PATHOTYPE PROFILE OF Xanthomonas oryzae pv. oryzae ISOLATES FROM THE RICE ECOSYSTEM IN JAVA

Abstract

At present, bacterial leaf blight of rice caused by Xanthomonas oryzae pv. oryzae is highly damaging to rice production in Indonesia as most of the existing commercial rice varieties are susceptible to the existing pathotypes of the bacteria. To solve such problems, varietal rotation should be based on information on the existence and dominance of local pathotypes in a particular rice ecosystem. To obtain this information, a total of 117 isolates of X. oryzae pv. oryzae, collected from West Java, Central Java, and Yogyakarta, were evaluated for their pathotype variation on five differential rice varieties during the dry season of 2000. When disease severity was < 10%, the reaction was classified as resistant (R) and when > 11%, was susceptible (S). The data indicated that 3.42% of the isolates were pathotype III, 12.82% were pathotype IV, and 83.76% were pathotype VIII. In West Java, the bacterial pathotypes III, IV, and VIII were 4.94%, 14.81%, and 80.25%, respectively. In low elevation areas, 4.94%, 9.88%, and 45.68% were pathotypes III, IV, and VIII, respectively and in medium areas, 4.94% were pathotypes IV and 34.57% were pathotype VIII. In Central Java, no pathotype III was found, while pathotypes IV and VIII were as much as 4.52% and 90.48%, respectively. In low elevation areas, no pathotypes III was recovered, and a total of 9.53% and 76.19% were identified as pathotypes IV and VIII, respectively, and in medium areas only pathotype VIII (14.29%) was identified. In Yogyakarta, pathotypes IV and VIII were found. In low elevation areas, 6.67% and 93.33% were pathotypes IV and VIII, respectively and in medium areas, 14.29% and 85.71% were pathotypes IV and VIII, respectively. The data indicated that variation in pathotype composition over different locations was obvious and locally specific resistant varieties to the disease are needed in the management of this important bacterial disease in rice.

Genetic Variabilities of Agronomic Traits and Bacterial Leaf Blight Resistance of High Yielding Rice Varieties

“…Three main Xoo isolates used in this study (pathotype III, IV and VIII) were the most dominant pathotypes in the paddy field. pathotype III was less virulent than pathotype VIII and the most virulent was pathotype IV (Suparyono et al 2004). All Indonesian HYVs were either resistant or moderately resistant to pathotype III.…”

“…In India, the yield losses due to BLB ranged from 65 to 95% (Nayak et al 2008). In Indonesia, the yield losses in the wet season were 21-36%, while in the dry season ranged from 18 to 28% (Suparyono et al 2004). The use of high yielding varieties (HYVs) and resistant to BLB is the most effective way to control the disease to minimize yield losses (Khush et al 1989).…”

Morphological Variability in Leaf of Indonesian Rice Landraces and Its Correlation to Bacterial Leaf Blight Disease Resistance

“…Pengamatan dilakukan dengan cara mengukur lima daun bergejala terpanjang tiap rumpun pada dua dan empat MSI. Keparahan penyakit adalah nilai rasio panjang gejala (cm) terhadap panjang daun (cm) yang diinokulasi dikali 100% (Suparyono et al 2004). Reaksi ketahanan padi lokal dikelompokkan berdasarkan keparahan penyakit dengan Standard Evaluation System (SES) IRRI untuk padi (Tabel 2).…”

Keragaman Ketahanan Padi Lokal Jawa, Sumatra, dan Sulawesi terhadap Patogen Hawar Daun Bakteri Patotipe III, IV, dan VIII

“…HDB yang disebabkan oleh Xanthomonas oryzae pv. oryzae (Xoo) tergolong penyakit penting di banyak negara penghasil padi (Suparyono et al 2004). Hal ini disebabkan karena HDB dapat mengurangi hasil panen dengan tingkat yang bervariasi.…”

“…Berbagai varietas dan galur padi dengan berbagai tingkat ketahanan terhadap HDB telah dikembangkan (Sudir et al 2013). Namun, seringkali ketahanan patah oleh patogen HDB yang mampu membentuk patotipe baru yang lebih virulen (Suparyono et al 2004). Kondisi ini memicu para pemulia untuk terus merakit varietas yang tahan terhadap HDB.…”