Enhancing the blast resistance of an elite thermo-sensitive genic male sterile line (TGMS) Longke638S and its derived hybrid varieties by incorporating Pigm gene

Rice blast, caused by the fungus Magnaporthe oryzae, is one of the most destructive diseases of rice worldwide. The utilization of host resistance (R) genes in rice breeding program is considered as the most economical, effective, environment-friendly strategy for rice blast control. The R gene Pigm, shows high, broad-spectrum and durable resistance to rice blast. Here, we report the successful integration of Pigm into Longke638S (LK638S), an elite thermo-sensitive genic male sterile (TGMS) line in hybrid rice production in China. The integration significantly enhanced the blast resistance of LK638S and the derived hybrid varieties demonstrated exceptional performance in both yield and blast resistance. The improved line Longzhen36S (LZ36S), which recovered 91.84% of the recurrent parent genome. LZ36S exhibited a high blast resistance frequency of 96.4% against 28 blast isolates. Furthermore, the LZ36S-derived hybrids exhibited enhanced resistance to both seedling and panicle blast compared to LK638S-derived hybrids carrying the heterozygous Pi2 gene, all without yield penalty. A total of ninety LK638S derived hybrid varieties have been state or provincial approved and certified with an annual promoting area exceed 964.0 thousand hectares. The LZ36S-derived hybrids can serve as improved versions with enhanced blast resistance, making them viable replacements for LK638S-derived hybrids in commercial production. Moreover, sixteen LZ36S-derived hybrid varieties, all possessing moderate (MR) or high (R) level blast resistance, along with excellent yield and grain quality, have been state or provincial approved and certificated. These LZ36S-derived hybrids show great potential for rapid commercialization, with promoting area of ~ 200 thousand hectares by 2023.