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The phytohormone abscisic acid (ABA) regulates plant growth and development and stress resistance through the ABA receptor PYLs. To date, no interaction between CPK and PYL has been reported, even in Arabidopsis and rice. In this study, we found that MdCPK4 from Malus domestica (Md for short) interacts with two MdPYLs, MdPYL2/12, in the nucleus and the cytoplasm in vivo and phosphorylates the latter in vitro as well. Compared with the wild type (WT), the MdCPK4- or MdPYL2/12-overexpressing Arabidopsis lines showed more sensitivity to ABA, and therefore stronger drought resistance. The ABA-related genes (ABF1, ABF2, ABF4, RD29A and SnRK2.2) were significantly upregulated in the overexpressing (OE) lines after ABA treatment. These results indicate that MdCPK4 and MdPYL2/12 act as positive regulators in response to ABA-mediated drought resistance in apple. Our results reveal the relationship between MdCPK4 and MdPYL2/12 in ABA signaling, which will further enrich the molecular mechanism of drought resistance in plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Background: The basolateral potassium channels play an important role in maintaining the membrane transport in the renal proximal tubules (PT) and adenosine receptors have been shown to regulate the trans-epithelial Na + absorption in the PT. The aim of the present study is to explore whether adenosine also regulates the basolateral K + channel of the PT and to determine the adenosine receptor type and the signaling pathway which mediates the effect of adenosine on the K + channel. Methods: We have used the single channel recording to examine the basolateral K + channel activity in the proximal tubules of the mouse kidney. All experiments were performed in cell-attached patches. Results: Single channel recording has detected a 50 pS inwardly-rectifying K + channel with high channel open probability and this 50 pS K + channel is a predominant type K + channel in the basolateral membrane of the mouse PT. Adding adenosine increased 50 pS K + channel activity in cell-attached patches, defined by NP o (a product of channel Numbers and Open Probability). The adenosine-induced stimulation of the 50 pS K + channel was absent in the PT pretreated with DPCPX, a selective inhibitor of adenosine A1 receptor. In contrast, adenosine was still able to stimulate the 50 pS K + channel in the PT pretreated with CP-66713, a selective adenosine A2 receptor antagonist. This suggests that the stimulatory effect of adenosine on the 50 pS K + channel of the PT was mediated by adenosine-A1 receptor. Moreover, the effect of adenosine on the 50 pS K + channel was blocked in the PT pretreated with U-73122 or Calphostin C, suggesting that adenosine-induced stimulation of the 50 pS K + channels of the PT was due to the activation of phospholipase C (PLC) and protein kinase C (PKC) pathway. In contrast, the inhibition of phospholipase A2 (PLA2) with AACOCF3 or inhibition of protein kinase A (PKA) with H8 failed to block the adenosine-induced stimulation of the 50 pS K + channel of the PT. Conclusion: We conclude that adenosine activates the 50 pS K + channels in the basolateral membrane of PT via adenosine-A1 receptor. Furthermore, the effect of adenosine on the 50 pS K + channel is mediated by PLC-PKC signaling pathway., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Liu, Sun, Ding, Shi, Wang and Zhang.)

Plants usually suffer from phosphorus starvation because of the low inorganic phosphate (Pi) status of most soils. To cope with this, plants have evolved an adaptive phosphate starvation response (PSR) which involves both developmental and metabolic changes regulated mainly by PHOSPHATE STARVATION RESPONSE1 (PHR1) and its homologs. Here, we elucidated how perennial woody plants, such as poplars (Populus spp.), respond to low-Pi stress. We first performed RNA-seq analysis of low-Pi-treated poplars and identified PtoWRKY40 is rapidly downregulated and protein degraded after stress. Overexpressing and knocking-down PtoWRKY40 downregulated and upregulated the expression of Pi starvation signaling genes, respectively, such as PHOSPHATE TRANSPORTER1 (PHT1)-type genes and PURPLE ACID PHOSPHATASE genes. PtoWRKY40 bound to the W box in the promoter of several PtoPHT1s and repressed their expression. Moreover, PtoWRKY40 interacted with PtoPHR1-LIKE3 (PtoPHL3), a PHR1 homolog in poplar, to inhibit the latter binding to the P1BS element and thus reduced PtoPHT1s' transcription under Pi-sufficient conditions. However, Pi deficiency decreased PtoWRKY40 abundance and therefore released its inhibition on PHT1s. In conclusion, we have uncovered a PSR mechanism mediated by PtoWRKY40 and PtoPHL3 which regulates Pi content in poplars, deepening our understanding of how poplars adapt to diverse Pi conditions and regulate appropriate responses to maintain Pi homeostasis., (© American Society of Plant Biologists 2022. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Abscisic acid (ABA) is an important plant hormone that mediates abiotic stresses in plant growth and development. A number of E3 ligases have been reported to be involved in ABA signaling pathway. In this study, we identified a C3H2C3 RING-type E3 ligase, Arabidopsis thaliana Tόxicos en Levadura 61 (ATL61), which regulated drought stress in planta. Enzyme assay in vitro demonstrated that ATL61 had E3 ubiquitin ligase activity, while point mutation of ATL61 H109A, H122A (mATL61) abolished its E3 ubiquitin ligase activity. ATL61 overexpression plants exhibited ABA hypersensitivity and were more tolerant to drought, while the atl61 mutant plants were insensitive to ABA. Moreover, mATL61 overexpression lines exhibited similar ABA-related phenotypes with wild type (WT) plants. The transcript abundances of ABA-mediated drought stress-related genes RD20 and RD22 were higher in ATL61 overexpression plants than those in WT, atl61, and mATL61 plants. Our results indicated that ATL61 acted as a positive regulator in the ABA-mediated drought stress response., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Apple mosaic disease has a great influence on apple production. In this study, an investigation into the incidence of apple mosaic disease in southwest China was performed, and the pathogen associated with the disease was detected. The results show that 2869 apple trees with mosaic disease were found in the Sichuan, Yunnan, and Guizhou Provinces, with an average incidence of 9.6%. Although apple mosaic virus (ApMV) is widespread in apples worldwide, the diseased samples were negative when tested for ApMV. However, a novel ilarvirus (apple necrotic mosaic virus, ApNMV) was identified in mosaic apple leaves which tested negative for ApMV. RT-PCR analysis indicated that ApNMV was detected in 322 out of 357 samples with mosaic symptoms. Phylogenetic analysis of coat protein (CP) sequences of ApNMV isolates suggested that, compared with ApMV, ApNMV was closer to prunus necrotic ringspot virus (PNRSV). The CP sequences of the isolates showed the diversity of ApNMV, which may enable the virus to adapt to the changeable environments. In addition, the pathology of mosaic disease was observed by microscope, and the result showed that the arrangement of the tissue and the shape of the cell, including the organelle, were seriously destroyed or drastically changed.