Cytological particularities in nuclear and nuclear-cytoplasmic male sterile pepper lines

Abstract

The meiosis in the pollen mother cells (PMCs) of nuclear and nuclear-cytoplasmic male sterile (CMS) pepper lines No.1647 ms 8 ms 8 and No.K587 Srfrf was evaluated to establish the causes of male steril- ity. The investigations of sterile (ms 8 ms 8 ) plants revealed that at diakinesis and metaphase one, along with the bivalents, up to 4 quadrivalents, and between 2 and 16 univalents were observed in 21.2% and in 6.2% of the PMCs, respectively,. In the remaining 72.6% of the cells normal pairing and formation of 12 bivalents was found. Lethality in ms 8 ms 8 plants occurred after the second telophase, as cytokinesis and microspore formation were blocked. Similar meiotic disturbances were not visible in the fertile analogues (Msms) from line No.1647 and that was refl ected in the: presence of cytokinesis after the second telophase; tetrad creation in about 99% of the cells; pollen fertility in the range of 60-100%. In the CMS line No.K587, the existence of 12 bivalents (73.8% of the PMCs), one or two quadrivalents, and up to six univalents (21.9% and 4.3% of the PMCs) were described. The microspore degeneration started either after the tetrad stage, as the callose was not dissolved and the microspores were not released from the sporads, or in some cases at various phases of the microgametogenesis. The chromosome rearrangements and chromosome breakage leading to those aberrations could damage the genetic system responsible for the regular initiation, running and termination of late meiotic stages, especially the termination of TII and initiation of cytokinesis in ms 8 ms 8 plants, and loss of callose dissolving in the CMS plants.