1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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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 Physiological and molecular assessment of abiotic stress tolerance in selectively fertilized coconut hybrids (Cocos nucifera L.)(Department of Plant Physiology, College of Agriculture,Vellayani, 2024-03-14) Afna Mol, O P; KAU; Roy Stephen; Gladis, RThe present study entitled “Physiological and molecular assessment of abiotic stress tolerance in selectively fertilized coconut hybrids (Cocos nucifera L.) was carried out in the Department of Plant Physiology, College of Agriculture, Vellayani during 2018-2023. The objective of the study was physiological and molecular evaluation of selectively fertilized coconut hybrids for water stress and temperature stress tolerance and to assess genetic variability for temperature stress tolerance through pollen selection at critical temperature. The study consisted of four experiments. In the first experiment, 10 year old field grown coconut palms of the following varieties Kerasree (WCT X MYD)- 198 selectively fertilized, Keraganga (WCT X GB)-selectively fertilized, Kerasree (WCT X MYD) Hybrid, Keraganga (WCT X GB) Hybrid and West Coast Tall at Regional Agricultural Research Station, Pilicode, Kasaragod were used as the experimental material for the study. The experiment was carried out in Randomized Block Design (RBD) with four replications during 2019 March to 2019 April. Water stress was imposed by withdrawing irrigation from the field for one month and physiological and biochemical observations were made at 15 days interval .Then the palms were irrigated on 30th day and recovery responses were analysed on 15th day after the irrigation rescheduling. On physiological analysis, selectively fertilized Kerasree showed higher relative water content and epicuticular wax of the leaves. Keraganga selectively fertilized showed maximum photosynthetic rate and cell membrane stability index. Leaf temperature was minimum in Kerasree selectively fertilized hybrids followed by Keraganga selectively fertilized hybrid. WCT recorded higher transpiration rate followed by Kerasree selectively fertilized hybrid. Stomatal conductance was higher in WCT and then in Kerasree selectively fertilized hybrids. In all the parameters tested both the selectively fertilized hybrids responded positively towards drought than their normal hybrids and this was an indication of higher water use efficiency in them. Recovery response after rewatering was also higher in selectively fertilized hybrids than their normal hybrids. The biochemical parameters like chlorophyll content, antioxidant enzymes viz SOD and peroxidase activities were found maximum in Kerasree selectively fertilized hybrids under water stress condition. Recovery response of these parameters were also found elevated in Kerasree selectively fertilized hybrids. Also Kerasree selectively fertilized hybrids showed lowest membrane damage (lipid peroxidation value) compared with normal hybrids and WCT. Amount of proline in leaves was found higher in WCT, which was on par with Kerasree selectively fertilized hybrid and Keraganga selectively fertilized hybrid. 199 In the second experiment, molecular characterization was carried out in the above five treatments. Protein profiling of leaves was done in all the five treatments of experiment one, using SDS-PAGE, in which, there was variation in the intensity of large subunit (55 kDa) as well as small subunit (around16 kDa) of RuBisCO, among the treatments. The intensity of those bands were found higher in WCT and Kerasree selectively fertilized hybrid .The band expressed in selectively fertilized hybrid in between 26 kDa to 36 kDa was absent in other treatments.. SSR markers CncirE2, CncirE10, CncirE12 and CncirH4 were screened in five treatments and polymorphism was observed in CncirE2, CncirE12, and CncirE10. RNA-seq tranascriptomic analysis of Kerasree selectively fertilized hybrid in reference with Kerasree was done to identify the key differentially expressed genes (DEGs) responding to water stress tolerance in Kerasree selectively fertilized hybrid. A total of 16671 genes were found expressed in Kerasree SF differing from Kerasree. 9635 genes were upregulated and remaining 7036 genes were down regulated in Kerasree SF.Abiotic stress related genes like late embryogenesis abundant protein Lea5 and HSPs were found differently expressed in Kerasree S.F hybrid in response to water stress. Gene ontology of the identified genes revealed that in terms of biological processes the following were the most represented GO terms (GO:0006749, 24 proteins, GO:0006468, 23 proteins,GO:0009415,12). In cellular component (GO: 0016020, 31 proteins) and in molecular function (GO: 0005524, 56 proteins, GO: 0009408, 21 proteins) the above shown were the most represented GO terms. In experiment three, physiological assessment of temperature stress tolerance of selectively fertilized coconut hybrids was done. Pollen grains were collected from the selectively fertilized coconut palms during summer season. The pollen grains were incubated in specific pollen germination media and exposed to different temperature ranging from 35oC to 45oC for a period of 2 hours. The temperature at which only 20-30 % of pollen germinated was identified as the critical temperature stress for pollen germination. From the results obtained, both the selectively fertilized hybrid of Kerasree and Keraganga were noted with maximum critical temperature for pollen germination (42oC) followed by WCT (40oC).This indicated 200 the temperature stress tolerance of selectively fertilized hybrids over their normal hybrids. Pollen viability was found maximum in WCT followed by Kerasree selectively fertilized hybrid. Accumulation of starch was found significantly higher in Kerasree selectively fertilized hybrid and the protein in WCT. The fourth experiment was conducted to screen temperature stress tolerance of 30 coconut genotypes in Regional Agricultural Research Station, Pilicode for recognizing the temperature stress tolerance through critical temperature for pollen germination. Significant genetic variation in critical temperature was discerned among the treatments. Andaman ordinary and Tanjore coconut genotypes were observed with higher critical temperature (42oC) for pollen germination. Hence they can be used as a pollen parent in hybridization programs for developing temperature stress tolerance. The present study revealed that Kerasree selectively fertilized and Keraganga selectively fertilized hybrids of coconut were more tolerant to water stress than normal hybrids in terms physiological, biochemical and molecular parameters. Selectively fertilized hybrids developed through pollen selection at critical water potential also have temperature stress tolerance. By selective fertilization techniques it may be possible to add water stress and temperature stress tolerance traits to high yielding coconut hybrids.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.