Juren Zhang

Stability of inheritance of transgenes in maize (Zea mays L.) lines produced using different transformation methods

The inheritance and stability of the acetolactate synthase (als) transgene were compared in transgenic maize plants, generated using the pollen-tube pathway, particle bombardment, or Agrobacterium-mediated methods of transformation. Progeny populations generated by successive selfing or backcrossing of primary transformants were analyzed over three generations, using PCR and herbicide screening, to examine segregation and als activity, respectively, and transgenic homozygous plants were selected. The pollen-tube method resulted in a higher rate of primary normal transgenic plants and a less-stable transmission of the als locus than did the other two methods. When transferred by the particle bombardment and Agrobacterium-mediated methods, the als gene was in a much higher proportion of Mendelian transmission than transferred by the pollen-tube method. Compared to the Agrobacterium-mediated transformation, the particle bombardment method tends to create multiple copies and insert sites of the als gene in maize genome, which delaying the homogenization of the als locus with advancing generations. Agrobacterium-mediated transformation resulted in a greater proportion of stable, low copy number (in general 1–2) transgenic events, facilitating the stable inheritance of the als gene, and producing multiple desirable transgenic plants.

Genetic transformation of calli from maize and regeneration of herbicide-resistant plantlets

The herbicide-resistant geneals ofArabidopsis thaliana has been transferred into embryonic calli of maize by microprojectile bombardment. We have obtained chlorsulfuron-resistant calli and regenerated plantlets through selection by herbicide chlorsulfuron. The results of PCR analysis and Southern blotting indicate that geneals has been transferred into some plantlets. The test of spraying chlorsulfuron indicated that the transgenic plantlets had favorable herbicide-resistant trait. The purpose of the research was to obtain chlorsulfuron-resistant transgenic maize and hope that this kind of high efficient herbicide could be widely used in rotation soil of wheat and maize. In addition, through spraying herbicide, we could eliminate the hybrid plants and thereby increase the purity of F1 seeds.

Construction and characterization of a bacterial artificial chromosome library of maize inbred line 77Ht2

Maize inbred line 77Ht2 contains agriculturally important genes and has been widely used in corn breeding in China. A bacterial artificial chromosome (BAC) library of 77Ht2 has been constructed in order to identify useful genes and to facilitate the study of the maize genome. The library contains 175104 clones with an average insert size of 57 kb and represents about 4 maize haploid genome equivalents. Characterization of the library showed less than 0.5% of clones to not contain large inserts. Significant contamination of chloroplast and mitochondria DNA was not detected. BAC clones (152 arrays) were stored in 96 microtiter plates, with each well containing 12 clones. This is the first maize BAC library constructed in China. It is well suited for map-based cloning of maize genes and genome physical mapping.

Molecular Cloning, Expression, and Polyclonal Antibody Production of a Novel Flavin-Containing Monooxygenase from Thellungiella halophila

A novel flavin-containing monooxygenase (FMO)-like gene, designated as TsFMO, was cloned from Thellungiella halophila by reverse-transcriptase polymerase chain reaction (RT-PCR) coupled with rapid amplification of cDNA ends approach. The cDNA sequence of TsFMO had a complete open reading frame encoding a putative protein of 461 amino acids, which contained the conserved domains of FMOs. Sequence analysis showed that it had highest similarity with Arabidopsis FMOGS-OX1. RT-PCR analysis revealed that TsFMO was constitutively expressed in all examined tissues including the roots and rosette leaves of the seedlings and mature plants, bolts, and open flowers. Real-time PCR suggested that the gene was quickly and significantly upregulated in the leaves exposed to NaCl stress, which showed that TsFMO might be regulated with the redox state of plant cell. TsFMO was found to complement and rescue the retardant growth to dithiothreitol of yeast fmo mutant strain. In addition, TsFMO was expressed in Escherichia coli and the recombinant protein was purified to produce polyclonal antibody. Western blot with T. halophila extracts showed that the polyclonal antibody was effective and specific.