報告書番号

V07010

タイトル（和文）

イネにおける銅・亜鉛・カドミウム耐性と吸収能力の相関、およびその品種間差

タイトル（英文）

Differences in tolerance and accumulation abilities for Copper and Zinc, and Cadmium between Japonica and Indica cultivars of Rice.

概要 （図表や脚注は「報告書全文」に掲載しております）

我が国で栽培される主なジャポニカ種(ＪＰ)とインディカ種(ＩＮ)のイネに、銅と亜鉛、鉄、カドミウムを過剰量摂取させて、これらに対する耐性と主な二価金属の吸収特性に及ぼす影響を調べるとともに、相互の関連性を解析した。その結果、①亜鉛耐性とカドミウム耐性はＩＮがＪＰより強いが、銅耐性は有意な差がない、②亜鉛耐性と銅耐性の相関はＪＰだけで認められる、③主な二価金属濃度は、基本培地や銅、亜鉛、カドミウムの過剰培地で生育させた場合、地上部でジャポニカ型がインディカ型よりも高かったが、根部では有意な差がない。しかし、鉄過剰培地で生育させると地上部、根部ともにインディカ型がジャポニカ型よりも高い、④銅、亜鉛、カドミウムの過剰培地で生育させた場合、銅、亜鉛、鉄の地上部濃度と根部濃度の相関が低下するにもかかわらず、いずれの条件においても地上部-根部濃度比（Ｓ／Ｒ比）をみると銅濃度、鉄濃度などについてジャポニカ型がインディカ型よりも大きい、⑤主な地上部二価金属濃度間の相関を見たところ、カドミウム培地において生育させたイネではカドミウムと銅、カドミウムと鉄の濃度間に負の相関が認められる、などが明らかとなった。以上の結果、①インディカ型だけがもつ亜鉛耐性やカドミウム耐性機構、およびジャポニカ型だけがもつ亜鉛／銅共耐性機構が存在する可能性があること、②根部から地上部へ鉄や銅を輸送する機構についてインディカ型とジャポニカ型の間に差異が存在する可能性があること、などが示唆された。

概要 （英文）

Common rice cultivars in Japan, including 12 Japonicas and 7 Indicas, were grown on media containing normal or excess amounts of Cu, Zn, Fe, and Cd, respectively. Tolerance and accumulation abilities for major essential divalent metals (Cu, Zn, Fe, and Mn) and Cd were measured, and the co-relations among those metals were analyzed statistically. The major results are: (1) Indicas had stronger tolerances for excess Zn and Cd than Japonicas, but not for Cu. (2) Co-tolerance between Cd and Zn was observed both in Japonicas and Indicas, but that between Zn and Cu was observed only in Japonicas. (3) Generally, Japonicas accumulated higher concentrations of divalent metals in upper parts of plant than those in Indica, but not in roots. However, the divalent metal concentrations in both the shoots and roots were higher in Indicas than in Japonicas when plants were grown on a excess Fe medium. (4) Co-relations of Fe, Cu and Zn concentration between shoots and roots were significantly decreased when plants were grown in media containing excess Cu, Zn and Cd. (5) Japonicas had larger Shoot/Root ratio in Cu and Fe concentrations than Indicas. (6) A negative co-relations were observed between shoot concentrations of Cd and Cu, and Cd and Fe. These results indicate that cultivar (at least between Japonicas and Indicas) specific differences could be observed for metal tolerances and accumulation abilities. The properties were discussed with major known divalent metal accumulation systems in plants.

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