PG Thesis
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Item Effect of histone deacetylation in the regulation of somatic embryogenesis related genes in coconut (Cocos nucifera L.)(Department of Molecular Biology and Biotechnology, College of Agriculture,Vellayani, 2025) Beema, Y Basheer.The study entitled “Effect of histone deacetylation in the regulation of somatic embryogenesis-related genes in coconut (Cocos nucifera L.)” was conducted at the Department of Molecular Biology and Biotechnology, College of Agriculture, Vellayani, during 2023-2024. The objective of this study was to know the effect of histone deacetylation in the regulation of somatic embryogenesis related genes (SERK, BBM, WUS) and histone deacetylation gene (HDAC) in coconut (Cocos nucifera L.) in presence of HDAC inhibitor Trichostatin. Coconut somatic embryogenesis holds significant promise for cultivating superior coconut plants. Currently, no repeatable and efficient protocol exists for inducing somatic embryogenesis in this crop. Epigenetic regulators have been found to enhance cell differentiation and their role in promoting embryogenic induction has been observed in various recalcitrant crops (Abrahamsson et al., 2017). In many such species, histone acetylation modification of genes that control somatic embryogenesis has been reported to increase gene expression and subsequently improve the rate of somatic embryogenesis (Martinez et al., 2021). The acetylation of genes can be enhanced by using histone deacetylase inhibitors (HDAs). Trichostatin A (TSA), the most used histone deacetylase inhibitor (Görisch et al., 2005), blocks HDAC activity in cultured cells, leading to a significant increase in embryogenic growth (Wójcikowska et al., 2018). By specifically inhibiting HDAs, TSA causes an accumulation of acetylated histones, a corresponding reduction in DNA methylation, and an increase in gene activity (Wójcikowska et al., 2018). However, how HDAC inhibitors affect the acetylation of genes related to somatic embryogenesis in coconut is still not well explored. Keeping this in view, the present study was planned to find out the effect of Trichostatin in embryogenic callus induction. For analysing the effect of Trichostatin on callus induction, plumules from 11-month-old West Coast Tall (WCT) coconuts were scooped out, surface sterilized, and pre-cultured in Y3 basal medium for one month. The pre-cultured plumules were then inoculated into Callus Induction Medium (Y3 + 2,4-D (74.6μM), TDZ (4.5μM), spermine (50μM)) with varying concentrations of TSA (0.5μM to 2μM). The results showed no change in the rate of callus induction with Trichostatin treatment. In the control, a 20% embryogenic callus induction was achieved in 50 days. However, in the treatments with TSA, instead of callus development, enlargement of plumules was observed at 50 days of inoculation, with no change in status even after that period. The percentage of enlargement of plumules varied with TSA concentration and maximum was observed in 0.5μM TSA. Following the Trichostatin treatment, an analysis of the expression of somatic embryogenesis (SE) related genes and HDAC gene in control and treated samples was conducted. For gene expression analysis, RNA was isolated from plumules inoculated in 0.5μM TSA and control cultures using Trizol. Complementary DNA (cDNA) was synthesized by reverse transcription mix and subjected to quantitative real-time PCR (RT-qPCR) to analyze the expression levels of somatic embryogenesis marker genes (SERK, WUS, BBM) and histone deacetylase genes (HDAC). The results showed no significant change in the expression of the HDAC gene in both the control and the CIM with 0.5μM TSA. Additionally, the results revealed no expression of somatic embryogenesis-related genes in Trichostatin-treated samples. This finding suggests that Trichostatin treatment does not influence embryogenic callus induction, indicating a need to fine-tune the concentration and conditions of the treatment to optimize its effects. Conclusively, further optimization is required to achieve desirable results in somatic embryogenesis induction in coconut.Item Development of experimental kiln-drying schedules for different types of coconut (Cocos nucifera L.) palm wood flooring(Department of Forest Products and Utiliztion, College of Forestry, Vellanikkara, 2021) Shibu, C; Anoop, E VIn India, there is a significant gap existing between supply and demand for wood and wood products. Several factors influence wood consumption. For example, the construction sector is witnessing a shift to eco-friendly furnishings. Indeed, the eco-friendly amenity of wooden flooring in hotels and houses has contributed to an upswing in commercial wood consumption. In the current scenario, effective utilisation of existing lesser-known species such as Cocos nucifera L. (Coconut palm tree) is gaining prominence. The lesser known wood species will help to meet the domestic demand and may help to bridge the gap between supply and demand of timber. Seasoning of wood is a crucial step for producing defect-free timber for the ease of doing timber work and potential use of available timber. The purpose of this research is to develop experimental kiln-drying schedules for Cocos nucifera L. (Coconut palm tree) for various flooring methods (Tongue & Groove flooring (T&G flooring), Parquetry flooring, and Engineered overlay flooring). The substructure, base kiln-drying schedules were developed based on the Terazawa method (1965), and optimised using Rasialy (1993) classification. The critical conditions of equalizing treatment and conditioning treatment were established in relation to the product's desirable moisture content, which is 12% for general wood flooring products in climatic zone IV (Kerala). High-density wood samples with thicknesses of 25 mm and 50 mm (20 cm x 10 cm in length and width) were used to investigate drying defects under drastic conditions, and schedules for both thicknesses were developed. Similarly, schedules were developed using medium-density wood samples of 25 mm and 50 mm. The moisture content of the experimental samples (2 cm x 2 cm in length and width) was determined using the oven-dry method, and the basic density was determined based on the water displacement method. 83 The experimental kiln drying schedule recommended for 50 mm thick high-density coconut palm wood Tongue and Groove flooring and Parquetry flooring was MT4-B1 (schedule code). Initial Dry Bulb Temperature 39°C (Relative humidity 89%), Initial Wet Bulb Depression 2°C, and Final Dry bulb Temperature 57°C were the critical conditions for MT4-B1. The highdensity coconut palm wood (25 mm thick) is also suitable for Tongue & Groove flooring and Parquetry flooring and the schedule was MT6-B1 with Initial Dry Bulb Temperature 45°C (Relative humidity 90%), Initial Wet Bulb Depression 2°C, and Final Dry Bulb Temperature 62°C. The recommended experimental kiln drying schedule for medium-density coconut palm wood of 50 mm thickness was MT6-D2 as follows: Initial Dry bulb Temperature 42°C (Relative humidity 87%), Initial Wet Bulb Depression 2°C, and Final Dry bulb Temperature 57°C. The schedule for 25 mm thickness medium-density coconut palm wood was MT6-E1, which includes an Initial Dry bulb Temperature of 42°C (Relative humidity 87%), Initial Wet Bulb Depression of 2°C and a Final Dry bulb Temperature of 45°C. The medium-density coconut palm wood only can be used for overlay flooring because of its low strength. All the schedules are made, considering the desired moisture content (12%) for general flooring purposes under the prevailing conditions of Kerala (Relative humidity > 67%) as prescribed by the Bureau of Indian Standards (BIS).Item Morpho-molecular characterisation and evaluation of TxD, DxT and DxD hybrids of coconut cultivar ayiramkachi (Cocos nucifera L.)(Department of Plant Biotechnology, College of Agriculture, Padannakkad, 2021) Haritha, M R; Sujatha, RStudy on “Morpho-molecular characterisation and evaluation of TxD, DxT and DxD hybrids of coconut cultivar Ayiramkachi (Cocos nucifera L.)” was carried out at the Department of Plant Biotechnology, College of Agriculture, Padannakkad during 2018-2020. This investigation aimed at morphological and molecular characterisation of hybrids planted at RARS Pilicode during 1994, in the hybridization programme involving different tall and dwarf genotypes (WCT, Laccadive Ordinary, Philippines, Laccadive Micro, Andaman Ordinary and Malayan Yellow Dwarf) with Ayiramkachi, for important yield attributes and nut quality combined with dwarf stature. The evaluation based on morphological characters recorded during 2018-2020 revealed that the hybrids LMxAYK, MYDxAYK and LOxAYK were promising ones with high yield (155.50, 115.33 and 116.50 nuts/ palm/year respectively) and superior nut characters such as fruit weight, nut weight, shell and meat weight, kernel thickness and copra content. Hybrid PHIxAYK was superior for all the nut characters combined with a shorter stature but the yield was comparatively less (81.67 nuts/ palm/ year). The hybrid CCxAYK was high yielding (150.67 nuts/ palm/ year) but inferior in nut characters. Hybrid AOxAYK recorded good nut characters but was low yielding (61.50 nuts/palm/year). Hybrids of AYK with WCT recorded a moderate yield (95.00 nuts/ palm/ year) with inferior nut characters, and hybrid AYKxMYD was inferior for both yield (21 nuts/ palm/ year) and nut characters. On analysing the TxD, DxT and DxD groups with their tall (T) and dwarf (D) parents, all the hybrids recorded palm height statistically similar to the dwarf cultivars, which may be an indication of inheritance of shorter stature from the common parent AYK. Study on genetic parameters revealed that characters such as palm height, internode length, number of green leaves, rate of leaf production, petiole length, leaf length, number of female flowers per inflorescence, number of female flowers one month after pollination and shell and meat weight had shown high heritability (H2) coupled with high genetic advance as per cent means (GAM%). Hence choice of such characters are best suited for selective breeding. Yield and copra content had shownmedium heritability with high genetic advance. This might be due to the indirect effect of secondary characters contributing to them. Estimation of heterobeltiosis (superiority over better parent) and standard heterosis (superiority over standard check, Kerasree) for the nine hybrids of Ayiramkachi revealed that the hybrids LMxAYK and MYDxAYK were found to be better performers with respect to yield as well as nut characters, and can be exploited for developing commercially important hybrids suitable for culinary as well as processing purposes (copra and other value added products). The hybrid CCxAYK was high yielding but inferior in nut characters. As one of the parent in this cross, Cochin China, is suitable for tender nut purpose due to high nut water content, the hybrid nuts also may be further evaluated at tender nut stage for its suitability for tender nut purpose. Thirty four SSR markers were screened for polymorphism among the eight parental cultivars and the check palm (Kerasree). The markers produced an average of 52.94% polymorphism and 1 to 2 alleles/locus. Out of 34 SSR markers screened for polymorphism, 15 markers viz., CAC02, CAC11, CNZ40, CNZ44, CnCirA9, CnCirB12, CnCirE2, CnCirC7, CnCirH4, CnCirE12, CnCirC3, CnCirF2, CnCirH7, CnCirG11 and CnCirC5 were able to detect the polymorphism between the parental palms and hence can be utilized in future for fingerprinting the hybrid palms.