Impact of induced mutation-derived genetic variability, genotype and varieties for quantitative and qualitative traits in Mentha species.

PURPOSE: The genus Mentha spp. is an aromatic herb from the family 'Lamiaceae'. It is extensively predominant in temperate and sub-temperate regions of the world. The essential oil of this species is enriched with broad aroma constituents extensively utilized in food, beverages, flavor, cosmetics, perfumery, and pharmaceutical enterprises. With the global menthol market size estimated to be worth USD 765 million in 2022, India (accompanied by China and Brazil) is the world's primary manufacturer, consumer, and exporter of Mentha oil. Despite prominent global demand, the crucial bottleneck in mint cultivation is the need for more superior commercial cultivars. Predominant vegetative propagation mode with difficulties in manual emasculation, differential blooming times, sterile/sub-sterile hybrids, and low seed viability are the primary containment in creating genetic variability by classical breeding approaches. Therefore, genetic complications encountered in conventional breeding have led the breeders to apply mutation breeding as an alternative crop improvement approach in Mentha spp. These attempts at mutation breeding have produced some distinctive mutants as genetic pools for plant breeding programs, and some novel mutant mint cultivars have been made available for commercial cultivation. CONCLUSIONS: The prime strategy in mutation-based breeding has proven an adept means of encouraging the expression of recessive genes and producing new genetic variations. The present review comprises a significant contribution of mutation breeding approaches in the development of mutant mint species and its effects on physiological variation, photosynthetic pigment, essential oil content and composition, phytochemical-mediated defense response, pathogen resistivity, and differential expression of genes related to terpenoid biogenesis. Development and diversification have led to the release of varieties, namely Todd's Mitcham, Murray Mitcham, Pranjal, Tushar, and Kukrail in M. piperita L., Mukta, and Pratik in M. cardiaca Baker, Neera in M. spicata L., Kiran in M. citrata Ehrh., and Rose mint in M. arvensis L. that have revolutionized and uplifted mint cultivation leading to economic gain by the farmers and entrepreneurs.

Radio-frequency (RF) room temperature plasma treatment of sweet basil seeds (Ocimum basilicum L.) for germination potential enhancement by immaculation.

Ocimum basilicum L. is an antiviral and immunity boosting medicinal plant and culinary herb. Potential use of sweet basils in COVID 19 prevention and management is making its demand rise. This study is aimed at germination potential enhancement of sweet basil seeds. Reported study is evidenced with scientific data of radio-frequency cold plasma treatment using Ar + O2 feed gas. O. basilicum seeds, placed inside the rotating glass bottle, were directly exposed to RF (13.56 MHz) plasma produced in Ar + O2 feed gas. Seed treatment was done using RF source power (60 W, 150 W, 240 W), process pressure (0.2 mbar, 0.4 mbar, 0.6 mbar), and treatment time (5 min, 10 min, 15 min) at different combinations. Results show that, the most efficient treatment provide up to ∼89 % of the germination percentage which is an enhancement by 32.3 % from the control. SEM images revealed slight shrinkage in the seed size with eroded appearance over the seed. Enhancement of lipid peroxidation, show that oxidation of seed coat may propagate internally. Water imbibition analysis, of the treated seeds, was carried out for 2-12 hours. Further analysis of seed weight, on every one hour, after soaking shows enhanced water absorption capability except the treatment at 240 W, 0.6 mbar and 15 min. Plasma treatment enhanced carbohydrate content and protein content which is reported to be due to increased primary metabolism. Whereas, increased activity of secondary metabolism results in the enhancement of enzymatic (catalase) and non-enzymatic antioxidants (proline). Vital growth parameters, such as SVI I and SVI II, got amplified by 37 % and 133 % respectively after treatment. Ameliorative effects of plasma treatment are found highly significant with a positive and significant correlation value (p < 0.01) between germination percentages, SVI I, SVI II, carbohydrate, protein and proline show their interrelationship. Ar + O2 plasma treatment is found to bring forth significant changes in the O. basilicum seeds which eventually enhanced the germination potential and it could be a very promising technology for the medicinal crop.

Quantification of genetic variability and stable genotype selection over the years in the germplasm of critically endangered Prishanparni (Uraria picta Desv.).

Prishanparni (Uraria picta Desv.), a critically endangered annual shrub belonging to the family 'Papillionaceae'. It is widely distributed throughout India, Sri Lanka, Bangladesh, Tropical Africa, Malay Islands, and the Philippines. The consistent performances of U. picta accessions based on ten economic traits studied were identified as P-12, P-16, P-21, P-22, P-31, P-47, and P-48. These accessions could be used for commercial cultivation in northern Indian plains. Among the total twenty-three studied accessions P-50, P-21, P-48, and P-47 were found superior for rhoifolin content in their aerial as well as root part, which may have various therapeutic potentials used in traditional and modern systems of medicines. These accessions can be exploited for commercial cultivation or in a hybridization program for further crop improvement. Wide range cultivation of the selected accessions in the Indo-Gangetic plains will fit in the existing cropping systems of this region, resulting in comparatively better supplementation of herb to the pharmaceutical and herbal drug industries and reducing the pressure on the wild populations.

Gamma irradiation-induced variability in morpho-agronomic and oil quality traits of Mentha piperita L.

PURPOSE: To develop elite mutant in Mentha piperita having morphotype and oil content of Mentha arvensis, and oil quality of M. piperita. MATERIALS AND METHODS: The dormant runner of menthol rich genotype MPK-5 were subjected to different doses of γ- irradiation (10, 20, 30, 50, 70, 90, and 110 Gy) at a dose rate of 55 Gy/min to induce the genetic variability for herb and oil yield as well as oil quality. A wide spectrum of variability for agro-morphological traits, herb yield, and quality profile was observed among the mutants. RESULTS: The developed and selected superior mutants viz. MPK-5(1) and MPK-5(3) have a mean herb yield potential of 23.923 and 21.503 Kg/9 m2; mean oil yield of 92.953 and 80.047 ml/plot; mean menthol content of 69.012% and 69.160% with mean menthofuran content of 1.554% and 0.531%, respectively. CONCLUSIONS: Mutational breeding through γ- irradiation is considered complementary to the conventional breeding method, to broaden the spectrum of genetic variability. The developed and selected mutants namely viz. MPK-5(1) and MPK-5(3) identified as promising mutants, based on herb yield, oil yield, and essential oil quality, could be used as a parental line for exploitation in hybridization program/recombinant breeding.