A resveratrol synthase (RS) gene was isolated from peanut (Arachis hypogaea, L. cv. Jinpoong) plants. This gene was placed under the control of the cauliflower mosaic virus 35S promoter (CaMV35S) and introduced into two Korean varieties of potato (Solanum tuberosum L. cvs. Jasim and Jowon) plants by Agrobacterium-mediated gene transfer. Putative transformants were screened by PCR with primers designed from CaMV 35S promoter, NOS terminator and RS gene. Most of selected transgenic potato plants showed the amplification of expected fragments by PCR of genomic DNA with gene-specific primers, while they were absent in untransformed control plants. Expression of the resveratrol synthase gene was also examined by northern blot analysis. The transformants showed a band which was lacking in the control plant, confirming that the introduced gene is transcribed into mRNA in the transformants. The strength of the band, which reflected the level of mRNA expression, differed among the individual transformants. Among the transformants obtained, the highest trans-resveratrol content in the transgenic young leaves of purple-fleshed "Jashim" was 2.11 μgg-1 fresh weight and that in the microtubers in vitro of purple fleshed "Jashim" was 8.31 μgg-1 fresh weight. This amount of resveratrol may have a positive biological effect on human health.

"Chuyoung" as a new double cropping potato variety was bred in 2005 for table use through a cross between "Dejima" with short tuber dormancy and HRB-31 which is a tetraploid derived from an interspecific cross between "Russet Burbank" and Solanum phureja line. It was evaluated for short dormancy, growth and tuber characteristics every twice a year from 1997 to 2001. Regional yield trials were performed from 2002 to 2004 at three locations, Jeju, Namhae and Gangneung of Korea, respectively. Its tuber shape is oblong with yellow skin and flesh colors. Its dormant periods is 60~70days. It showed less incidence of physiological disorders such as cracking or knobs on tubers, and higher resistance to common scab by Streptomyces scabies compared to "Dejima". It has tall plant height and erect growth type with green-broad leaflets and white large inflorescence. Its average yields are 29.5 and 22.6 ton/ha at 90 days after planting in spring and autumn cropping, respectively. It also showed higher marketable yield due to the lower incidence of common scab and physiological disorders compared to "Dejima".

"Chugang" as a new double cropping potato variety for table use was bred in 2003 from a cross between H83005-2 with short dormancy and "Superior" with common scab resistance. It had been evaluated for short dormancy, growth adaptability and tuber characteristics every twice a year from 1990 to 1999. Regional yield trials had been performed from 2000 to 2002 at three locations, Jeju, Namhae and Gangneung of Korea, respectively. It has round oblong tuber shape with yellow skin and white flesh color. Its tuber dormant periods is approximately 50~60 days. It showed less physiological disorders such as cracking or knobs, and more tolerant to environmental stresses such as plant death by flooding and damages by frost or severe wind compared to "Dejima". Average yields of "Chugang" are 34.6 and 31.1 ton/ha at 90 days after planting in spring and autumn cropping, respectively. It is more resistant to common scab and less susceptible to late blight (phythophthora infestans) compared to "Dejima". However, it is susceptible to potato virus Y (PVY) and andean mosaic virus (AMV).

Lately, the autumn cropping areas of potato have been steadily increased to supply fresh potatoes all year round in Korea. Although "Dejima" is a main cultivar for autumn cropping, it is very susceptible to common scab (Streptomyces scabies) and show high frequency of physiological disorders such as knobs and cracking on tubers. "Chudong" was bred in 2002 for fresh table use from a cross between H83520-3 with short tuber dormancy and "Superior" with common scab resistance. It has attractive, round tuber shape with white skin and flesh colors. Its tuber dormant periods is 5 days longer than 65 days of "Dejima". Its average yields were 32.4 and 21.8 ton/ha at 90 days after planting in spring and autumn cropping of regional yield trials, respectively. It is more resistant to common scab and potato leaf roll virus and less susceptible to late blight (Phythophthora infestans) compared to "Dejima". However, it is susceptible to potato virus Y.

We performed field trials to assess levels of changes in intrinsic properties and resistance against soft rot of the potato cultivar ‘Irish Cobbler’ upon the introduction of the Shiva-1 gene. Each five lines, transformed with Shiva-1 gene controlled by the PAL5 promoter (P) and by the CaMV 35S promoter (E) were evaluated in the field. In based on evaluation of 10 defined morphological characteristics, all the transgenic clones of both lines proved to be true to type. When five agronomic characteristics were taken into account as well, all the transgenic lines except E8 were considered to be true to type. According to the result of northern blot analysis, seven (P1, P3, P4, P6, E10, E12, and E16) transgenic clones could be distinguished clearly from corresponding untransformed clones. But in three lines (P8, E5, and E8), no hybridization signal was detected. There seems to be positive correlation between the levels of resistance to soft rot and the transgenic expression at mRNA levels in P lines. But in the case of E lines, however, there doesn’t seem to be any correlation between the levels of disease resistance and mRNA expression