Characterization of a Gene Family Abundantly Expressed in Oenothera organensis Pollen That Shows Sequence Similarity to Polygalacturonase

Abstract

We have isolated and characterized cDNA clones of a gene family (P2) expressed in Oenothera organensis pollen. This family contains approximately six to eight family members and is expressed at high levels only in pollen. The predicted protein sequence from a near full-length cDNA clone shows that the protein products of these genes are at least 38,000 daltons. We identified the protein encoded by one of the cDNAs in this family by using antibodies to beta-galactosidase/pollen cDNA fusion proteins. Immunoblot analysis using these antibodies identifies a family of proteins of approximately 40 kilodaltons that is present in mature pollen, indicating that these mRNAs are not stored solely for translation after pollen germination. These proteins accumulate late in pollen development and are not detectable in other parts of the plant. Although not present in unpollinated or self-pollinated styles, the 40-kilodalton to 45-kilodalton antigens are detectable in extracts from cross-pollinated styles, suggesting that the proteins are present in pollen tubes growing through the style during pollination. The proteins are also present in pollen tubes growing in vitro. Both nucleotide and amino acid sequences are similar to the published sequences for cDNAs encoding the enzyme polygalacturonase, which suggests that the P2 gene family may function in depolymerizing pectin during pollen development, germination, and tube growth. Cross-hybridizing RNAs and immunoreactive proteins were detected in pollen from a wide variety of plant species, which indicates that the P2 family of polygalacturonase-like genes are conserved and may be expressed in the pollen from many angiosperms.

Molecular cloning of the second major allergen, Cry j II, from Japanese cedar pollen

“…However, searching the SWISS-PROT database revealed that the Cryj II amino acid sequence shares a significant homology with polygalacturonases (PGs), especially that derived from tomato, Lycopersicon esculentum (40% identity, Fig. 2) [14,15], from Zea mays (34% identity) [16,17], and that from Oenothera organensis (34% identity) [18].…”

Different Temporal and Spatial Gene Expression Patterns Occur during Anther Development.

“…The gene expression programs that we have identified take place within sporophytic tissues and probably represent only a fraction of the regulatory programs that occur during anther development. Other anther-specific gene expression programs have been identified that occur within the developing male gametophyte or pollen grain (Stinson et al, 1987;Mascarenhas, 1988;Hanson et al, 1989;Ursin et al, 1989;Brown and Crouch, 1990;Twell et al, 1990). In each case, these programs deal with the prevalent mRNA sets that are regulated during phase 2 of anther development and represent only a small fraction of the thousands of anther-specific mRNAs known to occur Goldberg, 1980, 1984).…”

“…Stamen primordia specification depends upon the action of several genes (Bowman et al, 1989;Meyerowitz et al, 1989;Carpenter and Coen, 1990) which may encode transcriptional activator proteins (Sommer et al, 1990;Yanofsky et al, 1990). Following stamen primordia initiation, several highly specialized anther tissues are differentiated from cell lineages present in the floral meristem (Satina and Blakeslee, 1941) and are responsible for carrying out nonreproductive functions (e.g., support, dehiscence) and reproductive functions (e.g., spore and gamete formation).…”

Global Identification of Target Genes Regulated by APETALA3 and PISTILLATA Floral Homeotic Gene Action

“…Genes that encode proteins with high similarity to GAST-1 appear to play a specific role in corolla cell elongation (Shi et al, 1992;Ben-Nissan and Weiss, 1996;Kotilainen et al, 1999). Screens for stamen-and pollen-expressed genes also have yielded many cell wall-associated genes, including polygalacturonases, pectate lyases, and Gly-rich proteins (McCormick et al, 1987;Wing et al, 1989;Brown and Crouch, 1990;Nacken et al, 1991;Chen et al, 1994;Rubinelli et al, 1998). However, several of these genes probably have a specific function in pollen development or pollen tube growth.…”