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Elevated ozone (O3) modulates phytohormone signals, which subsequently alters the interaction between plants and herbivorous insects. It has been reported that elevated O3 activates the plant abscisic acid (ABA) signaling pathway, but its cascading effect on the performance of herbivorous insects remains unclear. Here, we used the ABA-deficient tomato mutant notabilis (not) and its wild type, Ailsa Craig (AC), to determine the role of ABA signaling in mediating the effects of elevated O3 on Bemisia tabaci in field open-top chambers (OTCs). Our results showed that the population abundance and the total phloem-feeding duration of B. tabaci were decreased by O3 exposure in AC plants compared with not plants. Moreover, elevated O3 and B. tabaci infestation activated the ABA signaling pathway and enhanced callose deposition in AC plants but had little effect on those in not plants. The exogenous application of a callose synthesis inhibitor (2-DDG) neutralized O3-induced resistance to B. tabaci , and the application of ABA enhanced callose deposition and exacerbated the negative effects of elevated O3 on B. tabaci. However, the application of 2-DDG counteracted the negative effects of O3 exposure on B. tabaci in ABA-treated AC plants. Collectively, this study revealed that callose deposition, which relied on the ABA signaling pathway, was an effective O3-induced priming defense of tomato plants against B. tabaci infestation. [ABSTRACT FROM AUTHOR]

Summary: Fumonisin B1 (FB1) and Alternaria alternate f. sp. lycopersici (AAL)‐toxin are classified as sphinganine analog mycotoxins (SAMTs), which induce programmed cell death (PCD) in plants and pose health threat to humans who consume the contaminated crop products. Herein, Fumonisin B1 Resistant41 (FBR41), a dominant mutant allele, was identified by map‐based cloning of Arabidopsis FB1‐resistant mutant fbr41, then ectopically expressed in AAL‐toxin sensitive tomato (Solanum lycopersicum) cultivar. FBR41‐overexpressing tomato plants exhibited less severe cell death phenotype upon AAL‐toxin treatment. Analysis of free sphingoid bases showed that both fbr41 and FBR41‐overexpressing tomato plants accumulated less sphinganine and phytosphingosine upon FB1 and AAL‐toxin treatment, respectively. Alternaria stem canker is a disease caused by AAL and responsible for severe economic losses in tomato production, and FBR41‐overexpressing tomato plants exhibited enhanced resistance to AAL with decreased fungal biomass and less cell death, which was accompanied by attenuated accumulation of free sphingoid bases and jasmonate (JA). Taken together, our results indicate that FBR41 is potential in inhibiting SAMT‐induced PCD and controlling Alternaria stem canker in tomato. [ABSTRACT FROM AUTHOR]

The Mediator complex is an essential, multisubunit transcriptional coactivator that is highly conserved in eukaryotes. Mediator interacts with gene-specific transcription factors, the RNA polymerase II transcriptional machinery, as well as several other factors involved in transcription, and acts as an integral hub to regulate various aspects of transcription. Recent studies of the plant Mediator complex have established that it functions in diverse aspects of plant development and fitness. Jasmonate (JA) is an oxylipin-derived plant hormone that regulates plant immunity and development. The basic helix–loop–helix transcription factor MYC2, which is a master regulator of JA signaling, orchestrates genome-wide transcriptional reprogramming of plant cells to coordinate defense- and growth-related processes. Here, we review the function of the plant Mediator complex in regulating JA signaling. We focus on the multifunctional Mediator subunit MED25, which emerges as an integrative hub for the transcriptional regulation of jasmonate signaling. [ABSTRACT FROM AUTHOR]

In rice, there are five members of the auxin carrier AUXIN1/LIKE AUX1 family; however, the biological functions of the other four members besides OsAUX1 remain unknown. Here, by using CRISPR/Cas9, we constructed two independent OsAUX3 knock‐down lines, osaux3‐1 and osaux3‐2, in wild‐type rice, Hwayoung (WT/HY) and Dongjin (WT/DJ). osaux3‐1 and osaux3‐2 have shorter primary roots (PRs), decreased lateral root (LR) density, and longer root hairs (RHs) compared with their WT. OsAUX3 expression in PRs, LRs, and RHs further supports that OsAUX3 plays a critical role in the regulation of root development. OsAUX3 locates at the plasma membrane and functions as an auxin influx carrier affecting acropetal auxin transport. OsAUX3 is up‐regulated in the root apex under aluminium (Al) stress, and osaux3‐2 is insensitive to Al treatments. Furthermore, 1‐naphthylacetic acid accented the sensitivity of WT/DJ and osaux3‐2 to respond to Al stress. Auxin concentrations, Al contents, and Al‐induced reactive oxygen species‐mediated damage in osaux3‐2 under Al stress are lower than in WT, indicating that OsAUX3 is involved in Al‐induced inhibition of root growth. This study uncovers a novel pathway alleviating Al‐induced oxidative damage by inhibition of acropetal auxin transport and provides a new option for engineering Al‐tolerant rice species. This study reveals biological functions of OsAUX3. OsAUX3, an auxin influx carrier plays important roles in acropetal auxin transport, regulating PR growth, LR initiation and RH development, and response to Al stress. This study provides a new option for engineering Al‐tolerance rice species. [ABSTRACT FROM AUTHOR]

Toxin‐antitoxin (TA) systems are regarded as genetic modules that facilitate bacterial survival under stress conditions. In this study, a novel TA system in Mycobacterium tuberculosis H37Rv chromosome was identified, termed as mt‐PemIK, which consists of antitoxin mt‐PemI and toxin mt‐PemK (Rv3098A). Induction of mt‐PemK leads to growth arrest in Mycobacterium smegmatis, while the toxic effect of mt‐PemK is eliminated by co‐expression of mt‐PemI. mt‐PemK is characterized as an endoribonuclease whose activity is pH‐dependent. mt‐PemK, as well as some other M. tuberculosis toxin/antitoxin proteins, can be modified by pupylation, suggesting that the Pup‐proteasome system is involved in the regulation of TA systems. These results are helpful to understand the mechanisms of M. tuberculosis growth regulation under stress conditions. [ABSTRACT FROM AUTHOR]

Summary: Auxin gradients are sustained by series of influx and efflux carriers whose subcellular localization is sensitive to both exogenous and endogenous factors. Recently the localization of the Arabidopsis thaliana auxin efflux carrier PIN‐FORMED (PIN) 6 was reported to be tissue‐specific and regulated through unknown mechanisms. Here, we used genetic, molecular and pharmacological approaches to characterize the molecular mechanism(s) controlling the subcellular localization of PIN6. PIN6 localizes to endomembrane domains in tissues with low PIN6 expression levels such as roots, but localizes at the plasma membrane (PM) in tissues with increased PIN6 expression such as the inflorescence stem and nectary glands. We provide evidence that this dual localization is controlled by PIN6 phosphorylation and demonstrate that PIN6 is phosphorylated by mitogen‐activated protein kinases (MAPKs) MPK4 and MPK6. The analysis of transgenic plants expressing PIN6 at PM or in endomembrane domains reveals that PIN6 subcellular localization is critical for Arabidopsis inflorescence stem elongation post‐flowering (bolting). In line with a role for PIN6 in plant bolting, inflorescence stems elongate faster in pin6 mutant plants than in wild‐type plants. We propose that PIN6 subcellular localization is under the control of developmental signals acting on tissue‐specific determinants controlling PIN6‐expression levels and PIN6 phosphorylation. [ABSTRACT FROM AUTHOR]

* Systemin (SYS), an octadecapeptide hormone processed from a 200-amino-acid precursor (prosystemin, PS), plays a central role in the systemic activation of defense genes in tomato in response to herbivore and pathogen attacks. However, whether PS mRNA is transferable and its role in systemic defense responses remain unknown. * We created the transgenic tomato PS gene tagged with the green fluorescent protein (PS-GFP) using a shoot- or root-specific promoter, and the constitutive 35S promoter in Arabidopsis. Subcellular localization of PS-/SYS-GFP was observed using confocal laser scanning microscopy and gene transcripts were determined using quantitative real-time PCR. * In Arabidopsis, PS protein can be processed and SYS is secreted. Shoot-/root-specific expression of PS-GFP in Arabidopsis, and grafting experiments, revealed that the PS mRNA moves in a bi-directional manner. We also found that ectopic expression of PS improves Arabidopsis resistance to the necrotrophic fungus Botrytis cinerea, consistent with substantial upregulation of the transcript levels of specific pathogen-responsive genes. * Our results provide novel insights into the multifaceted mechanism of SYS signaling transport and its potential application in genetic engineering for increasing pathogen resistance across diverse plant families. [ABSTRACT FROM AUTHOR]

Objective Subclinical hypothyroidism (SCH) has been associated with atherosclerosis and increased risk of ischaemic stroke. However, whether SCH is associated with cerebral small vessel disease (cSVD) remains largely unexplored. This study aimed to investigate the relationship between SCH and total cSVD burden, a composite measurement detected with magnetic resonance imaging (MRI), in patients with minor ischaemic stroke or transient ischaemic attack (TIA). Design This was a prospective observational cohort study conducted in a tertiary referral hospital. Methods Subclinical hypothyroidism (SCH) was defined as with mildly or moderately increased thyroid-stimulating hormone levels (TSH, 4.5-10.0 mIU/L), but with normal free thyroxine levels. Brain MRI presence of silent lacunar infarcts (LIs), white matter lesions (WMLs), cerebral microbleeds (CMBs) and enlarged perivascular spaces (EPVs) were summed to a validated scales ranging from 0 to 4 to represent the load of cSVD. The associations between SCH and cSVD were analysed by logistic regression analyses. Results Subclinical hypothyroidism (SCH) was identified in 43 of 229 (18.8%) patients with minor stroke or TIA. Compared with patients without SCH, those with SCH had higher risks of WMLs, CMBs and total cSVD burden. Adjustment of potential confounders did not change these associations. Conclusions These findings showed that SCH might be associated with the presence of WMLs, CMBs, as well as cSVD burden in patients with minor stroke or TIA. [ABSTRACT FROM AUTHOR]