Study On Genetics Of Callus Induction,And Plant Regeneration From Immature Inflorescences Among Chinese Wheat(Triticum Aestivum L.)Varieties

Tissue culture is a basic technique in the study on gene engineering. In study on transferring alien genes into wheat using a transgenic system, the receptor plant is veiy important for its capability in callus induction and plant regeneration. Now it is known, that the major present limitation to the genetic engineering of many crop species is the lack of regeneration and transformation systems, because the capability of transformation and regeneration of many crop species including wheat is highly genotype-specific. The present study was made for selection of excellent germplasm which should exhibit high tissue culture response and good agronomic characteristics. In the study 101 local varieties, 83 modern cultivars, 72 new families of wheat were analysed for the days of callusing at 50% (DCH), the number of callusing in 4 weeks (NCW) in callus induction; and rate of Calli of root formation (in %, RCRF) and the rate of calli of shoot formation (in %, RCSF) in differentiation culture. The gene location was made using Chinese Spring monosomes for DCH, RCRF, and RCSF. The results indicated: 1. An extensive variation was found in DCH, NCW, RCRF, and RCSF among different wheat genotypes. The same trend of variation of these characters was observed in the three populations of local varieties, modern cultivars and new families of wheat. 2. The days of callusing at 50%(DCH) was observed to 8 distribute from 6d to over 28d. The distribution of DCH was continuous in the three populations. In the distribution wave two peak values were observed at 12 days and 26 days. 3. The Numbers of callusing in 4 weeks (NCW) exhibited extensive variation from 16.7-100%, 18.3-100%, and 4 1.7-100% in local, cultivars and families populations, respectively. 4. The rate of calli of root formation (RCRF) exhibited broadly variation and RCRF are from 0-70.97%, 0-48.39%, 0-77.42% in local, cultivar and family populations, respectively. 5. A low frequency of the rate of calli of shoot formation (RCSF) was found in all three populations with the average at 1.4 1%, 0.84%, and 1.66% in local, cultivar and family populations, respectively. 6. A high correlation between DCH and NCW was found with the correlation coefficients of ?0.7689, ?0.7506 and ?.6778. No correlation was observed among DCH, RCRF, and RCSF. The results suggested that the DCH, RCRF and RCSF were controlled by different genetic background. 7. The gene location was made by using Chinese Spring monosomes. The results indicated that the genes for DCH were located on chromosomes of 5A, 1B, 1D, in which 1D chromosome exhibited the most strong effect. The genes for RCRF were located on chromosome 2A and 2D, of which the gene on 2D is more strong. The genes for RCSR were located on chromosome 3A, 3B, 3D, 7A, and 4D, in which the genes of 3A, 3B and 3D exhibited stimulative effect and the genes of 7A and 4D represented a suppressive effect. 8. Several excellent parents of wheat with high tissue response, such as Duohuabai, R1395, were screened from these varieties and families in the present study.