DNA SeqUeNCINg ANAlySIS Of AfRICAN Xanthomonas oryzae pv. oryzae vIRUleNCe geNe (aXaVrg) DNA MARkeR

Global rice production is constrained by bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo). BLB disease incidence in West Africa was between 70–85% and yield loss in farmers’ fields was in the range of 50–90% from 2005 to 2010. In the present study, African Xoo virulence gene OPP-172000 DNA marker was identified and purified using randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) products from 50 Xoo isolates. Genomic DNA of 50 Xoo isolates were analyzed using OPP-17 primer in RAPD-PCR during which African Xoo virulence gene OPP-172000 DNA marker was identified, purified, cloned, and sequenced. Cloning and DNA sequencing of African Xoo virulence gene OPP-172000 DNA generated a 1953 bp nucleotide sequence consequently tagged as AXaVrg-1953. BLAST homologous analysis of the AXaVrg-1953 sequence provides comprehensive identification of the type II secretion genes and secreted proteins, type III secretion genes and secreted proteins in African Xoo virulence gene. Phylogenetic unweighted pairgroup method arithmetic (UPGMA) analysis revealed the African AXaVrg-1953 sequence was distinct from the other Xoo virulence gene sequences from China, Japan, Korea, Germany, and the United States. This information is potentially useful for effective management of BLB disease in West Africa. Bacterial leaf blight, Operon primer, RAPD-PCR products, Xoo virulence gene DNA marker, cloning, Secreted proteins, BLAST, West Afric

Genetic analysis of resistance to rice bacterial blight in Uganda

Rice bacterial blight ( Xanthomonas oryzae pv. oryzae ) is a major constraint to rice ( Oryza sativa L.) production in Uganda and as part of strategies to develop resistant cultivars, it is important to evaluate resistance of commonly used cultivars. A full-diallel mating design involving three resistant and three susceptible rice cultivars was used to produce F1 and F2 progenies in a screen-house at the National Crop Resources Research Institute (NaCRRI), Namulonge in Uganda. The parents and F2 populations were challenged with the 64 Xanthomonas oryzae pv. oryzae isolate (UX00) and lesion lengths were scored 21 days after inoculation (DAI). Griffing\u2019s combining ability analysis showed significant specific combining ability (SCA) and non-significant general combining ability (GCA) effects, indicating the preponderance of non-additive gene effects in controlling the resistance to bacterial leaf blight (BLB) in rice. Rice genotypes, NERICA14, NERICA10 and NERICA4 had desirable GCA estimates, and were, therefore, the best general combiners. Crosses CO39 x NERICA10 and NERICA14 x IRAT104 had favorable SCA values. These hybrids are thus, promising in developing the BLB resistant progenies. Significant reciprocal effects indicate the importance of maternal contribution in controlling the BLB virulence. For this, resistant lines can be used as female parents for fear of affecting transfer of resistance to the progenies, and the hybrids and their reciprocals would be handled separately. Low estimates of narrow sense coefficient of genetic determination (NSCGD) (0.9%) and medium broad sense coefficient of genetic determination (BSCGD) estimates (16.4%) highlight the influence of non-additive gene action in controlling the resistance to BLB, confirming an effective selection of superior genotypes at advanced generations when the maximum homozygosity is fixed.Le fl\ue9trissement bact\ue9rien des feuilles du riz ( Xanthomonas oryzae ) constitue une contrainte majeur \ue0 la production du riz ( Oryza sativa L.) en Uganda. L\u2019\ue9valuation de la r\ue9sistance des cultivars commun\ue9ment utilis\ue9s s\u2019av\ue8re n\ue9cessaire comme une des strategies de d\ue9veloppement des cultivars r\ue9sistants. Des cultivars de riz (Oryza sativa L.) dont trois r\ue9sistants et trois susceptibles \ue9taient crois\ue9s en dispositif diall\ue8le complet pour produire des g\ue9n\ue9rations F1 et F2 dans une serre de l\u2019 Institut National de Recherche sur les Resources V\ue9g\ue9tales (NaCRRI) \ue0 Namulonge en Ouganda. Les parents et les populations F2 \ue9taient soumis \ue0 l\u2019isolat UX00 du Xanthomonas oryzae pv.oryzae et les longueurs de la l\ue9sion \ue9taient \ue9valu\ue9es 21 jours apr\ue8s l\u2019inoculation. L\u2019analyse de l\u2019aptitude \ue0 la combinaison par la m\ue9thode de Griffing ont r\ue9v\ue9l\ue9 des effets significatifs de l\u2019Aptitude Sp\ue9cifique \ue0 la Combinaison (ASC) et non significatifs de l\u2019Aptitude G\ue9n\ue9rale \ue0 la Combinaison (AGC), indiquant la pr\ue9pond\ue9rance des effets g\ue9n\ue9tiques non additifs dans le contr\uf4le de la r\ue9sistance au fl\ue9trissement bact\ue9rien des feuilles (FBF). Des g\ue9notypes NERICA14, NERICA10 et NERICA4 avaient des valeurs souhaitables d\u2019AGC, et \ue9taient ainsi des meilleurs combinants pour la r\ue9sistance au FBF. Des hybrides CO39 x NERICA10 et NERICA14 x IRAT104 avaient des valeurs favorables d\u2019ASC. Ils sont donc promettant dans le d\ue9veloppement des descendants r\ue9sistants au FBF. Des effets r\ue9ciproques significatifs indiquent l\u2019importance de la contribution maternelle dans le contr\uf4le de la virulence du FBF. Pour ce faire, des lign\ue9es r\ue9sistantes peuvent \ueatre utilis\ue9es comme parents femelles de peur d\u2019affecter le transfert de la r\ue9sistance aux descendants, et les hybrids ainsi que leur r\ue9ciproques pourraient \ueatre manipul\ue9s s\ue9par\ue9ment. De faibles valeurs (0.9%) du coefficient g\ue9n\ue9tique de d\ue9termination au sens restreint et valeurs moyennes (16.4%) du coefficient g\ue9n\ue9tique de d\ue9termination au sens large accentuent l\u2019influence de l\u2019action g\ue9n\ue9tique non additive dans le contr\uf4le de la r\ue9sistance au FBF, ce qui confirme une s\ue9lection effective des meilleurs g\ue9notypes aux g\ue9n\ue9rations avanc\ue9es quand le maximum d\u2019homozygotie est fix\ue9

Molecular Characterization and DNA Fingerprinting of Xanthomonas oryzae pv. oryzae Isolates from Climate Change Prone Areas in East Africa

Genomic DNA fingerprinting is a useful tool for effective and reliable identification and differentiation of Xanthomonas oryzae pv. oryzae (Xoo) pathogen from rice. The study aimed to conduct molecular characterization and DNA fingerprinting of 23 Xoo isolates from East Africa and two Xoo isolates from IRRI (Philippines) as control. PCR analysis was carryout on genomic DNA of 25 Xoo isolates using 6 Xoo specific primer pairs. Cluster analyses of genetic data obtained from 25 Xoo DNA fingerprints revealed two major genotypes (GrpA and GrpB) among the 25 Xoo isolates. GrpA has three subgroups (GrpA1; GrpA2; GrpA3) and GrpB (GrpB1; GrpB2; GrpB3). GrpA genotype consists of 20 Xoo isolates from Uganda, Rwanda and Philippines while GrpB genotype has 5 Xoo isolates from Rwanda. Some Xoo isolates were identical (PX-1, PX-2; UX621, RX2101; RX554, UX623, RX4113; UX211, UX213, UX214, RX4112, UX215). The emergence of subgroup genotypes could possibly be due to mutations and interactions among isolates and strains in host cells. Some Xoo isolates from Rwanda and Uganda were identical suggesting possible pathogen migration between these countries and long-term survival. Durable resistance rice cultivars would need to overcome both GrpA and GrpB Xoo genotypes in order to survive after their deployment into different rice ecologies in East Afric

Genetic analysis of resistance to rice bacterial blight in Uganda

Rice bacterial blight ( Xanthomonas oryzae pv. oryzae ) is a major constraint to rice ( Oryza sativa L.) production in Uganda and as part of strategies to develop resistant cultivars, it is important to evaluate resistance of commonly used cultivars. A full-diallel mating design involving three resistant and three susceptible rice cultivars was used to produce F1 and F2 progenies in a screen-house at the National Crop Resources Research Institute (NaCRRI), Namulonge in Uganda. The parents and F2 populations were challenged with the ≤ Xanthomonas oryzae pv. oryzae isolate (UX00) and lesion lengths were scored 21 days after inoculation (DAI). Griffing’s combining ability analysis showed significant specific combining ability (SCA) and non-significant general combining ability (GCA) effects, indicating the preponderance of non-additive gene effects in controlling the resistance to bacterial leaf blight (BLB) in rice. Rice genotypes, NERICA14, NERICA10 and NERICA4 had desirable GCA estimates, and were, therefore, the best general combiners. Crosses CO39 x NERICA10 and NERICA14 x IRAT104 had favorable SCA values. These hybrids are thus, promising in developing the BLB resistant progenies. Significant reciprocal effects indicate the importance of maternal contribution in controlling the BLB virulence. For this, resistant lines can be used as female parents for fear of affecting transfer of resistance to the progenies, and the hybrids and their reciprocals would be handled separately. Low estimates of narrow sense coefficient of genetic determination (NSCGD) (0.9%) and medium broad sense coefficient of genetic determination (BSCGD) estimates (16.4%) highlight the influence of non-additive gene action in controlling the resistance to BLB, confirming an effective selection of superior genotypes at advanced generations when the maximum homozygosity is fixed.Le flétrissement bactérien des feuilles du riz ( Xanthomonas oryzae ) constitue une contrainte majeur à la production du riz ( Oryza sativa L.) en Uganda. L’évaluation de la résistance des cultivars communément utilisés s’avère nécessaire comme une des strategies de développement des cultivars résistants. Des cultivars de riz (Oryza sativa L.) dont trois résistants et trois susceptibles étaient croisés en dispositif diallèle complet pour produire des générations F1 et F2 dans une serre de l’ Institut National de Recherche sur les Resources Végétales (NaCRRI) à Namulonge en Ouganda. Les parents et les populations F2 étaient soumis à l’isolat UX00 du Xanthomonas oryzae pv.oryzae et les longueurs de la lésion étaient évaluées 21 jours après l’inoculation. L’analyse de l’aptitude à la combinaison par la méthode de Griffing ont révélé des effets significatifs de l’Aptitude Spécifique à la Combinaison (ASC) et non significatifs de l’Aptitude Générale à la Combinaison (AGC), indiquant la prépondérance des effets génétiques non additifs dans le contrôle de la résistance au flétrissement bactérien des feuilles (FBF). Des génotypes NERICA14, NERICA10 et NERICA4 avaient des valeurs souhaitables d’AGC, et étaient ainsi des meilleurs combinants pour la résistance au FBF. Des hybrides CO39 x NERICA10 et NERICA14 x IRAT104 avaient des valeurs favorables d’ASC. Ils sont donc promettant dans le développement des descendants résistants au FBF. Des effets réciproques significatifs indiquent l’importance de la contribution maternelle dans le contrôle de la virulence du FBF. Pour ce faire, des lignées résistantes peuvent être utilisées comme parents femelles de peur d’affecter le transfert de la résistance aux descendants, et les hybrids ainsi que leur réciproques pourraient être manipulés séparément. De faibles valeurs (0.9%) du coefficient génétique de détermination au sens restreint et valeurs moyennes (16.4%) du coefficient génétique de détermination au sens large accentuent l’influence de l’action génétique non additive dans le contrôle de la résistance au FBF, ce qui confirme une sélection effective des meilleurs génotypes aux générations avancées quand le maximum d’homozygotie est fixé