Preliminary studies on the genome and chromosome markers of wild soybeans collected in Taiwan

Soybean (Glycine max (L.) Merr.) is the most important crop in the Leguminosae families. And the wild Glycine species are very momentous breeding resources for soybean improvement. Taiwan is the northern boundary of the annual wild soybeans, and the southern boundary of the perennial wild soybeans. They are the annual one G. soja (GG genome) , also the three perennial ones G. tomentella (DDD1D1 genome) , G. dolichocarpa (A6A6DD genome) and G. tabacina (A6A6B3B3 genome) .
The basic chromosome number of the Glycine species is 2n=40. Their chromosomes are similar in size and lacks of obvious morphological characters. Little is known about the repeat sequences composition in the genomes of the Glycine species, hence the research about genome taxonomy and chromosome karyotyping are limited. Using fluorescent in situ hybridization (FISH) method, target sequences can be labeled with repeat sequences, and thus labeling specific genomes or the particular regions of chromosomes. FISH can also be used to reveal the genome diversity between species, and perform karyotyping. Thus, it is helpful to solve the problems among taxonomy controversies or chromosome or studies.
Three G. max repeat sequences were isolated by bioinformatics analysis using soybean whole-genome shotgun (WGS) sequences, and designated SBRS1、SBRS2 and SBRS3. SBRS1 could be used on the special specific probe of the GG genome. SBRS2 and SBRS3 could be used to label the pseudomolecules 9, 13, 14 and 20 in the GG genome. The searches were carried out, and then the compared with the result of FISH. Thus, it indicated that the WGS data could be used for predicting the distribution of repeats, while not suitable for estimating the amount of these repeat sequences.
Two useful ISSR amplified fragments are selected by Dot blotting hybridization. The SBRS4 could be used for GG genomic chromosomes karyotyping. And the SBRS5 could be a specific probe of the G. tomentella genome and would label two pairs of chromosomes. It is thus suggested that, the unspecific sequences still may offer the potential to be applied as the genomic or chromosome markers.