Chen Wang

Summary: The phytohormone abscisic acid (ABA) is important during abiotic stresses, especially drought stress. Although mitogen‐activated protein kinase (MAPK) cascades are crucial for ABA‐mediated drought tolerance, how these cascades integrate and deliver the downstream ABA signals is poorly understood. Here, the group C MAPK GhMPK7 was found to positively regulate ABA‐mediated drought tolerance in cotton. Silencing GhMPK7 decreased drought tolerance in transgenic cotton plants. After ABA treatment, the GhMPK7‐silenced transgenic plants were not sensitive to ABA, exhibited restricted stomatal closure, faster germination rates and longer roots. Importantly, GhSDIRIP1, a negative regulator of ABA signaling, was found to interact with GhMPK7 as a downstream. Silencing GhSDIRIP1 in GhMPK7‐silenced transgenic cotton plants restored the drought‐intolerant phenotype caused by GhMPK7 silencing. The results of the phosphorylation experiments revealed that GhMPK7 can phosphorylate the Ser‐19 residue of GhSDIRIP1 to regulate its stability. GhMPK7‐induced GhSDIRIP1 protein degradation increased ABA signaling intensity in response to drought stress. Overall, our findings provide insights into the positive regulatory mechanism of ABA‐involved drought tolerance, which is mediated by the GhMPK7‐GhSDIRIP1 module. This study expands our knowledge of how MAPK cascades regulate the intensity of ABA‐mediated drought tolerance in plants and advances our understanding of the interplay between phosphorylation and ubiquitination.

Wheat is a globally important staple crop. However, the weak regeneration ability of wheat significantly restricts the progress of wheat molecular design breeding. Screening for key factors that can enhance the regeneration ability of wheat is crucial for the development of the wheat industry. In this study, a DOF transcription factor, TaDOF4.7-B, was identified as a crucial factor regulating the wheat regeneration ability. Transcriptome analysis results indicated that TaDOF4.7-B could improve the regeneration ability of wheat by directly promoting the expression of regeneration related genes, such as TaWOX5, or indirectly regulating the expression level of TaARFs. Importantly, combined with the experimental results of ChIP-qPCR and luciferase activation assays, TaDOF4.7-B can specifically bind to the promoters of multiple TaCKXs and inhibit their expression. The cytokinin concentration in overexpression TaDOF4.7-B wheat was significantly higher than that in the control. On the SIM medium without cytokinin, the wheat immature embryos transformed with the Ubi::TaDOF4.7-B-6MYC vector maintained a higher regeneration frequency and regeneration shoot frequency. Furthermore, the T₂-generation of TaDOF4.7-B overexpression transgenic wheat lines still hold a highly regenerative capacity. The present findings demonstrate a novel regeneration factor, TaDOF4.7-B, and shed light on the mechanism by which DOF transcription factors promote plant regeneration through regulating cytokinin homeostasis.

The vesicular transport system is important for substance transport in plants. In recent years, the regulatory relationship between the vesicular transport system and plant disease resistance has received widespread attention; however, the underlying mechanism remains unclear. MdSYP121 is a key protein in the vesicular transport system. The overexpression of MdSYP121 decreased the B. dothidea resistance of apple, while silencing MdSYP121 resulted in the opposite phenotype. A metabolome and transcriptome dataset analysis showed that MdSYP121 regulated apple disease resistance by significantly affecting sugar metabolism. HPLC results showed that the levels of many soluble sugars were significantly higher in the MdSYP121-OE calli. Furthermore, the expression levels of genes related to sugar transport were significantly higher in the MdSYP121-OE calli after B. dothidea inoculation. In addition, the relationships between the MdSYP121 expression level, the soluble sugar content, and apple resistance to B. dothidea were verified in an F1 population derived from a cross between ‘Golden Delicious’ and ‘Fuji Nagafu No. 2’. In conclusion, these results suggested that MdSYP121 negatively regulated apple resistance to B. dothidea by influencing the soluble sugar content. These technologies and methods allow us to investigate the molecular mechanism of the vesicular transport system regulating apple resistance to B. dothidea.

Glucosinolates and their degradation products have a wide range of actions and are important components of plant defense. NSP2 (nitrile-specific protein 2) is a key regulator in the breakdown process of glucosinolates. However, the precise function of NSP2 in plant disease resistance beyond its role in glucosinolate degradation is still unclear. In this study, we discovered that NSP2 which was induced by Pst DC3000, influenced PR genes expression and reactive oxygen burst. Additionally, omics analysis revealed that NSP2 was engaged in plant-pathogen interaction and several hormone signal transduction pathways. Furthermore, immunoprecipitation-tandem mass spectrometry analysis (IP-MS), bimolecular fluorescence complementation (BiFC), and co-immunoprecipitation demonstrated that NSP2 interacts with MPK3. Genetic analysis shows that NSP2 may be a function downstream of MPK3. Upon pathogen inoculation, NSP2 protein levels increase while MPK3 protein levels decrease. Moreover, the level of phosphorylated NSP2 decreases. Taken together, this study sheds light on a new mode of synergistic action between NSP2 and MPK3 in the disease resistance process.

BACKGROUND: The widespread use of glyphosate has many adverse effects on Apis cerana cerana. Due to the incomplete understanding of the molecular mechanisms of glyphosate toxicity, there are no available methods for mitigating the threat of glyphosate to Apis cerana cerana. Small heat shock proteins (sHSPs) play an important role in resisting oxidative stress, but their mechanism of action in Apis cerana cerana remains unclear.RESULTS: In this experiment, we cloned and identified AccsHSP21.7. Studies have shown that AccsHSP21.7 contains binding motifs for various transcription factors related to oxidative stress. Abiotic stresses induced the expression of AccsHSP21.7. Bacteriostatic testing of a recombinant AccsHSP21.7 protein proved that Escherichia coli overexpressing AccsHSP21.7 showed increased resistance to oxidative stress. Knocking down the AccsHSP21.7 gene caused significant damage to midgut cells, which seriously disrupted the antioxidant system in Apis cerana cerana and greatly increased mortality under glyphosate stress.CONCLUSION: This study investigated the relationship between antioxidant regulation and the AccsHSP21.7 gene at the molecular level, and the results have guiding significance for the improvement of stress resistance in Apis cerana cerana. © 2023 Society of Chemical Industry.

SUMMARY: Anthocyanins are important secondary metabolites in plants. They are important for human health because of their antioxidant activities and because their dietary intake reduces the incidence of cardiovascular and cerebrovascular diseases and tumors. The biosynthesis of anthocyanins and its regulation in fruits and vegetables is a global research hotspot. Compared with cultivated apples, the red‐fleshed apple is a relatively new and popular commodity in the market. Previous studies on red‐fleshed apples have focused on the basis for the high anthocyanin content and the transcriptional regulation of anthocyanin synthesis. In the present study, we focused on the mechanism of microRNA‐mediated post‐transcriptional regulation of anthocyanin synthesis in red‐fleshed apples. We identified a microRNA (miRNA), designated mdm‐miR858, that is specifically expressed in the flesh of apple fruit. The expression level of miR858 was significantly lower in red‐fleshed apples than in white‐fleshed apples. The overexpression of mdm‐miR858 significantly inhibited anthocyanin accumulation, whereas the silencing of mdm‐miR858 promoted anthocyanin synthesis in STTM858 transgenic apple calli. Further analyses showed that mdm‐miR858 targets the transcription factor genes MdMYB9 and MdMYBPA1 to participate anthocyanin accumulation in apple. Our results also show that MdHY5, a transcription factor in the light signaling pathway, can bind to the promoter of mdm‐miR858 to inhibit its transcription, thereby regulating anthocyanin synthesis. Based on our results, we describe a novel HY5‐miR858‐MYB loop involved in the modulation of anthocyanin biosynthesis. These findings provide new information about how plant miRNAs regulate anthocyanin anabolism and provide a basis for breeding new anthocyanin‐rich, red‐fleshed apple varieties.

Summary: WRKY transcription factors (TFs) are crucial regulators in response to pathogen infection. However, the regulatory mechanisms of WRKY TFs in response to Fusarium oxysporum f. sp. vasinfectum (Fov), the most devastating pathogen of cotton, remain unclear. Here, transcriptome sequencing indicated that the group IIc WRKY TF subfamily was the most important TF subfamily in response to Fov. Gain‐of‐function and loss‐of‐function analyses showed that group IIc WRKY TFs positively regulated cotton resistance to Fov. A series of chromatin immunoprecipitation sequencing, yeast one‐hybrid assay and electrophoresis mobility shift assay experiments indicated that group IIc WRKY TFs directly bound to the promoter of GhMKK2 and regulated its expression. Importantly, a novel mitogen‐activated protein kinase (MAPK) cascade composed of GhMKK2, GhNTF6 and GhMYC2 was identified. The functional analysis indicated that group IIc WRKY TFs induced the GhMKK2‐GhNTF6 pathway to increase resistance to Fov by upregulating the GhMYC2‐mediated expression of several flavonoid biosynthesis‐related genes, which led to flavonoid accumulation. In conclusion, our study demonstrated a novel disease defense mechanism by which the WRKY‐MAPK pathway promotes flavonoid biosynthesis to defend against pathogen infection. This pathway improves our understanding of the interaction mode between WRKY TFs and MAPK cascades in plant immunity and the vital role of plant flavonoids in pathogen defense.