Diversity and genetic study of stevia populations in Malaysia /
This project was conducted to study the genetics in Stevia rebaudiana Bertoni cultivated under Malaysian condition. A total of 17 stevia accessions were assessed for morphological features, chemical compositions, genetic variabilities as well as genetic diversity. Qualitative and quantitative morph...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
Kuantan, Pahang :
Kulliyyah of Science, International Islamic University Malaysia,
2018
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| Subjects: | |
| Online Access: | Click here to view 1st 24 pages of the thesis. Members can view fulltext at the specified PCs in the library. |
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| Summary: | This project was conducted to study the genetics in Stevia rebaudiana Bertoni cultivated under Malaysian condition. A total of 17 stevia accessions were assessed for morphological features, chemical compositions, genetic variabilities as well as genetic diversity. Qualitative and quantitative morphological features were observed on leaf shape, leaf tip, leaf base, leaf margin, plant height, days to flowering, number of stems, number of leaves, leaves size and stem girth. Chemical analysis was focused on the concentration of stevioside and rebaudioside A. Genetic variabilities for both morphological features and chemical compositions were estimated based on heritability and genetic advance. Genetic diversity among the accessions was assessed through Inter Sequence Simple Repeats (ISSR) markers. All stevia accessions showed considerable variability with regards to qualitative and quantitative morphological features as well as in the chemical parameters. MS012 had the highest plant (36.6 cm), Langat was the latest accession to start flowering (49 days), Bertam had the most stems (13 stems), MS007 had the most leaves (272 leaves) and biggest leaves (14.2 cm2) and MS012 had the widest girth (2.2 cm). Bangi performed the best in terms of stevioside (20.36%), rebaudioside A (3.43%) and total stevioside and rebaudioside A (23.79%) while MNQ had the highest rebaudioside A to stevioside ratio (0.33). Overall, MS007, MS012 and Bangi are among promising accessions that can be utilised in stevia improvement programme based on the morpho-agronomic and chemical result. High heritability and high genetic advance as percentage of mean (GAM) was observed for all the morphological and chemical characters studied except plant height, leaves size, stevioside and rebaudioside A to stevioside ratio which exhibited high heritability but moderate genetic advance as percentage of mean (GAM). Therefore, these characters can be used in the selection process to effectively improve stevia in any breeding cycle. Genetic diversity study through ISSR analysis also revealed wide genetic variations among stevia used in this study. ISSR using 32 primers revealed high polymorphism (78%) an indicator for wide genetic variations among stevia accessions studied. Phylogenetic tree analysis also revealed that all stevia accessions were grouped under 3 major groups (I, II and III) with Group II consisted of only Souq Bukhori and group II comprised of Bertam which departed from the rest of the 15 stevia accessions under group I. The closely related accessions also showed similarities either morphologically or chemically. Findings from this study will contribute to future stevia breeding programmes by harnessing the genetic variability found in this study as a resource to further improve future stevia varieties in Malaysia. |
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| Physical Description: | xxii, 173 leaves : illustrations ; 30cm. |
| Bibliography: | Includes bibliographical references (leaves 145-171). |