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Abstrak :
ABSTRACT
The bacterial blight (BB) disease severity on two rice genotypes i.e.; BP 4110-2d-33 (backcross between Ciherang x Angke; containing Xa-4, xa-5) and BP 3688e-23 (sister lines derived from cingri/memberamo//widas///IRBB 8; containing xa-8) were lower compare with TN-1 (containing Xa-14). The total amino acid content in cultivar?s TN-1 was accounted for about one third to about a half of total amino acid than those of other rice genotypes where the total amino acid was ranging from 1.95% to 4.22%. In BP 3688e-23, and BP 3688e-22 genotypes more amino acid levels were decline although these advance lines showing xa-8 background. BB resistant gene carried by BP 4110-2d-33 and BP 3688e-23 were stable, whilst BP 3688e-22 was less effective to inhibit BB disease severity. Overall, amino acids were not found to be related to the level of BB resistance; where correlation between amino acid content and BB disease severity is not significant. The slower growth of Xoo on rice genotypes BP 4110-2d-33 and BP 3688e-23 may probably due to other than nutritional factors. The degree of resistance in rice genotypes infected by races of pathogen; as well as the resistance gene possessed by genotype BP 3688e-23 need to be further determined.

Abstrak :
The objective of this work was to study the virulence of 15 Xanthomonas oryzae pv. oryzae (Xoo) isolates collected in three provinces in Indonesia (North Sumatra, South Sumatra, and South Sulawesi) based on five Indonesian differential rice genotypes and 10 near isogenic lines (NILs) that have been known to differ in their resistance to bacterial leaf blight (BLB), in a greenhouse assessment. In addition, this study also aims to monitor the responses of 31 rice genotypes (21 NILs, five differentials, five improved cultivars) to BLB disease in a field experiment. The 15 isolates showed different virulence patterns on the NILs?genotypes with a single resistance gene indicating the pathogen diversity. Eight different pathotypes were present, as demonstrated by a particular virulence pattern of each isolate on the genotypes. Determination of Xoo pathotype revealed that Xoo pathotypes responded differently based on their reaction to NILs and Indonesian differential genotypes. The field assessment demonstrated the incidence and severity of BLB disease on rice genotypes ranging from 25% to 100% and 5.5% to 72.91%, respectively, while the mean disease index ranged from 1.15% to 72.9%. The disease response varied among rice genotypes. IRBB50 (Xa4+xa5), IRBB51 (Xa4+xa13), IRBB52 (Xa4+Xa21), IRBB53 (Xa4+Xa21), IRBB56 (Xa4+xa5+xa13), IRBB57 (Xa4+xa5+Xa21), IRBB59 (Xa4+xa13+Xa21), IRBB64 (Xa4+xa5+Xa7+Xa21), IRBB66 (Xa4+xa5+Xa7+xa13+Xa21), IRBB7(Xa7), Angke (Xa4+xa5) and Code (Xa4+Xa7) were revealed to be highly resistant to the BLB pathogen. These genotypes have potential as genetic material for the pyramiding of several resistance genes for the development of rice resistance to BLB disease in Indonesia.

Penentuan Patotipe Xanthomonas oryzae pv oryzae Asal Populasi Indonesia Penyebab Penyakit Hawar Daun Bakteri dan Reaksinya pada Padi Diferensial. Tujuan dari penelitian ini adalah untuk mempelajari virulensi 15 isolat Xanthomonas oryzae pv. oryzae (Xoo) yang dikumpulkan dari tiga provinsi di Indonesia (Sumatera Utara, Sumatera Selatan, dan Sulawesi Selatan) berdasarkan reaksinya pada lima genotipe padi diferensial Indonesia dan 10 galur padi isogenik (NIL) yang telah diketahui perbedaan ketahanannya terhadap penyakit hawar daun bakteri (HDB) pada uji di rumah kaca. Selain itu, penelitian ini juga bertujuan untuk memantau tanggap 31 genotipe padi (21 NIL, lima diferensial, lima kultivar unggul) terhadap penyakit HDB pada pengujian di lapangan. Sebanyak 15 isolat menunjukkan pola virulensi yang berbeda pada genotipe NIL dengan gen ketahanan tunggal, yang menunjukkan adanya keragaman patogen. Tercatat delapan patotipe yang berbeda, seperti ditunjukkan oleh pola virulensi tertentu isolat pada setiap genotipe. Hasil penentuan patotipe Xoo mengungkapkan bahwa tanggap reaksi patotipe Xoo berdasarkan reaksinya terhadap NIL dan genotipe diferensial Indonesia berbeda-beda. Hasil penilaian di lapangan menunjukkan kejadian dan keparahan penyakit HDB pada genotipe padi masing masing berkisar dari 25-100% dan 5,5-72,91%, sedangkan indeks penyakit berkisar antara 1,15-72,9%. Tanggap penyakit bervariasi antar genotipe padi. IRBB50 (Xa4 + xa5), IRBB51 (Xa4 + xa13), IRBB52 (Xa4 + Xa21), IRBB53 (Xa4 + Xa21), IRBB56 (Xa4 + xa5 + xa13), IRBB57 (Xa4 + xa5 + Xa21), IRBB59 (Xa4 + xa13 + Xa21), IRBB64 (Xa4 + xa5 + Xa7 + Xa21), IRBB66 (Xa4 + xa5 + Xa7 + xa13 + Xa21), IRBB7 (Xa7), Angke (Xa4 + xa5) dan Code (Xa4 + Xa7) bereaksi sangat tahan terhadap patogen HDB. Genotipe tersebut memiliki potensi sebagai bahan genetik piramida beberapa gen ketahanan untuk mengembangkan padi tahan terhadap penyakit HDB di Indonesia.