{"id":{"repo_id":"nus","oai_identifier":"oai:scholarbank.nus.edu.sg:10635/182416"},"canonical_url":"https://search.dev.ndltd.org/etd/nus/oai:scholarbank.nus.edu.sg:10635/182416","repository":{"repo_id":"nus","name":"National University of Singapore","base_url":"https://scholarbank.nus.edu.sg/oai/request"},"display":{"title":"PHYSIOLOGICAL STUDIES USING TISSUE CULTURES OF PLATYCERIUM CORONARIUM (KOENIG) DESV","abstract":"Direct plantlet regeneration from frond and rhizome explants of Platycerium coronarium cultured in vitro was achieved. Ethylene was produced during this process and its level in the culture vessels increased with time, resulting in a decrease in th, percentage of sporophytes produced. The presence of ethylene action inhibitor, silver thiosulphate, in the culture medium resulted in an increase in the percentage of plants regenerated, indicating an inhibitory effect of ethylene on regeneration. Inhibitors of ethylene biosynthesis (aminoethoxyvinylglycine, benzylisothiocyanate, cobalt chloride and salicylic acid) were ineffective in increasing sporophyte regeneration. Also, 1-aminocyclopropane-1-carboxylic acid, the ethylene precursor, was ineffective it, increasing the level of ethylene in the culture vessels. Therefore, the biosynthetic pathway of ethylene in P. coronarium appears to be different from that of higher plants, but similar to that of some other ferns. Apogamous sporophytes were produced on gametophytes cultured in the presence on 40 µM indole-3-acetic acid (IAA). When ethylene was allowed to accumulate in the culture vessels in the presence of IAA, the frequency of regeneration and the total number of apogamous sporophytes producted decreased significantly. Light arm confocal laser scanning microscopy were successfully used to check nuclear size which serves as a quick parameter to estimate ploidy level in P. coronarium. Callus was induced from both gametophyte and rhizome explants. Cell suspension culture was successfully initiated from gametophyte-derived callus and plating of cells on semi-solid MS medium with kinetin resulted in the production of two population, of callus distinguishable by their colouration. These were allowed to proliferate on MS medium with 2 µM 2,4-D. Subsequent culturing on basal MS medium resulted in the regeneration of gametophytes from the dark green callus and sporophytes from the pale green callus. Sporophytic callus (pale green) differentiated into both gametophytes and sporophytes after prolonged period in culture (7 months). The results indicate that cells of gametophytes are totipotent and plastic. Progressive reduction of sucrose concentration in the medium on which gametophyte .. derived callus was cultured resulted in a reduction in growth but an increase in total chlorophyll content, chlorophyll fluorescence, autofluorescence of chloroplasts and ribulose bisphosphate carboxylase (RuBPC) activity. Under prolonged CO2 enriched conditions, photoautotrophic callus of P. coronarium showed an increase in biomass and phosphoenolpyruvate carboxylase (PEPC) activity but a decrease in total chlorophyll content, autofluorescence of chloroplasts, chlorophyll fluorescence and RuBPC activity as compared to the control (0.03% CO2). Short-term Na14HCO3 fixation indicated that a high ratio of 14C was in the organic acid and amino acid fractions as compared to the sugar and phosphate ester fraction. Nitrate reductase (NR) activity of photoautotrophic callus under CO2 enrichment was, significantly lower than that of the control but higher as compared to callus under non-photoautotrophic conditions with 2% sucrose in the culture medium. Rate of uptake 0.1 nitrate and ammonium from the culture medium did not appear to be related to the level of NR activity in the callus. The level of NR activity in the callus was dependent on the photosynthetic status of the tissue which, in turn, was dependent on the CO2 availability in the headspace of the cultures. Photosynthesis, nitrate uptake and nitrate assimilation are therefore closely linked phenomena governing growth and development of P. coronarium tissues under in vitro conditions.","abstract_html":"Direct plantlet regeneration from frond and rhizome explants of Platycerium coronarium cultured in vitro was achieved. Ethylene was produced during this process and its level in the culture vessels increased with time, resulting in a decrease in th, percentage of sporophytes produced. The presence of ethylene action inhibitor, silver thiosulphate, in the culture medium resulted in an increase in the percentage of plants regenerated, indicating an inhibitory effect of ethylene on regeneration. Inhibitors of ethylene biosynthesis (aminoethoxyvinylglycine, benzylisothiocyanate, cobalt chloride and salicylic acid) were ineffective in increasing sporophyte regeneration. Also, 1-aminocyclopropane-1-carboxylic acid, the ethylene precursor, was ineffective it, increasing the level of ethylene in the culture vessels. Therefore, the biosynthetic pathway of ethylene in P. coronarium appears to be different from that of higher plants, but similar to that of some other ferns. Apogamous sporophytes were produced on gametophytes cultured in the presence on 40 µM indole-3-acetic acid (IAA). When ethylene was allowed to accumulate in the culture vessels in the presence of IAA, the frequency of regeneration and the total number of apogamous sporophytes producted decreased significantly. Light arm confocal laser scanning microscopy were successfully used to check nuclear size which serves as a quick parameter to estimate ploidy level in P. coronarium. Callus was induced from both gametophyte and rhizome explants. Cell suspension culture was successfully initiated from gametophyte-derived callus and plating of cells on semi-solid MS medium with kinetin resulted in the production of two population, of callus distinguishable by their colouration. These were allowed to proliferate on MS medium with 2 µM 2,4-D. Subsequent culturing on basal MS medium resulted in the regeneration of gametophytes from the dark green callus and sporophytes from the pale green callus. Sporophytic callus (pale green) differentiated into both gametophytes and sporophytes after prolonged period in culture (7 months). The results indicate that cells of gametophytes are totipotent and plastic. Progressive reduction of sucrose concentration in the medium on which gametophyte .. derived callus was cultured resulted in a reduction in growth but an increase in total chlorophyll content, chlorophyll fluorescence, autofluorescence of chloroplasts and ribulose bisphosphate carboxylase (RuBPC) activity. Under prolonged CO2 enriched conditions, photoautotrophic callus of P. coronarium showed an increase in biomass and phosphoenolpyruvate carboxylase (PEPC) activity but a decrease in total chlorophyll content, autofluorescence of chloroplasts, chlorophyll fluorescence and RuBPC activity as compared to the control (0.03% CO2). Short-term Na14HCO3 fixation indicated that a high ratio of 14C was in the organic acid and amino acid fractions as compared to the sugar and phosphate ester fraction. Nitrate reductase (NR) activity of photoautotrophic callus under CO2 enrichment was, significantly lower than that of the control but higher as compared to callus under non-photoautotrophic conditions with 2% sucrose in the culture medium. Rate of uptake 0.1 nitrate and ammonium from the culture medium did not appear to be related to the level of NR activity in the callus. The level of NR activity in the callus was dependent on the photosynthetic status of the tissue which, in turn, was dependent on the CO2 availability in the headspace of the cultures. Photosynthesis, nitrate uptake and nitrate assimilation are therefore closely linked phenomena governing growth and development of P. coronarium tissues under in vitro conditions.","abstract_has_math":false,"creators":["KWA SIEW HWA"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1996,"date_issued":"1996","date_published":"1996","updated_at":"2026-07-24T03:31:26Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["KWA SIEW HWA"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.issued","label":"Date","values":["1996"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://scholarbank.nus.edu.sg/handle/10635/182416"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://scholarbank.nus.edu.sg/bitstreams/99fe7c35-005b-4c9f-9f2e-ce4284c57764/download"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Direct plantlet regeneration from frond and rhizome explants of Platycerium coronarium cultured in vitro was achieved. Ethylene was produced during this process and its level in the culture vessels increased with time, resulting in a decrease in th, percentage of sporophytes produced. The presence of ethylene action inhibitor, silver thiosulphate, in the culture medium resulted in an increase in the percentage of plants regenerated, indicating an inhibitory effect of ethylene on regeneration. Inhibitors of ethylene biosynthesis (aminoethoxyvinylglycine, benzylisothiocyanate, cobalt chloride and salicylic acid) were ineffective in increasing sporophyte regeneration. Also, 1-aminocyclopropane-1-carboxylic acid, the ethylene precursor, was ineffective it, increasing the level of ethylene in the culture vessels. Therefore, the biosynthetic pathway of ethylene in P. coronarium appears to be different from that of higher plants, but similar to that of some other ferns. Apogamous sporophytes were produced on gametophytes cultured in the presence on 40 µM indole-3-acetic acid (IAA). When ethylene was allowed to accumulate in the culture vessels in the presence of IAA, the frequency of regeneration and the total number of apogamous sporophytes producted decreased significantly. Light arm confocal laser scanning microscopy were successfully used to check nuclear size which serves as a quick parameter to estimate ploidy level in P. coronarium. Callus was induced from both gametophyte and rhizome explants. Cell suspension culture was successfully initiated from gametophyte-derived callus and plating of cells on semi-solid MS medium with kinetin resulted in the production of two population, of callus distinguishable by their colouration. These were allowed to proliferate on MS medium with 2 µM 2,4-D. Subsequent culturing on basal MS medium resulted in the regeneration of gametophytes from the dark green callus and sporophytes from the pale green callus. Sporophytic callus (pale green) differentiated into both gametophytes and sporophytes after prolonged period in culture (7 months). The results indicate that cells of gametophytes are totipotent and plastic. Progressive reduction of sucrose concentration in the medium on which gametophyte .. derived callus was cultured resulted in a reduction in growth but an increase in total chlorophyll content, chlorophyll fluorescence, autofluorescence of chloroplasts and ribulose bisphosphate carboxylase (RuBPC) activity. Under prolonged CO2 enriched conditions, photoautotrophic callus of P. coronarium showed an increase in biomass and phosphoenolpyruvate carboxylase (PEPC) activity but a decrease in total chlorophyll content, autofluorescence of chloroplasts, chlorophyll fluorescence and RuBPC activity as compared to the control (0.03% CO2). Short-term Na14HCO3 fixation indicated that a high ratio of 14C was in the organic acid and amino acid fractions as compared to the sugar and phosphate ester fraction. Nitrate reductase (NR) activity of photoautotrophic callus under CO2 enrichment was, significantly lower than that of the control but higher as compared to callus under non-photoautotrophic conditions with 2% sucrose in the culture medium. Rate of uptake 0.1 nitrate and ammonium from the culture medium did not appear to be related to the level of NR activity in the callus. The level of NR activity in the callus was dependent on the photosynthetic status of the tissue which, in turn, was dependent on the CO2 availability in the headspace of the cultures. 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The presence of ethylene action inhibitor, silver thiosulphate, in the culture medium resulted in an increase in the percentage of plants regenerated, indicating an inhibitory effect of ethylene on regeneration. Inhibitors of ethylene biosynthesis (aminoethoxyvinylglycine, benzylisothiocyanate, cobalt chloride and salicylic acid) were ineffective in increasing sporophyte regeneration. Also, 1-aminocyclopropane-1-carboxylic acid, the ethylene precursor, was ineffective it, increasing the level of ethylene in the culture vessels. Therefore, the biosynthetic pathway of ethylene in P. coronarium appears to be different from that of higher plants, but similar to that of some other ferns. Apogamous sporophytes were produced on gametophytes cultured in the presence on 40 µM indole-3-acetic acid (IAA). When ethylene was allowed to accumulate in the culture vessels in the presence of IAA, the frequency of regeneration and the total number of apogamous sporophytes producted decreased significantly. Light arm confocal laser scanning microscopy were successfully used to check nuclear size which serves as a quick parameter to estimate ploidy level in P. coronarium. Callus was induced from both gametophyte and rhizome explants. Cell suspension culture was successfully initiated from gametophyte-derived callus and plating of cells on semi-solid MS medium with kinetin resulted in the production of two population, of callus distinguishable by their colouration. These were allowed to proliferate on MS medium with 2 µM 2,4-D. Subsequent culturing on basal MS medium resulted in the regeneration of gametophytes from the dark green callus and sporophytes from the pale green callus. Sporophytic callus (pale green) differentiated into both gametophytes and sporophytes after prolonged period in culture (7 months). The results indicate that cells of gametophytes are totipotent and plastic. Progressive reduction of sucrose concentration in the medium on which gametophyte .. derived callus was cultured resulted in a reduction in growth but an increase in total chlorophyll content, chlorophyll fluorescence, autofluorescence of chloroplasts and ribulose bisphosphate carboxylase (RuBPC) activity. Under prolonged CO2 enriched conditions, photoautotrophic callus of P. coronarium showed an increase in biomass and phosphoenolpyruvate carboxylase (PEPC) activity but a decrease in total chlorophyll content, autofluorescence of chloroplasts, chlorophyll fluorescence and RuBPC activity as compared to the control (0.03% CO2). Short-term Na14HCO3 fixation indicated that a high ratio of 14C was in the organic acid and amino acid fractions as compared to the sugar and phosphate ester fraction. Nitrate reductase (NR) activity of photoautotrophic callus under CO2 enrichment was, significantly lower than that of the control but higher as compared to callus under non-photoautotrophic conditions with 2% sucrose in the culture medium. Rate of uptake 0.1 nitrate and ammonium from the culture medium did not appear to be related to the level of NR activity in the callus. The level of NR activity in the callus was dependent on the photosynthetic status of the tissue which, in turn, was dependent on the CO2 availability in the headspace of the cultures. 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