‘Tocomi-1’, a new japonica rice cultivar derived from a 200 Gy gamma ray irradiation with high tocopherol content and red pericarp. The local adaptability test of MRXII-1001-1 was carried out from 2012 to 2014 and it was named as ‘Tocomi-1’ in 2014. This variety is medium matured with heading date of August 12 in honam plain area of Korea. This variety is about 80 cm tall culm length and 106 spikelets per panicle. Its 1,000 grain-weight of rice seeds is 25.4 g. The yield potential of this variety is about 5.15 MT/ha in local adaptability test for three years. This variety exhibited greater seed longevity than the Donganbyeo, indicating a crucial role for tocopherols in maintaining viability during quiescence, and displayed faster seedling growth during the early growth stage. Tocopherol contents was 50% higher than the Donganbyeo. To study the molecular mechanism underlying vitamin E biosynthesis, we examined the expression patterns of seven rice genes encoding vitamin E biosynthetic enzymes. Accumulation levels of the OsVTE2 transcript and OsVTE2 protein in the ‘Tocomi-1’ were significantly higher than in the Donganbyeo. Sequence analysis revealed that the ‘Tocomi-1’ harbored a point mutation in the OsVTE2 promoter region, which resulted in the generation of MYB transcription factor—binding cis-element. These results help identify the promoter regions that regulate OsVTE2 transcription, and offer insights into the regulation of tocopherol content in ‘Tocomi-1’.

Tocopherols (α-, β-, γ- and δ-tocopherols) represent a group of lipophilic antioxidants which are synthesized only by photosynthetic organisms. It is widely believed that protection of pigments and proteins of photosynthetic system and polyunsaturated fatty acids from oxidative damage caused by reactive oxygen species (ROS) is the main function of tocopherols. In the present study, NtTC, which encodes a tobacco tocopherol cyclase ortholog, was cloned and characterized. Compared with control plants, NtTC transgenic rice showed higher tolerance to drought stress, and total tocopherol content increased by 52 % in leaf. Additionally, total antioxitant activity of NtTC transgenic lines was increased significantly by 19%. These results demonstrate that over-expressing NtTC could improve the tolerance to abiotic stress in rice, and tocopherols play a crucial role in the protection of oxidative stress.

Tocopherol belongs to the Vitamin E class of lipid soluble antioxidants that are essential for human nutrition. Tocopherols consist of a chromanol ring and a 15-carbon tail derived from homogentisate (HGA) and phytyl diphosphate, respectively. Condensation of HGA and phytyl diphosphate, the committed step in tocopherol biosynthesis, is catalyzed by HGA phytyltransferase (HPT). To increase tocopherol level in cucumber fruit, we performed Agrobacterium-mediated transformation with mdhpt gene, encoding HPT, isolated from apple (Malus domestica). We obtained two independent T0 cucumber plants from transforming 2,142 explants. Southern blot analysis of T0 showed that mdhpt was inserted in the genome. In order to test the tocopherol level, T1 cucumber fruits were screened by GC analysis. From 39 T1 fruits tested, some fruits showed 1.5-2 fold in α- and β-tocopherol content comparing to control. However, most of fruits contained lower levels of γ- and δ- tocopherol indicating a partition of metabolites in tocopherol biosynthesis pathway. We selected these T1 line and made a self-cross to obtain T2 seeds.

미강에 함유되어 있는 토코페롤 및 토코트리에놀의 함량을 비파괴적으로 신속하게 추정하기 위하여 NIRS(근적외선 분광분석기)를 이용한 분석 방법을 검토하였다. 벼 유전자원 80계통의 미장을 사용하여 HPLC에서 분석된 토코페롤 및 토코트리에놀의 함량치를 NIRS 스펙트럼에 적용시킨 후 검량식을 작성하였다. NIRS의 검량식을 몇가지 방법에 의하여 비교 분석한 결과 2차 미분된 스펙트럼을 MPLS(Modified Partial Least Squares)를 이용한 회귀식에 이용하는 것이 가장 적합하였다. HPLC를 이용한 유전자원들의 성분 함량과 NIRS에서 도출된 검량식과의 상관계수는 토코페롤과 토코트리에놀이 각각 0.992, 0.953을 나타내었다. 이들 검량식은 validation file 에서도 0.846 및 0.956의 높은 상관을 보여 미강 상태에서 토코페롤 및 토코트리에놀의 함량을 NIRS를 이용하여 신속하게 분석할 수 있을 것으로 판단되었다.

우리나라에서 재배되고 있는 콩 강낭콩 보리 옥수수 율무 들깨 차조기 홍화 해바라기를 비롯하여 달맞이꽃 타래붓꽃의 종실에 함유되어 있는 tocotrienol(T), tocopherol(T)과 vitamin E 함량을 탐색 하였던 바 그 결과는 다음과 같다. 1. 종실 100g에 함유되어 있는 tocotrienol 함량은 차조기 25.06mg, 보리 4.50mg, 옥수수 3.54mg, 타래븟꽃 3.04mg, 율무 2.58mg, 홍화 0.12mg이었다. 2. tocotrienol이 전혀 검출되지 않은 작물은 콩 강낭콩 달맞이꽃 해바라기 들깨이었고, tocotrienol의 4가지 동족체 중 율무와 옥수수는 β-T3 , 타래못꽃과 차조기는 δ -T3 , 홍화는 α~textrm, β~textrm, δ -T3 가 검출되지 않았다. 3. 종실 100g에 함유되어 있는 tocopherol 함량은 타래붓꽃 51.82mg, 들깨 40,90mg, 콩 34.11mg, 해바라기 20.88mg 순으로 높았으며, 탐색한 작물 모두 4가지 동족체를 함유하였다. 4. vitamin E 함량은 타래붓꽃 54.86, 차조기 41.80, 들깨 40.90, 콩 34.11, 해바라기 20.88, 홍화 14.73, 옥수수 11.49, 달맞이꽃 10.07, 보리 7.48, 율무 6.24, 강낭콩 5.27mg/100g 이었다.

The content and composition of tocopherol were analyzed in peanuts produced in Korea. The tocopherol assay was consisted of an extraction with n-hex-ane:isopropanol mixture followed by high pressure liquid chromatography with fluorescence detection. Tocopherol content was higher in leaves and seeds but lower in seed coats and shells. α -/~gamma - Tocopherol ratio was as low as 0.53 in seeds and as high as 22.5 in shells. Tocopherol content in seeds of nine varieties ranged from 142 to 220 ng/mg dry weight, and the α -/~gamma -tocopherol ratio from 0.40 to 0.75. Tocopherol content decreased by 18% but α -/~gamma -tocopherol ratio increased by 44% in roasted seeds. The results indicate that the level of tocopherol in Korean peanut varieties is moderate and the ratio of α - to ~gamma -tocopherol is low.