Meiotic Investigation in Reciprocal Translocation Heterozygotes of Commelina benghalensis L. (Commelinaceae) Induced by Gamma Irradiations

抄録

Commelina benghalensis L. is a diploid plant with 2n=2x=22 median size chromosomes. Gamma irradiations (10, 15, 20, 25 kR) to C. benghalensis seeds induced 14 translocation heterozygotes. The translocation heterozygotes exhibited the formation of either a ring or a chain of four chromosomes in PMCs (ranged from 79.84 to 100%). The translocation lines showed the preponderance of ring quadrivalents as compared to chain quadrivalents. After comparative analysis, the quadrivalents frequently displayed alternate disjunction (52.91%) than adjacent disjunction (47.09%). At anaphase I/II and telophase I/II, the translocation heterozygotes showed the presence of lagging chromosomes and chromatin bridges. Micronuclei were sometimes formed in tetrads. Heterozygous plants showed high pollen sterility (ranged from 21.30 to 81.82%) due to the presence of adjacent orientation in quadrivalents and the cumulative effect of other meiotic irregularities. Also, pollen sterility showed a positive and significant correlation (r²=0.7285) with adjacent segregation of quadrivalents (ranged from 20.0 to 74.22%) in translocation heterozygotes.