DESYNAPSIS INPISUM SATIVUMINDUCED THROUGH GENE MUTATION

Abstract

A mutant of Pisurn sativum showing various meiotic anomalies was isolated from X-irradiated material. These irregularities are due to a severe redncdon of chiasmata frequency in pachytene resulting in univalent formation in the following meiotic stages. The action of this secssive gene shows conqiderable variations from PMC to PMC. As a consequence of this behaviour a large number of microspores is produced in each PMC having different chromosome numbers. The mutant is completely sterile in both sexes. Only very negligible differences were noted in the meiotic behaviour of this mutant in subsequent generations demonstrating that the action of gene dsmA is not influenced by extrinsic factors. It has been demonstrated that mutant 82A attains an extreme position in the scheme as compared with other desynaptic genotypes.

Desynapsis due to Temperature Stress in Three Species of Solanum L.

“…Both the phenomena are known to occur in plants ( Gottschalk and Baquar 1971, Gottschalk and Kaul 1980a, 1980b, Koduru and Rao 1981, Kaul and Murthy 1985. In S. torvum, the average frequency of bivalents at diplotene during the presently investigated aberrant meiosis was 11.21 per cell, a figure close to 12 bivalents formed during the normal meiosis.…”

Induced desynapsis in grain Sorghum.

“…It is probable that two different recessive gene mutations are involved and therefore designated tentatively as, and as,. The present study confirms and extends the previous reports on similar lines and points to the possibility of polygenic control of meiosis in Sorghum species as has been reported in most of the higher plants including Pisum (Gottschalk and Baquar 1971).…”

Cytology of desynaptic Sternbergia fischeriana (Herb.) Roem. (Amaryllidaceae)

“…Li et al (1945) attributed the dissocia tion of chromosomes at or after pachytene to a recessive gene. Over the years desy napsis has been established as a gene mediated phenomenon in a large number of Gottschalk and Baquar 1971). Though the precise mode of action of these genes is not fully understood as yet, nevertheless, some attempts have been made to explain their effect through either imbalance in DNA: histone ratio (Ansley 1954) or inactivation of genetically controlled protein synthesis (Parchman andStern 1969, Jauhar andSingh 1969).…”