Gamma irradiation to induce beneficial mutants in proso millet (Panicum miliaceum L.): an underutilized food crop

Abstract

Purpose

Proso millet is a potential crop for food, nutritional security, and sustainable agriculture, particularly in the context of climate change. It is one of the traditional millet crops in cultivation in Tamil Nadu and India. Self-pollinated nature of this crop makes evolutionary process a terminal one and creating variability to broaden the genetic base is important. The objective of the study was to optimize mutagenic dose of gamma mutagen, document types of mutations and identify mutants for high grain yield (GY) and fodder yield (FY), hence to determine the feasibility of gamma mutagenesis in proso millet crop improvement.

Materials and methods

A mutation breeding program with 10 doses of gamma irradiation, i.e. 100, 200, 300, 400, 500, 600, 700, 800, 900 and 1000 Gy were imposed on seeds of variety ATL 1, a popular variety in India. Roll paper method, tray method and field evaluation were carried out to determine the LD₅₀ and GR₅₀ doses. Based on viable mutation frequency in M₂ generation, mutagenic effectiveness and efficiency was estimated. Targeted selection for yield and yield contributing traits was carried out in M₂, M₃ and M₄ generation to identify high yielding mutants.

Results

The LD₅₀ and GR₅₀ doses of gamma were estimated to be 418 Gy and 542 Gy, respectively. Based on results from probit analysis, mutagenic effectiveness, mutagenic efficiency and mutation spectrum, the optimum treatment dose of gamma was concluded to be 400 Gy. High frequency, i.e. 10.96% of phenotypic mutants was identified in the M₂ generation. The broad range of mutants identified in M₂ generation had mutations for plant height, plant habit, panicle shape, compactness, and length, days to 50% flowering (DFF), lodging resistance, tillering, leaf phenotype, apiculus color, culm branching, stem and leaf hairiness, sheath pigmentation, seed color and shape and seed coat attachment. Eight high yielding mutant families were isolated in M₄ generation. The mean single plant GY and FY of these mutants ranged between 25 to 51 g and 40 to 68 g respectively while in control it was 15 g and 30 g, respectively.

Conclusions

The wide spectrum and high frequency of mutations both for qualitative and quantitative traits suggest mutation induction as a promising method for creating novel variations in proso millet. The high yielding mutants identified can be utilized for varietal development both for grain and fodder purpose after further stability and quality evaluations in the advanced generations.

Keywords:

• Gamma rays
• mutation
• proso millet
• optimum dose
• yield mutants

Acknowledgements

We would like to thank the Department of Millets, CPBG, TNAU, Coimbatore, Department of Genetics and Plant Breeding, CPBG, TNAU, Coimbatore and Centre of Excellence in Millets, Athiyandal, TNAU, Tamil Nadu, India for providing the resources and facilities for research.

Disclosure statement

The authors report no conflict of interest.

Additional information

Funding

This research was funded by Tamil Nadu Agricultural University.

Notes on contributors

Neethu Francis

Neethu Francis, is a Doctoral Research Scholar, Department of Genetics and Plant Breeding, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, India. Her current research focus is proso millet crop improvement through mutation breeding.

Ravikesavan Rajasekaran

Ravikesavan Rajasekaran, is the Professor and Head, Department of Millets, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, India. He is a senior Plant Breeder with expertise in Cotton, Maize and millet crops.

Iyanar Krishnamoorthy

Iyanar Krishnamoorthy, is a Professor, Department of Millets, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, India. His area of expertise includes pearl millet and forage crop breeding and biometrical Genetics.

Raveendran Muthurajan

Raveendran Muthurajan, is a Professor and Head, Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. He is an expert in Plant Biotechnology, Molecular Breeding and Functional genomics.

Chitdeshwari Thiyagarajan

Chitdeshwari Thiyagarajan, is a Professor, Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. She is an expert in micronutrients and heavy metals research in soil and crops.

Senthil Alagarswamy

Senthil Alagarswamy, is a Professor, Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. He is an expert in abiotic stress and hormonal physiology