Evaluation of bacterial blight resistance in marker assisted selection (MAS) Bred Rice Lines against Philippines Isolates of Xanthomonas oryzae pv oryzae
| dc.contributor.author | Ronel T. Aguilar, Jr. | |
| dc.date.accessioned | 2026-06-03T00:26:14Z | |
| dc.date.available | 2026-06-03T00:26:14Z | |
| dc.date.issued | 2016 | |
| dc.description.abstract | Among rice diseases, bacterial blight (BB) was named as one of the most destructive causing yield losses ranging from 74 to 81% in severe conditions (Srinivasan and Gnanamanickam, 2005). Xanthomonas oryzae pv. oryzae (Xoo), the causative agent of BB is a gram negative bacterial pathogen infecting the xylem of the rice, causing lesions and eventually leading to plant death (Liu et al., 2006). One of the major goals of rice improvement programs has been to develop rice cultivars with stable BB resistance. Through Marker Assisted Selection (MAS), rice breeders in the Philippine Rice Research Institute (PhilRice) had generated several elite lines introgressed with 2 4 BB resistance genes in various combinations. In this study, thirteen promising MAS bred rice lines were evaluated for reactions to BB using three most virulent Xoo races (Pxo 99, Pxo 79 and Pxo 347) under controlled conditions. The absorbance at 600 nanometer (A600) of each inoculum suspension used was adjusted to 2.0 using Uv Vis spectrophotometer. IR24 and IRBB64 were used as susceptible and resistant checks, respectively. Datagathered were analyzed using one way analysis of variance (ANOVA) and Tukey HSD for multiple comparisons of means. Results revealed that the reaction to Xoo of MAS bred rice lines introgressed with Xa4 alone are not significantly different from Ir24. Further lines with Xa4 +Xa21 and Xa4+Xa7+Xa21 combinations showed high level of resistance comparable to IRBB64, which carries Xa4=Xa5+Xa7+Xa21. satistically, the level of resistance exhibited by rice lines introgressed with 2 4 BB resistance genes against the three selected Pxoo races was not significantly different. However, it has been predicted through regression analysis, that for every increase in the number of genes, there is a significant decrease in the leaf lesion length; thus it is imperative to pyramid lines with more than three BB resistance genes. Moreover, rice lines with at least two resistance genes prevented the expression of BB infection on grain apperance. Results of this study had once again proven the effectiveness of MAS in generating BB resistant rice. | |
| dc.identifier.uri | http://granarium.clsu.edu.ph/handle/123456789/1438 | |
| dc.language.iso | en_US | |
| dc.relation.supervisor | JERWIN R. UNDAN, Ph.D. | |
| dc.title | Evaluation of bacterial blight resistance in marker assisted selection (MAS) Bred Rice Lines against Philippines Isolates of Xanthomonas oryzae pv oryzae | |
| dc.type | Thesis |