Fruit Quality of Grafted Watermelon (Citrullus lanatus): Relationship between Rootstock, Soil Disinfection and Plant Stand

Grafting of vegetable transplants is a unique horticultural technology, which was adapted from the practice in perennial crops. However, rootstock/scion combinations may affect and alter the final size, yield, and quality of fruits of grafted plants, both immediately postharvest and during prolonged storage. We evaluated the effect of two rootstocks [TZ148 and Nurit (commercial Cucurbita spp. hybrids)] grafted on one scion (seedless watermelon cv. 1262) in two plant stands (2500 and 5000 plant ha-1), on plant viability, number of marketable fruits (fruits weight above 5 kg) and fruit quality after one week storage at 20°C, in non- or disinfested soil. Soil disinfection significantly improved the viability of non-grafted plants. All grafted plants significantly performed better vine vigor, with no wilt or vine decline symptoms, in either disinfested or non-treated soil, regardless of the type of the rootstock. Plant stand did not affect plant viability. The number of marketable watermelon fruits per m2 was 75 to 700% higher in grafted plants than in non-graft ed. Grafting on Nurit produced significantly more marketable fruits than grafting on TZ148. The quality of fruits harvested from grafted plants was significantly better than non-grafted fruit in both plant stands and soils. Watermelons harvested from Nurit-grafted plants had better taste and texture and almost seedless compared to control and TZ-148-grafted plant

Metabolic Versatility and Antibacterial Metabolite Biosynthesis Are Distinguishing Genomic Features of the Fire Blight Antagonist Pantoea vagans C9-1

Smits THM, Rezzonico F, Kamber T, et al. Metabolic Versatility and Antibacterial Metabolite Biosynthesis Are Distinguishing Genomic Features of the Fire Blight Antagonist Pantoea vagans C9-1. PLoS ONE. 2011;6(7): e22247.Background: Pantoea vagans is a commercialized biological control agent used against the pome fruit bacterial disease fire blight, caused by Erwinia amylovora. Compared to other biocontrol agents, relatively little is currently known regarding Pantoea genetics. Better understanding of antagonist mechanisms of action and ecological fitness is critical to improving efficacy. Principal Findings: Genome analysis indicated two major factors contribute to biocontrol activity: competition for limiting substrates and antibacterial metabolite production. Pathways for utilization of a broad diversity of sugars and acquisition of iron were identified. Metabolism of sorbitol by P. vagans C9-1 may be a major metabolic feature in biocontrol of fire blight. Biosynthetic genes for the antibacterial peptide pantocin A were found on a chromosomal 28-kb genomic island, and for dapdiamide E on the plasmid pPag2. There was no evidence of potential virulence factors that could enable an animal or phytopathogenic lifestyle and no indication of any genetic-based biosafety risk in the antagonist. Conclusions: Identifying key determinants contributing to disease suppression allows the development of procedures to follow their expression in planta and the genome sequence contributes to rationale risk assessment regarding the use of the biocontrol strain in agricultural systems

Endothelial Differentiation of Human Stem Cells Seeded onto Electrospun Polyhydroxybutyrate/Polyhydroxybutyrate-Co-Hydroxyvalerate Fiber Mesh

Tissue engineering is based on the association of cultured cells with structural matrices and the incorporation of signaling molecules for inducing tissue regeneration. Despite its enormous potential, tissue engineering faces a major challenge concerning the maintenance of cell viability after the implantation of the constructs. The lack of a functional vasculature within the implant compromises the delivery of nutrients to and removal of metabolites from the cells, which can lead to implant failure. In this sense, our investigation aims to develop a new strategy for enhancing vascularization in tissue engineering constructs. This study's aim was to establish a culture of human adipose tissue-derived stem cells (hASCs) to evaluate the biocompatibility of electrospun fiber mesh made of polyhydroxybutyrate (PHB) and its copolymer poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHB-HV) and to promote the differentiation of hASCs into the endothelial lineage. Fiber mesh was produced by blending 30% PHB with 70% PHB-HV and its physical characterization was conducted using scanning electron microscopy analysis (SEM). Using electrospinning, fiber mesh was obtained with diameters ranging 300 nm to 1.3 µm. To assess the biological performance, hASCs were extracted, cultured, characterized by flow cytometry, expanded and seeded onto electrospun PHB/PHB-HV fiber mesh. Various aspects of the cells were analyzed in vitro using SEM, MTT assay and Calcein-AM staining. The in vitro evaluation demonstrated good adhesion and a normal morphology of the hASCs. After 7, 14 and 21 days of seeding hASCs onto electrospun PHB/PHB-HV fiber mesh, the cells remained viable and proliferative. Moreover, when cultured with endothelial differentiation medium (i.e., medium containing VEGF and bFGF), the hASCs expressed endothelial markers such as VE-Cadherin and the vWF factor. Therefore, the electrospun PHB/PHB-HV fiber mesh appears to be a suitable material that can be used in combination with endothelial-differentiated cells to improve vascularization in engineered bone tissues

Extended Storage of Yellow Pepper Fruits at Suboptimal Temperatures May Alter Their Physical and Nutritional Quality

Yellow sweet peppers (Capsicum annuum L. cv. Dinamo) are generally more susceptible than red sweet peppers to physiological and pathological deterioration after harvest. Yellow peppers also fetch higher prices at market. In this study, we examined the external and nutritional quality attributes of yellow pepper fruits stored at suboptimal temperatures of 1.5 and 4 °C for 3 weeks, followed by a 3-day shelf-life simulation. Notably, yellow peppers kept in plastic (Xtend®, Stepac, Tefen, Israel) bags at 4 °C maintained their external quality just as well as peppers stored at the optimum temperature of 7 °C. In addition, nutrient content (namely ascorbic acid) and total phenolic and hydrophilic antioxidant contents were not reduced when the peppers were kept at suboptimal storage temperatures of 4 or 1.5 °C in Xtend® plastic packaging. Thus, the external and nutritional qualities of yellow pepper fruits can be preserved at suboptimal temperatures of 4 °C with Xtend® plastic packaging. This is particularly significant in light of the fact that storage at such temperatures is sometimes used as a quarantine method to eliminate pests on produce imported into Israel

Multiple plasmid-borne virulence genes of Clavibacter michiganensis ssp capsici critical for disease development in pepper

Clavibacter michiganensis ssp. capsici is a Gram-positive plant-pathogenic bacterium causing bacterial canker disease in pepper. Virulence genes and mechanisms of C. michiganensis ssp. capsici in pepper have not yet been studied. To identify virulence genes of C. michiganensis ssp. capsici, comparative genome analyses with C. michiganensis ssp. capsici and its related C. michiganensis subspecies, and functional analysis of its putative virulence genes during infection were performed. The C. michiganensis ssp. capsici type strain PF008 carries one chromosome (3.056 Mb) and two plasmids (39 kb pCM1(Cmc) and 145 kb pCM2(Cmc)). The genome analyses showed that this bacterium lacks a chromosomal pathogenicity island and celA gene that are important for disease development by C. michiganensis ssp. michiganensis in tomato, but carries most putative virulence genes in both plasmids. Virulence of pCM1(Cmc)-cured C. michiganensis ssp. capsici was greatly reduced compared with the wild-type strain in pepper. The complementation analysis with pCM1(Cmc)-located putative virulence genes showed that at least five genes, chpE, chpG, ppaA1, ppaB1 and pelA1, encoding serine proteases or pectate lyase contribute to disease development in pepper. In conclusion, C. michiganensis ssp. capsici has a unique genome structure, and its multiple plasmid-borne genes play critical roles in virulence in pepper, either separately or together

The Potential Use of Hot Water Rinsing and Brushing Technology to Extend Storability and Shelf Life of Sweet Acorn Squash (Cucurbita pepo L.)

Acorn squash fruits (Cucurbita pepo L.) are very sweet and are an excellent source of nutrients and vitamins. Very little information is available about their optimal storage temperature or how to extend their shelf life. The present goal was to elucidate the best storage temperature of this fruit, and to evaluate hot water rinsing and brushing (HWRB) technology to maintain fruit quality for several months. The optimal storage temperature was found to be 15 °C. However, treating the fruits with HWRB at 54 °C for 15 s and then storing them at 15 °C significantly maintained fruit quality for 3.5 months, as indicated by higher fruit firmness, lower decay incidence, and improved retention of green skin color