64,404 research outputs found
Climacteric fruit ripening: Ethylene-dependent and independent regulation of ripening pathways in melon fruit
No full textCantaloupe melons have a typical climacteric behaviour with ethylene playing a major role in the regulation of the ripening process and affecting the ripening rate. Crossing of Cantaloupe Charentais melon with a non-climacteric melon indicated that the climacteric character is genetically dominant and conferred by two duplicated loci only. However, other experiments made by crossing two non-climacteric melons have generated climacteric fruit, indicating that different and complex genetic regulation exists for the climacteric character. Suppression of ethylene production by antisense ACC oxidase RNA in Charentais melon has shown that, while many ripening pathways were regulated by ethylene (synthesis of aroma volatiles, respiratory climacteric and degreening of the rind), some were ethylene-independent (initiation of climacteric, sugar accumulation, loss of acidity and coloration of the pulp). Softening of the flesh comprised both ethylene-dependent and independent components that were correlated with differential regulation of cell wall degrading genes. These results indicate that climacteric (ethylene-dependent) and non-climacteric (ethylene-independent) regulation coexist during climacteric fruit ripening. In addition, ethylenesuppressed melons allowed demonstrating that the various ethylene-dependent events exhibited differential sensitivity to ethylene and that ethylene was promoting sensitivity to chilling injury. Throughout this review, the data generated with melon are compared with those obtained with tomato and other fruit
The effects of different combinations and varying concentrations of growth regulators on the regeneration of selected Turkish cultivars of melon
No full textCucurbits are an economically important family of plants. The majority of the vegetable production in Turkey, for example, derives from the species beloning to the family Cucurbitaceae. Despite the importance of cucurbits among vegetable crops worldwide, the development of genomic tools in these species has been rather limited. Although melon production has been improved by conventional plant breeding methods, output is still insufficient. One useful technique in overcoming such problems in melon is functional genomics’ studies, and the other one is abiotic stress resistance and improved fruit quality has been gene transfer via Agrobacterium tumefaciens mediated transformation. The availability of an optimized plant regeneration system is crucial for genetic transformation techniques as well as obtaining an entire plant. Although Hasanbey and Cinikiz in Turkey, for example, are important commercial melon cultivars used in the breeding programs and molecular biology of fruit ripening and genetic mapping of melons, there is no study to date on the regeneration of these cultivars
A reliable system for the transformation of cantaloupe charentais melon (Cucumis melo L. var. cantalupensis) leading to a majority of diploid regenerants
No full textAn efficient system of transformation leading to a majority of transformed diploid plants from leaf explants of Cucumis melo L. var. Cantalupensis (cv. Védrantais) was developed. Several regeneration protocols using cotyledon or leaf explants were analysed with particular emphasis on the regeneration efficiency and the ploidy level of the regenerated melon plants. The use of leaf explants excised from 10 day-old seedlings, cultured in Murashige and Skoog's medium supplemented with 1 mM 6-benzylaminopurine (BAP) and 1 mM 6-(g,g-dimethylallylamino)-purine (2iP), resulted in a high regeneration frequency (73%). In these conditions, more than 84% of the regenerated plants were found to be diploid. Addition of an Agrobacterium-mediated transformation step did not significantly change the percentage (81.8%) of diploid plants regenerated. This protocol was successfully used to produce diploid transgenic melon plants expressing the antisense ACC oxidase gene, encoding ACC oxidase which catalyses the last step of ethylene biosynthesis. Ethylene production and ACC oxidase activity of the leaf explants from transgenic plants was reduced by more than 80% as compared to the control untransformed tissues. This transformation/regeneration method could be routinely used for the introduction of other genes of interest in melon
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Diversity in expression of phosphorus (P) responsive genes in Cucumis Melo L.
No full textPhosphorus (P) is a major limiting nutrient for plant growth in many soils. Studies in model species have identified genes involved in plant adaptations to low soil P availability. However, little information is available on the genetic bases of these adaptations in vegetable crops. In this respect, sequence data for melon now makes it possible to identify melon orthologues of candidate P responsive genes, and the expression of these genes can be used to explain the diversity in the root system adaptation to low P availability, recently observed in this species
Two highly divergent alcohol dehydrogenases of melon exhibit fruit ripening-specific expression and distinct biochemical characteristics
No full textAlcohol dehydrogenases (ADH) participate in the biosynthetic pathway of aroma volatiles in fruit by interconverting aldehydes to alcohols and providing substrates for the formation of esters. Two highly divergent ADH genes (15% identity at the amino acid level) of Cantaloupe Charentais melon (Cucumis melo var. Cantalupensis) have been isolated. Cm-ADH1 belongs to the medium-chain zinc-binding type of ADHs and is highly similar to all ADH genes expressed in fruit isolated so far. Cm-ADH2 belongs to the short-chain type of ADHs. The two encoded proteins are enzymatically active upon expression in yeast. Cm-ADH1 has strong preference for NAPDH as a co-factor, whereas Cm-ADH2 preferentially uses NADH. Both Cm-ADH proteins are much more active as reductases with Kms 10–20 times lower for the conversion of aldehydes to alcohols than for the dehydrogenation of alcohols to aldehydes. They both show strong preference for aliphatic aldehydes but Cm-ADH1 is capable of reducing branched aldehydes such as 3-methylbutyraldehyde, whereas Cm-ADH2 cannot. Both Cm-ADH genes are expressed specifically in fruit and up-regulated during ripening. Gene expression as well as total ADH activity are strongly inhibited in antisense ACC oxidase melons and in melon fruit treated with the ethylene antagonist 1-methylcyclopropene (1-MCP), indicating a positive regulation by ethylene. These data suggest that each of the Cm-ADH protein plays a specific role in the regulation of aroma biosynthesis in melon fruit
Identification of Cucumisin (Cuc m 1), a subtilisin‐like endopeptidase, as the major allergen of melon fruit
No full textBackground: Allergenic components in melon extracts have not been described in spite of the fact that melon (Cucumis melo) is a frequent allergy-eliciting fruit. The aim of this study was to evaluate allergenic components in melon extract and to report the identification of cucumisin as a major melon allergen.
Materials and methods: Sera from 35 patients allergic to melon were selected on the basis of clinical symptoms, skin prick tests and oral challenge test. Allergenic components were detected by sodium dodecyl sulphate polyacrylamide gel electrophoresis and immunoblotting. Molecular characterization of IgE-binding bands was performed by N-terminal amino acid sequencing.
Results: More than 10 IgE-binding bands, between 10 and 80 kDa, were identified in melon extract. Out of them, four IgE-binding bands were major allergens: 14 kDa, 36 kDa, 54 kDa and 67 kDa. These major allergens, except 14 kDa band, showed the same N-terminal sequence: T-T-R-S-W-D-F-L. Research conducted with protein databases identified this N-terminal sequence as cucumisin, an alkaline serine protease, which shares structural homology with microbial subtilisin. The molecular mass of the identified bands corresponds with different molecular forms of cucumisin produced during the processing or degradation of the enzyme: 67 kDa native cucumisin, 54 kDa mature cucumisin and 36 kDa NH2-terminal cucumisin fragment.
Conclusion: Cucumisin (Cuc m 1) and several N-terminal cucumisin fragments are the major allergens of melon. The ubiquitous distribution of this protein family (cucumisin-like proteases) in many plant species and its high structural similarity suggest its potential role as a new panallergen in plant foods.Depto. de Bioquímica y Biología MolecularFac. de Ciencias QuímicasTRUEpu
Supply Chain Management of Fresh Produce: Melons in Western China
No full textThe western part of China has a long history and reputation of growing a variety of quality melons largely due to its semi arid agronomic environment. In the past decade, the industry suffered from the interrelated issues of unreliable quality and intense price competition. Even though both the government and supply chain stakeholders are aware of the problems, there is a need to look at the issues from a supply chain perspective and new ways of managing the melon supply chains are to be explored. This paper analysed the melon supply chain in western China in the areas of logistical efficiency and supply chain relationship management. The results of the analysis offer insights for improving the efficiency of the melon supply chain and the competitiveness the industry. The results also shed lights for other supply chains of fresh produce in developing countries in general.melon, China, supply chain, value chain, Crop Production/Industries, Industrial Organization, O13, O5, Q13,
Improving nitrogen use efficiency in melon by grafting
No full textIdentification of rootstocks capable of improving the nitrogen use efficiency
(NUE) of the scion could reduce N fertilization and nitrate leaching; however, screening
different graft combinations under field conditions can be costly and time-consuming. This
study evaluated a rapid and economicalmethodology for screening of melon rootstocks for
NUE. Two experiments were designed. In the first, melon plants (Cucumis melo L. cv.
Proteo) either ungrafted or grafted onto four commercial rootstocks: ‘Dinero’ and ‘Jador’
(Cucumis melo L.), ‘P360’, and ‘PS1313’ (Cucurbita maxima Duchesne · Cucurbita
moschata Duchesne) grown in hydroponics were compared in terms of shoot dry biomass,
leaf area, root-to-shoot ratio, SPAD index, shoot N uptake, and nitrate reductase (NR)
activity at the early developmental stage in response to nitrate availability (0.5, 2.5, 5, 10, or
15mM of NO3
–). The second experiment was aimed to confirmwhether the use of a selected
rootstock with high NUE (‘P360’) could improve crop performance and NUE of grafted
melon plants under field conditions. In the first experiment, carried out under greenhouse
conditions, melon plants grafted onto ‘Dinero’, ‘Jador’, and ‘P360’ rootstocks needed 5.7,
5.2, and 6.1 mM of NO3
–, respectively, to reach half-maximum shoot dry weight, whereas
plants grafted onto ‘PS1313’ rootstock and the control treatment (ungrafted plants)
needed 9.1 and 13.1 mM of NO3
–, respectively. Total leaf area, SPAD index, and shoot N
uptake increased linearly and quadratically in response to an increase of the N
concentration in the nutrient solution. At 2.5 mM of NO3
–, melon plants grafted onto both
C. melo and Cucurbita maxima · Cucurbita moschata rootstocks had the highest NR
activity, whereas no significant difference was observed at 10 mM of NO3
–. In the second
experiment, carried out under open field conditions, increasing the N fertilization rates
from 0 to 120 kgha–1 increased the total and marketable yields of melon plants, whereas
the NUE decreased. When averaged over N levels, the marketable yield, NUE, and N
uptake efficiency were higher by 9%, 11.8%, and 16.3%, respectively, in ‘Proteo’ grafted
onto ‘P360’ than in ungrafted ‘Proteo’ plants
Fungi associated with root rot and collapse of melon in Italy
No full textMelon represents the most widespread cucurbit in Italy. In recent years melon has been subjected
to significant losses in yield and quality due to an increasing number of soil-borne fungal diseases.
The collapse of melon, caused by a complex of fungal pathogens, including
Monosporascus
cannonballus
,
Acremonium cucurbitacearum
,
Plectosporium tabacinum
and
Rhizopycnis vagum
,
represents one of most destructive diseases worldwide. The purpose of this study was to determine
the occurrence of collapse throughout melon-producing areas in Italy in recent years, to verify the
identification of isolates collected, and to test their pathogenicity on melon and other cucurbits.
Several fungi were isolated from symptomatic roots of melons in the Italian production areas.
The identification was supported by PCR with a species-specific primer and DNA sequence data.
RFLP and sequence analyses showed the existence of a substantial homogeneity among Italian
M. cannonballus
isolates. Given the self-incompatibility of these isolates it is impossible to
ascertain vegetative compatibility groups (VGC) and consequently genetic relatedness cannot
be studied. The frequency of isolation of fungal species varied with geographic locations,
M. cannonballus
being present mainly in Central Italy, while
A. cucurbitacearum
and
P. tabacinum
were most common in Apulia. In pathogenicity tests under greenhouse conditions
M. cannonballus
,
A. cucurbitacearum
and
P. tabacinum
caused collapse symptoms and root rots, whereas
R. vagum
was found to be a weak pathogen
Fungi associated with root rot and collapse of melon in Italy
No full textMelon represents the most widespread cucurbit in Italy. In recent years melon has been subjected to significant losses in yield and quality due to an increasing number of soil-borne fungal diseases. The collapse of melon, caused by a complex of fungal pathogens, including Monosporascus cannonballus, Acremonium cucurbitacearum, Plectosporium tabacinum and Rhizopycnis vagum, represents one of most destructive diseases worldwide. The purpose of this study was to determine the occurrence of collapse throughout melon-producing areas in Italy in recent years, to verify the identification of isolates collected, and to test their pathogenicity on melon and other cucurbits. Several fungi were isolated from symptomatic roots of melons in the Italian production areas. The identification was supported by PCR with a species-specific primer and DNA sequence data. RFLP and sequence analyses showed the existence of a substantial homogeneity among Italian M. cannonballus isolates. Given the self-incompatibility of these isolates it is impossible to ascertain vegetative compatibility groups (VGC) and consequently genetic relatedness cannot be studied. The frequency of isolation of fungal species varied with geographic locations, M. cannonballus being present mainly in Central Italy, while A. cucurbitacearum and P. tabacinum were most common in Apulia. In pathogenicity tests under greenhouse conditions M. cannonballus, A. cucurbitacearum and P. tabacinum caused collapse symptoms and root rots, whereas R. vagum was found to be a weak pathogen
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