Genetic Diversity and Antioxidant Activities in Cucumis sativus Genetic Resources

다국어 초록 (Multilingual Abstract)

Fruits of eighty-six cucumber accession were collected for analysis of total polyphenol content, total flavonoid content and antioxidant activity. The total polyphenol content ranged from 0.52 to 1.96 mg GAE/g of dry fruit at the mean of 1.25. In addition, the total flavonoid content ranged from 1.22 to 3.72 mg CE/g of dry fruit at the mean of 2.06. The IC50 for DPPH scavenging activity ranging from 360.0 to 1036 µg/ml in methanol extract at the mean of 589.36

다국어 초록 (Multilingual Abstract)

There were 10 quantitative traits and 25 qualitative traits evaluated. At P=0.05, there were significant differences between cucumber germplasm collected from different continents for length of first 15 internodes, stem diameter, leaf lobe length, fruit peduncle length, and fruit weight. High significant coefficient variances were seen in the following traits: number of primary stem per plants, fruit peduncle length, fruit length, fruit weight, ratio of fruit length and fruit diameter. At P=0.01, length of first 15 internodes was positively correlated to leaf length (r=0.392), peduncle length (r=0.322), fruit length (r=0.345) and fruit weight (r=0.333), while the number of primary stems per plants was negatively associated to fruit length (r=-0.299). Leaf blade length had positive correlation to leaf lobe length (r=0.662), fruit length (r=0.302) and fruit weight (r=0.228), whereas placental diameter had negative correlation to leaf length (r=-0.245). Peduncle length was positively correlated to fruit length (r=0.280) and fruit weight (r=0.245). Fruit length was positively correlated to fruit weight (r=0.543), whereas it had negatively correlated to fruit diameter (r=-0.267) and placental diameter (r=-0.518). Fruit diameter had high correlation to placental diameter (r=0.734) and fruit weight (r=0.571). The principal components of 10 quantitative traits were evaluated. The first principal component (PC1) represented 47% of the variability. The second principal component (PC2) represented 27% of the variation. The Asian cucumber germplasm evenly distributed in the figure, while Europe and America cucumber germplasms were more located in the leaf hand side of the figure, indicating that they shared common characteristics. The Shannon-Weaver’s diversity index of the cucumber germplasm range from 0.05 to 1.50 at the mean of 0.81. The fruit traits had higher diversity index at the mean of 0.915, whereas the diversity index of leaf and flowers traits were 0.604 and 0.445 by the mean values, respectively.

다국어 초록 (Multilingual Abstract)

Cucumber (Cucumis sativus) is one of important fruit vegetable, which ranked third in term of total production area in 2014, after tomato and cabbage. Cucumber can be used for fresh eating, processing and cooking. In cosmetics, it has an excellent potential for cooling, healing and soothing to irritated skin, whether caused by sun, or the effects of a cutaneous eruption. Cucumber is one of very low calorie veggies, contain no saturated fats or cholesterol, a good source of dietary fiber, a very good source of K, and moderate anti-oxidants, which provide us with valuable antioxidant, anti-inflammatory, and anti-cancer benefits.

다국어 초록 (Multilingual Abstract)

Cucumber has a narrow genetic base, with genetic variability of only 3-8%, which are more susceptible to pests, diseases and environmental changes. In order to overcome the problems associated to limited genetic diversity, it is necessary to construct characterized gene banks. One-hundred twenty-three cucumber accessions collected from 28 countries of four different continents (Asia, Africa, America, and Europe) were experimented to evaluate the diversity in morphology, biology, EST-SSR markers and antioxidant activity; and to find out valuable traits from these cucumber accessions in order to use in breeding programs as well as in conservation, exploitation and improvement of cucumber genetic resources.

다국어 초록 (Multilingual Abstract)

The cucumber germplams were more diversity in term of morphology than molecular markers. For the fruit qualitative traits, the similarity coefficient of the cucumber germplasm varied from 0.45 to 1.00 with the mean similarity coefficient of 0.73. At the similarity coefficient of 0.674, the germplasm was divided into 10 groups. Group 1, 2 and 3 shared common characteristics of no fruit dot, while other groups presented dot in fruit at different distribution and density. Group 6 showed white ground color at both market stage and physiological ripeness stage. Meanwhile group 1, 5, 6 showed angular fruit shape in transverse section, round fruit shape in transverse section was seen in group 3, 4 and round to angular in group 10. Hair and pickles were both seen in groups 4 and 5, while group 3, 6, 8, 9, 10 showed pickles vestitures only. Genetic diversity of the cucumber germplasm were also evaluated by 28 pairs of EST-SSR markers. There were 9 pairs of primers showed polymporphism, occupied for 32.14%. The polymorphic primers detected from 2 to 4 alleles. Polymorphism information content (PIC) values ranged from 0.16 to 0.64 at a mean of 0.34, while the expected heterozygosity values varied from 0.18 to 0.64 with a mean of 0.43. For EST-SST markers, the mean similarity coefficient was 0.68 (range, 0.64-0.89). At the similarity coefficient of 0.832, the germplasm can be divided into 10 groups. Group 10 accounted for 90.35% of the germplasm. Group 1, 2, 3, 4, 5, 6, 8, 9 collected from Asia; Group 7 included accessions collected from Europe; Group 10 include 60 accessions from Asia, 17 accessions from Europe, 1 accession from Asia and 5 accessions from America.

목차 (Table of Contents)

• (ABSTRACT) i
• TABLE OF CONTENTS iv
• LIST OF TABLES vii
• LIST OF FIGURES ix
• INTRODUCTION 1
• LITERATURE REVIEW 3
• 1. Origin, distribution and taxonomy of cucumber 3
• 1.1. Origin and distribution of cucumber 3
• 1.2. Taxonomy of cucumber 5
• 2. Cucumber genetic characteristics and resources. 7
• 2.1. Cucumber genetic characteristics 7
• 2.2. Cucumber genetic resources 12
• 2.3. Genetic diversity on cucumber 14
• 3. Antioxidant activity in cucumber 18
• 3.1. Total polyphenol content in cucumber 19
• 3.2. Total flavonoid content 19
• 3.3. DPPH free radical scavenging 20
• REFERENCES 22
• CHAPTER 1 30
• Abstract 31
• I. Introduction 33
• II. Materials and Methods 34
• 2.1. Materials 34
• 2.2. Statistical analysis 38
• III. Results and Discussion 39
• 3.1. Descriptive statistics for quantitative growth traits of the cucumber germplasm 39
• 3.3. Correlation coefficient of quantitative traits evaluated in the cucumber germplasm 47
• 3.4. Evaluation of qualitative traits for the cucumber germplasm 48
• 3.5. Cluster analysis of qualitative fruit traits of the cucumber germplasm. 52
• 3.6. Principal component analysis (PCA) for 10 quantitative fruit traits of the cucumber germplasm 55
• 3.7. Shannon-Weavers diversity index for the cucumber germplasm 55
• IV. References 57
• CHAPTER 2 61
• Abstract 62
• I. Introduction 63
• II. Materials and Method 65
• 2.1. Plant materials 65
• 2.2. EST-SSR primers 65
• 2.3. DNA extraction 65
• 2.4. EST- SSR amplification 66
• 2.5. Statistical analysis 67
• III. Results and Discussion 68
• 3.1. EST-SSR polymorphism in cucumber germplasm 68
• 3.2. Cluster analysis 69
• IV. References 73
• CHAPTER 3 75
• Abstract 76
• I. Introduction 77
• II. Materials and Methods 79
• 2.1. Plant materials 79
• 2.2. Apparatus 79
• 2.3. Chemical Reagents 79
• 2.4. Sample extraction 80
• 2.5. Determination of antioxidant compounds 80
• 2.5.1. Total polyphenol contents 80
• 2.5.2. Total flavonoid contents 81
• 2.5.3. DPPH free radical scavenging activity 82
• 2.6. Statistical analysis 83
• III. Results and discussion 84
• 3.1. Descriptive statistic of total polyphenol, flavonoid and antioxidant activity of Cucumis sativus fruit extracts 84
• 3.2. Correlation of total polyphenol, flavonoid contents and antioxidant activity of cucumber fruit extracts 86
• 3.3. Principal Component Analysis (PCA) for Total polyphenol, Total flavonoid, and IC50 of the cucumber germplams 87
• IV. References 88