Obtaining And Identification Of Interspecific Hybrids From False Pakchoi×Kailan

The diploid False pakchoi(2n=2x=AA=20), tetraploid False pakchoi(2n=4x=AAAA=40), diploid Kailan(2n=2x=CC=18)and tetraploid Kailan(2n=4x=CCCC=36)were used to establish interspecies hybirids of tetraploid and triploid by means of artificial pollination and hybrid ovary culture in vitro, and the hybrids were identified by karyotype analysis, DNA relative content mensuration, meiotic examination, morphological observation and so on, and the main results were showed as follws:1. Paraffin slice observation of the ovaries from tetraploid False pakchoi×diploid Kailan showed the days of embryo abortion is about 10d after fecundation, the main reason of which is endosperm die ahead.2. Study of the ovary culture showed that the suitable medium for interspecies hybrid immature embryo culture of tetraploid False pakchoi×diploid Kailan is Nitsch with V_B10.5mg/l, V_B60.5mg/l, V_H0.01mg/l, BA0.5mg/l, IAA0.1mg/l, sucrose 70g/l; and the suitable culture stage is 7-8d after pollenation.3. DNA relative content mensuration by Flow Cytometry, and chromosome karyotype analysis showed that the allotetraploid and allotriploid obtained are true interspecific hybrids and their chromosome sets are AACC and AAC respectively.4. The guard cell size, stoma density and chloroplast number per guard cells of the lower epidermis are without obvious difference between the tetraploid or triploid hybrids and their diploid parents, therefor, these characters can not regarded as the criterions for the interspecies hybrid identification.5. Observation of the allotriploid miosis showed that one chromosome at least of Kailan existed homologous or part homologous with one chromosome of False pakchoi.6. Investigation and analysis of morphological characters of the hybrids showed that most characters of the hybrids are between parents. The chromosomes(C Genome)with white flower gene and purple point gene on top of anther are no homologous with any of chromosomes of the A genome.7. Self-pollinated offspring of the allotetraploid display consistent traits and strong heterosis.8. the allotriploid can produce about 2.5％n+1 gametes, and the seed setting of the allotriploid(AAC)×diploid False pakchoi (AA) was about 25.79％, which established a solid basis for selection of the alien addation lines.