Papers by Michael Muhitch
… and Molecular Plant …, 2007
Zea mays often is colonized with the fungus Gibberella moniliformis, which produces fumonisin tox... more Zea mays often is colonized with the fungus Gibberella moniliformis, which produces fumonisin toxins. The role of fumonisins in seedling colonization and blight was studied using complementary genetic analyses of host and pathogen. Only one of two fumonisin B1 (FB1)-insensitive maize backcross lines was more resistant than the FB1-sensitive parent to seedling blight, indicating that the increase in FB1-insensitivity was not associated with an increase in resistance. FB1-producing and nonproducing isogenic fungal strains did not differ in ability to cause seedling blight, but the FB1-producing strain was more effective in systemic colonization of seedlings in reciprocal strain challenge tests. Together, these and previous results indicate that the role of fumonisins depends on complex environmental and genetic contexts in this host-pathogen interaction. Published by Elsevier Ltd.
Journal of plant physiology, 2003
In maize (Zea mays L.), GSp1, the predominant GS isozyme of the developing kernel, is abundant in... more In maize (Zea mays L.), GSp1, the predominant GS isozyme of the developing kernel, is abundant in the pedicel and pericarp, but absent from the endosperm and embryo. Determinations of GSp1 tissue distribution in vegetative tissues have been limited thus far to root and leaves, where the isozyme is absent. However, the promoter from the gene encoding GSp1 has been shown to drive reporter gene expression not only in the maternal seed-associated tissues in transgenic maize plants, but also in the anthers, husks and pollen (Muhitch et al. 2002, Plant Sci 163: 865-872). Here we report chromatographic evidence that GSp1 resides in immature tassels, dehiscing anthers, kernel glumes, ear husks, cobs and stalks of maize plants, but not in mature, shedding pollen grains. RNA blot analysis confirmed these biochemical data. In stalks, GSp1 increased in the later stages of ear development, suggesting that it plays a role in nitrogen remobilization during grain fill.
One isoform of maize glutamine synthetase, encoded by GS 1-2 , is localized exclusively in the ma... more One isoform of maize glutamine synthetase, encoded by GS 1-2 , is localized exclusively in the maternal tissues of the developing kernel. Previously, we have demonstrated the ability of the proximal 664 base pair 5 0 upstream portion of GS 1-2 to drive maternal tissue-specific GUS expression in transgenic maize kernels . In this report, a series of GS 1-2 promoter/GUS reporter transgenes, progressively truncated from the 5 0 end of the full length 664 base pair promoter, were evaluated for transformation efficiency and their ability to drive tissue-specific gene expression in transgenic maize. Analysis of transgene integration and expression suggests that GS 1-2 /GUS transgenes were incorporated efficiently into the maize genome, but were not expressed efficiently in maize cells. Truncation of the promoter from À664 to À394, À206 or À72, relative to the putative transcription start site, resulted in the loss of tissue specific expression within the kernels of transformed plants. Among the truncated series, moderate staining was exhibited by the À394 promoter/GUS gene transformants, stronger staining was found in À206 promoter/ GUS gene transformants, but relatively weak and variable staining occurred in plants transformed with the À72/GUS gene. Likely explanations for these observations are considered.
Plant Science, 2000
Mycotoxins are fungal secondary compounds that are toxic to vertebrates. Their presence in food a... more Mycotoxins are fungal secondary compounds that are toxic to vertebrates. Their presence in food and feeds, as the result of fungal disease in crops, can present a danger to animal or human health. Many mycotoxins have also been shown to be phytotoxic and in some cases, such as with trichothecenes produced by the wheat head blight fungus Fusarium graminearum, mycotoxins
Plant Science, 2002
The accumulation and localization of the transcript and peptide corresponding to the gene that en... more The accumulation and localization of the transcript and peptide corresponding to the gene that encodes the putative glutamate receptor isoenzyme 3.2 in Arabidopsis thaliana (AtGLR3.2 ) is reported. Polyclonal antibodies, raised to the C-terminal region of AtGLR3.2, were used to determine that the putative plant glutamate receptor is an integral membrane protein with an apparent molecular weight of 1119/1 kDa. RNA blot analysis revealed temporal accumulation of the AtGLR3.2 transcript in developing seedlings, results that were confirmed by polymerase chain reaction with reverse transcriptase-polymerase chain reaction (RT-PCR). Accumulation of the AtGLR3.2 transcript was highest in rapidly dividing tissues. Immunoblot analysis established that the presence of the AtGLR3.2 peptide mirrored, in most cases, the accumulation of the AtGLR3.2 transcript and suggests that AtGLR3.2 peptide accumulation is controlled in part by gene expression or RNA turnover. Affinity purified antibodies were used to localize the AtGLR3.2 protein in thin tissue sections. Immunohistochemical staining was intense and generalized in the rapidly dividing tissues of the developing floral buds, but mostly confined to the vascular tissue of the more mature hypocotyl, leaf and floral shoot tissues. Localization of the AtGLR3.2 protein to the rapidly growing tissues and vascular tissues is consistent with its proposed role in the translocation of calcium. #
Plant Cell Reports, 1998
Kernel culture was assessed for evaluating novel gene expression in developing maize (Zea mays L.... more Kernel culture was assessed for evaluating novel gene expression in developing maize (Zea mays L.) seeds by comparing the transient expression of maize ubiquitin (Ubi-I) promoter-driven ,B-glucuronidase (GUS) delivered by particle bombardment in kernels grown in culture with those grown in planta. With kernels from either source, GUS expression, as determined by histochemical staining, was widespread in young, actively growing kernels, but it diminished with kernel age and by 25 days after pollination was found only in the embryo. Transient expression of Ubi-l in kernels grown in vitro was not affected by wounding, ethylene treatment, pathogen invasion, or heat shock. In contrast, the plant hormones indole-3-acetic acid and kinetin both stimulated transient Ubi-1 expression in the endosperm, particularly at the periphery. Transient gene expression in developing maize seeds grown in vitro should allow for facile and rapid evaluation of the tissue-specificity and environmental responses of novel gene constructs in developing maize seeds.
Physiologia Plantarum, 1988
... and em-bryo tissues and homogenized in the isolation buffer of Ericson (1985) eontaining in a... more ... and em-bryo tissues and homogenized in the isolation buffer of Ericson (1985) eontaining in addition 15% (v/v) ethy-lene glycol. ... Colanduoni, J, Nissan, R, & Villafranca, J, J, 1987, Studies of the mechanism of glutamine synthetase utilizing pH-de-pendent behavior in catalysis ...
Physiologia Plantarum, 1991
ABSTRACT
Environmental Toxicology and Chemistry, 1985
The US. Environmental Protection Agency and the Organization for Economic Cooperation and Develop... more The US. Environmental Protection Agency and the Organization for Economic Cooperation and Development have recommended or are considering recommendations for phytotoxicity testing. A study was conducted to determine the amount of quantitative data published on the species suggested in those tests. Also, the sensitivity to herbicide applications was examined by use of a computerized database, PHYTOTOX, developed at the University of Oklahoma. The format and content of this database permitted an analysis of data reported in more than 3,500 publications. Such a comprehensive consideration of data was possible only through the use of the PHYTO-TOX database and, as a result, the computer analysis reported herein can be viewed as a novel approach in addressing plant toxicology questions.
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Papers by Michael Muhitch