Low-pollen-allergen ryegrasses: towards a continent free of hay fever?

The ryegrasses (Lolium spp.) are the major grass species sown for forage and amenity use in temperate areas of the world. Pollen of ryegrass is a widespread source of airborne allergens and is a major cause of hay fever and seasonal allergic asthma, which affect approximately 25% of the population in cool temperate climates. The main allergens of ryegrass pollen are the proteins Lol p 1 (35 kDa) and Lol p 2 (11 kDa). Lol p 1 and Lol p 2 belong to two major classes of grass pollen allergens to which over 90% of pollen-allergic patients are sensitive. In spite of being conserved in many plant species, the functional in planta role of these pollen allergen proteins remains largely unknown. We have generated and analysed transgenic plants with reduced levels of the main pollen allergens, Lol p 1 and Lol p 2 in the most important worldwide cultivated ryegrass species, L. perenne (perennial ryegrass) and L. multiflorum (Italian ryegrass). These transgenic plants will allow the study of the functional in planta role of these pollen proteins and the determination of potential for development of hypo-allergenic ryegrass cultivars. The commercial release of cultivars of perennial ryegrass and Italian ryegrass with reduced pollen allergens offers the potential to reduce subsequently the incidence of seasonal allergic responses. The prospects of reducing the incidence of hay fever in Australia will be increased through the widespread use of low-allergen ryegrasses