TRIPLOIDY INDUCED BY GAMMA IRRADIATION DURING MEIOSIS IN SUNFLOWER

Journal Article · Tue Jan 01 04:00:00 EST 1963 · Zeuchter

OSTI ID:4120620

Pozsar, B I; Kurnik, E; Parragh, J

The selected lregi csikos (Striped Ireg) sunflower variety was irradiated prior to the onset of flowering in the early phase of microsporogenesis with a 20-kr dose of gamma rays from a Co/sup 60/ source. Profound alterations in cytologic, morphologic, and physiologic behavior resulted from this dose. In untreated flowers, microsporogenesis is regular, and four haploid cells (tetrad) are produced during the mitosis following meiosis. The chromosome sets disintegrate under the effect of the 20-kr dose, and not all of them move away one from the other. The four haploid chromosome components are formed regularly, but the two mitoses taking place in the cell are no longer synchronous. Compared with the regularly disintegrating two chromosome sets, the other two chromosome sets remain near one another, even at the end of the disaster stage. During the spirem stages a tetrad is not produced but a triad, due to synchronous divergence. In the triad the first and second chromosome sets are haploid and enable the production of normal pollens, while the third member of the triad is diploid and leads therefore to the formation of pollen of abnormal shape and function. Some develop fruits of triploid (3n = 51) progenes. Samples taken from the root tips of seedlings developing from selfed fruits showed a large number with triploid chromosome number. Thus, irradiation of plants which originally had a diploid chromosome number of 34 led to the production of a considerable number (3.80%) of triploid progeny. The chromosomes were either thinned and stained poorly or shortened and more intensely stained than controls. Decreased nucleic acid or nucleoprotein content in the poorly stainable chromosomes of relatively thin structure observed in the mitotic division of triploids was regarded as evidence of x-ray injury. (BBB)

• Research Organization: Agricultural Experimental Inst., Iregszemcse, Hungary
• NSA Number: NSA-18-006678
• OSTI ID: 4120620
• Journal Information: Zeuchter, Journal Name: Zeuchter Vol. Vol: 33
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BIOLOGY AND MEDICINE
CHROMOSOMES
COBALT 60
GAMMA RADIATION
GAMMA SOURCES
MEIOSIS
MICROSPORES
MITOSIS
MUTATIONS
NUCLEIC ACIDS
PLANT CELLS
PLANTS
PROTEINS
QUANTITY RATIO
RADIATION DOSES
RADIATION EFFECTS
RADIATION INJURIES
SUNFLOWERS
VARIATIONS
X RADIATION