RADIOBIOLOGICAL STUDIES IN PLANTS. VII. CHROMOSOME ABERRATIONS INDUCED BY GAMMA-IRRADIATION IN A JAPANESE WHEAT VARIETY

Journal Article · Mon Oct 01 04:00:00 EDT 1962 · Seiken Jiho (Japan)

OSTI ID:4042558

Nishiyama, I; Ichikawa, S

A study of the effects of gamma irradiation on oats and wheat, especially Triticum vulgare variety Shinchunaga, showed many morphologic and physiologic mutants in the X/sub 2/ and the later generations of the irradiated wheat. From the genetic behavior of the mutant characters, it is assumed that most of them were induced through chromosome aberrations. Cytologic and genetic observations on these mutants are described in detail. X/sub 2/ plants derived from 118 X/sub 1/ spikes and of their progenies (X/sub 3/ -- X/sub 5/) which showed aberrant changes in morphologic or physiologic characters were examined cytologically in the meiosis of the pollen mother cells. Of 44 X/sub 2/ lines investigated cytologically, 34 showed abnormal meiotic configurations, such as multivalents, univalents, heteromorphic bivalents, aneuploidy, partial asynapsis, or mixoploidy in their progenies. Of 546 plants examined cytologically, 342 (63%) showed chromosome aberrations. Various types of abnormal meiotic corfigurations and their frequencies are tabulated. The plants with 38 to 45 somatic chromosomes were found in the progenies of the irradiated wheat. Excluding the plants which showed partial asynapsis or mixoploidy, about 50% of plants had 42 chromosomes, 21% had 41, 9% had 40, 9% had 43, 7% had 44, and the remainder had 38, 39, or 45 chromosomes. In the X/sub 2/ -X/sub 5/ progenles were often found various abnormal characters, e.g., dwarfness, short spike, lax spike, speltoid, compactoid, square head, thick culm, slender culm, bent culm, narrow leaf, and sterility. Most of these abnormalities appeared to be associated with various chromosome aberrations. For instance, speltoid plants had always 42 or less chromosomes whereas compactoid plants had always 42 or more. On the other hand there were some mutants showing oniy normal 21 bivalents, probably induced through gene mutations. Generally, plants with 42 chromosomes had high fertilities but those with chromosome numbers deviating from 42 showed decreased fertilities. Moreover, wide variations in the fertility were often observed in the plants with the same chromosome number, probably due to the presence of multivalent pairings of chromosomes or other chromosome aberrations, Partially asynaptic plants with 41 to 43 chromosomes usually showed higher seed fertilities than those with 40 chromosomes, most of which were completely sterile and accompanied by dwarfness with a few exceptions. It is proposed that the high sterility and dwarfness might mainly be caused by the nullisoraic nature of chromosome constitution. (BBB)

• Research Organization: Kyoto Univ.
• NSA Number: NSA-18-017607
• OSTI ID: 4042558
• Journal Information: Seiken Jiho (Japan), Journal Name: Seiken Jiho (Japan) Vol. Vol: No. 13; ISSN SEZIA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BIOLOGY AND MEDICINE
CELL NUCLEI
CEREALS
CHROMOSOMES
CYTOLOGY
GAMMA RADIATION
GENETICS
IRRADIATION
MALFORMATIONS
MEIOSIS
MITOSIS
MUTATIONS
NUCLEIC ACIDS
OATS
PHYSIOLOGY
PLANT CELLS
PLANTS
PLOIDY
POLLEN
QUANTITY RATIO
RADIATION INJURIES
RADIOSENSITIVITY
REPRODUCTION
STATISTICS
TABLES
TRITICUM
VARIATIONS
WHEAT