Somatic embryogensesis and plant regeneration in selected Malaysian cocoa clone (Theobroma cacao L.)

Norhashimah, Abdul Razak (2016) Somatic embryogensesis and plant regeneration in selected Malaysian cocoa clone (Theobroma cacao L.). Masters thesis, Universiti Malaysia Sarawak.

PDF (Please get the password by email to repository@unimas.my, or call ext: 3914/ 3942/ 3933) Norhashimah Abdul Razak ft.pdf Restricted to Registered users only Download (7MB)

Abstract

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.

Actions (For repository members only: login required)

View Item