Genome-wide identification and molecular characterization of Ole_e_I, Allerg_1 and Allerg_2 domain-containing pollen-allergen-like genes in Oryza sativa.

Pollen allergens play important roles in plant development in addition to their allergenic nature for human. More than 10 groups of pollen allergens have been reported. Among them, Pollen_Ole_e_I (Ole), Pollen_allerg_1 (Allerg1) and Pollen_allerg_2 (Allerg2) domain-containing proteins are the majority of allergens. We have identified 114 pollen-allergen-like genes in rice genome by bioinformatics using public databases. Among them, 45 genes encode Ole domain-containing proteins, 62 with Allerg1 and 7 with Allerg2. They are distributed on 11 of 12 rice chromosomes excluding chromosome 11. Comparison analysis of coding regions from both predicted genes and isolated full-length cDNAs showed that most of predicted genes were correct in the splicing of exons and introns, and only 7 exhibited wrong predictions. The fact suggested the applicability of the prediction programs to identify pollen-allergen genes. Phylogenetic analysis revealed the high diversity within OsOle genes and recent evolutionary event in OsAllerg1 genes, and suggested that some of OsOle genes were new members of the family. Expression analysis by RT-PCR showed that most of the genes were expressed in all tested tissues and only eight genes exhibited panicle-specific expression, suggesting that pollen-allergen genes play roles in not only productive but also vegetative development.