Sweet cherry (Prunus avium L.) is a delicious nutrient-rich fruit widely cultivated in countries such as China, America, Chile, and Italy. However, the yield often drops severely due to the frequently-abnormal fruitlet abscission, and few studies on the metabolism during its ripening process at the proteomic level have been executed so far. To get a better understanding regarding the sweet cherry abscission mechanism, proteomic analysis between the abscising carpopodium and non-abscising carpopodium of sweet cherry was accomplished using a newly developed Liquid chromatography-mass spectrometry/mass spectrometry with Tandem Mass Tag (TMT-LC-MS/MS) methodology. The embryo viability experiments showed that the vigor of the abscission embryos was significantly lower than that of retention embryo. The activity of cell wall degrading enzymes in abscising carpopodium was significantly higher than that in non-abscising carpopodium. The anatomy results suggested that cells in the abscission zone were small and separated. In total, 6280 proteins were identified, among which 5681 were quantified. It has been observed that differentially accumulated proteins (DAPs) influenced several biological functions and various subcellular localizations. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that plenty of metabolic pathways were notably enriched, particularly those involved in phytohormone biosynthesis, cell wall metabolism, and cytoskeletal metabolism, including 1-aminocyclopropane-1-carboxylate oxidase proteins which promote ethylene synthesis, and proteins promoting cell wall degradation, such as endoglucanases, pectinase, and polygalacturonase. Differential expression of proteins concerning phytohormone biosynthesis might activate the shedding regulation signals. Up-regulation of several cell wall degradation-related proteins possibly regulated the shedding of plant organs. Variations of the phytohormone biosynthesis and cell wall degradation-related proteins were explored during the abscission process. Furthermore, changes in cytoskeleton-associated proteins might contribute to the abscission of carpopodium. The current work represented the first study using comparative proteomics between abscising carpopodium and non-abscising carpopodium. These results indicated that embryo abortion might lead to phytohormone synthesis disorder, which effected signal transduction pathways, and hereby controlled genes involved in cell wall degradation and then caused the abscission of fruitlet. Overall, our data may give an intrinsic explanation of the variations in metabolism during the abscission of carpopodium.

Pitaya (Hylocereus polyrhizus L.) is highly tolerant to drought stress. Elucidating the response mechanism of pitaya to drought will substantially contribute to improving crop drought tolerance. In the present study, the physiological and proteomic responses of the pitaya cultivar ‘Zihonglong’ were compared between control seedlings and seedlings exposed to drought stress (−4.9 MPa) induced by polyethylene glycol for 7 days. Drought stress obviously enhanced osmolyte accumulation, lipid peroxidation, and antioxidant enzyme activities. Proteomic data revealed drought stress activated several pathways in pitaya, including carbohydrate and energy metabolism at two drought stress treatment time-points (6 h and 3 days). Other metabolic pathways, including those related to aspartate, glutamate, glutathione, and secondary metabolites, were induced more at 3 days than at 6 h, whereas photosynthesis and arginine metabolism were induced exclusively at 6 h. Overall, protein expression changes were consistent with the physiological responses, although there were some differences in the timing. The increases in soluble sugar contents mainly resulted from the degradation and transformation of insoluble carbohydrates. Differentially accumulated proteins in amino acid metabolism may be important for the conversion and accumulation of amino acids. GSH and AsA metabolism and secondary metabolism may play important roles in pitaya as enzymatic and nonenzymatic antioxidant systems. The enhanced carbohydrate and energy metabolism may provide the energy necessary for initiating the above metabolic pathways. The current study provided the first proteome profile of this species exposed to drought stress, and may clarify the mechanisms underlying the considerable tolerance of pitaya to drought stress.

Auxin response factors (ARFs) play a vital role in plant growth and development. In the current study, 16 ARF members have been identified in the sweet cherry (Prunus avium L.) genome. These genes are all located in the nucleus. Sequence analysis showed that genes in the same subgroup have similar exon-intron structures. A phylogenetic tree has been divided into five groups. The promoter sequence includes six kinds of plant hormone-related elements, as well as abiotic stress response elements such as low temperature or drought. The expression patterns of PavARF in different tissues, fruitlet abscission, cold and drought treatment were comprehensively analyzed. PavARF10/13 was up-regulated and PavARF4/7/11/12/15 was down-regulated in fruitlet abscising. These genes may be involved in the regulation of fruit drop in sweet cherry fruits. This study comprehensively analyzed the bioinformatics and expression pattern of PavARF, which can lay the foundation for further understanding the PavARF family in plant growth development and fruit abscission.

In this paper, an auxin-responsive transcription factor, CpARF7, was isolated from the roots of Chinese cherry (Cerasus pseudocerasus Lindl. Cv. “Manao Hong”). CpARF7 is highly homologous to AtARF7 or AtARF19 in Arabidopsis, and PavARF1 or PavARF14 in sweet cherry. However, in the phenotype of transgenic tomatoes, the root morphology changed, the main root elongated, and the lateral root increased. Both drought treatment and low-phosphorus conditions can elongate the roots of transgenic tomatoes. In addition, the drought resistance and low-phosphorus tolerance of the transgenic lines are improved, and the POD, SOD, and CAT activities under drought and low-phosphorus environments are increased. There is an effect on the tomato somatotropin suppressor gene, SlIAAs, in which SlIAA1/14/19/29 are up-regulated and SlIAA2/11/12/16 are down-regulated. These results indicate that CpARF7 plays an essential regulatory role in root formation and abiotic stress response, and deepens the understanding of auxin-responsive genes in root growth and abiotic stress.

Acinetobacter baumannii (A. baumannii) is a gram-negative coccobacillus that can cause a variety of infectious diseases. The Quorum Sensing (QS) system is a widespread mechanism regulating group behavior in bacteria, playing a crucial role in the virulence regulation of several Gram-negative pathogenic bacteria. To investigate the effects of the A. baumannii quorum sensing system on mucus and pathogenicity. In this work, a clinical mucus carbapenem-resistant A. baumannii (CRAB110) was used to construct abaI knockout strain (CRAB110ΔabaI) using CRISPR/Cas9 system, then, the abaI complemented strain (CRAB110ΔabaI+) was constructed by the pYMAb2 plasmid. Afterwards, the capsule changes, virulence and host immunity were analyzed from the aspects of bacterial phenotype, physiology, molecules and the impact of A. baumannii on the host. The results showed CRAB110ΔabaI significantly affected capsule, virulence, and immunity compared to CRAB110, with a smoother wall, a thinner capsule, and lower virulence; Mice infected with CRAB110ΔabaI exhibited a reduction in inflammation compared to those infected with CRAB110. A comparison of the transcriptomes of CRAB110 and CRAB110ΔabaI identified differentially expressed genes related to polysaccharide synthesis (wza, wzb, wzc), galactose metabolism (GalM), ABC transport, and amino acid metabolism. Mouse lung transcriptomic and cellular Western blot data indicate that quorum sensing (QS) exerts its pro-inflammatory effect through Acinetobacter baumannii by influencing the IL-17 and NF-κB pathways. This study suggest that the abaI gene boosts mucus production and pathogenicity of A. baumannii, giving new insights for clinical management of drug-resistant A. baumannii diseases and a foundation for new antimicrobial drugs.