Cytogenetic comparison of restorers TP-4 and Dminghui63 with maintainer D46B of autotetraploid rice

Abstract

Cytogenetical comparison was made between high seed setting restorers TP-4 and Dminghui63 with eminent maintainer line D46B of autotetraploid rice. The meiosis observation demonstrated that the genomes of our autotetraploid materials were all 2n = 48, which was the same as those in mitosis observation. Low percentages of univalent and trivalent in diakinesis-metaphase I (MI) of restorers TP-4 and Dminghui63 as well as maintainer line D46B of autotetraploid rice were observed. And the percentages of chromosome pairing were all over 99%, showing eminent cytological character. The frequency of TP-4 and Dminghui63 in diakinesis-metaphase I was 2.00/PMC (pollen mother cell) and 2.26/PMC, respectively. However, the frequency of D46B was 6.00/PMC, significantly higher than those of TP-4 and Dminghui63. It indicated that the maintainer D46B had better chromosome pairing capability in diakinesis-metaphase. While, the frequency of lagging chromosomes of the maintainer D46B in anaphase I (AI) was 10.62%, significantly lower than that of TP-4 (19.44%) or Dminghui63 (23.14%), and close to the level of diploid control (7.30%). In telophase I (TI), maintainer D46B exhibited lower frequency of microkernel, and in telophase II (TII) the frequency of normal quartered microspore of maintainer D46B was not only higher than that of TP-4 or Dminghui63 but also than that of diploid control. The percentage of the cell observed chromosome lagging in AI and the percentage of abnormal cell in TI showed a greatly significant positive correlation. That may demonstrate that chromosome separation in AI and microkernel formation in TI are controlled by the same dominant single gene or the major gene of a QTL.