Organization and characterization of Cucurbita phloem lectin genes

The phloem of pumpkin and squash contains a dimeric chitin-binding lectin called PP2 (phloem protein 2). We have isolated three genomic clones from pumpkin (Cucurbita maxima Duch.) that encoded PP2. One clone, lambda gPC13-1, contained two PP2 genes that were 99.8% identical over a region of 3055 nu...

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Bibliographic Details
Published in:Plant molecular biology 1994-11, Vol.26 (3), p.887-897
Main Authors: Bostwick, D.E. (Arizona Univ., Tucson, AZ (USA). Dept. of Plant Sciences), Skaggs, M.I, Thompson, G.A
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Base Sequence
Cell Nucleus - genetics
CODE GENETIQUE
CODIGO GENETICO
Conserved Sequence
CUCURBITA
Cucurbita maxima
FLOEMA
GENE
Gene Dosage
GENES
Genes, Plant - genetics
GENETIC CODE
Genomic Library
LECTINA
LECTINE
LECTINS
Lectins - genetics
Molecular Sequence Data
NUCLEOTIDE SEQUENCE
PHLOEM
PHLOEME
Plant Lectins
Plant Proteins - genetics
Plant Proteins - immunology
Plant Proteins - isolation & purification
Polymerase Chain Reaction
Polymorphism, Genetic
Restriction Mapping
SECUENCIA NUCLEICA
SEQUENCE NUCLEIQUE
Species Specificity
Transcription, Genetic
Vegetables - anatomy & histology
Vegetables - genetics
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Summary:The phloem of pumpkin and squash contains a dimeric chitin-binding lectin called PP2 (phloem protein 2). We have isolated three genomic clones from pumpkin (Cucurbita maxima Duch.) that encoded PP2. One clone, lambda gPC13-1, contained two PP2 genes that were 99.8% identical over a region of 3055 nucleotides. This conserved region included 1922 bp of 5' non-coding sequence, 844 bp of protein coding sequence (including two introns), and 289 bp of 3' non-coding sequence. To examine the conservation of the phloem lectin within the genus Cucurbita, we analyzed nine different species for PP2, its mRNA, and the genes that encode PP2. DNA blot analysis indicated that each species contained genes that encoded PP2, however, there was considerable restriction fragment length polymorphism (RFLP) among the species. PP2 gene copy number reconstructions indicated that PP2 is encoded by a small gene family (two to eight genes). Although a high level of PP2 DNA polymorphism existed among species, a single mRNA (ca. 1 kb) was detected in each species. PP2, affinity-purified from the vascular exudate of each species, reacted with PP2-specific antibodies; five species contained a single PP2 polypeptide while four species contained two PP2 polypeptides.
ISSN:0167-4412
1573-5028
DOI:10.1007/bf00028856