‘대유미’는 국립식량과학원 바이오에너지작물센터에서 2008년에 육성한 바이오에탄올용 고구마 신품종으로 주요 특성과 수량성을 요약하면 다음과 같다. 1. 넝쿨색은 녹색, 잎모양은 심장형, 잎색은 녹색을 띤다. 또한 엽맥색은 녹색으로 자색을 포함하지 않으며, 끝잎색은 녹색, 잎자루색은 녹색이다. 2. 괴근 모양은 방추형으로 껍질색은 홍색을 띤다. 육색은 대조품종 ‘율미’가 담홍색인데 비하여 농황색이다. 상품성을 좌우하는 표피의 형태는 골파짐이 없이 메끄럽다

Sweetpotato is one of the important starch crops, current more considered as an industrial crop rather than food because it has higher starch content (over 80% of biomass), it is used for bio resources for industrial area. In this study, we generated S598A (a mutant gene of oat phytochrome A) sweetpotato plant using Agrobacterium-transformation method. Morphological characteristics of S598A plant were compared with the wild type sweetpotato, S598A had darker green leaves, increased chlorophyll content higher than to two-fold, delayed leaf senescence, shorter plant height (60% shorter than that of the wild type), more number of leaves and petioles about 1.8-fold, shorter petiole length (30% shorter), 1.2-fold more branches and 1.6-fold thicker stem diameters. From this study, S598A plants with such phenotypic characteristics might be able to use the solar energy efficiently, to have increased tolerance to biotic and abiotic stresses and finally to increase productivity (not only starch yield but also root biomass yield). S598A sweetpotato lines are under field trials.

고구마 멀칭재배에서 생분해성 플라스틱 피복재 이용 가능성을 검토하고자 시험을 수행 한 결과 다음과 같다. 1. 필름의 물성은, 생분해성인 PBSA와 PLC + Starch는 일반멀칭재료인 LDPE 에 비하여 인장강도는 2~27 % 상승하였으나 신율은 2~22 % 낮았고, 인열강도도 2~6 %가 낮았다. 2. 피복기간에 따른 인장강도의 변화는 생분해성 필름의 경우 피복 후 60~70 %일 동안 급격히 감소하다가 그 후 완만한 감소를 보였고 제조 원료별로는 PLC + Starch가 PBSA에 비하여 변화율이 낮았다. 3. 신율의 변화는 피복 후 60~70 %일 동안 매우 급격히 감소하다가 그 후 완만한 감소를 보였다. 제조 원료별로는 PLC + Starch와 PBSA 제품간의 뚜렷한 차이는 보이지 않았으나 15 um PBSA의 경우 60~70 %일이 지나면서 급격한 물성저하를 보였다. 4. 생분해성 필름에 대한 용출시험에서는 중금속들이 아주 작거나 검출되지 않았고, 국내 환경마크협회가 정하는 생분해성 수지 제품에 대한 유해물질 함량기준을 충족하였다. 5. 멀칭재료간의 윌별 지온차이는, 6월 하순~7월 중순에는 PLC + starch > PBSA > LDPE > None 순으로 온도가 높아지는 경향을 보이다가 7월 하순~9월 하순에는 LDPE > PLC + starch > PBSA > None 순으로 온도가 높아졌다. 6. 고구마 멀칭재배 후 분해양상은, 생분해성 필름 PBSA(EA, EB, EC)과 PLC + Starch(DD, DE, DF)는 고구마 삽식 후 60일이 지나면서 분해되기 시작하였고, 수확기인 120일이 지나서는 95%이상이 분해되었다. 7. 피복재별 괴근 수량은 PBSA는 3,070 kg/10a, PLC + Starch은 3,093 kg/10a, LDPE는 2,946 kg/10a으로 멀칭재료간에 뚜렷한 차이를 나타내지 않았다. 이상을 종합하여 볼 때 고구마 재배에서 생분해성인 PBSA와 PLC + Starch와 같은 필름을 사용한다면, 필름의 물성, 분해도, 환경친화성, 수확작업의 간편성 등을 고려해볼 때 실제 농업현장에서 이용 가치가 매우 높을 것으로 생각된다.

‘Morningwhite’ is a new sweetpotato variety developed by Mokpo Experiment Station, National Institute of Crop Science (NICS), RDA in 2007, with white flowering. This variety was selected from the cross between “Sinjami” and “Muan 10” in 2004, seedling and line selections were applied in 2005 and 2006. ‘Morningwhite’ is morning glory type flowers with white color. It has Lobed leaf, green vine and petiole, elliptic storage root, red skin and yellow flesh color of storage root. The average yield of storage root was 14.0 ton/ha. Number of storage roots over 50 gram per plant was 2.5 and the average weight of storage root was 140 gram.

‘'Morningpurple’' is a new sweetpotato variety developed by Mokpo Experiment Station, National Institute of Crop Science (NICS), RDA in 2007, for flowering. This variety was selected from the cross between Sinchunmi and Hi-dry in 2004, seedling and line selections were practiced from 2005 to 2006. ‘'Morningpurple’' has morning glory type flowers with purple color. It has triangular leaf, green with purple vine and petiole, elliptic storage root, red skin and yellow flesh color of storage root. The average yield of storage root was 15.0 ton/ha. Number of storage roots over 50 gram per plant was 2.6, and the average weight of storage root was 143 gram.

Plant peroxidases (PODs) have been shown to reduce hydrogen peroxide (H2O2) in the presence of an electron donor. Extracellular POD also induce H2O2 production, and can perform a significant function in responses to environmental stresses. We previously described the isolation of 10 POD cDNA clones from cell cultures of sweetpotato (Ipomoea batatas). Among them, the expression of the swpa4 gene was profoundly induced by a variety of stresses. In this study, transgenic tobacco (Nicotiana tabacum) plants overexpressing the swpa4 gene under the control of the CaMV 35S promoter were generated in order to assess the function of swpa4. Both transient expression analysis with the swpa4-GFP fusion protein and POD activity assays in the apoplastic washing fluid revealed that the swpa4 protein is secreted into the apoplastic space. The transgenic plants also evidenced a significantly enhanced tolerance to a variety of abiotic and biotic stresses. These plants harbored increased lignin and phenolic content, and H2O2 was also generated under normal conditions. Furthermore, they manifested increased expression levels of a variety of apoplastic acidic pathogenesis-related (PR) genes following enhanced H2O2 production. These results suggest that the expression of swpa4 in the apoplastic space functions as a positive defense signal in the H2O2-regulated stress response signaling pathway.

고구마 용도 다양화와 지상부의 채소적 가치를 구명키 위하여, 괴근에서 자라난 싹 중 부드러운 잎과 잎자루를 포함한 줄기끝 10 cm의 끝순을 수확하여, 끝순 추출물의 페놀화합물 함량, 식중독균인 Listeria monocytogenes, Salmonella Typhimurium에 대한 항균 활성, 식품안전성과 관련된 돌연변이원성 및 항돌연변이원성 등을 조사한 결과는 다음과 같다. 1. 고구마 끝순에는 6종의 페놀화합물이 함유되어 있었으며, 그 중 chlorogenic acid와 caffeic acid의 함량이 총페놀함량의 89~93% 로 대부분을 차지하였다. 또한 용매분획별 페놀화합물 함량은 ethyl acetate 및 buthyl alcohol 추출물이 다른 용매추출물에 비하여 월등히 높았다. 2. 고구마 끝순의 80% ethanol 조추출물의 수율은 12.5 g이었고, 용매분획별로는 water 분획물이 8.9 g으로 가장 많았으며, 다음은 chloroform 분획물이 1.6 g이었고, 나머지 용매 분획물은 0.7~1.1g 의 수율을 나타내었다. 3. 고구마 끝순에는 6종의 페놀화합물이 함유되어 있었으며, 그 중 chlorogenic acid와 caffeic acid의 함량이 총페놀 함량의 89~93% 로 대부분을 차지하였다. 또한 용매분획별 페놀화합물 함량은 ethyl acetate 및 buthyl alcohol 추출물이 다른 용매추출물에 비하여 월등히 높았다. 4. Listeria monocytogenes에 ethyl acetate 및 buthyl alcohol 추출물을 첨가한 결과 16시간까지는 3 log 이상 균의 성장을 억제하였으며 특히 20 mg/ml butanol 추출물은 균의 성장을 억제시키다 12시간 이후에는 완전히 균을 사멸시키는 것으로 나타났다. Salmonella Typhimurium에 대해서도 고구마 끝순 추출물은 0.5~1 log 정도의 감소를 나타내었다. 5. 고구마 끝숱 추출물의 Salmonella Typhimurium TA98 및 TA100에 대한 돌연변이 활성을 조사한 결과 TA98은 29~33 CFU/plate이었고, TA100은 159~188 CFU/plate로 돌연변이 활성이 없었다. 6. 직접 돌연변이원 물질인 2-NF와 MMS를 처리하여 복귀돌연변이수를 측정한 결과 ethyl acetate 및 buthyl alcohol에서 돌연변이로 인한 복귀변이원성 집락수가 낮게 나타남으로써 고구마 끝순 추출물이 항돌연변이 활성이 있는 것으로 나타났다.

This study was conducted to investigate nitrite scavenging and Angiotensin Converting Enzyme (ACE) effects by antioxidant ingredient and the contents of phenolic compounds is isolated and purified from various sweetpotato cultivars. Various sweetpotato cultivars contained 4 phenol compounds including gallic acid, chlorogenic acid, gentisic acid and caffeic acid. The range of total phenol compound contents within cvs. Saengmi, Seonmi, Hongmi and Zami was at 23.0~48.8mg/100g and cv. Zami containing anthocyanins pigment whose total phenol compound content was at 48.8mg/100g was by far higher than the other cultivars. The assay of antioxidant activity using solvent fractionated extraction methods was investigated in various sweetpotato cultivars. Antioxidant activity of ethyl acetate (41.2~86.2%) was much higher than chloroform and butanol. Antioxidant activity from cvs. Sangmi, Seonmi, Hongmi, Shinyulmi, Zami and Sinchunmi was much higher than α-tocopherol well-known as natural antioxidant. Rancidity inhibitory effect about soybean oil of extracts fractionated by ethyl acetate from cvs. Saengmi, Seonmi, Hongmi and Zami was high considerably. Ethyl acetate layer among various solvent fractionated extraction had a good effect on nitrite scavenging rate but not had a effect on AEC inhibitory. Solvent of column chloromatography to isolate antioxidant contents from ethyl acetate layer was even better on 30% (MeOH) : 70% (Water) condition. There are 5 ingredients at HPLC chromatogram and antioxidant activity effect of individual ingredients was slightly better on Rt 11.9 and Rt 16.9 fraction.

“Matnami” is a new sweetpotato variety developed by Mokpo Experiment Station, National Institute of Crop Science (NICS), RDA in 2006, for table use and food processing. This variety was selected from the cross between “Hongmi” and MI9510-12 in 1999. Seedling and line selections were performed from 2000 to 2002. Preliminary and advanced yield trials were carried out from 2003 to 2004. The regional yield trials were conducted at six locations from 2005 to 2006. “Matnami” has cordate leaf, green with purple vine and petiole, elliptic storage root, red skin and yellow flesh color of storage root. The average yield of storage root was 27.0 ton/ha in the regional yield trials, which was 11% higher than that of Yulmi variety. Number of storage roots over 50 gram per plant was 2.6. The average weight of one storage root was 173 gram. This variety is also resistant to fusarium wilt and nematode. In addition, steamed “Matnami” has higher polyphenol contents as 3.3 mg/g dw and higher biological activitiesas, which improve the bioactivity in human. The total sugar content was higher, thereby, sweeter than “Yulmi”. It shows lower (68.6℃) initial temperature of starch gelatinization and slower retrogradation process than “Yulmi”.

Sweetpotato tips are known to be very useful parts as a vegetable because of their high nutritive values and great biomass yield. This study was carried out to select a variety that is suitable to the tips of sweetpotatoes as vegetables. Twenty-two varieties were planted in polyethylene (PE) houses and upland field. The tips were cropped, tested and their tips' external characteristics, quantity, sweetness, toughness and taste were likewise tested. This research found that the external characteristics of the sweetpotato tips were mostly colored green or greenish purple and the leaves were of heart shape. When it comes to texture, the crops from the PE houses presented softer sense than those from the upland field, and due to the blanching, the degree of hardness was reduced by 60 percent. The varieties that presented soft texture after blanching were Yulmi, Geonmi, Hwangmi, Sinchunmi, M301, Eunmi, Juhwangmi, Singeonmi and Gogeonmi. The sweetness, which gives a great influence to the taste, was found to be 3.8 Brix°％ on the average for raw tips of sweetpotatoes cropped in P.E. houses, lower than the crops from the upland field which yielded 4.6 Brix°％. By varieties, those that were commonly high in both P.E. houses and upland field crops were three kinds - Geonmi, Sincheonmi and Juhwangmi. The yield derived was on the average 150 tons/ha, which was considerably high yield, compared to the greens like the Korean leeks, which were repeatedly cropped once planted, like the tips. The investigation into the external appearances, texture, sweetness and acceptability found that the varieties that are suitable for sweetpotato tips production are Yulmi, Geonmi, Hwangmi, Yeonmi, Chinmi and Juhwangmi.

Sweetpotato fields in Korea are highly infected with virus and virus like diseases that greatly diminish both yield and quality as indicated by field observations and laboratory tests. In order to solve this problem, there is an urgent need to produce and mass propagate virus-free planting materials for distribution to the farmers. These experiments were conducted, firstly, to determine the most appropriate culture media, nutrient solution, and cutting intervals to maintain growth and vigor of tissue cultured plantleta as mother plants for propagation in insect-proof greenhouse. And as a labor saving method, the production efficiency of plug trays for rapid propagation of stem cuttings as a source of planting materials was likewise evaluated. Results showed that plants grown in medium B supplied with 0.5 and 1.0 strength of MS nutrients had high growth rate, and 20-day cutting interval was the best. 72-plug tray was better than 128-plug. Secondly, it was to develop a technique for the production of first-generation seed roots using hydroponics cultivation system. The yield of virus-free plants propagated in the non-insect proof and open-field cultivation was 2,402 kg/10a, 6% higher than those in the insect-proof cultivation, and the rate of virus re-infection was 18% higher compared to 3.3% with insect-proof cultivation. Lastly, it was to investigate the growth performance of virus free plants in farmers' field. Differences were existed in the yield depending on the variety used, but virus free plants showed an increase of 6~24% over virus infected plants.

고구마의 이용성을 증대하고, 고구마 끝순의 채소적 가치를 구명키 위해 페놀화합물의 함량, 지질산화 억제 효과, 전자공여능, 아질산염소거능, ACE저해활성 등 생리활성을 조사한 결과를 요약하면 다음과 같다. 1. 고구마에 함유된 phenolics는 gallic, chlorogenic, gentisic, caffeic, couramic, ferulic acid 등 6종이었고, 이중 간독성 회복 및 항산화 효능이 큰 것으로 보고되고 있는 chlorogenic acid, gentisic acid, caffeic acid가 많이 함유되어 있었다. 부위별로는 괴근에 비하여 잎과 끝순의 함량이 높았고, 고구마 끝순이 콩나물이나 들깨잎, 시금치보다 16~122 배 높은 함량이었다. 용매분획별로는 총 함량 175.8 mg/g 중에서 EtOAc층에 55%, BuOH층에 39%가 함유되었다. 2. Rancimat를 이용하여 산패 유도기간을 조사한 결과, 고구마 끝순의 항산화력은 옥배유, 팜유 및 돈지에서 합성 항산화제인 토코페롤이나 BHT보다 높았고, 용매분획별로는 EtOAc>BHT>BuOH>Tocopherol>Water>CHCl3 >Hexane층 순으로 높았다. 3. 과산화물가에의한 항산화 활성은, 각 추출물별로는 끝순, 괴근, 토코페롤이 들깨잎, 콩나물, 시금치보다 낮은 과산화물가를 나타냈고, 이중 끝순은 토코페롤보다 더 높은 항산화성을 나타냈다. 고구마 끝순의 용매분획별 항산화활성은 대두유와 옥배유 및 팜유에서 BuOH와 water층의 항산화활성이 높았다. 4. 전자공여능에 의한 항산화 활성은, 고구마 끝순의 항산화 활성은 78.2%로 괴근 42.3%에 비하여 매우 높았고, 들깨잎, 시금치, 콩나물은 28.9~18.0% 로 낮았다. 이와 같은 결과는 고구마 끝순에 다량 함유된 페놀화합물과 관련된 것으로 사료된다. 용매분획별로는 EtOAc>BuOH>Tocopherol>Water>CHCl3 >Hexane층 순으로 높은 활성을 나타냈다. 5. 아질산염소거능은 끝순, 들깨잎, 콩나물이 우수하였고 그중 들깨잎이 저해율 72%로 가장 높았으며, 용매분획 중에는 BuOH과 water추출물의 활성이 가장 높았다. 6. ACE 저해 효과는 고구마 부위별로는 끝순이 괴근에 비하여 1.5배 높았고, 들깨잎, 콩나물, 시금치보다 1.9~3.7 배 높았다. 용매분획별로는 EtOAc, BuOH, water 추출물이 높은 활성을 보였다. 7. 이상을 종합하여 볼 때 고구마 끝순에는 페놀화합물이 다량 함유되어 있어 높은 항산화 활성을 가지며, 아질산염소거능 및 ACE저해활성과 같은 생리적 효과도 높아 기능성 채소로 이용하기에 충분한 가치가 있다고 판단된다.