Coconut Tissue Culture: The Indian Initiatives, Experiences and Achievements
Coconut is one of the principal crops of India cultivated in over 35 districts mainly in the southern states. The productivity of the crop is declining in many of the traditionally cultivated regions owing to ageing plantations as well as biotic and abiotic stresses. These plantations are to be replanted with high yielding varieties/hybrids for which adequate quantity of quality planting material is not available. Even though tissue culture research was initiated in many laboratories in the country, the work was eventually phased out in most of the laboratories for want of a repeatable protocol. At ICAR-CPCRI, coconut tissue culture programs have been continuing for the past three decades. The attempts made include experimentation with different explants viz., immature inflorescence, plumular tissues, mature palm shoot meristem, ovary and anthers and different culture media supplemented with varying levels and types of hormones. Some of the successful protocols developed at the Institute include coconut zygotic embryo culture for collection and exchange of germplasm, cryopreservation and retrieval of zygotic embryos and pollen and plantlet regeneration from plumular tissues. Even though ICAR-CPCRI has succeeded in obtaining plantlets via direct organogenesis from inflorescence explants, the absence of friable calli formation from explants, the low rate of somatic embryo formation, large number of cultures turning to abnormal shoot development, non conversion of somatic embryos into plantlets, and formation of abnormal somatic embryos remain the major bottlenecks. Gene expression studies are being currently undertaken to decipher the molecular basis of in vitro recalcitrance.
Bhavyashree, U., Lakshmi Jayaraj, K., Rachana, K.E., Muralikrishna, K.S., Sajini, K.K., Rajesh, M.K. and Karun, A. 2015. Maintenance of embryogenic potential of calli derived from shoot meristem of West Coast Tall cv. of coconut (Cocos nucifera L.). Journal of Plantation Crops 43(2): 105-116.
CPCRI. 2011. Research Highlights 2010-11. Central Plantation Crops Research Institute Kasaragod, Kerala, India. pp. 36.
CPCRI. 2012. Annual Report 2011-12, Central Plantation Crops Research Institute Kasaragod -671124, Kerala, India, pp. 128.
Diekmann, M. 1997. The use of biotechnology for the safe movement of coconut germplasms. Paper presented at International Symposium on Coconut Biotechnology Merida, December 1-5.
Fernando, S.C., Vidhanaarachchi, V.R.M., Weerakoon, L.K. and Santha, E.S. 2010. What makes clonal propagation of coconut difficult? Asia-Pacific Journal of Molecular Biology and Biotechnology 18: 163-165.
Karun, A, Shivasankar, S., Sajini, K.K., and Saji, K.V. 1992. Field collection and in vitro germination of coconut embryos. Journal of Plantation Crops 21: 291-294.
Karun, A. and Sajini, K.K. 1994. Short-term storage of coconut embryos in sterile water. Current Science 67 (2): 118-120.
Karun, A. and Sajini, K.K. 2010. Cryopreservation of coconut zygotic embryos and pollen. Technical Bulletin No. 63, ICAR-CPCRI, Kasaragod, India.
Karun, A., Rajesh, M.K. and Muralikrishna, K.S. 2015. Somatic embryogenesis and bioreactors: Meeting report. Current Science 108(10): 1782-1783.
Karun, A., Sajini, K.K. and Parthasarathy, V.A. 2002. Increasing the efficiency of embryo culture to promote germplasm collecting in India. In: (Eds) Engelmann, F., Batugal, P. and Oliver, J. Coconut embryo in vitro culture: Part II. pp. 7-26.
Karun, A., Sajini, K.K. and Parthasarathy, V.A. 2005. Cryopreservation of mature zygotic embryos of coconut by desiccation methods. Cord 21(1): 13-19.
Karun, A., Sajini, K.K. and Shivashankar, S. 1999. Embryo culture of coconut: the CPCRI protocol. Indian Journal of Horticulture 56(4): 348-353.
Karun, A., Sajini, K.K., Kumaran, P.M. and Samsudheen, K. 2006. Cryopreservation of coconut (Cocos nucifera L.) pollen. Journal of Plantation Crops 34: 568 571.
Karun, A., Sajini, K.K., Niral, V., Amarnath, C.H., Remya, P., Rajesh, M.K., Samsudeen, K., Jerard, B.A. and Engelmann, F. 2014. Coconut (Cocos nucifera L.) pollen cryopreservation. Cryo-Letters 35(5): 407-417.
Karun, A., Sajini, K.K., Radha, E. and Parthasarathy, V.A. 2004. Efficacy of CPCRI embryo culture protocol in germplasm expedition. Journal of Plantation crops 32: 139-143.
Karun, A., Shivasankar, S., Sajini, K.K. and Saji, K.V. 1993. Field collection and in vitro germination of coconut embryos. Journal of Plantation Crops 21: 291-294.
Rajesh, M.K., Fayas, T.P., Naganeeswaran, S., Rachana, K.E., Bhavyashree, U., Sajini, K.K. and Karun, A. 2016. De novo assembly and characterization of global transcriptome of coconut palm (Cocos nucifera L.) embryogenic calli using Illumina paired-end sequencing. Protoplasma 253(3): 913-928.
Rajesh, M.K., Gangaraj, K.P., Jamshinath, T.P., Fayas, T.P., Naganeeswaran, S., Sajini, K.K. and Karun, A. 2015. Virtual screening and in vitro evaluation of potential growth regulators against somatic embryogenesis receptor-like kinase (SERK) in Cocos nucifera L. Indian Journal of Biochemistry and Biophysics 52(5&6): 328-340.
Rajesh, M.K., Radha, E., Sajini, K.K. and Karun, A. 2014. Polyamine-induced somatic embryogenesis and plantlet regeneration in vitro from plumular explants of dwarf cultivars of coconut (Cocos nucifera). Indian Journal of Agricultural Sciences 84 (4): 527-530.
Rajesh, M.K., Radha, E., Sajini, K.K., Karun, A. and Parthasarathy, V.A. 2005. Plant regeneration through organogenesis and somatic embryogenesis from plumular explant of coconut. Journal of Plantation Crops 33(1): 9-17.
Raju, C.R. 2006. Direct in vitro shoot development from immature rachilla explants of coconut (Cocos nucifera L.). Cord 22(1): 51-58.
Raju, C.R., Kumar, P.P., Chandramohan, M. and Iyer, R.D. 1984. Coconut plantlets from leaf tissue cultures. Journal of Plantation Crops 12: 75-78.
Sajini, K.K., Karun, A. and Kumaran, P.M. 2006. Cryopreservation of coconut zygotic embryos by pre growth desiccation. Journal of Plantation Crops 34: 576-581.
Sajini, K.K., Karun, A., Amarnath, C.H. and Engelmann, F. 2011. Cryopreservation of coconut (Cocos nucifera L.) zygotic embryos by vitrification. Cryo-Letters 32 (4): 317-328.
Samsudeen, K., Rajesh, M.K., Nagwaker, D.D., Raghavan Reshmi, Ajith Kumar, P., Devadas, K. and Karun, A. 2013. Diversity in Mohachao Narel, a sweet endosperm coconut (Cocos nucifera L.) population from Maharashtra, India. National Academy of Science Letters 36 (3): 319-330.
Shareefa, M., Thomas, R.J., Sreelekshmi, J.S., Raju, C.R and Karun, A. 2016. In vitro shoot regeneration from immature inflorescence of coconut. In: Book of Abstracts, 3rd International Symposium on Coconut Research and Development (ISOCRAD-3). (Eds.) Chowdappa, P., Muralidharan, K., Samsudeen, K. and Rajesh, M.K. 10-12th December 2016, ICAR-CPCRI, Kasaragod, Kerala. pp.32.