriendly plant protection methods compatible with sustainable agriculture are strongly desirable. Here, we tested two chemical inducers β-aminobutyric acid (BABA) and benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and the two biotic inducers Pseudomonas protegens CHA0 (CHA0) and P. chlororaphis PCL1391 (PCL) for their ability to induce resistance against STB in wheat seedlings. At 21 days after inoculation, only plants treated with BABA showed a smaller area covered by lesions and less pycnidia compared to the untreated control plants. We evaluated spore germination and fungal development on inoculated wheat leaves at early infection stages using calcofluor white staining. Overall, spores of Z. tritici germinated less on plants soil-drenched with BABA and BTH and their hyphal growth was significantly delayed. On the contrary, CHA0 and PCL seed treatments did not affect fungal growth in wheat leaves. In conclusion, BABA efficiently enhanced plant resistance to Z. tritici, BTH delayed fungal development at early stages while the two biotic inducers did not influence the resistance against STB disease. [ABSTRACT FROM AUTHOR]

This study attempted to characterize the involvement of a change in the redox status and subcellular localization in the BABA-induced priming resistance of peach fruit against Rhizopus rot. Specifically, 50 mM BABA primed the peaches for the enhanced disease resistance against R. stolonifer, as demonstrated by suppression of the disease development upon pathogen challenge accompanied by the clearly elevated level of TGA transcription factor (PpTGA1) and NPR1 gene (PpNPR1). In addition, the BABA elicitation enhanced the activities of a series of critical enzymes in the PPP and AsA-GSH cycle, and eventually promoted the NADPH and GSH pools, which altered the intracellular redox state towards a highly reductive condition. Additionally, PpTGA1-GFP was localized in the cytoplasm in the absence of BABA treatment or R. stolonifer inoculation, while BABA elicitation plus R. stolonifer inoculation caused PpTGA1-GFP to specifically translocate to the nucleus, where it interacted with PpNPR1 and regulated the positive expression of PR genes. Therefore, the observations implied that BABA could promote the reduction of the redox state, resulting in the translocation of PpTGA1 to the nucleus, which was a prerequisite for the induction of a priming defence against Rhizopus rot in peach. [ABSTRACT FROM AUTHOR]

Chilling is a major abiotic factor limiting the growth, development, and productivity of plants. β-aminobutyric acid (BABA), a new environmentally friendly agent, is widely used to induce plant resistance to biotic and abiotic stress. Calcium, as a signaling substance, participates in various physiological activities in cells and plays a positive role in plant defense against cold conditions. In this study, we used tobacco as a model plant to determine whether BABA could alleviate chilling stress and further to explore the relationship between BABA and Ca2+. The results showed that 0.2 mM BABA significantly reduced the damage to tobacco seedlings from chilling stress, as evidenced by an increase in photosynthetic pigments, the maintenance of cell structure, and upregulated expression of NtLDC1 , NtERD10B , and NtERD10D. Furthermore, 0.2 mM BABA combined with 10 mM Ca2+ increased the fresh and dry weights of both roots and shoots markedly. Compared to that with single BABA treatment, adding Ca2+ reduced cold injury to the plant cell membrane, decreased ROS production, and increased antioxidant enzyme activities and antioxidant contents. The combination of BABA and Ca2+ also improved abscisic acid and auxin contents in tobacco seedlings under chilling stress, whereas ethylene glycol-bis (β-aminoethylether)- N,N,N ′, N ′-tetraacetic acid (EGTA) reversed the effects of BABA. These findings suggested that BABA enhances the cold tolerance of tobacco and is closely related to the state of Ca2+ signaling. [ABSTRACT FROM AUTHOR]

BACKGROUND: Pistachio fruits suffer from postharvest decay, caused by Aspergillus flavus. This results in aflatoxin B1 (AFB1) accumulation in kernels, which is hazardous for human health due to its carcinogenic activity. In this study, the mechanism used by exogenous β‐aminobutyric acid (BABA) treatment for attenuating Aspergillus decay, minimizing aflatoxin B1 (AFB1) accumulation, and maintaining nutritional quality in fresh‐in‐hull pistachio kernels, infected by A. flavus during storage at 25 °C for 18 days, was investigated. RESULT: Results of an in vivo assay showed that the spore germination and germ tube elongation of A. flavus was repressed by BABA treatment at 7.5 mM. Aspergillus decay accompanied by AFB1 accumulation was also minimized in fresh‐in‐hull pistachio kernels treated with BABA at 7.5 mM and infected by A. flavus. Fresh‐in‐hull pistachio kernels, infected by A. flavus, treated with BABA at 7.5 mM, also exhibited higher phenol and flavonoid accumulation and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) scavenging capacity accompanied by higher phenylalanine ammonia lyase (PAL) enzyme activity. CONCLUSION: Promoting phenylpropanoid pathway activity with higher PAL enzyme activity in fresh‐in‐hull pistachio kernels treated with BABA may not only reduce Aspergillus decay in kernels by cell wall fortification but also may be favorable for maintaining the kernels' nutritional quality through its effects on ROS scavenging capacity. As oxidative stress, represented by ROS accumulation, is responsible for A. flavus growth and AFB1 accumulation, higher phenol and flavonoid accumulation in fresh‐in‐hull pistachio kernels treated with BABA may be beneficial for attenuating Aspergillus decay and minimizing AFB1 accumulation. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Bacterial canker caused by Clavibacter michiganensis subsp. michiganensis is an economically important disease of tomato. In this study after isolation and characterization of the pathogen, effects of tomato pretreatment with DL-β-aminobutyric acid (BABA) on bacterial canker was investigated under laboratory conditions. BABA is known as a powerful chemical resistance inducer in plants against diverse pathogens. In this study, tomato plants were treated with a 0.2 mM concentration of BABA and distilled water served as control. The plants were subsequently challenged with a 1×108 CFU ml−1 bacterial suspension. The results of experiments in different time intervals showed that BABA pre-treatment resulted in a significant reduction of bacterial population and symptoms severity of inoculated plants as compared to their controls. Furthermore, late appearance of disease symptoms indicated longer incubation periods for BABA treated plants. Also, a significant increase was observed in the expression of PR1 and catalase genes in treated plants. Based on our results and regarding the lack of proper management options against the disease, application of BABA as an environmentally safe agent is recommended as a valuable contribution to disease management. [ABSTRACT FROM AUTHOR]

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Highlights • β-Aminobutyric acid-treated blueberries had delayed fruit skin color changes. • β-Aminobutyric acid-treated blueberries enhanced individual organic acids and sugars. • β-Aminobutyric acid-treated blueberries retained higher fruit skin firmness. • β-Aminobutyric acid-treated blueberries had higher fruit cell wall material contents. • β-Aminobutyric acid-treated blueberries had lower polygalacturonase and endo-1,4-β-xylanase activities. Abstract We examined the effect of preharvest β-aminobutyric acid (BABA) treatment on postharvest quality and the softening of 'Bluecrop' highbush blueberry fruit during postharvest refrigerated storage. Reddish purple-colored fruit on shrubs were treated with 20 mM BABA and harvested 7 days after treatment when they turned dark purple. The harvested fruit were stored in clear polyethylene terephthalate clamshells at 2 °C for up to 20 days. Preharvest BABA treatment significantly delayed color changes, enhanced individual soluble sugars and organic acids, and reduced decay incidence. BABA-treated fruit also retained higher skin firmness throughout the storage period. Cell wall materials, closely associated with fruit softening, were significantly higher in BABA-treated fruit than in control. Moreover, preharvest BABA treatment significantly enhanced fruit pectin content at harvest and reduced activities of polygalacturonase and endo-1,4-β-xylanase, although hemicellulose content was unchanged. These results suggest that preharvest BABA treatment alleviates the deterioration of postharvest quality in 'Bluecrop' highbush blueberry fruit including skin firmness during refrigerated storage. [ABSTRACT FROM AUTHOR]

The effect of β-aminobutyric acid (BABA) on Rhizopus rot produced by Rhizopus stolonifer in harvested peaches and the possible action modes were investigated. Treatment with 50 mmol L−1 of BABA resulted in significantly lower lesion diameter and disease incidence compared with the control. The activities of defense-related enzymes chitinase and β-1,3-glucanase were notably enhanced by this treatment. Meanwhile, BABA treatment also increased lignin accumulation and maintained higher energy status in peaches by enhancing activities of enzymes in the phenylpropanoid and energy metabolism pathways. Semiquantitative reverse transcription PCR results indicated that the transcription of four defense-related genes was substantially and rapidly enhanced only in that BABA-treated fruit upon inoculation with the pathogen. Thus, our results demonstrated that BABA was effective on controlling Rhizopus rot by inducing disease resistance, which includes the increase in gene transcription and activity of defense-related enzymes, the enhancement of cell wall strength, and the maintenance of high energy status in Prunus persica fruit. Moreover, the disease resistance induced by BABA was demonstrated through priming model rather than direct induction.

In cut flowers, the post-harvest turgor is a critical aspect in a system in which, in the absence of the root system, transpiration water losses must be compensated. Two experiments were conducted in order to elucidate the effect of osmoprotectants (L-Proline) as well as of molecules with antitranspirant behavior (ß-aminobutyric acid - BABA or Pinolene) on the water relations and vase life of rose cut stems. Applications of L-Proline enhanced water fluxes, water conductivity, relative water content and stomatal conductance of rose cut stems in comparison to untreated plants, thus increasing the vase-life of rose cut flowers. BABA treatment reduced the stomatal conductance in rose as well as the daily water consumption, on the other hand senescence phenomena occurred earlier. The water used by pinolene treated stems was lower compared to the control and this was associated with a medium increase of the vase life. Overall, enhanced osmoregulation prolonged the vase life of cut flowers since the improved water status allowed the cut stem to partially continue its metabolic functions. On the other hand, the control of transpirational flux was functional in maintaining cellular turgor in pinolene treated cut stems, whereas with BABA, senescence phenomena occurred probably due to the activation of biochemical pathway of senescence involving abscisic acid. Taking all together, osmoregulation or direct control of transpirational fluxes may provide a promising avenue for improving the post-harvest longevity of cut roses.

Highlights • BABA treatment induced SAR in grape berries via a priming mechanism. • BABA treatment shifted redox towards a high reductive condition by regulation of PPP and ascorbate-glutathione cycle. • Altered redox status in BABA-treated grape berries was associated with defense activation. Abstract This study aimed to determine the specific form of the disease resistance using BABA elicitation and to illustrate the involvement of an alteration of the redox status in the BABA-activated defense response in grape berries. The BABA treatment at 10 mmol L−1 primed the grape berries for efficient disease resistance against Botrytis cinerea infection, as exhibited by the significantly enhanced levels of PR genes upon the B. cinerea challenge. In addition, the priming defense was associated with the onset of the SA-dependent SAR reaction. The BABA treatment induced higher activities of key enzymes in PPP and ascorbate-glutathione cycle, thus promoting the pools of GSH and NADPH and correspondingly elevating the [NADPH]/[NADP+] and [GSH]/[GSSG] ratios, which shifted the cellular redox towards a highly reductive condition. Meanwhile, the BABA-treated fruits also showed higher contents of intercellular redox signalling molecules, such as NO and SA, than those in the controls. This increase in the redox status coincided with the enhanced expression of a series of PR genes and with lower disease incidence. In contrast, 6-AN completely diminished the increases in the NADPH and GSH pools elicited by BABA in grape berries in parallel with an inhibitory effect on induction of the PR genes transcript levels. Thus, these findings indicated that BABA can prohibit the oxidation of the redox state necessary for the induction of a priming response in grape berries against B. cinerea infection. [ABSTRACT FROM AUTHOR]