Tissue-specific and light-regulated expression of a pea nuclear gene encoding the small subunit of ribulose-1,5-bisphosphate carboxylase

Light-regulated and organ-specific expression of a wheat Cab gene in transgenic tobacco

Many of our most important crop plants are monocotyledons, including wheat, corn, rice and barley. No routine transformation system for monocotyledons has been reported, such as the Ti-mediated gene transfer system for dicotyledons facilitated by Agrobacterium tumefaciens. Indirect evidence suggests that Ti-plasmid DNA is transferred into and expressed in A. tumefaciens-infected wound tissues of plants from Liliaceae and Amaryllidaceae, but these observations have not been extended to monocotyledons of greatest agricultural importance. Regeneration of monocotyledons is usually blocked at the callus-stage, further complicating the possibility of exploring the regulated expression of their genes, and thus preventing identification of the regulatory domains of monocotyledonous genes in a homologous nuclear background. To circumvent these difficulties, we investigated whether monocotyledonous genes can be expressed and correctly regulated in dicotyledons. We have introduced a wheat gene (whAB1.6) encoding the major chlorophyll a/b binding protein (Cab) of the light-harvesting complex into the genomes of tobacco (Nicotiana tabacum SR1) and petunia (Petunia hybrida) via a Ti-DNA-mediated gene transfer system which allows the transformed cells to regenerate into whole plants. Here we report for the first time the light-regulated and organ-specific expression of a monocotyledonous gene in transgenic dicotyledonous plants.

Characterization of two Phaseolus vulgaris phytohemagglutinin genes closely linked on the chromosome

A lambda 1059 library of Phaseolus vulgaris cv. 'Tendergreen' DNA was screened with a cloned lectin-like cDNA. Among the phages selected was clone lambda B10 containing two complete lectin genes in the same orientation approximately 4 kb apart. The DNA sequences of the lectin genes and their flanking regions have been determined and their transcriptional initiation sites were located by S1 nuclease mapping. On the basis of the deduced amino acid sequences and compositions and the mol. wts. of their encoded glycoproteins, the genes, dlec1 and dlec2, are predicted to encode erythro- and leucoagglutinating phytohemagglutinins (PHA-E and PHA-L), respectively. The mRNA coding regions of dlec1 and dlec2 are 90% homologous, suggesting an origin involving duplication of an ancestral gene. Both lectin genes are intronless and have at least two ATG codons in a short (11-14 bp) 5'-untranslated region. Most of their 5'-untranslated regions consist of alternating pyrimidines and purines (RY repeats). Upstream sequences are also highly conserved between dlec1 and dlec2, including stretches of nine or more alternating R and Y residues. RY repeats of such length are not found within the protein coding portion of dlec1, dlec2 or a Phaseolus lectinlike gene previously described. Overlapping double (dlec1) or triple (dlec2) polyadenylation addition signals are found and there is an unusually high degree of homology (84%) between their 3'-untranslated regions.(ABSTRACT TRUNCATED AT 250 WORDS)