MSc

Ginger (Zingiber officinale Rosc.) is an important spice crop bestowed with numerous therapeutic properties. The therapeutic properties are attributed by various bioactive compounds, the most potent of which are the gingerols. The investigations entitled “Gingerol yield in microrhizome derived rhizomes and clonal fidelity analysis at different subculture passages of microrhizome production in ginger (Zingiber officinale Rosc.)” were carried out at the Centre for Plant Biotechnology and Molecular Biology (CPBMB), College of Horticulture, Vellanikkara, Thrissur, Kerala during 2018-2020. The objectives of the study were to assess gingerol yield in elicited microrhizome derived ginger rhizomes and to assess genetic fidelity at different subculture passages of microrhizome production using specific ISSR marker. Microrhizomes received from previous doctoral study (Manjusha, 2018) of the variety Aswathy were evaluated in the present investigations. The study was conducted as two separate experiments one in high tech polyhouse available at CPBMB and the other in open condition. Various planting materials viz. T1 (Microrhizomes in MMS medium), T2 (Microrhizomes in MMS medium with 5 % salicylic acid elicitation), T3 (Microrhizome in MS medium) and T4 (Conventional seed rhizomes-20g seed bit) were evaluated in high tech polyhouse as per the production technology standardized at CPBMB (Shylaja et al., 2018). The experiment in open condition was done as per PoP recommendations of KAU (KAU, 2016). The plant growth, yield of fresh rhizomes, oleoresin recovery and gingerol content were compared in both the experiments. For clonal fidelity analyses, multiple shoot cultures of three ginger varieties viz. Athira, Karthika and Aswathy received from CPBMB in the 5th subculture stage were advanced up to 9th subculture passage and fidelity was analysed using specific ISSR marker as per Gavande (2013). Microrhizome derived plants and conventional seed rhizome plants exhibited the same growth performance in characters like height of the pseudostem and number of leaves per longest tiller. The area of the longest fully opened leaf recorded at 120 DAP was more for microrhizome derived plants compared to conventional seed rhizomes. The fresh yield of rhizome per plant was on par in the different planting materials studied in both the experiments and ranged from 114.84g to 148.59g/ plant in poly house. The rhizome characters studied were on par in different planting materials except for the girth of secondary and tertiary fingers in which the microrhizome derived plants in MMS medium exhibited significantly higher values. The oleoresin yield was found higher in the microrhziome derived rhizomes in MS medium in polyhouse. Oleoresin yield was found higher in various treatments in the open condition. Conventional seed rhizomes showed the highest total gingerol content of (16.45%) in polyhouse. Among the microrhizome derived rhizomes, the microrhizomes in MMS medium recorded the highest total gingerol content (14.73%) in polyhouse. Highest gingerol content was recorded in conventional seed derived rhizomes followed by microrhizome derived rhizomes from MMS medium in poly house. The same result was observed in open condition experiment also but the recovery of gingerol was more in poly house experiment. The microrhizome derived rhizomes from MMS medium without elicitation recorded 14.5 per cent increase in gingerol yield compared to microrhizome derived rhizomes from MMS medium with elicitation in the polyhouse experiment. In clonal fidelity analysis, amplification with the ISSR primer (ISSR 05) generated clear amplicons in the size range 350- 1100 bp. Monomorphic amplicons were observed in all the three ginger varieties viz. Athira, Karthika and Aswathy for the 7th, 8th and 9th subculture passages. When compared with the source mother plant, polymorphism was not observed up to the 9th subculture stage for all the three ginger varieties and hence the plants produced are true to type. The study revealed that microrhizome plants have the potential to give high yield and quality rhizomes as evident by the same growth parameters exhibited by microrhizomes and conventional seed rhizome plants and higher leaf area and better rhizome characters exhibited by microrhizome plants. The yield realized in microrhizome plants are also on par with conventional seed rhizomes. The high gingerol content in the induced microrhizomes was seen exhibited in the harvested microrhizome derived rhizomes also. Microrhizomes perform better in high-tech poly house with precision agriculture. Clonal fidelity analyses with specific ISSR marker revealed that the regenerants produced up to 9th subculture cycle were true to type.