The present study was conducted to investigate the effects of feed types (powder vs. pellet) from potato by-product containing glycoalkaloid on rumen fermentation with different rumen pH (low vs. high) using in vitro technique. Rumen fluid was collected from two cannulated Hanwoo heifers before morning feeding (high rumen pH at 6.71) and 3 h after feeding (low rumen pH at 6.20). A 0.5 gram of powder or pellet from potato by-product was incubated in the rumen buffer for 48 h at 39℃. Four replications for each treatment were used along with two blanks. Pellet had higher (p<0.05) the immediately degradable fraction, the fractional degradation rate, and the lag phase than those of powder. However, feed type had no effects on the potentially degradable fraction and the total degradable fraction. In fermentation characteristics, powder had higher (p<0.05) concentrations of ammonia-N, total volatile fatty acid (VFA), and acetate than those of pellet. In addition, a high rumen pH had higher (p<0.05) concentrations of ammonia-N and acetate, but lower (p<0.05) total VFA concentration than those of a low rumen pH. The interaction effects between feed type and rumen pH were found on the total degradable fraction and concentrations of ammonia-N, total VFA, and acetate. The present study concluded that generally feed type had no effects on rumen degradation kinetics, but potato by-product in the powder form is recommended due to produce higher fermentation characteristics than in the pellet form.

본 연구는 재배종 감자 덩이줄기에 존재하는 glycoalkaloid (PGA) 중 특히 α-chaconine, α-solanine, demessine을 산가수분해 처리하여 분해 생성물인 아그리콘 및 배당체를 분석하는 방법으로 PGA의 정량 가능 유무를 조사하였다. 1. 표준품의 solanidine을 1 N-HCl로 가수분해하면 산 가수분해 반응 10분 후부터 solanidine이 급속하게 감소하였고 새로운 피크가 급증하였다. 이 피크를 GC-MS로 분석한 결과, 분자 이온 피크(M+=379)가 검출되어 이 물질을 solanthrene으로 분류하였다. 이 solanidine-solanthrene의 반응은 시간의 경과에 따라 진행되었다. 2. 표준품의 demissidine을 solanidine과 같은 방법으로 가수분해하여 GC-MS로 분석한 결과, solanidine의 경우와는 상이하게 solanthrene는 검출되지 않았고 demissidine (M+=399, 204,150)의 피크만이 검출되었다. 이로써 demissidine은 산 가수분해 처리에 의한 분해가 일어나지 않는 것을 추측 할 수 있었다. 3. α-chaconine, α-solanine, demessine를 산분해하면 α-chaconine과 α-solanine은 solanidine에서 solanthrene으로 분해 반응이 일어났다. 이 두 물질의 아그리콘인 solandine을 측정하는 방법으로는 PGA량을 산출하는 것은 불가능하리라 생각된다. 그러나 산 분해에 의해 생성된 배당체는 매우 안정하여 이 배당체의 당함량을 측정하여 이 두 물질의 PGA 함량을 산출하는 것은 가능하였다. demissine는 산 분해에 의해 생성된 아그리콘(demissidine)은 매우 안정하여 생성된 아그리콘의 양으로부터 demissine 함량을 산출하는 것은 가능하였다.

The potato tuber is known as a rich source of essential nutrients, used throughout the world. Although potatobreeding programs share some priorities, the major objective is to increase the genetic potential for yield through breeding or to eliminate hazards that reduce yield. Glycoalkaloids, which are considered a serious hazard to human health, accumulate naturally in potatoes during growth, harvesting, transportation, and storage. Here, we used the AMMI (additive main effects and multiplicative interaction) and GGE (Genotype main effect and genotype by environment interaction) biplot model, to evaluate tuber yield stability and glycoalkaloid content in six potato cultivars across three locations during 2012/2013. The environment on tuber yield had the greatest effect and accounted for 33.0% of the total sum squares; genotypes accounted for 3.8% and G×E interaction accounted for 11.1% which is the nest highest contribution. Conversely, the genotype on glycoalkaloid had the greatest effect and accounted for 82.4% of the total sum squares), whereas environment and G×E effects on this trait accounted for only 0.4% and 3.7%, respectively. Furthermore, potato genotype ‘Superior’, which covers most of the cultivated area, exhibited high yield performance with stability. ‘Goun’, which showed lower glycoalkaloid content, was the most suitable and desirable genotype. Results showed that, while tuber yield was more affected by the environment, glycoalkaloid content was more dependent on genotype. Further, the use of the AMMI and GGE biplot model generated more interactive visuals, facilitated the identification of superior genotypes, and suggested decisions on a variety of recommendations for specific environments.

감자 수요를 확대하기 위해서는 소득 증가와 함께 소비자 의 관심이 증대하고 있는 신선편이식품으로 시장을 보다 더 넓혀 나가야 한다. 이를 위해서는 감자에 존재하는 유독 물질 인 glycoalkaloids에 대한 주의가 필요하다. 본 연구에서는 도 입품종인 대서, 수미와 최근 국내에서 개발된 하령, 고운, 홍 영, 자영 품종을 포함하여 국내 주요 24품종을 대상으로 부위 별 PGA 함량을 분석하였으며 그 연구 결과를 요약하면 다음 과 같다. 1. 총 PGA 함량(mg/100g·FW)은 하령(10.1), 수미(9.3), 홍영(7.3), 자영(6.9), 대서(4.8), 고운(3.4), 자심(3.1) 순으로 나타났다. 2. 공시품종의 껍질부위 PGA 함량은 전체 함량의 41 ~ 85% 분포를 보였으며, 국내주요 재배 품종에서 대서는 PGA 함량이 껍질(85%)에서 높고 육질 부위(0.7)에서 낮아 PGA 독성으로부터 가장 안전한 품종이었다. 3. 특히 고운, 자심 품종은 PGA 함량이 제일 낮아 껍질째 감자를 이용하기에 적절하며 중간모본으로 활용가치가 크다 고 판단된다.

PGA 함량 정보가 없는 유전자원을 활용한 다양한 용도의 감자 품종 개발은 괴경 내 PGA 함량을 높이는 비의도적 결과를 초래할 가능성이 있다. 이러한 배경에서 신품종에 대한 정밀한 PGA 함량 분석은 감자의 식품안전성 제고와 PGA 저 함유 품종 개발을 위한 교배 모부본 확보차원에서 중요하다. 본 연구에서는 도입품종인 대서, 수미와 최근 개발된 하령, 고운, 홍영, 자영 4품종을 대상으로 괴경 부위, 저장기간별 PGA 함량변화를 분석하였다. 그 연구 결과를 요약하면 다음과 같다.

Steroidal glycoalkaloids which serve the plant defense, are toxic secondary metabolites present in the plants of solanaceae family. The upper safe limit of glycoalkaloids for human consumption is 20mg/KG FW, excess of which may cause severe health disorders. Several factors like drought, high temperature, light exposure, and wounding increase tuber glycoalkaloid content. Among these, drought is an important factor which causes a rapid increase in potato glycoalkaloid content. Glycoalkaloid biosynthetic genes and their expression pattern need to be characterized to regulate the glycoalkaloid accumulation. Three key genes SGT1, SGT2 and SGT3 are demonstrated to be directly participated in the biosynthetic pathway for glycoalkaloid formation. Present study was focused on the study of expression pattern of key genes in GA pathway under drought stress in two different potato cultivars Atlantic and Haryoung which are low and high glycoalkaloid accumulating respectively. Drought stress was imposed by withholding water to the plants grown in pots and control plants kept irrigated. Expression analysis of SGT1, SGT2 and SGT3 was done from the leaf and tuber sample of three time intervals i.e 5, 10 and 20 days after imposing stress. Variation in the expression level of genes was observed in leaf and tuber where the fold increase in expression over control was higher in tuber sample compared to leaf. Expression levels also varied in leaf and tuber among two cultivars. However, expression of SGT1, SGT2 and SGT3 is significant indicating the involvement of these genes in glycoalkaloid accumulation under drought stress.

Glycoalkaloids are a family of toxic secondary metabolites present in the plants of solanaceae family, which serve for plant defense. Two major glycoalkaloids present in plants are a-solanine and a-chaconine. The upper safe limit of glycoalkaloids for human consumption is 20mg/KG FW and its excess may cause severe health disorders. Light is the major factor known to increase the glycoalkaloid content in post harvest potato tuber. Glycoalkaloid pathway is not completely understood. Hence, identification and characterization of SGA biosynthetic genes and the genetic factors that control their expression levels assumes significance. Present investigation was focused on the study of expression pattern of key genes in steroidal glycoalkaloidal pathway under various light qualities in potato (Solanum tuberosum L). Two potato cultivars Atlantic and Haryeong which accumulates low and high glycoalkaloids respectively were used to check the levels of gene expression under various light qualities viz., red, blue, white, green, yellow, purple, UV light and in dark at different time intervals. Expression of three genes viz., SGT1, SGT2 and SGT3 which are directly involved and four other genes, HMG1, SQS1, SMT1 and SMT2 in the pathway envisaged to be indirectly involved in the glycoalkaloid formation was quantified by RT PCR. Varietal variation in the expression among the genes was observed in different light qualities. White, red and green light compared to other light qualities majorly contributed for the increased expression of genes for glycoalkaloid accumulation at different time intervals. Importantly, there is no significant transcript accumulation of these genes in dark condition. However, more efforts would be extended for further understanding of glycoalkaloid accumulation under light.