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Bitter melon or bitter gourd (Momordica charantia L.) of the Cucurbitaceae family is valuable plant for their nutritive and medicinal properties. In this study, molecular, morphological and some biochemical properties of 12 bitter gourd genotypes from different parts of Turkey were determined. Considerable morphological variation among the genotypes was observed for fruit properties such as fruit length (9.33 to 14.33 cm) and time for maturity (late June to late September). For molecular caharacterization fifteen ISSR primers were produced, on average, 113 bands in the accessions were examined and 59 (52%) of them were detected as to be polymorphic, which resulted in a Jaccard’s similarity range from 0.80 to 0.98. According to biocehmical analyses, palmitic, stearic, oleic, linoleic and eleostearic acids were detected as the major fatty acids in the studied bitter gourd seeds. Eleostearic acid had the highest proportion among the fatty acids (42.66-61.99%). The bitter gourd genotypes showed different fractions of vitamin E. G1 contained alpha, gamma and delta tocopherol, while G2, G18, G19 and G24 contained only gamma and delta tocopherols. Beta carotene was also present in all genotypes and the ratio was between 56.57 and 116.75 mg/kg. In addition, the genotypes were evaluated for their mineral composition and phosphorus was the major mineral for the genotypes and only sodium was not observed in all genotypes among the studied minerals. This study provided useful information for nutritional perspective of bitter melon and also breeding studies.

Plant peroxidases are a family of stress-related proteins possessing highly conserved domains, which previously allowed to develop peroxidase gene polymorphism (POGP) markers. Diversity, population structure and linkage disequilibrium (LD) based on POGP markers among 256 watermelons [Citrullus lanatus (Thunb.) Matsum. and Nakai] genotypes along with two outgroups were evaluated by using 14 peroxidase gene-specific primers and several statistical procedures. Ratio of polymorphism of POGP markers was high (98%). The unweighted pair-group method arithmetic average (UPGMA), neighbor-joining (NJ) and principle component analysis (PCA) indicated low level of genetic diversity and few geography-based clustering among the watermelon accessions. Substructuring Bayesian analysis revealed that there were three subpopulations among 258 watermelons. Analysis of molecular variance (AMOVA) indicated that 54% of the molecular variation resided within subpopulations, 39% within geographic origins and 7% among subpopulations. Linkage disequilibrium (LD) analysis indicated presence of LD among POGP loci. Overall, this study concluded that LD existed despite that it was variable among subpopulations, association studies were possible among watermelons, and substructuring analysis was efficient in analyzing population structure among watermelons. This study also indicated that the POGP markers would be useful for clarifying genetic parameters such as population structure and relationships among watermelons. (C) 2014 Elsevier B.V. All rights reserved.

In this study, the effect of flooding on plant growth and photosynthetic activity of grafted watermelon were investigated. The watermelon [C itrullus lanatus (Thunb.) Matsum and Nakai] cv. ‘Crimson Tide’ was grafted onto Lagenaria siceraria SKP (Landrace). Grafted and ungrafted watermelon plants were flooded at the soil surface for 20 days. For every 5 days, three plants were sampled to determine plant fresh and dry weight, leaf number and main stem length. Leaf colour, single leaf CO 2 exchange rate (CER), stomatal conductance (SC) and transpiration rate (Ts) were determined at 3 days interval. Flooding caused chlorosis on both grafted and ungrafted plants but such effect was more pronounced on ungrafted watermelon plants. CER, SC and Ts began to decrease from the 4th day of the flooding in both grafted and ungrafted plants as compared with non-flooded controls. However, grafted plants showed higher tolerance to flooding and had two-folds more CER, SC and Ts. Plant growth rate was also significantly lower in flooded plants than when compared to unflooded controls. Ungrafted plants had lower dry weight than grafted plants under flooding conditions. At the end of the experiment, decrease in fresh weight of plants was about 180% in ungrafted and 50% in grafted watermelons. Dry weight also decreased about 230% in ungrafted and 80% in grafted watermelons. Similar results were found in leaf number and main stem length. Adventitious roots and aerenchyma formation were observed in grafted watermelon but not in ungrafted watermelon under flooding. Adventitious root formation began from 3rd or 4th day of flooding and adventitious roots grew towards the soil surface. Flooding tolerance of watermelon could be improved by grafting onto L. siceraria .