A novel locus from the wild allotetraploid rice species Oryza latifolia Desv. confers bacterial blight (Xanthomonas oryzae pv. oryzae) resistance in rice (O. sativa)

Abstract

Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is a major limiting factor to rice productivity worldwide. Genetic control through the identification of novel sources of bacterial blight resistance and their utilization in resistance breeding remains the most effective and economical strategy to manage the disease. Here we report the identification of a novel locus from the wild Oryza species, Oryza latifolia, conferring a race-specific resistance to Philippine Xoo race 9A (PXO339). The locus was identified from two introgression lines i.e. WH12-2252 and WH12-2256 that segregated from O. latifolia monosomic alien addition lines (MAALs). The discrete segregation ratio of susceptible and resistant phenotypes in the F 2 (χ 2 [3:1] = 0.22 at p>0.05) and F 3 (χ 2 [3:1] = 0.36 at p>0.05) populations indicates that PXO339 resistance in the MAAL-derived introgression lines (MDILs) is controlled by a single, recessive gene. Genotyping of a total of 216 F 2 , 1130 F 3 and 288 F 4 plants derived from crossing either of the MDILs with the recurrent parent used to generate the MAALs narrowed the candidate region to a 1,817 kb locus that extends from 10,425 to 12,266 kb in chromosome 12. Putative candidate genes that were identified by data mining and comparative sequence analysis can provide targets for further studies on mapping and cloning of the causal gene for PXO339 resistance in the MDILs. To our knowledge, this is the first report of a genetic locus from the allotetraploid wild rice, O. latifolia conferring race-specific resistance to bacterial blight.

Foliar Application or Seed Priming of Cholic Acid-Glycine Conjugates can Mitigate/Prevent the Rice Bacterial Leaf Blight Disease via Activating Plant Defense Genes

“…Fungicides, such as Hexaconazole, nanohexaconazole, Validamycin, and propiconazole, and formulation of Contaf 5 EC was effective against sheath blight caused by R. solani (Gopal et al, 2012;Uppala and Zhou, 2018). However, rice cultivation has spurred the emergence of new and more virulent races of Xoo or R. solani making the chemical means of disease management largely ineffective (Angeles-Shim et al, 2020). Therefore, instantaneous crop protection is a prerequisite to achieve the real yields of the crop.…”

Alien introgression and morpho-agronomic characterization of diploid progenies of Solanum lycopersicoides monosomic alien addition lines (MAALs) toward pre-breeding applications in tomato (S. lycopersicum)

“…In rice for example, Oryza latifolia MAAL progenies have been shown to segregate into both MAALs and fertile diploid lines at a ratio of 1:3, with the diploids mostly resembling the overall morphology of the cultivated parent. Genotyping of the identified diploids mapped distinct patterns of alien introgressions in the genetic background of the recurrent parent which were later associated with novel agronomic traits lacking in cultivated rice (Angeles-Shim et al 2014 , 2020 ).…”

Deployment of Genetic and Genomic Tools Toward Gaining a Better Understanding of Rice-Xanthomonasoryzae pv. oryzae Interactions for Development of Durable Bacterial Blight Resistant Rice

“…meyeriana ) ( Ruan et al, 2008 ), Xa32t ( O. australiensis ), Xa33 ( O. nivara ) ( Natrajkumar et al., 2012 ), Xa35t ( O. minuta ), and Xa38 ( O. nivara ) ( Cheema et al., 2008 ). A novel locus on chromosome 12 of O. latifolia (wild allotetraploid rice species) was identified recently, and it confer race specific resistance of Xoo strain PXO339 ( Angeles-Shim et al., 2020 ). Based on these developments, it can be inferred that wild relatives of Oryza are expected to contribute significantly in developing durable BB resistant rice varieties.…”