A cold-tolerant evergreen interspecific hybrid of Ocimum kilimandscharicum and Ocimum basilicum: analyzing trichomes and molecular variations

Abstract

Ocimum (Lamiaceae) is an important source of essential oils and aroma chemicals especially eugenol, methyl eugenol, linalool, methyl chavicol etc. An elite evergreen hybrid has been developed from Ocimum kilimandscharicum and Ocimum basilicum, which demonstrated adaptive behavior towards cold stress. A comparative molecular analysis has been done through RAPD, AFLP, and ISSR among O. basilicum and O. kilimandscharicum and their evergreen cold-tolerant hybrid. The RAPD and AFLP analyses demonstrated similar results, i.e., the hybrid of O. basilicum and O. kilimandscharicum shares the same cluster with O. kilimandscharicum, while O. basilicum behaves as an outgroup, whereas in ISSR analysis, the hybrid genotype grouped in the same cluster with O. basilicum. Ocimum genotypes were analyzed and compared for their trichome density. There were distinct differences on morphology, distribution, and structure between the two kinds of trichomes, i.e., glandular and non-glandular. Glandular trichomes contain essential oils, polyphenols, flavonoids, and acid polysaccharides. Hair-like trichomes, i.e., non-glandular trichomes, help in keeping the frost away from the living surface cells. O. basilicum showed less number of non-glandular trichomes on leaves compared to O. kilimandscharicum and the evergreen cold-tolerant hybrid. Trichomes were analyzed in O. kilimandscharicum, O. basilicum, and their hybrid. An increased proline content at the biochemical level represents a higher potential to survive in a stress condition like cold stress. In our analysis, the proline content is quite higher in tolerant variety O. kilimandscharicum, low in susceptible variety O. basilicum, and intermediate in the hybrid. Gene expression analysis was done in O. basilicum, O. kilimandscharicum and their hybrid for TTG1, GTL1, and STICHEL gene locus which regulates trichome development and its formation and transcription factors WRKY and MPS involved in the regulation of plant responses to freezing and cold. The analysis showed that O. kilimandscharicum and the hybrid were very close to each other but O. basilicum was more distinct in all respects. The overexpression of the WRKY coding gene showed high expression in the hybrid as compared to O. kilimandscharicum and O. basilicum and the transcription factor microspore-specific (MPS) promoter has also shown overexpression in the hybrid for its response against cold stress. The developed evergreen interspecific hybrid may thus provide a base to various industries which are dependent upon the bioactive constituents of Ocimum species.

Detection of genetic variation among five basil species by using ISSR, SCOT and SRAP markers

“…ISSR markers also have the ability to amplify DNA fragments that are present at an amplifiable distance between two identical microsatellite repeat regions orientated in opposite direction (Reddy et al 2002). High polymorphism of ISSR was also reported in many previous studies, as in the case of Mentha arvensis, Ocimum (Malav et al 2015;Dhawan et al, 2016;Chaturvedi et al 2018;Alves et al 2019;Gupta et al 2021). Previous studies have also recommended that SCoT markers work better performance than other molecular marker systems in other plants (Luo et al, 2011).…”

Morpho-Physiological and Genomic Evaluation of Juglans Species Reveals Regional Maladaptation to Cold Stress

“…× intermedia but higher expression than pure J. regia as well. Some cold hardy gene expression studies reported that F1 hybrids of Ocimum kilimandscharicum (Camphor Basil) showed higher expression levels than pure species (Dhawan et al, 2016). Interspecific hybrid Pinus spp.…”

Ocimum basilicum (Basil) Modulates Apoptosis and Neurogenesis in Olfactory Pulp of Mice Exposed to Chronic Unpredictable Mild Stress

“…O. basilicum was found to ameliorate CUMS-induced neuronal changes in MOB especially mitral cells. This effect might be attributed to the bioactive compounds present in O. basilicum essential oils like linalool, eugenol, cineole, and many other compounds that exert free radical scavenging activity (8,24). These essential oils inhibit liposomal peroxidation and scavenge hydroxyl radicals, NO, and superoxide anion.…”

“…Ocimum basilicum (O. basilicum), also called basil or Raihan, is an annual plant used as a spice for culinary purposes in salads and pasta sauces. It is extensively utilized as a flavoring agent and in production of perfumes and soap (8,9). In addition, it is used for medicinal purposes due to its antidepressant, anxiolytic, sedative activities (10,11).…”