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Impact of cytomixis on meiosis, pollen viability and pollen size in wild populations of Himalayan poppy (Meconopsis aculeata Royle). J Biosci

Department of Botany, Punjabi University, Patiala, India.
Journal of Biosciences (Impact Factor: 1.94). 10/2008; 33(3):371-80. DOI: 10.1007/s12038-008-0057-0
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ABSTRACT We report the occurrence of cytomixis in wild populations of Himalayan poppy (Meconopsis aculeata Royle),which is considered to be an important and threatened medicinal plant growing in the high hills of the Himalayas. The impact of cytomixis on meiotic behaviour, reduced pollen viability and heterogeneous-sized pollen grains was also studied. Cytological studies in the seven wild populations from the high hills of Himachal Pradesh revealed that all the Himalayan populations exist uniformly at the tetraploid level (2n=56) on x=14. The phenomenon of chromatin transfer among the proximate pollen mother cells (PMCs) in six populations caused various meiotic abnormalities. Chromatin transfer also resulted in the formation of coenocytes, aneuploid, polyploid and anucleated PMCs. Among individuals that showed chromatin transfer, chromosome stickiness and interbivalent connections were frequently observed in some PMCs. The phenomenon of cytomixis in the species seems to be directly under genetic control; it affects the meiotic course considerably and results in reduced pollen viability.

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    • "Knight et al. 2010), cytology (e.g. Singhal & Kumar 2008) or ploidy level (e.g. Jacob & Pierret 2000; Pradeep & Jambhale 2000). "
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    • "Cathcartia species also have 2n = 2x = 14, supporting the ITS phylogeny that places them outside Papaver, rather than within Meconopsis. Karyotype studies of Meconopsis species suggest that all are polyploid (2n = 8–12x = 56–84) [81], [85], [86], [87], but see Kumar et al. [88]. We suggest that the Meconopsis clade originated with the polyploid transition to 2n = 2x = 56, possibly via a tetraploid intermediate with 2n = 4x = 28 chromosomes that is now extinct. "
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    • "Cytomixis in this species results into the production of chromosomally hypo-and hyper-ploid PMC's along with some empty PMC's from which almost complete transfer of chromatin has taken place (Figs. 8 and 9). Most of these observations are in line with the fi ndings of Falistocco et al. (1995), Ghanima and Talaat (2003), Ghaffari (2006), Singhal et al. (2008) and Kumar et al. (2008) for other species of the Angiosperms. However, Omara (1976) believes that the role of cytomixis is to be properly assessed since the chances of production of aneuploid gametes is less, in strictly sexually diploid taxa. "
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