Methionine and threonine synthesis are limited by homoserine availability and not the activity of homoserine kinase in Arabidopsis thaliana.

Homoserine kinase (HSK) produces O-phospho-l-homoserine (HserP) used by cystathionine gamma-synthase (CGS) for Met synthesis and threonine synthase (TS) for Thr synthesis. The effects of overexpressing Arabidopsis thaliana HSK, CGS, and Escherichia coli TS (eTS), each controlled by the 35S promoter, were compared. The results indicate that in Arabidopsis Hser supply is the major factor limiting the synthesis of HserP, Met and Thr.

Distribution of the glutamine synthetase isozyme GSp1 in maize (Zea mays).

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.

Transgenic expression of the TRI101 or PDR5 gene increases resistance of tobacco to the phytotoxic effects of the trichothecene 4,15-diacetoxyscirpenol.

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 may act as virulence factors.

The maize glutamine synthetase GS1-2 gene is preferentially expressed in kernel pedicels and is developmentally-regulated.

The pedicel region of Zea mays kernels contains a unique form of maize glutamine synthetase (GS), GSp1. RNA blot analysis using GS gene-specific probes revealed that the expression of the GS1-2 gene was specific to the pedicel and that it increased in the kernels during development. This pattern of the maize GS1-2 gene expression is consistent with the tissue specificity of the GSp1 protein and suggests that it encodes the GSp1 isoform of maize GS.

Regulation of the maize ubiquitin (Ubi-1) promoter in developing maize (Zea mays L.) seeds examined using transient gene expression in kernels grown in vitro.

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-1) promoter-driven β-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.