Molecular Identification of a Novel Fusarium fujikuroi Isolate and Genetic Characterization of Rice (Oryza sativa L.) Resistance to Bakanae Disease

Abstract

Bakanae disease, caused by Fusarium fujikuroi, is a major threat to rice production globally, especially in Egypt. No rice variety is completely resistant to bakanae disease. Here, we assessed resistance in 11 Egyptian rice genotypes, identified a novel F. fujikuroi strain using molecular techniques, and developed molecular markers for resistance breeding. ISSR and InDel PCR were used to determine the genetic distance between the genotypes and develop molecular markers for bakanae disease resistance. QRT-PCR was used to assess the gene expression of four resistance candidate genes. Sakha 103 and Sakha 104 were the most tolerant genotypes, while Sakha 101 and Sakha 108 were the most susceptible to bakanae disease. ISSR and InDel PCR showed high polymorphism values among genotypes and distinctive bands in the most tolerant varieties. Gene expression analysis revealed up-regulation of LOC_Os01g41770, LOC_Os01g41780, and LOC_Os01g41790, which encode leucine-rich repeat receptor-like proteins, in susceptible varieties. Additionally, LOC_Os01g41800, encoding a putative cytochrome P450 monooxygenase, was up-regulated in tolerant genotypes after inoculation. This study provides tools for screening rice genotypes for bakanae disease resistance and improving resistance breeding programs. The identified molecular markers and candidate genes could potentially be used in future breeding programs to develop new, Bakanae-resistant rice varieties, which is essential for sustainable rice production.