Marker-Assisted Introgression of Broad Spectrum Bacterial Blight Resistance Gene Xa33 to CO43, a Salt and Alkaline Soil Tolerant Indica Rice Variety

CO43 rice variety is widely grown in coastal areas of Tamil Nadu, India. Production is, however, often constrained by disease such as bacterial blight (BB). To develop CO43 with inbuilt resistance to BB, the broad spectrum BB resistance gene Xa33 was introduced. Marker-assisted foreground selection was employed using the SSR marker RMWR7.5 linked to Xa33 gene along with background selection and stringent phenotypic selection for fostering recovery of the recurrent parent genome. In foreground selected BC₁F₁ plants, up to 84% recovery of the recurrent parent genome was achieved. BB screening result shows that the introgression lines were resistant. The BC₁F₂ segregating plants were equivalent in performance for some of the agronomic traits with recurrent parent. Therefore, CO43 (Xa33) can be developed as a commercial variety or can be used as immediate donor of BB resistance in CO43 breeding program to enriches the diversity of the local rice varieties.