Morphologic And Cytogenetic Characterization Of Hybridization Progenies From The Zea.may×Zea.perennis

Wide relatives of maize in Genus Zea have contained a great number of such valuable genes such as resistant genes and anti-virus genes, maize and it's relatives karyotype are important for understanding the origin and evolution of maize, the introduction of alien genetic germplasm from related species was an important method for improving genetic base of maize. In order to reach the target, the karyotype of maize line 48-2 with high yield characters and other 3 maize relatives was studied. At the same time, line 48-2 and Zea perennis were used as parents, alien germplasm from Maize-Z.perennis hybrids was studied in the present paper. Results were shown as following:1. Maize line 48-2 and three species maize relatives karyotype formulae were as follows: Zea mays, 2n=2x=20=16m+4sm(2sat); Zea diploperennis, 2n=2x=20=10m+10sm(2sat); Zea mays ssp.mexicana, 2n=2x=20=10m+10sm(2sat); Zea perennis, 2n=40=24m+16sm(4sat). The results of karyotype analysis indicated: maize and three teosinte were belong to the same genus, teosinte is phylogenetically closed to maize, Zea diploperennis was primitive species in Genus Zea.2.Using some specially treated and genomic affinities, few F₂ aneuploid of maize×Zea.perennis could be obtained by chromosome elimination, the chromosome numbers variation from n=20 to n=28. There were 19 F₂ progenies plants obtained from F₂ generation by self-hybrid and back-cross. All the F₄ generation progenies chromosome numbers were n=20 through the third generation plants self-hybrid or back-cross with maize parent, n=30 bak-cross with the relative parent. In the introgression of Z.perennis genetic material to maize, the chromosome recovered n=20 after the F₂ generation hybridization with z.perennis.3. The study evaluated the major phenotypic traits of the progenies of which were from the different hybrid methods. Results showed different hybrid method had different effects for the plants, the variation degree were different to the same agronomic characters. Most of the agronomic characters had significant difference compare to the maize parents, all the third generation had inbreeding depression after the self-hybrid, there were large difference among plant height, ear height, tassel branch number, tillers number, ear leaf length, ear leaf wide et al.4. The study evaluated the major phenotypic traits of the back-cross progenies, Results showed there are large difference among plant height, ear height, cob diameter, tassel branch number, tillers number, 100-kernels weight, ear length, ear leaf length, kernel row and kernel number per row after the introgression of z.perennis genetic materials. Ear length which direct to the yield were significant difference among most of the combination, cob diameter and no kernels of ear were significant lower than the maize line.5. The study evaluated the major phenotypic traits of the progenies which back-cross with relatives, Results showed there are significant difference tillers numbers, plant height, ear leaf length, ear leaf wide compared to F₁ generation. A partial fertility allotriploid(2n=30) MT-71 plant(BC₁F₂×P₂) was generated. The meiotic configuration was 2.30â… +3.72â…¡+6.49â…¢+0.23â…£, which was different from the sterile allotriploid F₁(4.57â… +5.03â…¡+5.17â…¢), chromosome bridge, lagging chromosomes were be observed. So we can presume there were two maize chromosomes were substituted by Z.perennis C genome. The progenies of triploid-diploid(3n×2n) cross consisted of mostly aneuploid and the seed set percentage 7.84% was higher than other hybrid patterns: 3n×4n(0.52%), 2n×3n(0.56%), 3xopen-Pollinated(1.18%). These results indicated the cross compability of diatant hybridization is not relative to the heredity,but also to the maternal effect.6. Alien germplasm from maize-Z.perennis hybrids was identified by molecular marker SSR. The results showed that: Among the 246 pairs of microsatellite primers selected, 53 were found specific. 9 significant primers were selected to identified the maize-Z.perennis progenies, most of all had more than 1 specific SSR band.