Natural diversity of seed α-tocopherol ratio in wild soybean (Glycine soja) germplasm collection.

Alpha-tocopherol is one of four tocopherol isoforms and has the highest vitamin E activity in humans. Most cultivated soybean seeds contain γ-tocopherol as the predominant form, and the ratio of α-tocopherol content to total tocopherol content (α-tocopherol ratio) is <10%. Three soybean accessions from Eastern Europe have α-tocopherol ratios of >20%. This higher content is likely due to mutations in the promoter region of the γ-tocopherol methytransferase-3 (γ-TMT3) gene. We surveyed a wild soybean germplasm collection and detected 16 accessions with stable seed α-tocopherol ratios of >20% under different growth conditions. The α-tocopherol ratios were greatly reduced when the plants were grown under cool temperatures during seed maturation, but increased to varying degrees at higher temperatures. Sequence analysis of the γ-TMT3 promoter of 11 of the accessions identified four haplotypes, one of which corresponded to that of cultivars with higher contents. These wild accessions can thus serve as novel donors for breeding cultivars with high α-tocopherol ratios and for better understanding the genetic basis of α-tocopherol synthesis in soybean.

Genotypic variation of Agrobacterium-mediated transformation of Italian ryegrass

In the present study, genotypic variation of Agrobacterium-mediated transformation of Korean Italian ryegrass has been evaluated. Mature seed-derived calli of seven cultivars were inoculated and co-cultured with Agrobacterium tumefaciens carrying the binary vector pCAMBIA1301, which contains a reporter gene (gus) and a plant selectable marker gene conferring resistance to hygromycin (hpt) in the T-DNA region. The effects of several factors such as callus type and callus age on transformation effectiveness and the expression of the GUS gene were investigated. The highest transformation effectiveness (6.7 percent) was obtained with the Hwasan 101 cultivar when 9-week-old calli (type-I) were inoculated with Agrobacterium. The overall transformation rates of the examined cultivars ranged from 0.4 percent to 6.7 percent. GUS histochemical assays, PCR, and southern analysis of transgenic plants demonstrated that transgenes were successfully integrated into the genome of Italian ryegrass. Thus, evaluation of transformation effectiveness and selection of a suitable cultivar of Italian ryegrass may improve molecular breeding of this species.