Browsing by Author "Onaga, Geoffrey"

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    Genome-wide association analysis identifies resistance loci for bacterial blight in diverse East African rice germplasm
    (Academic Journals, 2023-07-31) Okello, Moses; Mildred, Ochwo S.; Lamo, Jimmy; Onaga, Geoffrey; Odong, Thomas L.; Tusiime, Geoffrey; Tukamuhabwa, Phinehas; Mukasa, Settumba B.; Wasswa, Peter; Ogwal, Jonathan; Oliva, Ricardo
    Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of rice bacterial blight disease has been extensively characterized, and loci against different races identified. Many rice cultivars have been developed and utilized to combat the disease, however, due to the rapid evolution of Xoo, several resistances have broken down. The continuous challenge of ever-evolving Xoo and the breakdown of resistance in cultivated rice varieties make it even more important to discover new loci to enable sustainable durable deployment of broad-spectrum resistance genes in elite breeding lines. African germplasm can be exploited as reservoirs of useful genetic variation for bacterial blight (BB) resistance. This study was conducted to identify loci associated with BB resistance and new genetic donors for the breeding program. To identify candidate sources of resistance for advancing breeding, four virulent strains of Xoo (PXO99, MAI1, BAI3, and Xoo3-1) were used to screen 78 East African accessions by genome-wide association studies. The diverse accessions' core genetic base exhibited high resistance to the Xoo strains. 50.63% of the accessions were highly resistant to the Philippines strain PX099, while 20.25% were highly susceptible to the virulent West African strain MAI1. Two novel resistant loci significantly associated hotspots were identified using 1901 SNPs. The two hits were located on chromosome 12 (Xa25) and Chr. 6 (Xa7, Xa27, Xa33). Novel loci were identified that gives a useful basis for more investigation and a wide core genetic pool of high resistance for broad-spectrum resistance for genetic improvement.
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    Genome-wide association mapping in rice MAGIC indica panel detects QTLs and genes for broad-spectrum resistance breeding against African bacterial blight
    (ORYZA-An International Journal of Rice, 2024-03-30) Okello, Moses; Ssemakula, Mildred Ochwo; Lamo, Jimmy; Onaga, Geoffrey; Odong, Thomas L; Geoffrey, Tusiime; Tukamuhabwa, Phinehas; Mukasa, Settumba B; Wasswa, Peter; Ogwal, Jonathan; Oliva, Ricardo
    Rice (Oryza sativa) bacterial blight (BB) is a direct threat to production in Africa. The extent of damage on the continent is not known. We conducted a genome-wide association study (GWAS) to seek out Quantitative trait loci (QTL) that confer the broad-spectrum resistance (BSR) to rice Xanthomonas oryzae pv. oryzae in the rice Multiparent advanced generation intercross (MAGIC) population. The diverse genetic composition and high levels of recombination, are potential resources for the identification of QTL for BSR. Dealing with the everevolving Xoo requires identification of novel R gene and resistance quantitative trait loci (QTL). We conducted a genome-wide association study (GWAS) using 250 rice MAGIC indica panel to evaluate for resistance to three Xoo strains from Cote D'Ivoire, namely XooCIkor, XooCIgag and XooCIcii2 which are prevalent highly virulent pathotypes. Using the 3 K RG 4.8mio filtered SNP Dataset, a total of 3 QTL associated with BB resistance on chromosome 9, 6 and 5 were identified. The results of the GWAS identified novel loci that gives useful insight for more investigation and also validated known genes underlying resistance to virulent African strains of BB. Genetic donors identified in this will help plant breeders in improving and broadening resistance to BB.