Journal of The Korean Society of Grassland and Forage Science (한국초지조사료학회지)

The Korean Society of Grassland and Forage Science (한국초지조사료학회)
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Development of High Quality Forage Grass by Down-regulating Lignin Biosynthetic Gene

리그닌 생합성관련 유전자의 발현조절에 의한 고품질 목초 개발

  • Woo Hyun-Sook (Division of Applied Life Science, College of Agriculture and Life Science, Gyeongsang National University) ;
  • Yun Jung-Woo (Division of Applied Life Science, College of Agriculture and Life Science, Gyeongsang National University) ;
  • Lee Byung-Hyun (Division of Applied Life Science, College of Agriculture and Life Science, Gyeongsang National University)
  • 우현숙 (경상대학교 농업생명과학대학, 응용생명과학부) ;
  • 윤정우 (경상대학교 농업생명과학대학, 응용생명과학부) ;
  • 이병현 (경상대학교 농업생명과학대학, 응용생명과학부)
  • Published : 2006.03.01
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Abstract

To develop a new variety of orchardgrass with improved digestibility, caffeic acid O-methyltransferase (Dgcomt), which is a methylation enzyme involved in the early stages of lignin biosynthesis, was isolated and characterized. Dgcomt was expressed not only in leaves but also in stems and roots. The expression levels of transcripts were high in stems and roots which are the most lignified tissues, and only moderate levels of transcripts were expressed in leaves. To develop transgenic orchardgrass plants by down-regulating the Dgcomt gene, an RNAi suppression vector with partial Dgcomt DNA fragment was constructed and transferred into the genome of orchardgrass via Agrobacterium-mediated gene transfer method. PCR and Southern blot analyses with genomic DNAs from putative transgenic plants revealed that the T-DNA region containing RNAi construct was successfully integrated into the genome of orchardgrass. Northern blot analysis revealed that the majority of the down-regulated transgenic lines showed significant reduction in Dgcomt gene expression. These RNAi transgenic orchardgrass will be useful for molecular breeding of new variety with improved digestibility by down-regulating lignin biosynthetic enzyme.

조사료로서 소화율을 향상시킨 신품종 형질 전환 오차드그래스를 개발할 목적으로 lignin 합성경로에 있어서 중요한 효소 유전자 중의 하나인 COMT 유전자를 cloning하여 그 특성을 해명하였다. 오차드그래스의 COMT 유전자는 식물체의 전 조직에서 발현되고 있었으며, 특히 줄기와 뿌리조직에서 높은 발현량을 나타냄으로서 목질화에 크게 관여하는 lignin 생합성 유전자일 것으로 판단되었다. Dgcomt 유전자의 발현을 억제시킨 형질전환 오차드그래스를 개발하기 위하여 Dgcomt 유전자를 RNAi 발현벡터에 도입한 후, Agrobacterium 형질전환시스템을 이용하여 오차드그래스에 도입하였다. PCR, Southern 및 Northern 분석 결과 RNAi 발현벡터가 genome에 도입되었으며, Dgcomt 유전자의 발현이 상당한 수준으로 저하되었음을 확인하였다. Dgcomt 유전자의 발현억제는 식물체의 목질화와 더불어 증가되는 lignin의 축적량을 감소시킬 것으로 기대되며 향후 소화율이 증가된 고품질 신품종 목초의 개발에 유용하게 활용될 것으로 판단된다.

Keywords

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