Evaluation of Rice Germplasm Reveals Sources of Bacterial Leaf Streak Disease Resistance in Uganda
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In 2014, researchers in Uganda spotted signs typical bacterial leaf streak disease (Xanthomonas oryzae pv. oryzicola) in rice fields in Eastern Uganda. The disease was later confirmed to be bacterial leaf streak. In order to effectively plan for measures to manage this potentially devastating disease, it was imperative to score rice germplasm in Uganda for reaction to Xoc. Eighty four genotypes from the National Rice Improvement program were evaluated for their reaction to BLS using two Xoc isolates collected from Namulonge and Iganga. These were inoculated by the infiltration method using a needless syringe 30 days after planting. Data were collected on the streak length induced by BLS on the leaves 15 days after inoculation. The mean streak length per genotype was interpreted as; Resistant (R), 0<SL≤1mm, Moderately Resistant (MR), 1<SL≤10mm, Moderately Susceptible (MS), 10<SL≤30 mm, Susceptible (S) SL>30mm. Genotypes showed signficant variability (P < 0.001) in their reaction to BLS. The Xoc isolates reacted signficantly differently (P=0.011) on the rice genotypes. For the Iganga isolate, 6 genotypes were resistant while 17 were moderately resistant. For the Namulonge isolate, 3 genotypes were resistant while 7 were moderately resistant. Three genotypes were resistant to both isolates. The observations ranged from highly resistant in Nerica1 to highly susceptible in Du 363. The resistant genotypes identified could be used as sources of genes for introgression into susceptible but agronomically desirable genotypes.