Induced Mutagenesis Expands Genetic Base and Drives Cultivar Development in Black Gram
Abstract
Black gram is a nutritionally rich grain legume constrained by a narrow genetic base. Induced mutagenesis is a valuable technique for creating novel variability. This study investigated the potential of gamma rays and electron beam irradiation to induce mutations in the black gram variety TU94-2 and characterized the biochemical basis of Urdbean Leaf Crinkle Virus (ULCV) resistance. Seeds were treated with 200, 300, 400, and 500 Gy of each mutagen. The M₁ generation was assessed for biological damage, while chlorophyll and morphological mutants were screened in the M₂ generation. Mutagenic effectiveness and efficiency were calculated. Selected mutants and control cultivars were evaluated for ULCV resistance and seed sugar composition. The results indicated that 400 Gygamma rays and 300 Gyelectron beams were optimal, causing low plant damage while inducing high genetic effects. Biochemical profiling revealed that the resistant cultivar VBN (Bg) 6 maintained chlorophyll and protein homeostasis under infection, unlike the susceptible CO 5. The study demonstrates that induced mutagenesis is a potent tool for generating valuable genetic diversity for black gram improvement.
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Introduction
Black gram (Vigna mungo (L.) Hepper), widely recognized as urdbean, is a nutritionally rich grain legume containing approximately 25–28% protein, primarily cultivated in the Indian subcontinent. Despite its value, genetic improvement has been constrained by a narrow genetic base due to its self-pollinating nature (Gupta et al., 2005). Since genetic variation is essential for crop improvement, induced mutagenesis has become a valuable tool for generating new genetic diversity. Various physical mutagens, including gamma rays, X-rays, and neutrons, have been effectively employed to generate mutants. Over the last eight decades, physical mutagens—especially ionizing radiations such as gamma-rays, X-rays, and neutrons— have been the most extensively used, accounting for over 70% of mutant varieties developed through physical mutagenesis (Mba, 2025). According to the FAO/IAEA Mutant Variety Database (MVD), more than 3,281 officially released mutant varieties with improved traits have been documented. The majority were developed using ionizing radiation, primarily gamma-rays (64%) and X-rays (22%). Since mutation is a random process, the successful recovery of desirable mutants depends on mutagenic efficiency, the genetic quality of the original material, and the effectiveness of the screening procedure (Hase et al., 2025).
In black gram, mutation breeding research began in the 1960s. Research efforts at the Bhabha Atomic Research Centre (BARC) have successfully integrated mutation and recombination breeding to develop several improved cultivars, such as TAU-1, which has seen widespread adoption in Maharashtra. In recent years, besides conventional radiations, electron beam radiation has emerged as a promising alternative. The present study investigates: (1) the potential of electron beam irradiation to induce chlorophyll and morphological mutations in black gram in comparison with gamma-rays, and (2) the biochemical response of contrasting genotypes to Urdbean Leaf Crinkle Virus infection.
Conclusion
This research successfully demonstrates the efficacy of gamma ray and electron beam irradiation in creating useful genetic variability in black gram. The identified optimal doses provide a guideline for future mutation breeding work in this crop. Furthermore, the biochemical characterization of virus resistance establishes key physiological markers—chlorophyll retention, stable protein levels, and controlled sugar accumulation—that can be used for screening mutant populations. The developed mutant lines offer valuable genetic resources for direct cultivation or for use as parental lines in hybridization programs aimed at developing high-yielding, virus-resistant black gram varieties. This integrated approach of mutation induction and physiological screening contributes significantly to strategies for sustainable pulse production. CONFLICT OF INTEREST The authors declare no conflict of interest.
