Integration of marker-assisted and field selection in developing TGMS lines for hybrid rice in the southern United States

Hybrid rice adoption in the southern United States, especially Arkansas, requires thermo-sensitive genic male sterile (TGMS) lines that combine stable sterility with glabrous foliage and grain quality preferred in U.S. markets. Over seven years (2014–2021), three TGMS lines—UAS3023, UAS20, and UAS4208—were developed through integration of marker-assisted and field-based selection targeting blast resistance ( Pi-ta , Pi-b ), semi-dwarf stature (sd1), amylose content, and gelatinization temperature. UAS3023 and UAS20 expressed ≥ 99% sterility at ~ 29 °C, while UAS4208 was sterile at ~ 32 °C, thresholds consistent with controlled-environment studies. All lines showed semi-dwarf stature, lodging resistance, glabrous leaves, and ~ 90% panicle exertion. Grain quality evaluations confirmed intermediate amylose (21–23%) and medium gelatinization temperature (70–74 °C), with milling yields comparable to long-grain checks Pat and Diamond. Field performance of their hybrids was similar in yield and agronomic traits to check cultivars. These adapted TGMS lines provide a foundation for hybrid seed production in the southern U.S., enabling the development of glabrous, high-quality hybrids with reliable sterility and desirable agronomic traits.