Abnormalitas bunga dan buah pada klon kelapa sawit (Elaeis guineensis Jacq) berdasarkan analisis morfologi, biokimia dan DNA genom

Abstract

Penyediaan bibit kelapa sawit melalui perbanyakan kultur jaringan merupakan solusi bijak untuk memenuhi kebutuhan bibit di dalam negeri. Namun 0-17% tanaman yang berasal dari kultur jaringan mengalami abnormalitas pada bunga yang dapat menurunkan produktivitas tanaman. Penelitian-penelitian sebelumnya mendapatkan bahwa bunga abnormal berhubungan dengan hipometilasi yang dideteksi pada jaringan kalus dan daun. Sedangkan metilasi DNA genom berhubungan dengan regulasi ekspresi gen spesifik pada jaringan. Pada kelapa sawit yang mengalami abnormal adalah jaringan bunga dan buah. Berdasarkan hal tersebut maka penelitian ini bertujuan mengkarakterisasi morfologi bunga dan buah, menetapkan tingkat abnormalitas pada buah, menetapkan kandungan minyak dan mempelajari hubungannya dengan kandungan malonil-KoA dan asetil-KoA pada beberapa tingkat abnormalitas buah, serta mempelajari hubungan perubahan pada status metilasi DNA dan DNA genom dengan tingkat abnormalitas pada bunga dan buah.

Phenomena of abnormal flowers found was around 0-17% among clones of oil palm, that reduce productivity. Previous research showed that abnormality of flower is related to DNA hipomethylation in calli and leaves tissues of the abnormality plant. The changes of DNA methylation correlates with gen expression in the specific tissue. In the case of oil palm abnormalities occur in flower and fruit tissues. The objectives of this research were to characterize the morphology of flower and fruit, to determine the oil content in relation to malonyl-CoA and asetyl-CoA, to study changes of DNA methylation status and genomic DNA changes related with flower and fruit abnormality. Eighty plants used in this research consisted of three clones, i.e MK152, MK 176, and MK 209. These were obtained from the collection of ”Badan Pengkajian dan Penerapan Teknologi (BPPT) Ciampea”. Characterization of plant morphology was conducted visually, whereas the oil content of mesocarp was analyzed by extracting the oil with soxhlet system, determination of the malonylCoA and acetyl-CoA content by HPLC (High Performance Liquid Chromathography), the quantification of cytosine methylation by performance RP-HPLC, and detection of alteration of the DNA genome was analysed by RAPD technique (Random Amplified Polymorphic DNA). The results showed that abnormalities of female and male flowers as well as fruits were found in tissue culture-derived plants. The rudimentary stamen in the female flower, and stamen of the male flowers were transformed into carpel-like structure. Fruit abnormality was catagorized into five classes, i.e normal, light abnormal (AbR), heavy abnormal (AbB) and two types of severe abnormal, AbSB1 and AbSB2. The content of palm oil in immmature fruit from the three type of fruits (normal, AbR and AbB) were similar. The normal fruit contained around 74.66 -77.26%, AbR 77.47-80.85%, and AbB 73.89-78.62%. The high palm oil content in the normal (MK 152), AbR (MK 209), and AbB (MK 176) were related to higher malonyl-CoA (0.069 0.085, dan 0.068 mg/ml respectively) than the acetyl-CoA (0.036, 0.021 dan 0.023 mg/ml respectively). On the contrary in the severe abnormal fruits, the acetyl-CoA was higher (0.066-0.087 mg/ml) and the malonyl-CoA lower (0.022-0.037 mg/ml). Compared to the normal plant, hypomethylation in leaves tissue was 1.31-4.01% and hypermethylation was 0.69-2.66% in flowers tissue of the abnormal plants. However, changes of DNA methylation status was not found in fruits tissue. Changes of the sequence of DNA genome in the plants within the same clone were detected using five random primers, i.e.OPC-08,OPD-15, W-15, OPC-09 and SC10-19. A band DNA of the normal plant was detected by OPC-08. Changes of the methylation status in leaf and flower tissues was not directly related to the abnormality of the oil palm flowers. The difference of DNA bands were found among plants of the MK 152.