Soybean (Glycine max L.) is an important agricultural crop for human food and animal feed. Soybean yield is severely constrained by abiotic stresses such as salinity and drought, which affect large proportions of arable and irrigated lands worldwide. This necessitates the development of new soybean varieties tolerant to these stress factors. Mutation breeding is an effective approach to improve the stress tolerance of plants due to increased genetic diversity. In this study, two gamma-induced salinity and drought-tolerant soybean mutants (SM1 and SM3-1) were compared with the parental line S04-05 using GO and KEGG pathway enrichment analyses. GO enrichment analyses revealed extensive differential gene expression in the mutant lines under stress conditions, with significant enrichment of pathways related to photosynthesis, hormone signaling, carbohydrate metabolism, and flavonoid and isoflavonoid biosynthesis. Genotype-specific analyses indicated that the SM3-1 mutant exhibited a dynamic regulatory response associated with maintaining the photosynthetic apparatus and chloroplast homeostasis under stress, whereas the SM1 mutant showed an adaptation strategy based on metabolite-mediated osmotic adjustment and ROS scavenging. Compared to the parental variety S04-05, the mutants showed distinct metabolic regulation in phenylpropanoid/isoflavone metabolism, with upregulation of many isoflavone biosynthesis genes under salinity, drought, and untreated conditions, indicating a key and sustained role of this pathway in stress tolerance. Most SNPs identified in the isoflavone biosynthesis pathway consist of moderate-impact and modifier variations. These findings suggest that gamma mutagenesis and subsequent selection processes allow for the development of novel genetic variants that operate through different physiological and metabolic mechanisms but exhibit similar levels of tolerance. In this respect, the study reveals that mutation breeding is a potentially sustainable and effective breeding strategy for increasing abiotic stress tolerance in soybeans.

Humankind has been curious about the sky and beyond since its existence. Since the most primitive times, researchers have been trying to find answers to this curiosity. In recent years, a relatively new discipline, astrobiology, has emerged to answers to frequently asked questions. Astrobiology is an interdisciplinary field that tries to explain beyond the sky, and extraterrestrial life, where life origin came from, evolution, and the big bang. Extremophiles draw attention as the only creatures that will enlighten us in understanding extraterrestrial conditions and the mechanisms of creatures living in these conditions. This review examines the recent discoveries and the principal advances concerning both bacteria (Chroococcidiopsis sp., Colwellia psychrerythraea, Planococcus halocryophilus) and archaea (Halorubrum lacusprofundi and Halobacterium salinarum NRC-1) species which have potentials to examine in astrobiology as model organisms. Obtaining findings from different studies open new perspectives and strategies for several unresolved questions in astrobiology.