MEIOTIC BEHAVIOUR IN TWO TRIPLOIDS: ERIGERON ANNUUS AND EUPATORIUM ADENOPHORUM (ASTERACEAE)

ABSTRACT The present study shows the meiotic behaviour in two species of Asteraceae family. Erigeron annuus (2n=27) and Eupatorium adenophorum (2n=51) are triploid (i.e. 3x based on x=9 and x=17, respectively) appear to be apomictic in nature due to the presence of highly abnormal meiotic course and high pollen sterility but with normal seed setting. Meiosis in these species is characterized by the formation of many univalents and trivalents with a few bivalents. Anaphases and telophases are highly abnormal with the formation of many laggards and micronuclei during microsporogenesis. Cytomixis is also a common phenomenon noticed in all Eupatorium adenophorum populations. Pollen sterility varies from 40-71%. Both the species are widespread in nature and grow as weeds certainly reproduce through asexual means. REFERENCES Asker, S.E. and Jerling, L. 1992. Apomixis in Plants. CRC Press, Boca Raton, FL. Bashaw, E.C. and Hanna, W.W. 1990. Reproductive versatility in the grasses. In: Chapman, G.P. (ed.) Apomictic reproduction. Cambridge U.K., Cambridge University Press. Pp. 100-130. Bicknell, R.A. and Koltunow, A.M. 2004. Understanding Apomixis: Recent advances and remaining conundrums. The Plant Cell, 16: 5228-5245. Carmen, J.G. 1997. Asynchronous expression of duplicate genes in Angiosperms may cause apomixis, bispory, tetraspory and polyembryony. Biol. J. Linn. Soc., 61: 51-94. Carneiro, V.T.C., Dusi, D.M.A. and Ortiz, J.P.A. 2006. Apomixis: occurrence, applications and improvements. In: Floriculture, ornamental and plant biotechnology: Advances and topical issues (Ist edn., vol. I) (Teixeira da Silva, J.A. ed.), Global Science Books, Isleworth, UK. Pp. 564-571. Chojnacki, W., Pawlak T and Bijok K 1980. Karyological studies of Erigeron annuus (L.) Pers. and E. acer L. from natural habitats in Poland. Zesz. Nauk. Wydz. Biol. Nauk Ziemi, Biol., 2: 41–47. Grimanelli, D., Leblane, O., Perotti, E. and Grossniklaus, U. 2001. Developmental genetics of gametophytic apomixis. Trends in Genetics, 17: 597-604. Jhansi Rani, P and Rama Kumar. 2013. Genetic parameters of yield and yield components pooled over environments in Sesamum (Sesamum indicum L. Biolife 1(4):231-234 Khonglam, A. and A. Singh. 1980. Cytological studies on the weed species of Eupatorium found in Meghalaya. Proc. Indian Sci. Congr. Assoc. (III, C) 67: 55. Holmgren, P.K. and Holmgren, N.H. 1998. Index Herbariorum: a global directory of public herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium [online] http://sweetgum.nybg. org/ih/. Hong, D.Y. and Zhang, S.Z. 1990. Observations on chromosomes of some plants from western Sichuan. Cathaya, 2: 191–197. Lewis, W.H. 1979. Polyploidy in species populations. Basic Life Science, 13: 103-144. Lu, H., Shen, J., Sang, W., Zhang, X. and Lin, J. 2008. Pollen viability, pollination, seed set, and seed germination of croftonweed (Eupatorium adenophorum) in China. Weed Science, 56 (1): 42-51. Mehra, P.N., Gill, B.S., Mehta, J.K. and Sidhu, S.S. 1965. Cytological investigations on the Indian Compositae. I. North-Indian taxa. Caryologia, 18: 35-68. Nesom, G.L. 1989. Infrageneric taxonomy of New World Erigeron (Compositae: Astereae). Phytologia, 67: 67-93. Nogler, G.A. 1984. Gametophytic apomixis. In: Embryology of Angiosperms, Springer-Verlag, Berlin (Johre, B.M. Ed.) pp. 475-518. Noyes, R.D. 2007. Apomixis in the Asteraceae: Diamonds in the Rough. Func. Plant Sci. & Biotech., 1 (2): 207-222. Noyes, R.D. and Rieseberg, L.H. 2000. Two independent loci control agamospermy (apomixis) in the triploid flowering plant Erigeron annuus. Genetics, 155: 379-390. Richards, A.J. 1997. Plant Breeding Systems, 2nd edn. (London: Chapman and Hall). Rudyka, E.G. 1988. Chromosome numbers in some vascular plant species from the far east of the USSR. Bot. Žurn. (Moscow & Leningrad), 73: 294-295. Stebbins, G.L.Jr. 1950. Variation and evolution in Plants, Columbia University Press, New York, pp. 643. Van Dijk, P.J. and Vijverberg, K. 2005. The significance of apomixis in the evolution of angiosperms: a reappraisal. In: Plant Species-Level Systematics: New Perspectives on Pattern and Process (Bakker, F., Chatroou, L., Gravendeel, B. and Pelser, P.B. Eds.), pp. 101-106. Gantner Verlag, Ruggell, Liechtenstein. Winkler, H. 1908. Über Parthenogenesis und Apogamie im Pflanzenreich. Progressus Rei Botanicae, 2 (3): 293-454