Kestabilan Genetik Kenikir (Cosmos sulphureus Cav.) Transgenik Generasi T2 Pembawa Gen SoSPS1

Ersa Nur Syafia, Prof. Dr. Ir. Aziz Purwantoro, M.Sc.; Widhi Dyah Sawitri, S.Si., M.Agr., Ph.D.

2023 | Skripsi | AGRONOMI

Kestabilan genetik dari tanaman hasil transformasi merupakan suatu komponen penting dalam pengembangan tanaman transgenik. Karakter target yang diintroduksikan ke tanaman harus memiliki ekspresi gen yang stabil agar mampu diwariskan ke keturunannya seperti gen-gen endogenous lain. Pada studi sebelumnya, telah dilaksanakan transformasi genetik secara in vitro pada tanaman kenikir (Cosmos sulphureus cav.) dengan menggunakan gen SoSPS1. Gen SoSPS1 berperan sebagai pengkode enzim SPS (Sucrose-phosphate synthase) yang bertugas sebagai enzim kunci dalam biosintesis sukrosa pada tanaman. Penelitian ini bertujuan untuk mengetahui kestabilan genetik serta pola segregasi dari populasi tanaman transforman gen SoSPS1 pada generasi kedua. Penelitian diawali dengan seleksi 140 biji tanaman transforman yang diperoleh dari tanaman transforman generasi pertama pada kertas saring dengan penambahan antibiotik kanamisin 50 ppm dan dihasilkan 23 bibit tanaman putatif yang selanjutnya dianalisis PCR untuk mengkonfirmasi keberadaan gen nptii sebagai gen penanda seleksi. Diperoleh hasil yang menunjukkan 21 tanaman terkonfirmasi positif gen nptii dengan pola segregasi yang tidak mengikuti Hukum Mendel. Tanaman transforman gen SoSPS1 menunjukkan perubahan karakter berupa keberadaan antosianin batang dan daun, tekstur daun, terbentuknya keragaman bentuk ujung daun, susunan pita. Panjang tangkai, jumlah pita, diameter pita, dan lebar pita juga menunjukkan peningkatan rerata karakter yang berbeda nyata dibandingkan dengan populasi tanaman tipe liar.

Genetic stability of transgenic plants is one of the most crucial matter that must be observed to develop transgenic products. Traits of interest that are introduced into plants must have a stable gene expression in order to be inherited to their progeny like any other endogenous genes.  In the previous study, in vitro genetic transformation of yellow cosmos plants (Cosmos sulphureus Cav.) using SoSPS1 gene are succesfully done. SoSPS1 is a SPS (Sucrose-phosphate synthase) enzyme coding gene that plays role as a key enzyme in sucrose biosynthesis. This research is conducted to analize the stability and segregation pattern of second generation of transgenic plants population carrying SoSPS1 gene. This research was started with a selection of 140 transgenic seeds gained from the first generation transgenic plants. The seeds were germinated on filter paper and soaked with 50 ppm kanamycin solution, 23 kanamycin resistant plants are obtained and further analized in PCR assay to confirm the presence of nptii gene as selectable marker gene. 21 plants are confirmed to be carrying the nptii gene, yet did not follow the Mendelian segregation pattern. Transgenic plants that are confirmed carrying SoSPS1 gene shows different characters in leaf texture, leaf’s lobe shape, arrangement of ray floret, and the presence of anthocyanins in stem and leaves. Increase of peduncle length, number of ray florets, diameter and width of ray floret characters are observed in the transgenic plants compared to its wildtype population.

Kata Kunci : cosmos, genetic stability, SoSPS1 gene, segregation pattern