Development of NSIC Rc 160-Sub 1: progress on marker assisted breeding

Submergence-prone of flash flood-prone rice areas in the country are estimated at 0.14 million hectares. Approximately 49% is found in the Visayas region and 36% is located in Mindanao. In Luzon, an estimated 21,000 hectares flash flood-prone is located in CAR, Region I (Ilocos Region) and Region 3 (Central Luzon). With the changes in climatic conditions and rainfall patterns become unpredictable, development of submergence tolerant rice cultivars is deemed important to reduce effects on yield and profit. PhilRice-bred cultivar NSIC Rc160 (Tubigan 14) can yield up to 8 tons/ha under favorable irrigated lowland condition. It has intermediate reactions to two major rice diseases, blast and bacterial leaf blight. This study aims to transfer the sub1 locus for submergence tolerance from IR64-Sub1 to NSIC Rc160 through marker-assisted back crossing. Sub1 markers ART5 and SC3 (RM8300) were evaluated in DNA analysis. However, NSIC Rc160 did not show polymorphism to IR64-Sub1 using RM8300. The authors have evaluated alternative markers located downstream of the sub1 locus in chromosome 9 including RM 316, RM464A and RM 219. Set of markers for recurrent parent genome selection was also evaluated. Initial results identified 14 SSRs showing polymorphic alleles between NSIC Rc160 and IR64-Sub1 out of 70 SSR markers analyzed. One thousand five hundred forty-one BC1F1, naked seeds of IR64-Sub1/NSIC Rc 160 were developed in 2010 wet season. The plants are being prepared for submergence screening in controlled facility and selection of lines with submergence tolerance. Progress and prospects on the development of NSIC Rc160 are discussed.