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RING‐POSITION AND FREQUENCY OF CHIASMA FAILURE IN RHOEO SPATHACEA
Author(s) -
Lin Yue Jee,
Paddock Elton F.
Publication year - 1973
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1973.tb06003.x
Subject(s) - chiasma , synapsis , biology , chromosome , ring (chemistry) , position effect , genetics , gene , chemistry , organic chemistry
The mean chiasma number per cell was 11.44 ± 0.04 in 489 cells. Due to chiasma failures, the ring‐of‐twelve chromosomes may be broken into two or three chains. Cells with four or more chains were not observed. All six possible two‐chain situations and eight different threechain situations were found. All possible lengths of chains from one to all twelve chromosomes were found, with “chain”‐of‐one inordinately frequent. The overall mean number of chromosomes in 273 chains in 188 cells is 8.26 ± 0.31 and 5.38 ± 0.31 among 154 chains in the 69 cells that had two or more chains. The mean number of chains per cell among these 188 was 1.45 ± 0.13. In 73 cells, 113 chiasma failures were found to be distributed at random among the twelve chromosome arm positions. The absence of association either between length of arm or between presence‐absence of secondary constriction and frequency of chiasma failure support the generally accepted theory that, in Rhoeo , synapsis and crossing over are restricted to small terminal segments on all chromosomes.