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The document explores the impact of biostimulants on horticultural crops, emphasizing the importance of food security and the challenges faced by horticultural production due to various factors. Six research articles in the Special Issue focus on different biostimulants and their effects on crops like apricots, olives, geraniums, carrots, tomatoes, and onions. The studies highlight the potential of biostimulants, including microbial and natural sources, to enhance plant growth, yield, and quality, offering sustainable solutions for horticultural practices. Further research is recommended to explore the long-term effects and scalability of biostimulants in horticulture. [Extracted from the article]

Strawberry (Fragaria x ananassa) is an exquisite food, which provides health benefits, making it the berry with the highest production and export in Mexico. However, it is highly perishable, susceptible to postharvest damage, mainly by Botrytis cinerea and Rhizopus stolonifer, among others. The use of pesticides in preharvest is the control strategy of these pathogens; however, pesticides are documented to harm human health and the ecosystem, showing the need to explore friendly alternatives. Reagent grade chitosan (QGR) is an innocuous polymer with widely reported antifungal activity, while sodium octanoate (8:0) (OS) also has this property; however, so far it is unknown whether commercial grade chitosan (QGC) (the most suitable candidate to conduct a larger commercial study, due to its cost), available in Mexico, has the same effect. Therefore, the objective of this research was to evaluate the effectiveness of QGR and the QGR-OS composite in the protection of strawberry in postharvest and compare it with that of QGC and that of the QGCOS composite. The compounds were sprayed on the fruits and incubated simulating export conditions. The results showed significant reduction in the severity and incidence of postharvest strawberry fungal diseases after the application of QGR, QGC and QGR-OS, QGC-OS, but not that of OS applied alone. QGC and the QGC-OS composite are excellent candidates for use in a larger commercial study. [ABSTRACT FROM AUTHOR]

Plant diseases with a negative impact on strawberry yield (Fragaria × ananassa), such as anthracnose and fruit rot, are mainly controlled using pesticides, which can cause harmful effects; thus, new control alternatives for fruit decay are needed. Chitosan is a compound already evaluated for fungal disease control at postharvest. The aim of this study was to evaluate the in vitro and in vivo control activity of chitosan against post-harvest fungal strawberry pathogens, such as Colletotrichum gloeosporioides, Colletotrichum acutatum, Fusarium oxysporum and Phytophthora sp. The experimental design was completely random, with at least three repetitions for each chitosan treatment (5, 7.5, 10 and 15 mg mL-1). The data obtained were transformed with the x ≤05. function. A variance analysis (p≤0.05), and a Tukey's test (p≤0.05) were conducted using the SAS software. In vitro bioassays showed the anti-fungal effects of chitosan (5, 7.5, 10 and 15 mg mL-1) against all pathogens tested, which are related to the inhibition of mycelial growth and spore germination. The best results were observed in F. oxysporum and Phytophthora sp. with 100% of mycelial growth and spore germination inhibition. In vivo bioassays showed that strawberry fruit inoculated with mycelium or spores, and then immersed in chitosan (7.5, 10 and 15 mg mL-1), displayed a significant reduction (p≤0.05) in disease severity index after two treatments: 1) exposure for 7 d at 2±2.0 °C, and 2) for 3 d at room temperature (25±2.0 °C). The best results were observed in fruit treated with 15 mg mL-1 chitosan, which showed a disease severity range of 1-1.2 for fruit inoculated with mycelium and 1-1.6 with spores. These findings show that chitosan is a promising alternative in post-harvest disease control in strawberries. [ABSTRACT FROM AUTHOR]

In the present study the antibiotic resistance patterns of E. coli isolated from bovine mastitis, as well as the presence of Extended-spectrum β-lactamases (ESBL), tetracycline, streptomycin, and quinolone resistance genes were analyzed. From mastitic cows, milk samples were obtained, of which E. coli were isolated and identified biochemically and confirmed at the molecular level. Genetic analysis revealed that 11.8 % of the E. coli contained a virulence gene encoding intimin (eaeA). All E. coli were resistant to one or more antibiotics, with higher rates of resistance to tetracycline, ampicillin, and cephalothin. In addition, 73.5 % of E. coli were resistant to three or more antibiotics. Of eleven resistance genes analyzed, seven were detected in 79.4 % of the bacterial isolates. Of these, bla CTX-M was found in 16 isolates, tetB in 11, tetA, strA and strB in nine, qnrB in four, and bla TEM in one isolate. About 5.9 % of the E. coli isolates carried class 1 integron integrase gene. In conclusion, a high prevalence of antibiotic resistance in E. coli isolated from bovine mastitis was identified. The bacteria also harbor a virulence gene related to human pathogens and genes conferring resistance to beta-lactam antibiotics, tetracycline, streptomycin, and quinolones. [ABSTRACT FROM AUTHOR]

The Bacillus subtilis strain 168 genome contains the chr3N- chr3C genes encoding the Chr3N/Chr3C protein pair of the chromate ion transporter (CHR) superfamily. Chr3N/Chr3C confers chromate resistance in Escherichia coli only when both proteins are expressed. Upstream of chr3N is the chrS gene encoding ChrS, a protein with homology to the Lrp/AsnC family of transcriptional regulators. When the chrS- chr3N- chr3C gene cluster was transferred to E. coli, a diminished level of chromate resistance was observed, as compared with E. coli transformants bearing only the chromate resistance genes, which displayed full resistance. These data suggested that the chrS gene product acts as negative regulator. RT-PCR assays demonstrated that expression of chrS diminishes transcription of the chromate resistance genes in E. coli, and that this repression was overcome by chromate. Electrophoretic mobility shift assays showed that purified ChrS protein specifically binds to the 5′ region of chrS. These results indicate that the chr gene cluster forms an operon regulated negatively by ChrS binding to its own gene’s regulatory region, and positively by chromate ions. Sequence analysis revealed similar operons in many Bacillales strains, suggesting some adaptive advantage. This is the first example of a bacterial heavy-metal resistance system controlled by an Lrp-type transcriptional regulator. [ABSTRACT FROM AUTHOR]

The membrane topology of the plasmid-encoded Pseudomonas aeruginosa ChrA protein, which effluxes chromate ions, was determined by the analysis of translational fusions with reporter enzymes alkaline phosphatase and β-galactosidase. A novel 13-TMS (transmembrane segments) topology, with the N-terminus located in the cytoplasm and the C-terminus in the periplasmic space, was consistent with the enzyme activities determined in both Escherichia coli and P. aeruginosa. Alignment of the two halves of ChrA showed significant sequence homology, with TMS I, II, III, IV, V and VI displaying similarity to TMS VIII, IX, X, XI, XII and XIII, respectively, although with opposite membrane orientations. This suggests that ChrA arose from the duplication of a gene encoding a 6-TMS ancestral protein, followed by the insertion of extra TMS VII. These data also suggest that the two halves of ChrA may carry out distinct functions for the transport of chromate. [ABSTRACT FROM AUTHOR]

Escherichia coli is an environmental bacterium frequently implicated in bovine mammary infections. Although specific virulence factors are unknown, biofilm-forming bacteria are associated with persistent infections, and motile bacteria exhibit increased virulence. An analysis was done of the genetic relationship, biofilm formation capacity and motility of bovine mastitis-associated E. coli, as well as the in vivo virulence of representative bacterial isolates. Of the 34 isolates, 67.7 % belonged to phylogenetic group A, 17.6 % to group B1 and 14.7 % to group D. Genetic relationship analysis done with (GTG)5-PCR indicated that the analyzed bacteria are diverse, with only two isolates exhibiting 100 % similarity, and the remaining 32 being grouped into seven main clusters with more than 70 % similarity. Biofilm formation capacity ranged from strong to moderate and weak in 76.5 % of the isolates. The csgA and fimA genes were detected in 52.9 % of the biofilm-forming isolates. Most (70.6 %) of the isolates were motile. In vivo infection assays using Galleria mellonella showed the biofilm-forming bacteria to be more pathogenic than the non-biofilm-forming ones. The studied bovine mastitis-associated E. coli were genetically diverse. Biofilm formation capacity and motility were variable among the isolates, but the biofilm-forming bacteria were more pathogenic than the non-biofilm-forming ones. [ABSTRACT FROM AUTHOR]