Abstract: Methods for fostering somatic embryogenic competence of a plant cell or tissue by contacting the plant cell or tissue with an arabinogalactan protein (AGP) composition effective for fostering somatic embryogenic competence in plant species and varieties that are recalcitrant to somatic embryogenesis and/or regeneration are provided. AGP compositions useful for fostering somatic embryogenic competence are provided, including total AGP and an AGP RP-HPLC hydrophobic fraction, both from embryogenic callus, from plant varieties including cotton lines Coker 315, Siokra 1-4, and Sicala 40, including at concentrations ranging from about 0.0008 mg/L to about 100 mg/L. Methods for regenerating plants, producing transformed plants, and impeding somatic embryogenic competence are also provided. Plant culture media and methods for making useful AGP compositions and media are also provided. Amino acid and nucleotide sequences for peptides and proteins eluting in hydrophobic AGP fractions are also provided.

Abstract: This invention provides plant arabinogalactan proteins (AGPs) and their genes. AGPs were isolated from Nicotiana alata, Nicotiana plumbaginafolia, and Pyrus communis. Amino acid sequences of isolated AGP peptide fragments are presented. Isolated AGP fragments were used to synthesize oligonucleotide probes to prepare oligonucleotide primers for PCR or prepare RNA probes to screen cDNA libraries of N. alata, N. plumbaginafolia, and P. communis. cDNA clones encoding amino acid sequences of isolated AGP fragments were isolated. The invention presents for the first time an intact AGP amino acid sequence derived from a corresponding AGP gene. The instant invention further provides methods useful in obtaining AGP genes encoding an AGP peptide comprising a specific isolated hydroxyproline-rich (OAST-rich) sequence or a specific isolated hydroxyproline-poor sequence.

Abstract: This invention provides plant arabinogalactan proteins (AGPs) and their genes. AGPs were isolated from Nicotiana alata, Nicotiana plumbaginafolia, and Pyrus communis. Amino acid sequences of isolated AGP peptide fragments are presented. Isolated AGP fragments were used to synthesize oligonucleotide probes to prepare oligonucleotide primers for PCR or prepare RNA probes to screen cDNA libraries of N. alata, N. plumbaginafolia, and P. communis. cDNA clones encoding amino acid sequences of isolated AGP fragments were isolated. The invention presents for the first time an intact AGP amino acid sequence derived from a corresponding AGP gene. The instant invention further provides methods useful in obtaining AGP genes encoding an AGP peptide comprising a specific isolated hydroxyproline-rich (OAST-rich) sequence or a specific isolated hydroxyproline-poor sequence.

Abstract: A method for the culturing of gum-secreting plant cells, recovery of the gum from the medium and use of the plant gum in food products is described. In particular, the plant gum product of cultured Pyrus, Prunus avium and Rosa cells can be used in food products as comprising complex carbohydrates and glycoproteins, for example, an emulsifying agent, an emulsion stabilizer, a thickening agent or a texture modifier.

Abstract: A method for the production of a plant gum product which comprises the steps of culturing gum-secreting plant cells in tissue culture in the presence of a culture medium; and recovering the gum product secreted by the cells from the culture medium. The gum product may be used in a food product, for example, as an emulsifying or stabilizing agent.

Abstract: A class of proteins associated with self-incompatibility alleles of plants, preferably of gametophytic self-incompatibility type, are provided. These proteins inhibit pollen tube growth in a plant style having the associated self-incompatibility allele, and have defined amino acid homologies and cross-reactivities.

Abstract: This invention provides an immunologic method for measuring plant pollen germination and pollen tube growth. This method is based on the finding that an antibody having specificity to .beta.-L-arabinofuranosyl residues binds to the surface of in vitro grown pollen tubes. Antibody binding can be measured qualitatively or quantitatively using a calibration curve. The immunoassay is useful for screening plants for response to substances that affect plant germination or pollen tube growth.