Ough durability of BB R genes is,in element,due to the fact mutation of Xoo to overcome R genes (Vera Cruz et alrecent field and laboratory research have also shown the influence of Aucubin temperature around the interactions of rice R gene with Xoo. High temperatures are conducive to BB disease,and most BB R genes,like Xa,are much less productive at controlling BB illness at high temperatures (Vera Cruz et al. ; Webb et al Xanthomonas oryzae (Xo) is usually a diverse species,with distinct phylogenetic lineages comprising US Xo,Asian Xoo,African Xoo,and Xanthomonas oryzae pv. oryzicola (Xoc) (Triplett et al. ; Hajri et al A further lineage improperly named Xanthomonas campestris pv. leersiae (Xcl) comprises strains isolated on weeds (Wonni et al Prior operate highlighted variations in the race structure between Asian and African Xoo strains (Gonzalez et al Virulence assays revealed 3 races (A,A and a) present in Mali,BurkinaFaso,Niger and Cameroon that don’t represent any on the known Xoo races characterized in Asia so far (Gonzalez et al. ; Triplett et al Based on experiments performed on BB isogenic lines (IRBB),BB resistance genes Xa,xa and Xa provide resistance to some African Xoo strains (Gonzalez et al Though in absence of a complete overview of Xoo race prevalence in Africa,we anticipated that Xa,xa and Xa could supply resistance against strains of Xoo in BurkinaFaso,Cameroun and Niger. In spite of the growing value of BB in Africa,little is identified on the genetic determinism of resistance. O. glaberrima and O. sativa accessions have been screened for resistance to African Xoo strains. The tropical japonica landrace Azucena is susceptible to all African Xoo strains. Couple of accessions,among them the indica cultivar IR,are extremely resistant to AfricanXoo strains. None of these accessions had the xa or Xa resistance alleles (Djedatin et al. suggesting that these accessions carry new resistance genes that might be very good targets for R gene discovery and additional deployment. With the completion of genome sequences for japonica and indica rice (Kawahara et al. and for O. glaberrima (Wang et al. a,b),it’s crucial to possess a improved image in the distinct Xa resistance genes and QTLs characterized so far and their positions in the rice genome. The objectives of this study are to: . Identify and analyse the genetic basis of rice resistance to African Xanthomonas oryzae pv. oryzae strains by building a QTL strategy employing the reference mapping population made of recombinant inbred lines (RIL) derived from the cross between IR and Azucena. . Map novel and known bacterial blight resistance genes and QTLs to Xoo strains and analyze their colocalization on the reference Nipponbare physical map. For the initial time in history,we report on precise resistance QTLs to African Xoo strains.RIL Recombinant Inbred LinesDjedatin et al. Rice :Page ofThis continuous variation of lesion lengths indicates the existence of QTLs underlying the segregation of resistance. Both parents,IR and Azucena,are susceptible to Asian Xoo strain PXO with an typical lesion length of . . and cm,respectively. Conversely,IR is resistant to PXO; the Philippines race ,with an typical lesion length of . . cm,whereas Azucena is susceptible with an average lesion length of . . cm. The lesion length of the RILs lines shows a continuous variation with an average PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/21710263 lesion length of . to . cm and . to . cm with PXO and PXO,respectively (Table,indicating the resistance to Asian strains is controlled by QTLs.Mapp.
