Pewarisan SNP2 Gen Lys-C dan Daya Tahan terhadap Aeromonas hydrophila pada Benih Hibrida Lele Sangkuriang >< Thailand

Abstract

Peningkatan produksi ikan lele (Clarias gariepinus) perlu didukung oleh penyediaan induk dan benih yang baik untuk mencegah penurunan mutu genetik. Ikan lele strain Sangkuriang membawa marka single nucleotide polymorphisms varian 2 (SNP2) gen lys-c yang berkaitan dengan ketahanan terhadap infeksi Aeromonas hydrophila. Ikan lele strain Thailand memiliki pertumbuhan yang lebih cepat. Penelitian bertujuan untuk menganalisis pewarisan SNP2 gen lys-c pada induk dan daya tahan benih hibrida Sangkuriang >< Thailand yang diinfeksi A. hydrophila. Ikan lele Sangkuriang betina dan lele Thailand jantan disilangkan dan benih dipelihara hingga mencapai ukuran 8-9 cm. Identifikasi marka dilakukan dengan metode polymerase chain reaction. Uji tantang menggunakan bakteri A. hydrophila dengan dosis 10^6 CFU/mL sebanyak 20 ekor setiap persilangan dengan 3 kali ulangan dari persilangan (TT >< CT), (CT >< CT), dan (TT >< CT). Parameter yang diamati yaitu kelangsungan hidup, jumlah leukosit, dan aktivitas fagositik. Hasil menunjukkan bahwa strain Sangkuriang memiliki variasi marka TT dan CT, sementara strain Thailand hanya memiliki marka CT. Hasil persilangan diperoleh marka TT dan CT, tetapi CC tidak ditemukan pada persilangan (CT >< CT). Tingkat kelangsungan hidup benih hibrida pasca uji tantang berkisar 36,67%?70,00%. Benih hibrida dengan proporsi marka TT dominan memiliki tingkat kelangsungan hidup dan respons imun lebih baik.

The increase in catfish (Clarias gariepinus) production must be supported by the availability of high-quality broodstock and seeds to prevent genetic quality degradation. The Sangkuriang strain of catfish carries a single nucleotide polymorphism variant 2 (SNP2) marker in the lys-c gene, which is associated with resistance to Aeromonas hydrophila infection. Meanwhile, the Thailand strain of catfish is known for its faster growth rate. This study aimed to analyze the inheritance of SNP2 in the lys-c gene in broodstock and the disease resistance of hybrid seeds from a Sangkuriang >< Thailand cross infected with A. hydrophila. Female Sangkuriang catfish were crossed with male Thailand catfish, and the seeds were reared until they reached 8–9 cm in length. Genotyping was conducted using the polymerase chain reaction (PCR) method. A challenge test was performed using A. hydrophila at a dose of 106 CFU/mL. Twenty fish per treatment group were used with three replications from the following crosses: (TT >< CT), (CT >< CT), and (TT >< CT). Observed parameters included survival rate, leukocyte count, and phagocytic activity. The results showed that Sangkuriang catfish had TT and CT genotypes, while Thailand catfish had only the CT genotype. The hybrid offspring from crosses showed TT and CT genotypes, but no CC genotype was detected from (CT >< CT). The survival rate of hybrid seeds post-challenge ranged from 36.67% to 70.00%. Crosses that produced a higher proportion of TT genotype offspring exhibited better survival and immune responses.