Study On The Cytology Of Special Autopolyploid And The Genetic Analysis Of Hybrid Progeny Crossed By Diploid In Rice

Autotriploid and autotetraploid were derived from the rice twin-seeding basic populations of 9003 and 9004 respectively. Which were crossed with the common diploid as female parent by Wu Xianjun(1999) and Xing Shaochen(2000). Some diploid plants were obtained in F1 generations and F2 populations of partial diploid F1 individuals were uniform.The phenomenon of stability in early generation is important. The research have been proceeded mainly in following aspects with autotriploid plant strains 146-B, 148-B, 149-B derived from SAR-2: (1)Chromosome behavior during meiosis and embryo sac of autotriploid. (2)Reproductive behavior of autotriploid and embryo development of pollination process of 3N X 2N. (3)Testing the genetic stability of progenies of 3NX2N. In addition, meiotic behavior of 006 plant strains, generated naturally in rice twin-seedling population 9005, were observed by cytology technique. The main results are as follows:1. Root-tip was identified. As a result, 146-A, 148-A, 149-A were diploid; 146-B, 148-B, 149-B were triploid; 006 was tetraploid.2. The pollen stainability was constructed by using the method of I2~KI. The results were summarized as follows: the pollen stainability of autotriploid was very low, only 11%; the pollen stainability of autotetraploid was higher than that of autotriploid (64.7%).3. The autopolyploid PMCs were observed and the results showed: ㏕he average paring form of autotriploid was 9. 75III+2. 71II+1. 37 I at diakinesis and 8. 65III+4. 32 II +1. 41 I at metaphase I. The equilibrium segregation was prevailing at anaphase I. Lag chromosomes were also observed at the same phase, which was probably the main reason for the formation of haploid gamete. (2) The average paring form of tetraploid was 6. 77IV + 1. 82III+6. 45 II +2. 09 I at diakinesis and 6. 25IV+2. 25III+6. 67 II+1. 50 I at metaphase I. The equilibriumsegregation was also prevailing at anaphase I. The absolute majority gametes had 24 chromosomes.4. The research for the embryo sac structure of triploid lines of SAR-2 showed that: 47% embryo sacs were normal and 53%were not. And in the latter, twin-ovules, twin-sacs, multi-eggs, multi-polar nuclei, multi-antipodal cells and non-egg apparatus were observed.5. The process of pollination and embryo sac development showed that the abnormity and the abortion were caused by barriers of double fertilization, prolonged and abnormal development of proembryo, and even development stopping or differentiation failure of embryo and endosperm.6. The seed setting rate was very low, only 0. 566%. There was one diploid plant among eight F1 hybrid plants obtained from the autotriploid crossed with diploid. Chromosome behavior during meiosis of the diploid plant was normal and a uniform population was obtained in its F2 progeny. The others were aneuploids or chimeras. The multivalent, univalent, chromosome loss and lag were observed during the meiosis. At the same time, the self-hybrid progenies segregated madly.7. The agronomic traits were constructed in the F2 population. As a result, there was no significant difference in plant height, panicle length, heading date between the F2 population and the CK, Shanyou63. The stability population was further verified through microsatellite marker technique. It was concluded that the F2 population was really stable.