Two genomic regions of a sodium azide induced rice mutant confer broad-spectrum and durable resistance to blast disease

Abstract

Rice blast, one of the most destructive epidemic diseases, annually causes severe losses in grain yield worldwide. To manage blast disease, breeding resistant varieties is considered a more economic and environment-friendly strategy than chemical control. For breeding new resistant varieties, natural germplasms with broad-spectrum resistance are valuable resistant donors, but the number is limited. Therefore, artificially induced mutants are an important resource for identifying new broad-spectrum resistant (R) genes/loci. To pursue this approach, we focused on a broad-spectrum blast resistant rice mutant line SA0169, which was previously selected from a sodium azide induced mutation pool of TNG67, an elite japonica variety. We found that SA0169 was completely resistant against the 187 recently collected blast isolates and displayed durable resistance for almost 20 years. Linkage mapping and QTL-seq analysis indicated that a 1.16-Mb region on chromosome 6 (Pi169-6(t)) and a 2.37-Mb region on chromosome 11 (Pi169-11(t)) conferred the blast resistance in SA0169. Sequence analysis and genomic editing study revealed 2 and 7 candidate R genes in Pi169-6(t) and Pi169-11(t), respectively. With the assistance of mapping results, six blast and bacterial blight double resistant lines, which carried Pi169-6(t) and/or Pi169-11(t), were established. The complementation of Pi169-6(t) and Pi169-11(t), like SA0169, showed complete resistance to all tested isolates, suggesting that the combined effects of these two genomic regions largely confer the broad-spectrum resistance of SA0169. The sodium azide induced mutant SA0169 showed broad-spectrum and durable blast resistance. The broad resistance spectrum of SA0169 is contributed by the combined effects of two R regions, Pi169-6(t) and Pi169-11(t). Our study increases the understanding of the genetic basis of the broad-spectrum blast resistance induced by sodium azide mutagenesis, and lays a foundation for breeding new rice varieties with durable resistance against the blast pathogen.

Assessment of Variations in Catharanthus Roseus L. Induced by Gamma Rays and Sodium Azide Using Rapd Markers

“…A report stated that, in general, polymorphism among the treatments could arise through nucleotide changes that prevent amplification by introducing a mismatch at one priming site; deletion of a priming site; and insertions that render the priming site too distant to support amplification (Fadoul et al, 2013). Gamma rays and sodium azide mutagenesis established effects in many plant species, including cowpea (Raina et al, 2022), peanuts (Okasha et al, 2021), sweet potatoes (Orji et al, 2021), rice (Lo et al, 2021), and barley (Dyulgerova and Dyulgerov, 2022). RAPD markers recorded their ability to detect chemical and physical mutagens in many crops, including rice (Ikhajiagbe and Omoregie, 2020), potato (Mahfouze, 2012), fenugreek (Al-Saadi, 2022), coriander (Al-Rehbawy, 2022), and C. roseus (Salama and Ali, 2016;EL-Sayed, 2013).…”

Sequence-related Amplified Polymorphism and Target Region Amplification Polymorphism Markers-based Profiling of Sodium Azide and Ethyl Methanesulfonate-derived Black Rot-resistant Dendrobium sp. ‘Earsakul’ Mutants from In Vitro Mutagenesis and Selection

“…Mutation breeding is an alternative for breeders to develop new cultivars through induction either of radiation or of chemical mutagens because they generate genetic variations or even novel alleles, which may be associated with desirable traits (i.e., disease resistance). Sodium azide (NaN 3 ) and ethyl methanesulfonate (EMS) are popular chemical mutagens that are available for purchase and highly effective (Arisha et al 2014;Kumar et al 2011;Savita et al 2017;Yoosumran et al 2018), and they can be successfully used to induce disease resistance in economically important crops (Chen et al 2014;Lo et al 2022). Generally, both mutagens induce mutations by base substitution, leading to incorrect base-pairing, and they also induce chromosomal abnormalities.…”