过量表达水稻细胞质型OsAPXs基因提高转基因烟草的耐盐性

为了验证水稻(Oryza sativa L.)细胞质型APXs与细胞耐盐性的关系，实验分别将OsAPXa和OsAPXb（基因登录号：D45423、AB053297）转化到烟草(Nictiana tabacum,N.plum)植株中。Southern结果表明，二基因分别整合到烟草的基因组；Northern分析表明，外源基因在转基因烟草中得到高效表达；在碳酸盐逆境下，T2代转基因植株与野生型对照相比，其APX活性呈现显著的提高，T₂代品系的H₂O₂含量和叶片受害程度显著低于野生型；T₂代品系分别在含有10 mmol·L^-1 NaHCO₃、5 mmol·L^-1 Na₂CO₃的MS培养基上生长，根的生长受到抑制，叶片产生黄化；野生型烟草则难以存活。水稻细胞质型OsAPXs基因的过量表达提高了转基因烟草的耐盐性，揭示出OsAPXa和OsAPXb在碳酸盐逆境应答过程中发挥着重要的作用。

Elevated Salt Tolerance in Transgenic Tobacco Plants Expressing Cytosolic Ascorbate Peroxidase Genes from Rice(Oryza sativa L.)

To identify cell salt tolerant ability generated by cytosolic ascorbate peroxidase (cAPX) from rice(Oryza sativa L.), two encoding genes, OsAPXa and OsAPXb(GenBank accession nos. D45423 and AB053297, respectively) were introduced into tobacco(Nictiana tabacum, N.plum), respectively. Southern blot confirmed that the two genes were integrated into genome of N.tabacum, respectively. Moreover, Northern blot further revealed that foreign genes effectively expressed in vitro. OsAPXa/b transgenic N.tabacum progeny T₁, T₂ generation were identified and assayed further. Under the carbonate stress, the T₂ independent homozygous transgenic lines showed the elevated activity of APX, the lower H₂O₂, and the lower ion leakage than that in wild type plants. Surprisingly, T₂ generation seedlings could survive on MS medium containing either 10 mmol·L^-1 NaHCO₃ or 5 mmol·L^-1 Na₂CO₃, just along with the retarded growth of root and yellowish leaf, whereas the wild type plants even could not grow under lower carbonate stress. Our results suggested that transgenic tobacco expressing cytosolic OsAPXs improved cell salt tolerance; both cytosolic OsAPXs played the crucial roles, especially in response to carbonate stress.