Molecular and physiological characterization of early semi-dwarf mutants of rice and localization of SNP variants in Sd1 locus generated through gamma radiation

• Published in: International journal of radiation biology 2024, Vol.100 (4), p.650-662
• Main Authors: Ramchander, Selvaraj, M T, Andrew-Peter-Leon, Khan, Yasin Jeshima, Souframanien, Jegadeesan, Arumugam Pillai, Madhavan
• Format: Article
• Language: English
• Subjects: Dwarfism; Gamma Rays; Gibberellins; Oryza - genetics; Phenotype; Polymorphism, Single Nucleotide; Syndactyly
• ISSN: 0955-3002; 1362-3095
• DOI: 10.1080/09553002.2024.2304827

The 'Improved White Ponni' (IWP) rice variety, which is susceptible to lodging, leading to yield losses. Our primary goal is to develop new rice lines with non-lodging traits, enhancing stem strength and resistance to adverse conditions. Additionally, we aim to improve yield-contributing agronomic traits, benefiting farmers, food security, and the environment. Our work contributes to scientific knowledge and addresses a significant issue in Southern Indian rice cultivation. In the present study, early and semi-dwarf early mutants of IWP were developed without altering the native grain quality traits using gamma ray-mediated mutagenesis. The seeds (500) were irradiated with γ-rays after fixing the Lethal Dose 50 (LD ), and selection for semi-dwarfism and earliness was imposed on a large M population. The selected traits were confirmed by evaluating the M lines at morpho-physiological, biochemical, and molecular levels. The response of mutants to gibberellic acid has been studied, which identified responsive mutants as well as slow-responding mutant lines including IWP-11-2, IWP-48-2, IWP-50-11, and IWP-33-2. Agar plate assay indicated low α- amylase content in IWP-50-11, IWP-33-2, IWP-43-1, IWP-47-2, and IWP-18-1. The scanning electron microscopy demonstrated that the mutants displayed an increased cellular dimension in comparison to the wild type. In dwarf mutants, null alleles were observed for the gene-specific primers which depicts gene undergone mutation. Further sequencing revealed the presence of single nucleotide polymorphisms in the gene resulting in semi-dwarfism in the mutant IWP-D-1. The impact of a defective gibberellic acid-mediated signaling pathway in mutants to produce a novel high-yielding and early maturing semi-dwarf rice variety.