Keragaman genetik populasi wereng hijau, Nephotettix virescens distant asal wilayah endemi dan nonendemi penyakit tungro padi

SUPRIYADI, Promotor Prof.Dr.Ir. Kasumbogo Untung, M.Sc

2006 | Disertasi | S3 Ilmu Pertanian

Studi mendalam hubungan antara wereng hijau, Nephotettix virescens Distant dengan virus tungro penting dilakukan guna memahami penyakit tungro padi. Tujuan penelitian untuk mengidentifikasi komposisi spesies vektor, keragaman geografik populasi N. virescens, dan karakter individu penular aktif. Komposisi spesies vektor diidentifikasi melalui survei populasi vektor di wilayah endemi dan nonendemi virus tungro. Keragaman geografik populasi N. virescens diidentifikasi berdasarkan atas ukuran morfologi, penanda molekular, dan kemampuan menularkan virus tungro. Metode sama digunakan untuk mengidentifikasi karakter individu N. virescens penular aktif. Empat spesies vektor, yakni N. virescens, N. nigropictus, N. malayanus, dan Recilia dorsalis ditemukan di wilayah endemi dan nonendemi. N. virescens selalu dominan di antara populasi spesies vektor virus tungro, sehingga tidak berkaitan dengan status wilayah endemi. Hasil uji penularan virus menunjukkan rata-rata persentase individu N. virescens penular aktif asal wilayah endemi sebesar 81,2%, sedangkan asal wilayah nonendemi 52,2%. N. virescens betina lebih efektif dalam menularkan virus tungro da ripada yang jantan. Gejala tungro pada bibit padi juga muncul lebih cepat apabila inokulasi dilakukan dengan N. virescens betina. Keragaman sifat morfologi dan profil protein total antar populasi N. virescens tidak berhubungan dengan asal dari wilayah endemi dan nonendemi. Antara kelompok N. virescens penular aktif dan bukan penular aktif tidak menunjukkan perbedaan sifat morfologi, tetapi berbeda profil protein totalnya. Tiga pita protein dengan berat molekul 173, 134, dan 68 kDa muncul pada N. virescens penular aktif, namun ketiga protein tersebut tidak dijumpai pada individu bukan penular aktif.

Understanding the interaction between green leafhopper Nephotettix virescens Distant and rice tungro virus is needed for management of tungro disease in rice. These studies were aimed to determine the species composition of tungro vectors, the geographical variation of N. virescens , and the characters of N. virescens active transmitters. The species composition of tungro vectors was identified from samples collected using sweep net on endemic and nonendemic areas of tungro virus. The geographical variation of leafhopper was determined by analyzing the morphological and molecular characters as well as its ability in transmitting tungro virus. The same methods were also employed to distinguish the active transmitter from the non transmitter of N. virescens . Four tungro virus vectors were found in both endemic and non-endemic tungro virus areas, namely N. virescens, N. nigropictus, N. malayanus, and Recilia dorsalis. It was observed that N. virescens dominated the population of tungro virus vectors. However, it was also found that there was no clear correlation between domination of N virescens with the spread of the disease in endemic area. Variations in the ability to transmit virus were observed among population of N. virescens . The number of N. virescens active transmitters in the endemic areas was higher (81.2%) than that in the non endemic areas (52.2%). The females of N. virescens were found to be more effective in transmitting tungro virus than the male. In addition, the occurrence of tungro virus symptom was more readily observable in plant inoculated by the female than male active vector. Based on morphological and protein banding pattern, the diversity among different N. virescens populations from endemic and non endemic areas did not correlate with their origin. It was observed that N. virescens active transmitter had different in protein banding pattern from that in the nontransmitter. Three distinct protein bands of 173, 134, and 68 kDa were observed in the active transmitter. The three protein bands, however, were absent from the protein profile of the non-transmitter leafhopper.

Kata Kunci : Wereng Hijau, Keragaman Genetik, Virus Tungro Padi