Kajian Hasil Penyisipan Gen Sucrose Phosphate Synthase dari Tebu (SoSPS1) Untuk Peningkatan Kandungan Asam Galat Bunga Cosmos sulphureus Cav. Sebagai Bioherbisida

Tantri Swandari, Prof. Dr. Ir. Aziz Purwantoro, M.Sc ; Dr. Dyah Weny Respatie, S.P., M.Si ; Dr. Ir. Endang Sulistyaningsih, M.Sc

2025 | Disertasi | S3 Ilmu Pertanian

Asam galat pada kosmos kuning (Cosmos sulphureus Cav.) berpotensi sebagai sumber bioherbisida. Upaya peningkatan kandungan asam galat kosmos kuning telah dilakukan dengan penyisipan gen SoSPS1 (Sucrose Phosphate Synthase dari cDNA tebu) secara floral dip menggunakan kuncup bunga ukuran 5-7 mm yang dicelupkan pada larutan berisi Agrobacterium tumefaciens strain GV3101 membawa plasmid pRI101AN SoSPS1 dan gen penanda seleksi nptII. Penelitian ini bertujuan untuk: (1) mengevaluasi konsistensi perubahan karakter morfologi, biokimia, fisiologi, dan molekuler pada tanaman kosmos kuning transforman generasi T0 dan T1; (2) menentukan peningkatan kandungan asam galat akibat penyisipan gen SoSPS1; (3) menentukan pola pewarisan gen SoSPS1 generasi T1; serta (4) mendapatkan tingkat toksisitas ekstrak bunga kosmos kuning transforman terhadap pertumbuhan gulma teki (Cyperus rotundus). Karakterisasi dilakukan pada generasi T0 hingga T1 melalui analisis morfologi, biokimia, fisiologi, dan molekuler. Deteksi keberadaan gen SoSPS1 dan nptII dilakukan menggunakan PCR dengan primer spesifik, yaitu CaMV-35S (Forward) dan SPS P9 (Reverse) untuk SoSPS1 dan nptII-F dan nptII-R untuk nptII. Pola pewarisan berdasarkan deteksi keberadaan sisipan gen dievaluasi menggunakan uji chi-square. Uji toksisitas dilakukan dengan aplikasi ekstrak bunga kosmos kuning transforman konsentrasi 10%, 20%, dan 40% (w/v) serta larutan kontrol berupa akuades dan asam galat sintetis 100 ppm pada umbi gulma teki. Hasil menunjukkan bahwa perubahan karakter morfologi, biokimia, dan fisiologi tanaman kosmos kuning sebagai akibat penyisipan gen SoSPS1 bersifat konsistengenerasi T0 hingga T1. Akumulasi asam galat pada bunga kosmos kuning transforman meningkat sebesar 65,07% (T0) hingga 81,28% (T1) dibandingkan tanaman tipe liar. Pola segregasi menunjukkan kesesuaian rasio 1:3 untuk gen SoSPS1 dan 1:1 untuk gen nptII. Uji toksisitas menunjukkan bahwa ekstrak bunga kosmos kuning transforman konsentrasi 10% (w/v) telah efektif menghambat pertumbuhan gulma teki setara dengan efek ekstrak bunga kosmos kuning tipe liar pada konsentrasi 40% (w/v).

Gallic acid in yellow cosmos (Cosmos sulphureus Cav.) is a promising candidate for development as a natural bioherbicide. To enhance its gallic acid content, the SoSPS1 gene (Sucrose Phosphate Synthase from sugarcane cDNA) was introduced using the floral dip method, in which 5–7 mm flower buds were immersed in a solution containing Agrobacterium tumefaciens strain GV3101 carrying the pRI101AN-SoSPS1 plasmid and the nptII selection marker. This study aimed to: (1) evaluate the consistency of morphological, biochemical, physiological, and molecular changes across T0 and T1 transformant generations; (2) quantify the increase in gallic acid content resulting from SoSPS1 insertion; (3) determine the inheritance pattern of the SoSPS1 gene in the T1 generation; and (4) assess the toxicity of transformant flower extracts on the growth of nutsedge (Cyperus rotundus). Characterization of T0 and T1 plants included morphological observations, biochemical and physiological measurements, and molecular analyses. The presence of SoSPS1 and nptII was confirmed by PCR using specific primer pairs: CaMV-35S (Forward) and SPS P9 (Reverse) for SoSPS1, and nptII-F/R for nptII. Gene inheritance patterns were evaluated using chi-square analysis. Toxicity assays were performed by applying 10%, 20%, and 40% (w/v) flower extract concentrations from transformant plants to nutsedge rhizomes, with distilled water and 100 ppm synthetic gallic acid as controls. The results showed that the morphological, biochemical, and physiological changes associated with SoSPS1 insertion were stable across both generations. Gallic acid levels in transformant flowers increased by 65.07% in T0 and 81.28% in T1 compared with wild-type plants. Segregation analysis indicated a 1:3 ratio for SoSPS1 and a 1:1 ratio for nptII. Toxicity tests revealed that a 10% (w/v) concentration of transformant flower extract effectively inhibited nutsedge growth, producing an inhibitory effect comparable to that of a 40% (w/v) extract from wild-type plants.

Kata Kunci : Cosmos sulphureus, overekspresi, SoSPS1, pola pewarisan, asam galat