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MUHAMAD RASYID ABDILAH

NIM

Judul Artikel

Abstrak (Bhs. Indonesia)

Penelitian ini bertujuan untuk mengkaji pengaruh sukrosa terhadap pertambahan berat basah kalus dahlia dan kadar inulin pada kalus dahlia. Metode penelitian ini terdiri dari dua tahapan. Penelitian 1 bertujuan untuk mendapatkan kalus dahlia dalam jumlah yang cukup untuk disubkultur pada media perlakuan sukrosa, serta untuk mencari kombinasi ZPT yang tepat pada media MS. Penelitian 2 bertujuan untuk mengkaji pengaruh sukrosa terhadap kandungan inulin pada kalus dahlia. Penambahan sukrosa pada media MS cair. Penambahan sukrosa terhadap pertambahan berat basah kalus dahlia menghasilkan pengaruh yang tidak berbeda nyata. Sukrosa yang tidak terhidrolisis karena penggunaan microfilter 0,02 µm diduga menjadi faktor utama penyebab rendahnya pertambahan berat basah kalus. Faktor penyebab lainnya adalah tekstur kalus yang kompak atau tidak friable. Kalus yang tidak friable tersebut diduga sedang tumbuh pada fase stationer atau hampir mati. Kandungan inulin pada kalus dahlia menjadi semakin rendah seiring tingginya tekanan osmotik karena penambahan sukrosa diatas 20 g/l. Tekanan osmotik tersebut diduga menjadi penyebab menurunnya pertambahan berat kalus dan kandungan inulin. Ketersediaan sukrosa yang relevan memiliki fungsi penting dalam biosintesis sucrose: sucrose 1-fructosyltransferase (1-SST) dan fructan: fructan 1-fructosyltransferase (1-FFT) sebagai enzim untuk percabangan unit fructosyl ß-(2,1)-linked yang terkandung dalam kalus dahlia. Faktor lain penyebab rendahnya kadar inulin yang dihasilkan secara in vitro adalah ketersediaan glukosa, ketersediaan enzim 1-fructan exohydrolase (1-FEh) dan ketidakstabilan enzim setelah waktu inkubasi yang cukup panjang.

Abtrak (Bhs. Inggris)

Inulin is polysaccharide which has many uses in food and pharmaceutical industries. Inulin is found in plants as food reserve, such as in dahlia tuber. The production of dahlia’s inulin using a conventional methode takes quite a long time and is inhibited by both biotic and a biotic stresses. Inulin production via an in vitro culture techniques has not been explored. The advantage of such methode is easier to observethe response induced by the addition inulin biosynthetic substrate such as sucrose.

The objectives of this study was to study the effect of  sucrose addition on the increase of dahlia callus fresh weight and the inulin content of dahlia callus. This research consists of two stages. The first stage has been aimed to get sufficient amount of calli, which will be subsequently used in the second stage of experiment.The effect of the interaction between 2,4-D (10 μM, 15 μM, 20 μM) and BAP (2.5 μM, 5 μM, 7.5 μM) on dahlia callus induction was studied. The second has been aimed to study the effect of sucrose addition on dahlia callusinulin content.  Four levels of sucrose concentration  i.e. S1 (20 gl-1), S2 (40 gl-1), S3 (60 gl-1) and S4 (80 gl-1) have been applied.

The research results showed that dahlia callus induction has been controlled by the the interaction between 2,4-D and BAP. It was also found that the combination between 20 µM 2,4-D and 7.5 µM BAP resulted in the highest percentage of callus formation (92.6%) and the highest increase of callus fresh weight (183.3 mg).  On the other hand, the addition of sucrosehas no significant influence on the increase of dahlia callus fresh weight. It is suggested that the added sucrose could not be absorbed by the explant since the sucrose was neither hydrolysed nor broken down.  The sucrose was  filter sterilised and added into the medium.  The addition of such high concentration of raw sucrose seemed to have resulted in the high osmotic stress in the medium causing the inhibition of callus growth leading to callus senescence as indicated by the low fresh weight increase and the formation of compact (unfriable) calli.Furthermore, the high osmotic stress seemed to lowered the inulin content of dahlia calli. The higher the sucrose concentration, the lower the inulin content of dahlia calli. The availability of cellular sucrose has an important function in the biosynthesis ofsucrose1-fructosyltransferase (1-SST)and fructan: fructan 1-fructosyltransferase (1-FFT), the key enzymes for branching fructosyl unit ß-(2,1)-linked in dahliacallus. The other factors, which were suggested to have causedthe low inulin content by in vitro culture is the availability of glucose, 1-fructant exohydrolase (1-FEh) and instability of enzymes(1-SST and1-FFT)after a long incubation.

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