Proteome Profiling of the Mutagen-Induced Morphological and Yield Macro-Mutant Lines of Nigella sativa L

Frequency and spectrum of M2 mutants and genetic variability in cyto-agronomic characteristics of fenugreek induced by caffeine and sodium azide

Trigonella foenum graecum L. (Fenugreek) is a valuable medicinal plant cultivated for decades for its therapeutic characteristics. Still no pronounced improvement concerning wild form was accomplished as it is a self-pollinating crop. Induced mutagenesis is encouraged as a remarkable tool on this plant to circumvent the genetic bottleneck of cultivated germplasms. As a result, novel allelomorphic combinations for short-term agronomic attributes were developed. Fenugreek cultivar Pusa Early Bunching, selected for the present experiment, was mutagenized with five doses (0.2%, 0.4%, 0.6%, 0.8%, and 1.0%) of caffeine and sodium azide (SA) to evaluate its impact on the qualitative and quantitative traits of M₁ and M₂ generation conducted in a Complete Randomized Block Design (CRBD), replicated five times during 2019-2020 and 2020-2021, respectively. The frequency of induced phenotypic variations was assessed in M₂ progenies, resulting in the identification and isolation of a broad spectrum of mutants with altered phenotypes. Mutagenic effectiveness and efficiency were found to be maximum at lower concentrations of the mutagen treatments and highest in SA, followed by caffeine. Various morphological mutants with modified characters were observed at different concentrations in M₂ generation. The spectrum of mutations was wider in SA than in caffeine, as caffeine produced 51 while SA produced 54 individual mutants under seven major categories. The maximum frequency of morphological mutants was associated with leaf, followed by plant size, plant growth habit, pod, seed size, seed shape, and seed color. Morphological and structural variations in the guard cells of stomata and seeds were observed through scanning electron microscopy. The variations created in the economically important traits may enrich the genetic diversity of this plant species. Moreover, these morphological mutants may serve as a source of elite genes in further breeding programs of fenugreek.

Mutagenesis Approaches and Their Role in Crop Improvement

Induced mutagenesis is one of the most efficient tools that has been utilized extensively to create genetic variation as well as for identification of key regulatory genes for economically important traits toward the crop improvement. Mutations can be induced by several techniques such as physical, chemical, and insertional mutagen treatments; however, these methods are not preferred because of cost and tedious process. Nonetheless, with the advancements in next-generation sequencing (NGS) techniques, millions of mutations can be detected in a very short period of time and, therefore, considered as convenient and cost efficient. Furthermore, induced mutagenesis coupled with whole-genome sequencing has provided a robust platform for forward and reverse genetic applications. Moreover, the availability of whole-genome sequence information for large number of crops has enabled target-specific genome editing techniques as a preferable method to engineer desired mutations. The available genome editing approaches such as ZFNs (Zinc Finger Nucleases), transcription activator like effector nucleases (TALENS), and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated9 (Cas9) endonuclease have been utilized to perform site-specific mutations in several plant species. In particular, the CRISPR/Cas9 has transformed the genome editing because of its simplicity and robustness, therefore, have been utilized to enhance biotic and abiotic stress resistance. The Special Issue of Plants highlights the efforts by the scientific community utilizing mutagenesis techniques for the identification of novel genes toward crop improvement.