CYTOGENETICAL STUDIES ON ASYNAPTIC RICE PLANT (ORYZA SATIVA L.) INDUCED BY X RAY

Journal Article · Thu Jun 01 04:00:00 EDT 1961 · Senshokutai (Japan)

OSTI ID:4083046

Katayama, T

Development of asynaptic rice plants was induced by x irradiation in X/ sub 2/ generation of the rice varieties Asahi and Aikoku. It was difficult to distinguish morphologically such asynaptic plants from the normal ones except for their high sterility and specific awn character. These asynaptic plants were also characterized by erect panicles and by their continuously producing fresh tillers until after the normal ones had stopped growth and attained their maturity. The asynaptic plants showed very high sterility, attaining a seed set of less than 1%. No seeds could be obtained from both reciprocal crosses between normal and asynaptic plants. From the segregating behavior of this asynaptic character in X/sub 2/, in the X/sub 3/ generation, and in the open-pollinated offspring of the asynaptic plants, it was concluded that the asynaptic character is inherited by a simple recessive gene which causes complete failure of chromosome pairing at the early stage of meiosis. No pairings of homologous chromosomes were ascertained at zygotene and pachytene stages in these asynaptic forms. The number of paired chromosomes at diakinesis and at Ml varied from 0 to 12, and the mean number varied from plant to plant, and from one another to another in the same plant. The average number of chiasmata per bivalent was 1.03 for the asynaptic plant and 2.21 for the normal one when all chromosomes, paired and unpaired, were taken into consideration. However, it was 1.83 for the asynaptic plant and 2.21 for the normal one when only paired chromosomes were counted. On the other hand, the numbers of chiasmata on each nucleolar chromosome were 2.14 and 2.11 for the asynaptic and the normal plants, respectively, if only paired chromosomes were considered, and 1.36 and 2.11 for the asynaptic plant and the normal one, respectively, if all chromosomes were taken into consideration. At anaphase I, various numbers of lagging chromosomes were usually observed. The asynaptic plants showed irregular behavior of univalent chromosomes, resuiting in the complete abortion of their pollen grain. (BBB)

• Research Organization: Kyushu Univ., Fukuoka
• NSA Number: NSA-18-013543
• OSTI ID: 4083046
• Journal Information: Senshokutai (Japan), Journal Name: Senshokutai (Japan) Vol. Vol: 48; ISSN SNSHB
• Country of Publication: Country unknown/Code not available
• Language: Japanese

Related Subjects

BIOLOGY AND MEDICINE
CEREALS
CHROMOSOMES
CYTOLOGY
GENETICS
IRRADIATION
MEIOSIS
MITOSIS
MUTATIONS
PLANTS
REPRODUCTION
RICE
X RADIATION