Molecular Biology Of Secale Germplasms

Secale L., one of the relative genera of Triticum, has great potential to be an important genetic resource to increase the genetic variations and introduce desirable genes for wheat improvement. It is of great necessity for wheat improvement to evaluate the genetic diversity and phylogenetic relationship of Secale, and to screen out germplasm resources with desirable traits and utilize them in wheat breeding. The purpose of this study were: 1) to evaluate the genetic diversity and phylogenetic relationships of Secale based on SDS-PAGE, SSR markers and 5S rRNA gene sequences; 2) to isolate and identify the LMW glutenin like genes from the R genome of Secale, and to obtain some valuable information for further investigation of the storage proteins in Secale. The results were desribed as following:1. The secalin compositions of Secale accessions were analyzed by SDS-PAGE. Four groups of storage protein, including HMW, γ -75k, ω and γ -40k secalins, were distinguished. A total of 54 patterns were detected in 72 Secale accessions, and each accession had 7 to 11 bands, with a majority of 9 to 10 bands. Six subunits and 21 subunit compositions were detected in HMW secalin. HMW and y -40k secalins could reveal a higher level of genetic diversity. The mean GS index of 72 Secale accessions was 0.748, with the range from 0.450 to 1.000. The highest GS index within species was observed in 5. sylvestre, whereas the lowest in S. cereale. The highest GS index between species was found between S. cereale and S. vavilovii, while the lowest between S. sylvestre and S. cereale. No obvious differentiation of GS level was observed in the accessions of cultivated rye from different continents. Clustering analysis could not distinguish all the 72 accessions. S. sylvestre were obviously divergent from other species, whereas S vavilovii was closely related to S. cereale. These results suggested that SDS-PAGE could reflect the genetic diversity and phylogenetic relationships of Secale. However, it could not reveal the relationships between accessions with different geographical distribution.2. The genetic diversity and phylogenetic relationships in the genus Secale L. was evaluated using 24 Secale cereale microsatellite (SCM) markers. The average polymorphism information content (PIC) value of each microsatellite locus in Secale was higher than that in the cultivated rye. The mean genetic similarity (GS) index in Secale was lower than that in the cultivated rye. The highest GS index within species was...