報告書番号

U01017

タイトル（和文）

分子育種法による高鉄含有量レタスの作出（その５） -－フェリチン遺伝子を導入した組換えレタスの環境に対する安全性評価－-

タイトル（英文）

Molecular breeding of high iron content lettuce (Lactuca sativa L.)(5) -Environmental Risk evaluation of the transgenic lettuce plants introduced ferritin gene.-

概要 （図表や脚注は「報告書全文」に掲載しております）

当所では鉄貯蔵タンパク質（フェリチン）の遺伝子の導入により鉄含有量が多いレタスを開発してきた。本レタスを実用化する条件として、野外で栽培した場合の環境に対する安全性の評価が必要であることから、本報告において環境に対する安全性を評価した。まず、以下にあげる安全性評価項目を設定した。①目的遺伝子の発現、②形態および生育特性、③生殖および繁殖特性、④雑草化の可能性、⑤有毒物質産性能、⑥周辺生物相への影響、⑦アグロバクテリウムの残存性である。そして、各項目について合計２３の小項目を設け、閉鎖系温室、非閉鎖系温室および隔離圃場の３ステップにわたって評価した。その結果、組換えレタスと非組換えレタスとの間には、導入遺伝子の直接的な効果である鉄含有量と生長速度の増加以外には差は認められなかったことから、フェリチン遺伝子を導入したレタスと非組換えレタスでは、環境に与える影響に差がないと判断された。

概要 （英文）

The environmental risk of transgenic lettuce plants (strain G17 andG31) expressing ferritin gene were evaluated. Ferritin, iron storage protein consists of 24 subunits and can store up to 4500 iron atoms in the ferritin shell. The evaluation was performed in a closed and a semi-closed greenhouse, and in an isolated field on careful comparison with non-transgenic lettuce plants. Evaluation items were categorized into seven: (1) stability and expression of the introduced ferritin gene, (2) morphological and growth characteristics, (3) reproductive characteristics, (4) possibility of expansion as weeds, (5) evaluation of harmful impact to other organisms, (6) influence on eco-system, and (7) residual Agrobacterium as vector. The results of the evaluation are described below. (1) At least one intact ferritin cDNA was integrated into the lettuce genome and inherited to the next generation. Soybean ferritin was constitutively synthesized in the transgenic lettuce leaves. The transgenic lettuce plants contained aproxmately 1.2 times more iron than controls (non-transgenic lettuce plants). (2) Morphological characteristics of transgenic lettuce plants were not different from those of controls, however, enhanced growth of transgenic lettuce plants was observed. (3) Reproductive characteristics: pollen form, pollen fertility, pollen longevity, wind pollination, seed fertility, germination ratio, and distance of pollen dispersion, were not different between transgenic lettuce plants and controls. (4)Both few transgenic lettuce plants and controls survived during winter. Few seeds stored in ground during winter germinated on the medium. (5) Specific phenolic acids, considered as allelochemical substances and volatile compounds were not detected from transgenic lettuce plants. (6)The influence of culture of the transgenic lettuce plants on phase of micro-organisms and higher plants was as same as that of controls. (7)Agrobacterium used as a vector for transformation of lettuce plants was not detected from transgenic lettuce seeds. In conclusion, there were no different risk for environment between transgenic lettuce plants and controls though iron accumulation and enhanced growth, which was thought to be results of ferritin gene expression, were observed in the transgenic lettuce plants.

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