Ekspresi Gen MT3 Pada Typha angustifolia Sebagai Respons Perlakuan Timbal (Pb)

Abstract

Timbal (Pb) adalah logam berat yang umum dan banyak dijumpai di lingkungan, termasuk pertambangan. Akumulasi Pb pada tanaman dapat menginduksi kerusakan fisiologis dan kerusakan DNA. Typha angustifolia dilaporkan sebagai tanaman yang mampu mentolerir dan mengakumulasi Pb. Tujuan penelitian ini adalah untuk menganalisia ekspresi gen MT3 dan respons fisiologis T. angustifolia terhadap perlakuan Pb. Ekspresi gen dianalisis menggunakan RNA total untuk mendapatkan informasi molekular terkait respons T. angustifolia. Terdapat 3 kelompok perlakuan dengan konsentrasi Pb yang berbeda-beda, yaitu 0 (control), 1, dan 1,5 ppm Pb. Setelah 2 minggu respons fisiologis dari tanaman terhadap perlakukan Pb diamati melalui analisis total klorofil, kadar MDA, dan aktivitas katalase daun. Hasil percobaan menunjukkan total klorofil daun pada perlakuan 1,5 ppm Pb lebih tinggi dari kontrol. Selain itu juga aktivitas katalase pada perlakuan 1,5 ppm Pb lebih tinggi dari kontrol. Hal ini dimungkinkan terdapat ambang batas Pb untuk menginduksi aktivitas katalase. Kadar MDA juga meningkat pada perlakuan 1 ppm dan 1.5 ppm Pb dibandingkan kontrol. Ekspresi gen MT3 mengalami peningkatan lebih tinggi dibandingkan kontrol yang menunjukkan bahwa ekspresi gen ini diinduksi oleh Pb di atas 1 ppm. Hasil penelitian memberikan indikasi bahwa ekspresi gen MT3 berperan penting dalam mekanisme toleransi T. angustifolia terhadap cekaman Pb.

Lead (Pb) is a common heavy metal pollutant that can be easily found in the environment, including mining site. Accumulation of Pb by plant can induce physiological changes and DNA damage. Typha angustifolia has been reported as Pb-tolerant and Pb-accumulating plant. The objective of this research was to analyze MT3 gene expression and physiological responsses of T. angustifolia to Pb stress applied in nutrient solution culture. Gene expression analyzed using total RNA was performed to obtain molecular information regarding the tolerant responsse of T. angustifolia. Three groups of plants were treated with solution containing different concentration of Pb. Group 1 was control plants treated with 0 ppm of Pb, group 2 with 1 ppm of Pb and group 3 with 1.5 ppm of Pb. After 2 weeks of experimental period, the physiological responsses of plant including leaf chlorophyll content, MDA content and catalase activity were analyzed. The result showed that the chlorophyll content of all groups in Pb treated plants was higher than control. Catalase activity of plant in 1.5 ppm treatment, was higher than control, suggesting that there was a threshold for Pb to induce activation of Catalase. MDA content was also increased significantly due to Pb treatment of 1 and 1.5 ppm treatment than control. Under 1.5 ppm of Pb, the expression of MT3 gene also increased by approximately as twice as higher than control suggesting that this gene was induced by Pb higher than 1 ppm. The result suggested that T. angustifolia has defense mechanism to responsse Pb stress through metallothionein gene expression.