Hypocotyl segments from aseptic seedlings of two important cultivars of upland cotton ( Gossypium hirsutum L.) in Northwest China, 'Xinluzao_1', 'Jinmian_7', 'Jinmian_12' and 'Jihe_321' were transformed respectively by two efficient plant expression plasmids pBinMoBc and pBinoBc via Agrobacterium tumefaciens . In pBinMoBc, cry 1Ac3 gene, which encodes the Bt toxin, is under the control of chimeric OM promoter. In pBinoBc, it is under control of CaMV 35S promoter. After co_cultivation with Agrobacterium tumefimpfaciens LBA4404 (containing pBinMoBc or pBinoBc), kanamycin_resistant selection, somatic embryos were induced and regenerated plants were obtained. Then the regenerated plantlets were grafted to untransformed stocks in greenhouse to produce descendants. The integration of cry 1Ac3 gene and its expression in T 2 generation of transgenic cotton plants were confirmed by Southern hybridization and Western blotting. The analyses of insect bioassay indicated that the transgenic plants of both constructions have significant resistance to the larvae of cotton bollworm ( Heliothis armigera ) and that cry 1Ac3 gene driven by chimeric OM promoter could endue T 2 generation cotton with high pest_resistant ability, implicating that it has a profound application in genetic engineering to breed new pest_resistant cotton varieties.
A novel cDNA sequencehtMT2, which encodes a type 2 metallothionein_like protein, was isolated from Helianthus tuberosus L. tuber cDNA library. The whole sequence is 509 bp, including an open reading frame (ORF) of 240 bp, a 5′ UTR of 62 bp and a 3′ UTR of 207 bp. Two genomic sequences covering the coding region ofhtMT2were cloned by PCR reaction. Sequence analysis revealed that the genomic sequences htMTG_1 of 986 bp and htMTG_2 of 982 bp were both composed of three exons and two introns. The deduced protein consisted of 79 amino acid residues with a predicted molecular weight of 7.8 ku (kD). Amino_terminal and carboxy_terminal domains contained 8 and 7 cysteine residues respectively, separated by a central cysteine free spacer. Sequence alignment revealed that the predicted protein ofhtMT2 was homologous to type 2 metallothioneins (MTs) of plants. Southern blotting analysis indicated that htMT2was encoded by a small multi_gene family in H. tuberosus genome. Northern blotting analysis showed that htMT2 transcripts were detected in stems, leaves and leafstalks, but no transcripts were detected in roots. The expression level in stems was the highest among the above tissues. Transcripts in stems were significantly reduced by Cu 2+ treatment. Judging from the homologies between the deduced HtMT2 and other type 2 plant metallothioneins as well as responses to metal ions, we believe thatwere cloned by PCR reaction. Sequence analysis revealed that the genomic sequences htMTG_1 of 986 bp and htMTG_2 of 982 bp were both composed of three exons and two introns. The deduced protein consisted of 79 amino acid residues with a predicted molecular weight of 7.8 ku (kD). Amino_terminal and carboxy_terminal domains contained 8 and 7 cysteine residues respectively, separated by a central cysteine free spacer. Sequence alignment revealed that the predicted protein ofhtMT2 was homologous to type 2 metallothioneins (MTs) of plants. Southern blotting analysis indicated that htMT2was encoded by a small multi_gene family in H. tube
