Cytomixis impairs meiosis and influences reproductive success inChlorophytum comosum (Thunb) Jacq. — An additional strategy and possible implications

Abstract

Spontaneous intercellular chromatin migration/cytomixis was observed to occur in the pollen mother cells (PMCs) of the Chlorophytum comosum for the first time. The migration through cytomictic channels was more pronounced in meiosis-I and very rare in meiosis-II. The process was associated with erratic meiosis, which was characterized by defects in chromosome organization and segregation. Cytomixis was more intense in the month of April than in July and consequently the frequency of meiotic irregularities was much more pronounced during the month of April. As a consequence of abnormal meiosis, fertility was drastically reduced resulting in meager seed efficiency of 17% only. Recombination system also does not guarantee the release of sufficient variability. We view the phenomenon of cytomixis as genetically controlled mechanism involving meiotic genes and operating through signal transduction pathway triggered by the environmental stimuli. The evolutionary significance and tenable hypothesis in the backdrop of existing literature is also proposed.

Analysis of Meiotic Behavior in <i>Eremurus himalaicus</i> Baker (Liliaceae): A Rare Endemic Perennial from Kinnaur, Himachal Pradesh, India

“…This phenomenon of cytomixis involving transfer of chromatin material among proximate meiocytes was first recorded by Koernicke (1901) in Crocus sativus. Since then, this phenomenon was reported by many workers in a wide range of flowering plants (Sarvella 1958, Omara 1976, Saggoo and Bir 1983, Sen and Bhattacharya 1988, Bedi 1990, Datta et al 2005, Lattoo et al 2006, Kumar et al 2010, Saggoo and Kumari 2013.…”

“…Recent evidence suggests that it is a normal, genetically controlled phenomenon influenced by physiological and environmental factors (Omara 1976, Lattoo et al 2006.…”

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).…”

“…The most important mechanism leading to polyploid plants is formation of the gametes with a diploid chromosome number (Bretagnolle and Thompson 1995). Diploid gametes can be produced in several ways, and cytomixis might well be one of them (Falistocco et al 1995;Ghaffari 2006;Lattoo et al 2006). On the other hand, cytomixis may be involved in elimination of the "surplus" DNA by discharging part of the chromatin from the nucleus to the cytoplasm of another cell, thereby providing for either stabilization of a polyploid genome or return from a polyploid to a diploid state (Cheng et al 1987;Baptista-Giacomelli and Pagliarini 2000;Zhou 2003;Kalinka et al 2010).…”

Cytomorphological investigations in Oxyria digyna Hill. from the Kashmir Himalaya, India

“…Migration of chromatin material among adjacent meiocytes occurs through cytoplasmic connections originating from the plasmodesmata formed within the anther tissues [23]. The role of cytomixis in plant evolution is considered an additional mechanism for the origin of aneuploidy and polyploidy as it results in the formation of unreduced pollen grains as reported in several plant species [23][24][25]. In some cases, cytomixis may lead to the migration of whole chromatin among neighbouring meiocytes and lead to the formation of un-reduced gametes.…”