Maize Transformation for Resistance to Aspergillus Flavus
Mei, Chuansheng
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https://hdl.handle.net/2142/87688
Description
Title
Maize Transformation for Resistance to Aspergillus Flavus
Author(s)
Mei, Chuansheng
Issue Date
2000
Doctoral Committee Chair(s)
Widholm, Jack M.
Department of Study
Agronomy
Discipline
Agronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Plant Pathology
Language
eng
Abstract
The chitinase18 (ch18) and beta-1,3-glucanaseII (glu) genes driven by globulin1 were delivered into H99 and Pa91 type I calli by particle bombardment. Sixteen different transformation events were obtained from H99 calli. Some were crossed with Pa91 the untransformed control and then self-pollinated up to six times. The transgenes have been confirmed to be integrated into the genome by PCR and Southern blots and the transgene expression detected by RT-PCR, Northern and Western blots, and enzyme activity assays. The ch18 transgene was expressed in embryos as expected and the embryos also had higher chitinase activity than that of the untransformed controls beginning 17 DAP. However, higher beta-1,3-glucanase activity was not detected although the glu transgene expression was detected in embryos by RT-PCR and Northern blots. Study of the ch18 transgene expression localization by Northern and Western blots indicated that the transgene was expressed not only in embryos but also in the pericarp plus aleurone and in the endosperm. Enzyme activity assays also showed higher chitinase and beta-1,3-glucanase activities both in pericarp plus aleurone and in endosperm even though no differences of beta-1,3-glucanase activity were found in embryos of the glu transgenic plants. No CH18 protein could be detected in leaves, stems, and roots of young ch18 transgenic seedlings by Western blots. Thus it appears that the globulin1 promoter is seed-specific and not embryo-specific. Mature kernels of line R4 (with glu), line R147 (with ch18), and their F2 progeny had higher activities of both chitinase and beta-1,3-glucanase than the untransformed controls, but the levels were not higher than resistant line Tex6. The kernel-screening assay showed that lines R4 and R147 were more resistant to A. flavus than the control, which was supported by the GUS activity assay. Studies carried out in 1999 indicate that some lines containing both the ch18 and glu genes are more resistant to A. flavus than the control in the field and may also have reduced levels of aflatoxins.
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