Initiation of coconut cell suspension culture from shoot meristem derived embryogenic calli: A preliminary study

An attempt was made to establish highly competent embryogenic cell suspension culture in coconut, a species recalcitrant to in vitro culture. Embryogenic calli were initiated from shoot meristem explants of coconut. Y3 medium supplemented with 2.4-D (4.5 μM) and glutamine (34.2 μM) was found to be the best medium to initiate cell suspension. Growth evaluation was done by packed cell volume (PCV) and it was found that maximum growth volume of 9.9% was reached at 200 days of culture initiation. About 52% of viable cells were detected through fluorescent microscopy. Cell aggregation was noticed in Y3 medium supplemented with glutamine (34.2 μM), malt extract (100mg/l), biotin (40.9 μM) and kinetin (9.3 μM), but further progress could not be achieved. It was also observed that embryogenic calli were not of a friable type, but were associated with densely aggregated cells. Because of its hard nature, we were unsuccessful to obtain high quality cell suspension

Histological studies of cellular differentiation during somatic embryogenesis of coconut plumule-derived calli

Since coconut is   one of the most recalcitrant species to generate in vitro, it is   necessary to study in detail about the cellular changes that occur during   somatic embryogenesis to enhance our knowledge about this phenomenon. In the   present study, coconut plumular tissues, the shoot meristem including leaf   primordia, were used as explants for in vitro regeneration studies.   Histological studies were carried out in different stages of plumule culture.   No noticeable growth was observed in 15 days old cultures. After 30 days,   meristematic cells could be identified. Abundance of meristematic cells,   foremost to the development of callus structures, was observed after 45 days.   After 75 days, globular friable calli were formed and histological studies   revealed the presence of meristematic centers which eventually formed somatic   embryos. The histological study of matured somatic embryos formed after 120   days of callus initiation showed a clear meristematic zone of parenchyma   cells, surrounded by vascular bundles. Histological studies, carried out for   certain abnormalities like compact calli, abnormal somatic embryoids with   rudimentary shoots and multiplied roots, revealed the presence of intact   cotyledonary leaves which seemed to inhibit the apical meristem development   of somatic embryoids. The presence of vascular bundles in the early stages of   callus formation might lead to the direct formation of meristemoids. These   results could aid future studies leading to enhanced control of the somatic   embryogenic process and greater efficiency of somatic embryo and plantlet   formation in coconut

A comparative study of three different methods of shoot meristem excision for induction of embryogenic calli in coconut

A protocol was standardized to maximize yields of embryogenic calli from shoot meristem culture of coconut. Three different shoot meristem excision methods were tested viz., excision of shoot meristem aseptically from in vitro germinated embryo after 10-12 days, excision of shoot meristem from in vitro germinated embryo subjected to GA3 treatment for five days and excision of shoot meristem from fresh embryo. The primary calli induction after 30 days of culture incubation for the three treatments were 21%, 27%  and 79% respectively.  Further, the primary calli formed from the shoot meristem excised from fresh embryo gave rise to 56% of embryogenic calli. The calli obtained from the shoot meristem which were excised from in vitro germinated embryo formed less percentage of embryogenic calli because of the presence of cotyledonary tissues which inhibited the multiplication of meristematic tissues. In the case of shoot meristem extracted from GA3-treated embryos, the percentage of non-embryogenic calli was more compared to the shoot meristem excised from fresh embryo. It was observed that the addition of GA3 in the initial stages of culture inhibited the formation of embryogenic calli and favored direct shoot development. Currently, the shoot meristem excised from fresh embryo is being employed for scaling up the planting material production from released varieties of coconut

Maintenance of embryogenic potential of calli derived from embryonic shoot of West Coast Tall cv. of coconut (Cocos nucifera L.)

Maintenance of embryogenic potential of calli is important as the totipotency is often lost in a short time in vitro. This caters to the need for year round availability of somatic embryos in a regenerable state. In the present study, 14 media combinations, with either 2,4-D or picloram as auxin source, were tested for maintaining embryogenic calli obtained from embryonic shoot explants of coconut. Irrespective of type and concentration of auxins, callusing was observed in all the media combinations. However, high dose of 2,4-D (above 74.6 μM) in the initial medium resulted in intense browning and lesser percentage of callusing. Embryogenic nature of calli could be maintained to a maximum of 21 weeks in medium supplemented with 2,4-D (74.6 μM) and subsequent culturing into higher concentration of 2,4-D (90.4 μM). Gene expression studies carried out using qRT-PCR revealed that genes such as ECP, GST, LEAFY and WUS were highly expressed in long term embryogenic calli (21 week old) and genes such as SERK, GLP, WRKY and PKL in initial embryogenic calli (21 days old). The study concludes that coconut plumular calli could be maintained for longer periods without compromising on the embryogenic potential of the calli

Not Available

Not AvailableAn attempt was made to establish highly competent embryogenic cell suspension culture in coconut, a species recalcitrant to in vitro culture. Embryogenic calli were initiated from shoot meristem explants of coconut. Y3 medium supplemented with 2.4-D (4.5 μM) and glutamine (34.2 μM) was found to be the best medium to initiate cell suspension. Growth evaluation was done by packed cell volume (PCV) and it was found that maximum growth volume of 9.9% was reached at 200 days of culture initiation. About 52% of viable cells were detected through fluorescent microscopy. Cell aggregation was noticed in Y3 medium supplemented with glutamine (34.2 μM) , malt extract (100mg/l), biotin (40.9 μM) and kinetin (9.3 μM), but further progress could not be achieved. It was also observed that embryogenic calli were not of a friable type, but were associated with densely aggregated cells. Because of its hard nature, we were unsuccessful to obtain high quality cell suspension.Not Availabl

Not Available

Not AvailableSince coconut is one of the most recalcitrant species to generate in vitro, it is necessary to study in detail about the cellular changes that occur during somatic embryogenesis to enhance our knowledge about this phenomenon. In the present study, coconut plumular tissues, the shoot meristem including leaf primordia, were used as explants for in vitro regeneration studies. Histological studies were carried out in different stages of plumule culture. No noticeable growth was observed in 15 days old cultures. After 30 days, meristematic cells could be identified. Abundance of meristematic cells, foremost to the development of callus structures, was observed after 45 days. After 75 days, globular friable calli were formed and histological studies revealed the presence of meristematic centers which eventually formed somatic embryos. The histological study of matured somatic embryos formed after 120 days of callus initiation showed a clear meristematic zone of parenchyma cells, surrounded by vascular bundles. Histological studies, carried out for certain abnormalities like compact calli, abnormal somatic embryoids with rudimentary shoots and multiplied roots, revealed the presence of intact cotyledonary leaves which seemed to inhibit the apical meristem development of somatic embryoids. The presence of vascular bundles in the early stages of callus formation might lead to the direct formation of meristemoids. These results could aid future studies leading to enhanced control of the somatic embryogenic process and greater efficiency of somatic embryo and plantlet formation in coconut.Not Availabl

Not Available

Not AvailableA protocol was standardized to maximize yiellds of embryogenic calli from shoot meristem culture of coconut three different shoot meristem excision method where tested viz.,excision of shoot meristem aseptically from in vitro germinated embryoafter 10-12 days excision of shoot meristem from in vitro germinated embryo subjected to GA3 treatment for five days and excision of shoot meristem from fresh embryo. the primary calli induction sfter 30 days of culture incubation for the three treatments was 21%, 27% and 79% respectively . Further, the primary calli formed from the shoot merstem excised from fresh embryo gave rise to 56% of embryogenic calli.The calli obtained from the shoot merstem, which were excised from in vitro germinated embryo, formed less percentage of embryogenic calli because of the presence of cotyledonary tissues which inhibited the multiplication of meristematic tissues. In the case of shoot meristem extracted from GA3 treated embryos, the percentage of non - embryogenic calli was more compared to the shoot meristem excised fro fresh embryo. It was observed that the addition of GA3 in the initial stages of culture inhibited the formation of embryogenic calli and favored direct shoot development. Currently, the shoot meristem excised from fresh embryo is being employed for scaling up the planting material production from released varieties of coconut.Not Availabl

Not Available

Not AvailableMaintenance of embryogenic potential of calli is important as the totipotency is often lost in a short time in vitro. This caters to the need for year round availability of somatic embryos in a regenerable state. In the present study, 14 media combinations, with either 2,4-D or picloram as auxin source, were tested for maintaining embryogenic calli obtained from embryonic shoot explants of coconut. Irrespective of type and concentration of auxins, callusing was observed in all the media combinations. However, high dose of 2,4-D (above 74.6 μM) in the initial medium resulted in intense browning and lesser percentage of callusing. Embryogenic nature of calli could be maintained to a maximum of 21 weeks in medium supplemented with 2,4-D (74.6 μM) and subsequent culturing into higher concentration of 2,4-D (90.4 μM). Gene expression studies carried out using qRT-PCR revealed that genes such as ECP, GST, LEAFY and WUS were highly expressed in long term embryogenic calli (21 week old) and genes such as SERK, GLP, WRKY and PKL in initial embryogenic calli (21 days old). The study concludes that coconut plumular calli could be maintained for longer periods without compromising on the embryogenic potential of the calli.Not Availabl

Decolonial reflections on urban pedagogy in India

This paper engages with deep and entrenched coloniality of the urban pedagogy, epistemology, and policy in India. After outlining the context, I will discuss my reflections on some relevant pedagogical initiatives that I had an opportunity to be part of as a faculty in a graduate-level programme in India