Abstract
BACKGROUND: Gamma ray induced mutation breeding has emerged as an excellent method for expedited development of improved varieties of rice, a staple food for more than half the world's population. However, the assessment of radiation induced variations are primarily phenotypic in nature. In this direction, evaluation of the metabolic signature of bio-active ingredients, which confer beneficial properties to rice, could be employed as a tool to select varieties which not only retain the health benefits of the parent variety but also exhibit better agronomic traits. The present study was, therefore, aimed at evaluating the metabolomic changes in the mutants of Gathuwan, an indigenous Indian rice with immunomodulatory properties. The mutant varieties were developed through gamma irradiation, and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolic profiling was performed. RESULTS: A total of 274 differentially expressed compounds were identified among Gathuwan and four of its mutants (mutant 6, mutant 7, mutant 8 and mutant 12), indicating that gamma irradiation induced stable metabolic alterations. Significant differences were observed in the phytochemical composition of mutants relative to the parent, emphasizing the importance of metabolic screening in functional rice breeding. Cluster analysis and phytochemical profiling revealed that mutant 6 was metabolically closest to the parent variety. Additionally, distinct phytohormonal variations among the mutants were observed which may account for the phenotypic differences in growth and development. CONCLUSIONS: Our study demonstrates that radiation-induced improvement in agronomic traits are accompanied by distinct alterations in phytochemical and phytohormonal profiles in stable rice mutants. These metabolic changes support the functional potential of the mutants and provide insights into the biological mechanisms underlying their traits. Among the mutants, mutant 6 emerges as a promising candidate due to its similarity to the parent in metabolite composition. Therefore, inclusion of metabolomic profiling as a selection criterion offers a powerful tool to identify robust and functionally superior rice varieties.