Diploid and Polyploid Gametes in Crop Plants: Mechanisms of Formation and Utilization in Plant Breeding

Use of 2n Gametes in Plant Breeding

“…Examples in maize (Zea mays; Rhoades & Dempsey, 1966), potato (Solanum tuberosum; Mok & Peloquin, 1975b;Veilleux, 1985;Watanabe & Peloquin, 1989), red clover (Trifolium pratense; Parrot & Smith, 1986), rye (Secale cereale; Lelley et al, 1987), alfalfa (Medicago sativa; Barcaccia et al, 2000;Ortiz & Peloquin, 1991) and banana (Musa; Ortiz, 1997) have shown the complexity of the genetic base of 2n gamete formation. Often, one major locus is responsible for 2n gamete formation while several other genes controls its frequency.…”

Meiotic irregularities in Capsicum L. species

“…Cytomixis is also considered a way to conserve genetic heterozygozity of the gametes (Veilleux 1985) and, according to Falistocco et al (1995), it is important for the phylogenetic evolution of karyotypes due to the reduction or increase of ploidy, creating aneuploids and polyploids that, if successful, result in variability. Cytomixis may occur for many reasons, one of them is the action of genes (Kaul and Nirmala 1991).…”

Cytogenetics of Four Species of Genus <i>Berberis</i> L. (Berberidaceae Juss.) from the Western Himalayas

“…Cytomixis or the occurrence of multipolar cells and meiotic irregularities in anaphase segregation of chromosomes may be the possible mechanisms for the formation of large-sized pollen grains and low pollen fertility in these meiotically abnormal populations as has been reported earlier in several angiospermic plants (Sheidai et al 2008, Jeelani et al 2011, Rani et al 2012. The production of hypo-and hyperploid PMCs due to cytomixis (Falistocco et al 1995, Sheidai and Bagheri-Shabestarei 2007, Fadaei et al 2010 accompanied by other meiotic abnormalities lead to anomalous microsporogenesis, resulting in the formation of variable-sized pollen grains, possibly with an aneuploid condition and low pollen fertility (Villeux 1985, Nirmala and Rao 1996, Sheidai and Fadael 2005, Sheidai et al 2003. The formation of large-sized pollen grains as seen at present is in accordance with previous information about the possibility of such pollen grains resulting from unreduced 2n pollen grains as has been observed in several angiosperms by Vorsa and Bingham (1979), Bertagnolle and Thomson (1995), Sheidai et al (2008), Fadaei et al (2010) and Jeelani et al (2011).…”