Registration of three long grain rice germplasm lines containing improved blast resistance with the Ptr gene, low chalk, excellent milling quality, and good yield

Abstract

Rice blast disease (caused by the fungus Magnaporthe oryzae B.C. Couch) is the most threatening disease of rice (Oryza sativa L.) worldwide. Three rice germplasm lines, designated as CS272 (Reg. no. GP-151, GSOR 201), CS324 (Reg. no. GP-152, GSOR 202), and CS353 (Reg. no. GP-153, GSOR 203) were selected from among nine 900 recombinant inbred lines (RILs) derived from a cross of the US-adapted cultivars ‘Cybonnet’ (PI 636726) and ‘Saber’ (PI 633624). These Cybonnet–Saber (CS) RILs were officially released by the USDA-ARS and the University of Arkansas Agricultural Experiment Station in cooperation with Louisiana State University, Crowley, LA. These three RILs have resistance to blast as determined under greenhouse conditions and uninoculated field trials conducted in Puerto Rico in 2017 and Crowley in 2018 and 2019. The RILs were resistant to most blast races as determined in inoculated greenhouse tests, resistant to leaf blast when tested in an upland blast nursery in Crowley, and resistant to panicle blast under flood conditions in Puerto Rico and Crowley. These CS RILs contain the major blast resistance gene Ptr identified on chromosome 12 originating from the Cybonnet parent. These three CS RILs are superior in panicle size and have many agronomic and grain-quality characteristics comparable to or better than those of both parents. The CS RILs can be used in rice-breeding programs for improving blast resistance, quality, and yield.