KAJIAN KETAHANAN GLAGAH (Saccharum spontaneum L.) TERHADAP CEKAMAN KEKERINGAN

Aminatun Munawarti, Dra.,M.Si., Prof. Sismindari, SU, PhD., Apt., Dr. Ir. Taryono, MSc.; Dr. Endang Semiarti, MS, MSc.

2014 | Disertasi | S3 Bioteknologi

Dalam upaya pengembangan tebu unggul tahan kekeringan, sangat diperlukan ketersediaan sumber gena ketahanannya. Tujuan penelitian ini adalah mendapatkan aksesi tahan, yang nantinya dapat digunakan sebagai sumber gena ketahanan terhadap kekeringan dan untuk mengetahui apakah akumulasi prolin dan protein spesifik dapat digunakan sebagai penanda biokimia untuk ketahanan terhadap kekeringan. Penelitian meliputi 1). pemilahan dan pemilihan aksesi glagah tahan kekeringan di sawah, 2). uji konsistensi ketahanan aksesi terpilih di rumah kaca serta 3). uji kemampuan tanaman untuk pulih setelah cekaman dihentikan. Keenam puluh empat aksesi glagah dapat dipilah menjadi 9 tahan, 28 medium tahan dan 27 peka. Pengujian lebih lanjut terhadap aksesi terpilih diperoleh 2 aksesi yang tetap tahan (BOT-53 dan BOT-54). Setelah cekaman dihentikan, kedua aksesi tersebut juga mampu tumbuh kembali. Cekaman kekeringan 4 dan 8 minggu nyata meningkatkan akumulasi prolin daun. Kedua aksesi tersebut mempunyai kandungan prolin tertinggi (339,25 μg/g berat basah dan 353,25 μg/g berat basah) dengan peningkatan 17 dan 28 kali kandungan prolin pada kondisi tanpa cekaman. Dengan cekaman 2 x 4 minggu, kedua aksesi tersebut mengalami peningkatan kandungan prolin yang sangat besar, yaitu 686 μg/g berat basah (BOT-53) dan 468,95 μg/g berat basah (BOT-54). Cekaman kekeringan juga menyebabkan perubahan sintesis protein. Pada kedua aksesi tersebut terdapat protein yang terekspresikan oleh kekeringan dengan berat molekul sekitar 100 kD, 75 kD, 65 kD, 16,5 kD dan 12 kD. Protein-protein tersebut sintesisnya kembali normal setelah cekaman dihentikan. Protein 16,5 kD (SsDip16.5) meningkat sangat tajam seiring dengan semakin beratnya tingkat cekaman. Protein tersebut bereaksi positif dengan antibodi SoDip22 dan mempunyai ujung N berupa asam amino histidin. Aksesi BOT-53 dan BOT-54 dapat direkomendasikan sebagai sumber gena tahan cekaman kekeringan. Ketahanan terhadap cekaman kekeringan pada glagah nampaknya diperantarai oleh prolin dan protein-protein tersebut, termasuk SsDip16.5. Akumulasi prolin dan protein SsDip16.5 berpotensi sebagai penanda biokimia untuk ketahanan terhadap kekeringan pada glagah.

In order to develop a superior cultivar of sugarcane for drought tolerance, the availability of a source of drought-tolerant genes is needed. This study was conducted to obtain the drought-tolerant glagah accessions, which can be used later as a source of drought-tolerant genes and whether proline accumulation and a specific protein can be used as biochemical markers for drought tolerance. The research was carried out to 1) classify and select of drought-tolerant of glagah accessions at the field, 2) test the consistency of tolerance of selected accessions at the greenhouse 3) test the ability of drought-stressed plant to recover. The sixty four glagah accessions could be classified into 9 tolerant, 28 medium-tolerant and 27 sensitive to drought stress. From the selected accessions, both BOT-53 and BOT-54 accessions were the most tolerant and showed consistent behavior for drought tolerant and these two accessions were also capable to recover after the drought end by re-watering for 2 weeks. Drought stress for 4 and 8 weeks significantly induced the accumulation of proline in leaves. Two accessions (BOT-53 and BOT-54) had the greatest increases in proline content (339.25 μg / g FW and 353.25 μg / g FW, respectively) with 17- fold and 28-fold respectively compared to the untreated one. With drought stress for 2 x 4 weeks, both BOT-53 and BOT-54 accessions had the highest proline content among the three levels of stress, which is 686 ug / g FW for BOT-53 and 468.95 ug / g FW for BOT-54. The content of proline back to normal after the drought end. Drought stress also caused change on protein synthesis. Two accessions (BOT-53 and BOT-54) showed a similar protein pattern. There were proteins induced by drought stress with a molecular weight of approximately 100 kD, 75 kD, 65 kD, 16.5 kD and 12 kD. Once the stress is stopped, the protein synthesis returned to normal as the condition without stress. Protein 16.5 kD (SsDip16.5) increased very sharply in line with the severity of drought stress. These proteins were positively reacted with SoDip22 antibodies and had a hydrophilic amino acid, histidine at the N terminus. Two accessions (BOT-53 and BOT-54) were identified as a droughttolerant accessions, both at the field and greenhouse, so that they can be recommended as a source of drought-tolerant genes. Accumulation of proline and SsDip16.5 protein could be potentially used as a biochemical markers for drought stress tolerance of glagah.

Kata Kunci : Saccharum spontaneum, glagah, cekaman kekeringan, prolin, pola protein