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

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.

Evaluation of Cytomorphological Diversity in <i>Filipendula vestita</i> (Wall. ex G. Don) Maxim., (Rosaceae) from Western Himalayas

“…Most of these observations are in line with the findings of Ghaffari (2006) and Singhal et al (2008) in some of the species of angiosperms. The present findings reveal that cytomixis may be responsible for a high rate of meiotic abnormalities coupled with the production of hypo-and hyperploid chromosome numbers in some PMCs in this species ultimately resulting in the formation of low apparently fertile pollen grains of variable sizes.…”

“…This phenomenon has been seen in many of the angiospermic plant species with different possible causes being advocated as physiological conditions, stress factors or purely under genetic control. However, in the present material, the cytomixis seems to be under genetic control as pointed out earlier by other researchers (Bellucci et al 2003, Singhal et al 2008. On the basis of these detailed cytomorphological studies, it is concluded that F. vestita represents single diploid taxon with n=7 but showing the well-marked, completely identified and segregated 2 additional morphovariants (Type-II and Type III) in addition to the existing 2 variants reported from the Western Himalayas.…”

“…The present findings reveal that cytomixis may be responsible for a high rate of meiotic abnormalities coupled with the production of hypo-and hyperploid chromosome numbers in some PMCs in this species ultimately resulting in the formation of low apparently fertile pollen grains of variable sizes. The same has been witnessed for many plants as re- ported earlier for Vicia faba (Haroun et al 2004) and Meconopsis aculeate (Singhal and Kumar 2008). This phenomenon has been seen in many of the angiospermic plant species with different possible causes being advocated as physiological conditions, stress factors or purely under genetic control.…”

Meiotic Studies and B-Chromosomes in <i>Sedum oreades</i> (Decne.) R. Hamet (Crassulaceae) from Alpine Regions of Northwest Indian Himalaya

“…However, in the current study, such gametes could not be ascertained. Non-synchronous disjunction of bivalents is either found in hybrid taxa or the species having structural differentiation between the homologous pair and rate of terminalization (Singhal 1982, Anis and Wani 1997, Aparicio and Albaladejo 2003, Wang et al 2004, Bhat et al 2007, Wen et al 2010 or associated with other meiotic abnormalities (Singhal and Kumar 2008. The occurrence of non-synchronous disjunction of bivalents in the asymmetric somatic hybrids of Brassica napus and Crambe abyssinica had been attributed to a type of asynchrony in the meiotic cycles between genomes of hybrid species by Wang et al (2004).…”

New insights into cytomixis: specific cellular features and prevalence in higher plants

“…Presumably, their fundamental role is in the transfer of part of genetic material from one cell to another via cytomixis resulting in an increase in genetic diversity of the produced pollen or an adjusting and balancing in unbalanced genomes (Falistocco et al 1995;Zhou 2003;Ghaffari 2006;Lattoo et al 2006;Negron-Ortiz 2007;Singhal and Kumar 2008;Song and Li 2009;Singhal et al 2011).…”