Cultivated rye

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Code: g12
Latin name: Secale cereale
Source material: Pollen
Family: Poaceae (Gramineae)
Sub family: Pooideae
Tribe: Triticeae
Common names: Cultivated Rye, Rye

Synonyms: S. montanum, Triticum cereale

There is a need to differentiate between Cultivated Rye grass pollen (Secale cereale) g12, Rye the foodstuff (Secale cereale) f5, Rye grass (Lolium perenne) g5, and Wild Rye grass (Elymus tricoides) g70.


A grass species producing pollen, which often induces hay fever, asthma and conjunctivitis in sensitised individuals.

Allergen Exposure

Geographical distribution

Probably native to the Mediterranean or south-western Asia, but now widely cultivated in the temperate regions of the world, Rye can be grown in a wider range of environmental conditions than any other small grain. Winter Rye is the most winter-hardy of all cereals. Rye is cultivated in Central and Eastern Europe, Russia and North America, often where conditions are unfavourable for Wheat. Less than 50% of the Rye grown in the US is harvested for grain, with the remainder used as pasture, hay, or as a cover crop.

Rye is a hardy, tufted annual grass, 1 to 1.5 m tall, with a blue-green cast and an extensive root system. The leaves are 1.2 cm or less broad, 7.5 to 15 cm long, smooth or slightly scabrous, and pointed; the leaf sheaths are long and flat and loose. A 7 to 15 cm bushy spike is the flower head. The spikelets contain two fertile florets with short awns; the kernels are oblong, 0.8 cm long, and light-brown.

Rye flowers from May to July (in the Northern Hemisphere), giving rise to the well-known ‘smoke’, when the Rye pollen is released in great masses. The seeds ripen from August to September. The flowers are hermaphrodite (have both male and female organs) and are pollinated by wind.


The grain is used in bread-making, alcoholic fermentation, and as feed for livestock. (See: Rye (Secale cereale) f5.) The straw is useful for thatching and as a feed for livestock. The plant grows in cultivated beds and requires full sunlight. It is also used as a pasturage grass, grazed in the fall or spring and then allowed to develop “heads” and mature. It may be considered a weed in wheat fields, and may escape along roadsides and to waste places; and can become established on wastelands and open rangeland (1).

Rye is widely cultivated for its grain and as valuable spring forage. A common cereal, Rye is used – especially in northern Europe – to make bread, cakes, etc. The seed can be sprouted and added to salads. Malt, a sweet substance produced by germinating the seed, is used as a sweetening agent and in making beer and whisky.

Unexpected exposure

Rye straw is used as a fuel or as a biomass in industry. It is quite strong, and can also be used in archery targets, mushroom compost, bedding, thatching, for paper-making, weaving mats and hats, and as a packing material for nursery stock, bricks and tiles. It is often dried for commercial flower arrangements.

Allergen Description

Cultivated Rye pollen contains more than 30 proteins that can be shown to be allergens in terms of their IgE binding in sera from Rye pollen-allergic individuals. Nine were determined to be major allergens. Using Western Blot, 17 allergens were isolated, 3 of them major allergens (2). Group 1, 4 and 5 allergens were inferred from studies on cross-reactivity between grasses. Although other allergens have not yet been fully characterised, a 28 kDa allergen has been isolated (3), and allergens of 33 kDa, 48 kDa and 67 kDa have been detected (4).

The following allergens have been characterised:

Sec c 1, an alpha-amylase / trypsin inhibitor (5-11).

Sec c 2, a Group 2 grass allergen (9, 12).

Sec c 3, a Group 3 grass allergen (13).

Sec c 4, a Group 4 grass allergen, a berberine bridge enzyme (14-16).

Sec c 5, a Group 5 grass allergen, a ribonuclease (9-11, 17, 18).

Sec c 12, a profiling (9, 19).

Sec c 13, a Group 13 grass allergen, a polygalacturonase (20, 21).

Potential Cross-reactivity

This pantemperate tribe Triticeae is notable for its cereal genera: Wheat, Barley and Rye. The close relation makes cross-reactivity likely between Wild Rye grass g70, Cultivated Wheat g15, Cultivated Rye grass g12, Barley g201, and Couch grass (Agropyron repens) as well as Lymegrass (Elymus arenarius). Extensive cross-reactivity among the different individual species of the genus may be expected. This is as a result of the variable degrees of cross-reactivity resulting from the presence of the Group 1, 2, 3, 4, 5 and 13 grass allergens, and of profilin.

There should be cross-reactivity with other members of the family Poaceae, particularly in the subfamily Pooideae (Rye grass (g5), Canary grass (g71), Meadow grass (Kentucky blue grass) (g8), Timothy (g6), Cocksfoot (g3), Meadow Fescue (g4), Velvet (g13), Redtop (g9), Meadow Foxtail (g16), Wild Rye grass (g70)) (22, 23), as a result of a common Group 1 grass allergen (6).

Extensive IgE cross-reactivity has been demonstrated between the group 1 grass allergens of the Pooideae grasses examined: Meadow grass, Meadow Fescue, Cocksfoot, False Oat, Rye, Velvet, Redtop, Sweet Vernal, Cultivated Rye, Common Reed and Timothy grass (24). Interspecies differences will result in varying degrees of cross-reactivity. Other grass pollens containing Group 1 grass allergens include Cultivated oat, Sweet vernal grass, Bermuda grass, Rye grass, Common Reed, Cultivated Rye, Cultivated Wheat and Maize pollen (7, 9, 10). Phl p 1, a major allergen of Timothy grass, harbours multiple T-cell epitopes. Species-specific and cross-reacting T-cell epitopes were reported to exist among Group 1 grass allergens, which include Secale (25).

However, variable degrees of cross-reactivity will occur for the amino acid sequence identity between the allergens from Festuciformes grasses (Lol p 1, Phl p 1, Hol l 1, Poa p 1 and Pha a 1 are greater than 90%), while Lol p 1 and Group 1 allergens from non-Festuciformes grasses (Bermuda grass, Common Reed and Rice pollen) share less than 66% (8).

Cultivated Rye grass contains a Group 2 grass allergen, as does Sweet Vernal grass, Cultivated Oat, Rye grass, Common Reed, Meadow grass (Kentucky blue), Cultivated Wheat, and Timothy grass; but not Bermuda grass or Maize pollen (9).

Group 4 grass allergens have been demonstrated in Cultivated Rye grass, Rye grass, Cocksfoot grass, Meadow Fescue, Velvet grass, Field Brome, Meadow grass, Cultivated Barley, and Timothy (15, 16).

Group 5 grass allergens have been found in Cultivated Rye grass, Rye grass, Sweet Vernal grass, Cultivated Oat, Common Reed, Meadow grass (Kentucky blue), Cultivated Wheat, and Timothy grass; but not Bermuda grass or Maize pollen (9, 18). However, the degree of cross-reactivity is highly variable, and individual sera of patients may not always be equally cross-reactive to all pollen species (10).

Natural pollen extracts from Anthoxanthum odoratum (Sweet Vernal grass), Avena sativa (Cultivated Oat), Cynodon dactylon (Bermuda grass), Lolium perenne (Rye grass), Phragmites australis (Common Reed), Poa pratensis (Meadow grass), Secale cereale (Cultivated Rye grass), Triticum sativum (Cultivated Wheat), and Zea mays (Maize or Corn pollen) were characterised regarding their allergen contents by means of specific antibodies, and by IgE immunoblot inhibition with recombinant allergens from Phl p 1, Phl p 2, Phl p 5, and Bet v 2, using the sera of 193 European, American, and Asian subjects. Immunologically detectable Group 5 and Group 2 allergens were found in all these species except for C. dactylon and Z. mays (9).

Pollen from 10 agricultural plant species was surveyed for the presence of proteins cross-reactive with Group 1, Group 4 and Group 9 allergens. Barley (Hordeum vulgare), Maize (Zea mays), Rye (Secale cerale), Triticale (xTriticosecale cereale), Oat (Avena sativa), Canola (Brassica napus) and Sunflower (Helianthus annuus) pollens contained numerous allergen-cognate proteins (26).

Cross-reactivity between Rye pollen and Rye seed has not been studied in detail. In a 1984 study, crossed-line immunoelectrophoresis showed that some of the Rye pollen antigens were partially identical, immunologically, with antigens of Wheat flour and Rye flour (27).

Clinical Experience

IgE-mediated reactions

Cultivated Rye grass pollen can induce asthma, allergic rhinitis and allergic conjunctivitis (2, 17, 28, 29).

In a study of the relationship between allergy and acute attacks of asthma in California, adult patients with acute asthma presenting during a defined pollen season were examined. Sera from 59 patients presenting with acute asthma during the spring asthma ‘epidemic’ were assayed for the presence of IgE antibody to five allergens (mite, Cat, cockroach, Cultivated Rye grass pollen, and Ragweed). Ninety-two percent of the patients with asthma had serum-specific IgE to Cultivated Rye grass pollen, compared to 14% of the control subjects. Some of the grass pollen-allergic patients also had increased levels of serum-specific IgE to Ragweed, but only 25% had high levels (27).

In an early French study, Barley pollen and Rye pollen were reported to be important sensitising allergens in children with grass pollen allergy, as determined by specific IgE studies (30).

The importance of grass pollen as a cause of hay fever in the South Plain of Hungary was studied. Of 642 patients with seasonal allergic rhinitis, 261 who experienced allergic rhinitis in May and June (when the daily pollen count of grass pollen was at its highest) were examined for specific IgE to various grasses. Eighty-four percent were positive to Poaceae grasses, and 63% to Secale (31).

A review of 335 female and 130 male asthmatic patients with asthma, by the Portuguese hospital of Cova da Beira, reported that 70% had allergic asthma, and 30% had non-allergic asthma. The major allergen sensitisers (as evaluated by skin-prick testing and specific IgE) included Rye grass (Lolium perenne), Timothy grass, Cocksfoot grass, Meadow grass and Cultivated Rye grass (32). In another Portuguese study – an evaluation of sensitisation to pollens in 32 children under eight years attending an allergy unit in Portugal – 72% presented with symptoms of allergic rhinitis, 66% with conjunctivitis, 50% with asthma and 34% with allergic rhinitis and asthma. According to skin-prick tests, all children were sensitised to grass pollen, and 38% were monosensitised. Degree of grass pollen sensitisation, in order of frequency, was Cocksfoot grass (94%), Barley pollen (75%), Timothy grass (72%), Meadow grass (69%), Cultivated Oat (66%), Meadow Fescue grass (63%), Cultivated Wheat (59%), Cultivated Rye grass (53%), Rye grass (Lolium) (50%) and Maize pollen (31%). Thirty-four percent of children were sensitised to tree pollen (33). In an earlier study conducted in Cova da Beira – an interior central region of Portugal – of 371 paediatric patients skin-prick tested, 25.3% were sensitised to Cultivated Rye grass (34).

One hundred Spanish patients with rhinitis and / or seasonal asthma were studied for sensitisation to a range of grass and tree pollen allergens. Sixty-five resided in the Rioja Media region, 20 patients in the Rioja Alta and 15 patients in the Rioja Baja. Skin-prick tests were positive to the pollen of grasses (Phleum and Secale) in 90% of the cases, to pollen of Olea in 62% of the cases, and to the pollen of Fraxinus in 28% of the cases (35).

In Saudi Arabia, Cultivated Rye pollen was shown to be one of the most abundant aeroallergens in sandstorm dust (36).

Other reactions

Antifreeze proteins, which are proteins that have the ability to retard ice crystal growth, have been identified as the most abundant apoplastic proteins in cold-acclimated Winter Rye leaves. All tests indicated that these antifreeze proteins are similar to members of three classes of pathogenesis-related proteins, namely endochitinases, endo-beta-1,3-glucanases, and thaumatin-like proteins (37). Chitinases have also been isolated from Rye seed (38), but the relationship between these and the chitinases from Rye leaves has not yet been determined.

Rye infested with a fungus called ergot was responsible for several epidemics in medieval times. 

Compiled by Dr Harris Steinman, developer of Allergy Advisor,


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As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.