Lysine is the first limiting essential amino acid in cereals for humans and monogastric animals, although its content is generally low. A chemically induced high-lysine barley mutant, M98, has an agronomically undesirable shrunken endosperm trait. In order to obtain detailed insight into the atypical traits of M98 grains, we characterized amino acid composition and protein profiles of M98 and its parent cultivar Chalssalbori. Among a total of 16 amino acids, the percentage of each of the 7

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... acids, including lysine, was 1.2∼1.8 times higher in M98, comparing to Chalssalbori. The percentage of proline and its precursor, glutamic acid, in M98 was about the half of that of the amino acids in Chalssalbori, but arginine synthesized from glutamic acid was 1.8 times higher in M98, compared that in the parent cultivar. Theses results indicated that the mutation in M98 grains might alter the proportion of amino acids linked to each other in a biosynthetic pathway. A comparison of grain proteome profiles between Chalssalbori and M98 revealed 70 differentially expressed protein spots, where 45 protein spots were up-regulated and 25 protein spots down-regulated in M98 compared to those in Chalssalbori. Of these changed protein spots, 53 were identified using nano-electrospray ionization liquid chromatography mass spectrometry. Most of these identified proteins were involved in various biological processes. In particular, 28 protein spots such as β-amylase, serpins and B3-hordein were identified as proteins associated with the atypical traits of M98. It was thought that a genetic study on the unique protein profile of M98 would be needed to develop an agronomically feasible barley cultivar with high-lysine trait. Lysine은 인간과 단위가축이 섭취해야 하는 필수아미노 산으로서 화곡류에 부족한 첫 번째 제한 아미노산이다. 화곡 류 종실의 lysine 함량은 정조를 기준으로 벼 299 mg/100g, 옥수수 254 mg/100 g, 귀리 517 mg/100g, 보리 406 mg/100 g, 호밀 401 mg/100 g 등으로써 콩 2,653 mg/100 g을 비롯한 두류에 비해 매우 낮다(www.fao.org/DOCREP/005/AC854T/ AC854T00.htm). 한편, 식품 및 단위가축 사료의 영양성분 으로서 단백질은 이것을 구성하는 아미노산의 균형 있는 조 성비가 품질을 결정하는 주요 요인이 되는데, 이러한 점에서 lysine의 조성비가 낮은 화곡류 단백질의 품질은 두류 단백 질에 비해 낮게 평가된다(Tallberg, 1982). 1960년대에 최초로 발견된 옥수수의 고-Lysine 돌연변이 opaque-2를 시작으로(Mertz et al., 1964) 보리를 비롯한 화 곡류 작물에서 종실의 영양가치 향상을 위한 고-Lysine 돌연 변이 개발 및 이것을 이용한 유전・육종학적 연구가 보고되 었으며(Eggum et al., 1995), 동물 사양시험을 통하여 일반 품종보다 영양가치가 높다는 사실이 판명되었다(Oria et al.,