Marios C. Kyriacou

Evolution of watermelon fruit physicochemical and phytochemical composition during ripening as affected by grafting

Flesh reflectance colorimetry, mechanical texture analysis, pH, titratable acidity (TA), and soluble solid (SS), soluble carbohydrate, lycopene and citrulline content of watermelon fruit were assessed throughout ripening (30-50 days post-anthesis; dpa) in grafted and self-rooted plants. Grafting increased firmness, TA, and lycopene content though it delayed its peak. Lycopene content was mostly ripening-dependant, highly correlated and synchronous with changes in pulp chroma (C) and colour a. The sweetness was affected only by ripening. However, total sugars and SS peaked later in fruit of grafted plants than in non-grafted ones, and significant interaction of ripening with grafting was observed. Citrulline content increased with ripening in fruit of grafted plants, reaching a peak at 45 dpa; whereas in non-grafted ones it was unchanged between 30 and 45 dpa and declined at 50 dpa. As ripening overall was retarded by grafting, fruit quality of grafted watermelon may benefit from belated harvest.

Configuration of watermelon fruit quality in response to rootstock-mediated harvest maturity and postharvest storage.

BACKGROUND The configuration of watermelon fruit quality was analysed in a multi-factorial approach accounting for the effects of grafting, harvest maturity and postharvest storage. Diploid, seeded, hybrid cv. Pegasus, cultivated as scion on interspecific hybrid squash rootstock TZ148 and as non-grafted control, was stored at 25 °C following sequential harvests from the onset of ripening to over-maturity. RESULTS Delayed rootstock-mediated climax in pulp lycopene and chroma was observed, while both were heightened by postharvest storage when harvest preceded full maturity. Pulp firmness was increased by 46.5% on TZ148, while postharvest decrease in firmness was non-significant. Non-grafted fruits attained their peak in pulp carbohydrate content earlier during ripening. Monosaccharide content declined and sucrose content increased both preharvest and postharvest; overall sugar content declined by 4.3% during storage. Pulp acidity decreased steadily with ripening but was moderately increased by grafting. Citrulline content increased by 12.5% on TZ148; moreover, it climaxed with ripening and declined with storage only in grafted fruit. CONCLUSION Grafting enhances pulp texture and bioactive composition. Potential suppression of sugar content as a result of grafting is minimized at full commercial maturity. Brief postharvest ambient storage enhances pulp lycopene and chroma, especially in early-picked fruit, notwithstanding the depletion of monosaccharides and citrulline and a limited deterioration of texture.

Vegetable Grafting: The Implications of a Growing Agronomic Imperative for Vegetable Fruit Quality and Nutritive Value

Grafting has become an imperative for intensive vegetable production since chlorofluorocarbon-based soil fumigants were banned from use on grounds of environmental protection. Compelled by this development, research into rootstock–scion interaction has broadened the potential applications of grafting in the vegetable industry beyond aspects of soil phytopathology. Grafting has been increasingly tapped for cultivation under adverse environs posing abiotic and biotic stresses to vegetable crops, thus enabling expansion of commercial production onto otherwise under-exploited land. Vigorous rootstocks have been employed not only in the open field but also under protected cultivation where increase in productivity improves distribution of infrastructural and energy costs. Applications of grafting have expanded mainly in two families: the Cucurbitaceae and the Solanaceae, both of which comprise major vegetable crops. As the main drives behind the expansion of vegetable grafting have been the resistance to soilborne pathogens, tolerance to abiotic stresses and increase in yields, rootstock selection and breeding have accordingly conformed to the prevailing demand for improving productivity, arguably at the expense of fruit quality. It is, however, compelling to assess the qualitative implications of this growing agronomic practice for human nutrition. Problems of impaired vegetable fruit quality have not infrequently been associated with the practice of grafting. Accordingly, the aim of the current review is to reassess how the practice of grafting and the prevalence of particular types of commercial rootstocks influence vegetable fruit quality and, partly, storability. Physical, sensorial and bioactive aspects of quality are examined with respect to grafting for watermelon, melon, cucumber, tomato, eggplant, and pepper. The physiological mechanisms at play which mediate rootstock effects on scion performance are discussed in interpreting the implications of grafting for the configuration of vegetable fruit physicochemical quality and nutritive value.

Microgreens as a Component of Space Life Support Systems: A Cornucopia of Functional Food

The future of space missions and extended human presence in space requires the ability to provide proper dietary intake for space travelers with minimal resupply from the Earth, as food and food packaging currently represent a significant burden on space mission consumables (Perchonok et al., 2012). This is critical for sustaining an optimal nutritional status for space travelers and for mitigating stress effects from long-duration space travel, including weight loss, hematological changes, and space radiation-induced oxidative cytotoxic stress, protein oxidation, increased muscle proteolysis, impairment of eye health and changes in the central nervous system (Kennedy et al., 2007; Vergari et al., 2010; Cohu et al., 2014). Such effects are further linked to emotional volatility, psychological stress, and depression among the crew (Rabin et al., 2005). Prevention of deleterious phenomena that accelerate tissue lethality must include targeted intake of whole food-based antioxidants rather than supplements (Wan et al., 2006). These comprise fresh plant sources produced aboard during mission, thereby providing emotional along with nutritional support to space travelers. For instance, the consumption of carotenoids through whole-food-based diet is a recommendable protective measure since the human body is unable to produce any of the major photoprotective carotenoids considered essential for human vision: β-carotene as precursor of retinal constituent vitamin A, and zeaxanthin and lutein for protecting the eyes by absorbing excess light intensity (Cohu et al., 2014). Production of bioactive and particularly carotenoid-rich vegetables as part of Space Life Support Systems (SSLSs) remains a critical goal for future space missions (Perchonok et al., 2012). Awareness of the importance of fresh functional food in physically and mentally fortifying crews during missions has been growing among space mission participants (Vergari et al., 2010). It is therefore critical to incorporate in SLSSs plant-based fresh functional food production to support human presence during long-distance space travel or extra-planetary habitation.

Biochemical and histological contributions to textural changes in watermelon fruit modulated by grafting

Increased watermelon fruit flesh firmness is systematically incurred with grafting on Cucurbita hybrid rootstocks (heterografting). Possible differences in mesocarp cell wall constitution and histology between heterografted, homeografted (self-grafted) and non-grafted watermelon were examined, as well as their contributions to fruit texture. Firmness correlated positively (r=0.78, p<0.001) with cell density (cellsmm-2) which was higher in heterografts (5.83) than homeografts (4.64) and non-grafted controls (4.69). Mean cell size was smallest in heterografts and correlated negatively (r=-0.75, p<0.001) with firmness. Cell wall material, particularly the water-insoluble pectin fractions associated with firmness, were highest in heterografts. No associations with firmness were found for cell wall neutral sugars and membrane permeability. Higher parenchymatic cell density with higher content of alcohol insoluble residue and more abundant water-insoluble pectin fractions underscore enhanced firmness in heterografts. Possible implication of osmolytes in rootstock-mediated cell pressure regulation warrants further investigation.

Characterization and Identification of Indigenous Olive Germplasm from Cyprus Using Morphological and Simple Sequence Repeat Markers

Implementation of the recently developed Cyprus National Register of Commercial Varieties mandates proper cataloguing of the material conserved in the ex situ Olive Collection at the Agricultural Research Institute of Cyprus. A total of 125 trees belonging to 32 accessions were analyzed using 11 morphological endocarp traits and 14 microsatellite [simple sequence repeat (SSR)] markers. The SSR variability allowed segregation of 16 genotypes among accessions, which were clustered into three main groups based on genetic similarity. Similarity indexes among groups ranged from 0.63 to 0.65 and within groups were ‡0.9. Lower morphological variability was detected among accessions, which conformed to three morphological profiles; moreover, the three morphological profiles corresponded to the three groups of genetic similarity obtained by SSRmarkers. The identification, based on the unique combination of SSR genotypes and endocarp morphologies, revealed the presence of three cultivars and 15 molecular variants that presented limited molecular differences but morphological profiles identical to their catalogued cultivars. Two cultivars, ‘Ladoelia’ and ‘Kato Drys’, demonstrated molecular variation. The current study underpins the efficient management of olive germplasm collections based on combined molecular and phenotypic characterization of their accessions. The complete cataloguing of olive germplasm ensures the correct distribution of identified and authenticated material across national or international institutions. The olive (Olea europaea L.) is among the most ancient crops of the Mediterranean basin (Zohary and Spiegel-Roy, 1975). In Cyprus, as in the entire eastern Mediterranean region, olive trees coexisted with humans in almost all Neolithic settlements (6000–3000 BCE); however, the initiation of olive culture dates to the second millennium BCE (Hadjisavvas, 1992). The olive crop is characterized by the existence of several clonally propagated traditional cultivars, which emerged through the empirical and local selection of exceptional trees (Trujillo et al., 2014). Subsequently, the spread of olive culture westwards across the Mediterranean basin by successive centers of diffusion led to complex genetic relations among cultivars (Besnard et al., 2013; Rallo, 2005; Trujillo et al., 2014). At present, traditional olive groves in Cyprus mainly are established with very old varieties, which yet remain unidentified due to the scarcity of systematic surveys and characterization studies on local olive germplasm. The traditional system of olive culture coexists with modern olive groves established with reputable foreign varieties introduced on the island since the late 1970s. Marked examples of such varieties, regarded as select oil varieties, include the ‘Koroneiki’, ‘Picual’, and ‘Moraiolo’, introduced from Greece, Spain, and Italy, respectively. Among table olive varieties most common are ‘Kalamon’ and ‘Amfissis’ from Greece and ‘Manzanilla de Sevilla’ from Spain. The lack of systematic information on local olive germplasm curbs the dynamic exploitation of the local ancient genetic material and facilitates the preferential use of profusely characterized foreign varieties. Gene banks ensure the long-term ex situ conservation of valuable genetic resources and command a vital role in the identification process of olive varieties. Their activity also contributes significantly to the control of genetic erosion of local olive germplasm, which in recent years poses a heightened risk as a result of the intensification of olive culture. The principle systematic survey conducted on indigenous olive germplasm from Cyprus focused solely on the clonal selection of the cv. Ladoelia, considered the main local variety (Gregoriou, 1996, 1999). The material collected in this study was conserved in the Olive Collection of the Agricultural Research Institute of Cyprus (OCARICY). This collection was partially characterized using random amplified polymorphic DNA markers (Banilas et al., 2003) and broad agronomic characters such as trunk cross-sectional area, yield per tree, fruit weight, fruit and endocarp length and diameter, fruit flesh percentage, and oil content (Gregoriou, 1996, 1999). The results obtained in these studies revealed high random amplified polymorphic DNA polymorphism as well as agronomic differences, identified mainly in respect to fruit weight and oil content. On the basis of the guidelines set out by the European Union on varietal olive certification, Cyprus has launched the development of the National Register of Commercial Varieties. The implementation of the Register requires a systematic characterization study for the material of OCARICY as well as the application of more current methodological protocols for varietal identification. In this regard, a protocol recently has been established based on the integrated use of morphological and molecular markers (microsatellites) to facilitate the identification of the varieties present in olive gene banks. This protocol has allowed identification of the World Olive Germplasm Bank of Cordoba (WOGBC) and established a broad base of molecular data that can be exploited in crossing data between diverse olive gene banks (Trujillo et al., 2014). Of several systems of morphological characterization applied on olive, the most optimal is the systematic use of pomological patterns, which include a large number of traits related to tree, leaf, fruit, and endocarp (Barranco et al., 2000, 2005). This protocol was adopted and referenced by the International Union for the Protection of New Varieties of Plants in 2011. Traits related to the endocarp stand out for their major discriminative capacity, limited fluctuation, and ease of conservation (Barranco et al., 2005; Trujillo et al., 2006). For these reasons, the description of the endocarp frequently has been used to catalogue olive cultivars (Barranco et al., 2000, 2005; Fendri et al., 2010; D’Imperio et al., 2011) and large collections of olive germplasm (Trujillo et al., 2014). The polymerase chain reaction (PCR)SSR technique has been used widely in olive varietal characterization, as it consists of a relatively simple methodology that permits an easy interpretation of results (Fendri et al., 2010; Rafalski and Tingey, 1993). Actually, the microsatellite markers (SSRs) are considered as leading markers for conducting varietal characterization and identification studies on olive (Anestiadou et al., 2017; Baldoni et al., 2009; Carriero et al., 2002; Received for publication 10 May 2018. Accepted for publication 23 July 2018. This research was held during the sabbatical stay of Mrs. Maria Emmanouilidou in Spain as a fellow of International Olive Council and in the context of her research affiliation with the Agricultural Research Institute of Cyprus. First author. Corresponding authors. E-mail:maria.emmanouelidou@ ari.gov.cy or ag2trnai@uco.es. 1306 HORTSCIENCE VOL. 53(9) SEPTEMBER 2018 Cipriani et al., 2002; De La Rosa et al., 2002; Díez et al., 2011, 2012; D’Imperio et al., 2011; Fendri et al., 2010; Haouane et al., 2011; Rallo et al., 2000; Sefc et al., 2000; Trujillo et al., 2014). Their discriminative capacity, consistency, codominant nature, easy interpretation, and low cost account for their success. The denomination of olive cultivars is usually a process synchronous to their diffusion. Accordingly, it may be based on outstanding morphological traits, on intended use, on geographical origin of the propagated material, or on other characteristics (Rallo, 2005; Trujillo et al., 2014). As a result of the large number of varieties and the fact that their denomination is based mainly on generic criteria and local origin, the existence of synonymy (different names for the same cultivar) and homonymy (same name for different cultivars) is very common among and within olive-growing countries (Barranco et al., 2000). It is estimated that there are more than 2000 olive varieties worldwide (Lavee, 1994), whereas 1200 autochthonous varieties with more than 3000 denominations have been documented (Bartolini et al., 1998). The crossing of characterization data (morphological and molecular) for olive varieties under identification with authenticated varieties of reference collections is the final step in the process of cultivar identification, capable of demonstrating the existence of synonymies. In Cyprus, it is believed that the local olive genetic material belongs entirely to one variety, although the results from the studies previously performed on olive by Gregoriou (1996, 1999) and Banilas et al. (2003) revealed in some cases a greater than expected morphological and genetic variability in the material derived from clonal selection. The main objective of the present study has been the characterization and identification of the genetic material included in the OCARICY collection using up-to-date molecular and morphological protocols optimized for olive. The current study facilitates the efficient management of olive germplasm collections based on combined molecular and phenotypic characterization of their accessions and highlights the promotion of agronomically valuable germplasm. In respect to the Cyprus indigenous germplasm, the current study lays the foundation for further enrichment of the OCARICY ex situ collection with additional olive genetic material currently preserved in situ under the threat of genetic erosion (Anestiadou et al., 2017). Moreover, the present work contributes toward the advancement of characterization studies on indigenous olive genetic material, as well as toward the furthering of transnational relations between gene banks of similar scope. Materials and Methods Plant material. Samples of 32 accessions of cultivated olive (Olea europaea L.) from the ex situ OCARICY were analyzed (Table 1). The OCARICY material was previously collected in a systematic survey of clonal material of the variety Ladoelia p

Enhancing Quality of Fresh Vegetables Through Salinity Eustress and Biofortification Applications Facilitated by Soilless Cultivation

Closed soilless cultivation systems (SCS) support high productivity and optimized year-round production of standardized quality. Efficiency and precision in modulating nutrient solution composition, in addition to controlling temperature, light, and atmospheric composition, renders protected SCS instrumental for augmenting organoleptic and bioactive components of quality. Effective application of eustress (positive stress), such as moderate salinity or nutritional stress, can elicit tailored plant responses involving the activation of physiological and molecular mechanisms and the strategic accumulation of bioactive compounds necessary for adaptation to suboptimal environments. For instance, it has been demonstrated that the application of salinity eustress increases non-structural carbohydrates and health-promoting phytochemicals such as lycopene, β-carotene, vitamin C, and the overall phenolic content of tomato fruits. Salinity eustress can also reduce the concentration of anti-nutrient compounds such as nitrate due to antagonism between nitrate and chloride for the same anion channel. Furthermore, SCS can be instrumental for the biofortification of vegetables with micronutrients essential or beneficial to human health, such as iodine, iron, selenium, silicon, and zinc. Accurate control of microelement concentrations and constant exposure of roots to the fortified nutrient solution without soil interaction can maximize their uptake, translocation, and accumulation in the edible plant parts; however, biofortification remains highly dependent on microelement forms and concentrations present in the nutrient solution, the time of application and the accumulation capacity of the selected species. The present article provides an updated overview and future perspective on scientific advances in SCS aimed at enhancing the sensory and bioactive value of vegetables.

Functional quality in novel food sources: genotypic variation in the nutritive and phytochemical composition of thirteen microgreens species

Compositional variation was examined across 13 microgreens species/subspecies representing Brassicaceae, Chenopodiaceae, Lamiaceae, Malvaceae and Apiaceae, grown in controlled environment. Macro-mineral concentrations were determined by ion chromatography, chlorophyll and ascorbate concentrations, and hydrophilic/lipophilic antioxidant potentials by spectrophotometry, and major carotenoids by HPLC-DAD. Nitrate hyper-accumulators and wide genotypic differences in Na, K and S concentrations were identified. Antioxidant capacity was highest in brassicaceous microgreens and significant genotypic variation was demonstrated in chlorophyll and carotenoid concentrations. High phenolic content was confirmed in Lamiaceae microgreens, with significant varietal differences, and alternative phenolics-rich microgreens from the Apiaceae were identified. Twenty-eight phenolic compounds were variably detected and quantitated through Orbitrap LC-MS/MS with flavonol glycosides, flavones and flavone glycosides, and hydroxycinnamic acids representing 67.6, 24.8 and 7.6% of the mean total phenolic content across species, respectively. The obtained information is critical for selecting new species/varieties of microgreens that may satisfy demand for both taste and health.