Somatic embryogensesis and plant regeneration in selected Malaysian cocoa clone (Theobroma cacao L.)
Cocoa (Theobroma cacao L.) is one of the economically important tropical trees for many countries around the world including Malaysia. Cocoa is the main ingredient to produce chocolate. The objectives of this study were to develop a somatic embryogenesis protocol for local cocoa clones plantlets...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2016
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| Subjects: | |
| Online Access: | http://ir.unimas.my/id/eprint/25005/1/Norhashimah%20Abdul%20Razak%20ft.pdf |
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| Summary: | Cocoa (Theobroma cacao L.) is one of the economically important tropical trees for many
countries around the world including Malaysia. Cocoa is the main ingredient to produce
chocolate. The objectives of this study were to develop a somatic embryogenesis protocol
for local cocoa clones plantlets by using floral explant, to determine the selected local cocoa
clones most responsive towards development of somatic embryogenesis and to regenerate
cocoa plantlets from secondary embryos as well as to evaluate the acclimatization of cocoa
plantlets into ex vitro condition. Initially, 12 local clones were selected randomly from four
different classes of cocoa clones. Cocoa flowers were collected at Cocoa Research and
Development Centre, Kota Samarahan. Staminodes derived from unopened and immature
cocoa flowers and cultured on two different media (Penn State versus Nestlé) for primary
embryogenesis. Secondary embryogenesis was pursued by cultures the cotyledons from
previous primary embryos as the explant sources on different media to compare their
performance. During this stage, the experiment was conducted for 10 clones with exception
for MCB C5 and KKM 19 due to very low primary embryos produced. Somatic
embryogenesis production of cocoa cultures on different media gave various responses. For
primary embryogenesis, Nestlé medium significantly displayed better response with 11 out
of 12 clones able to develop primary embryos, while Penn State medium able to induce
primary embryos for 7 clones only. For secondary somatic embryogenesis, there was no
significant difference between both media. Both media were successfully developed
secondary embryos for all ten clones tested. There was significant difference in the primary
somatic embryogenesis among 12 clones studied. MCB C8 recorded the highest mean
percentage compared to other clones. However, two clones MCB C5 and KKM 19 recorded very low production of primary embryos. There was significantly difference in the secondary
embryogenesis among 10 clones tested. Out of 10 clones, PBC 130 displayed the highest
percentage production of secondary somatic embryos. However, all clones multiplied rapidly
during secondary embryogenesis. MCB C2 recorded low production in both primary and
secondary embryogenesis. No significant difference found between two different media for
maturation and conversion of secondary embryos into plantlets (Penn State versus Nestlé).
However, all five cocoa clones expressed varied response in the media tested. MCB C8 and
KKM 22 displayed among the highest rate of conversion embryos into plantlets. In
acclimatization study of cocoa somatic embryos-derived plantlets, PBC 130 showed better
adaptation with ex vitro conditions with the highest percentage of survived plantlets with
48.33% while PBC 230 displayed the lowest percentage of survived plantlets with 18.33%.
However, the rate of survived plantlets was considered low with below than 50%. Overall
findings indicated that different media used and cocoa clones mainly influenced the somatic
embryogenesis and regeneration of cocoa somatic embryo-derived plantlets. |
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