Haploid Induction By Several Alloplasmic 1BL/1RS Wheat And Its Cytogenetic And Embryologic Study

The study was mainly focused on induction and cytogenetic and embryologic mechanism on apomixis of several alloplasmic 1BL/1RS male sterile wheat, Ae.kotschyi/Ae.variabilis /Ae.ventricosa-/Ae.bicornis-77(2)/yanshi9/80(6),8222,83(37)65, after pollination of maize (Shaan dan902) and rye (Secale cereale), by comparing them with their corresponding maintainer lines and some non- alloplasmic 1BL/1RS male sterile wheat and CHA-induced male sterile lines (chemical hybridization agent) employing the cytological and embryological techniques. And the results indicated that:1. The method of haploid production was reported by employing maize (Zea mays L.) and rye (Secale cereale) as the male parents to pollinate with 1BL/1RS male sterile wheat lines with spraying 2,4-D of concentration 120mg/L. The results showed that comparing with the corresponding maintainer lines, the haploid production frequency of 1BL/1RS wheat male sterile lines could be enhanced by crossing with maize (Zea mays L.), and the haploid production frequency was much higher when pollinated with rye (Secale cereale) . When crossing with same male sterile lines, the haploid production frequency was related to pollen sources. Pollen mixture of maize and rye (3:1) could not enhance haploid production frequency.2. By employing cytological technique,the frequency of abnormal chromosomes (including univalent at the meiotic metaphase and lagged chromosome and chromosome bridge at the meiotic anaphase etc.) was investigated, and the result indicated that comparing with non-1BL/1RS and CHA-induced (Chemical Hybridization Agents) sterile wheat lines, 1BL/1RS contained the higher frequency of abnormal chromosome both at the meiotic metaphase and anaphase with the correlation coefficient of 0.811995 . And the correlation coefficient of non-1BL/1RS and CHA-induced sterile wheat lines was much lower and the correlation was not so significant, implying that non-1BL/1RS and CHA-induced sterile wheat lines can be extensively applied in wheat hybrid breeding program. 3. The studies of apomixis of the 1BL/1RS wheat sterile lines were carried out to reveal cytogenetic mechanism of haploid production in F1 generation. The results show: (1) During the development of pollen mother cells (PMC), the abnormal chromosomal pairing at meiotic Metaphaseâ… could be observed in both euplasmic and alloplasmic 1BL/1RS wheat sterile lines at a very different rate, with the former lower. (2) Under specific Aegilops cytoplasmic background,the size of translocated segment of 1RS chromosome and interaction of nucleo-alloplasm jointly impaired the pairing of homologous chromosome at Metaphase ?. (3) The high frequency of abnormal chromosomal pairing formation in PMC directly affected the frequency of haploid production by parthenogenesis.4. The embryologic observation shows that the apomixis performance of the 1BL/1RS wheat sterile lines was probably derived from both egg cell (parthenogenesis) and synergid (apogamy)based on the pollination time.