Syncytes in Meiosis of Polyploid Sorghum¹

Abstract

Syncytes occurred in a triploid and tetraploid progeny of an interspecific hybrid between Sorghum bicolor and S. halepense. That they originated by the fusion of two or more microsporocytes as a result of environmental conditions of high temperature and moisture stress is suggested. Meiosis was relatively regular in material collected from the same plants during favorable growing conditions. Coalescence of pollen mother‐cells varied from complete fusion into one polyploid cell to merely peripheral connection. Although meiosis was very irregular in these fusion bodies, sufficiently regular and functional fusion bodies, sufficiently regular and functional polyploid polyploid spores could be formed which may subsequently give rise to a polyploid series within a species.

The Cytological Mechanism of Male Sterility in Intergeneric Hybrids of <i>Sorghum</i>&times;<i>Saccharum</i>

“…In the present case, the genetic imbalances caused by the presence of the alien chromosomes or cytoplasm of sorghum in the hybrid could be a reason for the breakdown of the meiotic process. Abnormal meiosis and syncyte formation has been reported in male sterile sorghum (Merwine and Bennett 1966, Sengupta and Weibel 1968, McClure 1965, and in the present case, these abnormalities in the male sterile sorghum parent are possibly manifested in the hybrid (somaclones) as well. The occurrence of syncyte formation is not uncommon among the sorghum lines and hybrids.…”

“…McClure (1965) reported syncytes in S. almum arising from the breakdown of the cell walls of the microsporocytes. Syncytes were reported in triploid and tetraploid progenies of an interspecific hybrid between Sorghum bicolor and S. halepense (Merwine and Bennett 1966). The bigger syncytes spreading over a larger sporogenous area were found to degenerate later.…”

Syncytes during male meiosis resulting in 2n pollen grain formation in Lindelofia longiflora var. falconeri

“…The possible causes of syncyte formation in plants may be diverse and can be presumed to be due to chemicals, X‐rays, temperature, moisture stress, culture condition, or genetic factors (Merwine & Bennett, 1966; Pantulu & Manga, 1971; Rao & Koduru, 1978; Rao et al, 1991; Nirmala & Rao, 1996; Kumar & Srivastava, 2009). In L. longiflora , the origin of syncytes due to the fusion of two meiocytes could be attributed to low temperature stress conditions prevailing in the Pangi Valley, where temperatures dip below freezing during the night in May and June when the species enters the flowering/bud stage.…”

Cytomixis Induced Meiotic Irregularities and Pollen Malformation in Clematis graveolens Lindley from the Cold Deserts of Kinnaur District of Himachal Pradesh (India)

“…The possible causes of cytomixis, syncyte formation and pollen grain fusion may be diverse and can be presumed to be due to chemicals, X-rays, temperature, moisture stress, or genetic factors (Merwine and Bennett 1966, Pantulu and Manga 1971, Rao and Koduru 1978, Rao et al 1991, Nirmala and Rao 1996, Kumar and Srivastava 2009. In the present case, cytomixis involving chromatin transfer and associated meiotic irregularities seem to be a natural phenomenon under direct genetic control as suggested by various other researchers (Omara 1976, De and Sharma 1983, Singhal and Gill 1985, Haroun 1995, Bellucci et al 2003, Ghanima and Talaat 2003, Haroun et al 2004, Lattoo et al 2006, Singhal et al 2007, Singhal and Kumar 2008.…”