**3. Infraspecific botanical names**

2 Current Insights in Pollen Allergens

these investigations.

**2. Taxonomy of allergenic plants** 

*var. italica*, *var. gemmifera*, *var. capitata*, *var. botrytis*).

somehow complementary strategies are defined:

Numerous analysis have raised the question that pollen grains, similarly to fruits may notably differ among different varieties/cultivars in terms of pollen micromorphology, as well as in their physiological characteristics (e.g. viability, vigour, ability to germinate, compatibility…) (Castro et al 2010; Ribeiro et al 2012), and eventually in their allergenic content. However, literature devoted to the comparison of the pollen allergenic characteristics intra- and inter- varieties is still relatively scarce. This article reviews most of

Excellent reviews have been made as regard to the taxonomical classification of the allergenic plants (Yman1982; Takhtajan 1997; D'Amato et al 1998; Mothes et al 2004; Mohapatra et al 2004; Esch 2004; Radauer et al 2006). Moreover, several broad databases have compiled profuse and well-documented information linking the most relevant plant allergenic sources, the identified allergens and their taxonomical classification. They include Pharmacia (Pharmacia Diagnostics, 2001) and later Phadia/Thermo Fisher Scientific (http://www.phadia.com/en/Allergen-information/ImmunoCAP-Allergens/Allergen-compo nents-list/), the Allergome database of allergenic molecules (Mari et al 2009; http://www.allergome.org/index.php) and the official site for the systematic allergen nomenclature approved by the World Health Organization and International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub-committee (http://www.allergen.org/index.php). Independently of the widespread presence of crossreactivity, most allergens are described in these works and databases as characterized in a single species (e.g. rBet v 2 Profilin, Birch= *Betula verrucosa*). Only a minority are referenced to taxonomical entities different to species, either to a combination of related species, cultigens or hybrids (e.g. *Musa acuminata* / *sapientum* / *paradisiaca*) or to a heterogeneous group of more than one (often numerous) species (e.g. *Eucalyptus* spp. Note that these abbreviations are not italicized or underlined, and can easily be confused with the abbreviations "ssp." or "subsp." referring to subspecies.). In several cases, allergens are referred to taxonomic ranks of higher entity than species (e.g. *Theaceae*). Only a few allergens are univocally attributed to infraspecific plant categories like varieties (e.g. *Brassica oleraceae*

As regards to pollen allergen analysis, two alternatives, apparently opposite, although

Mothes et al (2004) analyzed cross-reactivities to pollens of trees of the Fagales order, fruits and vegetables, between pollens of the Scrophulariales and pollens of the Coniferales. They proposed a classification of tree pollen and related allergies based on major allergen molecules instead of botanical relationships among the allergenic sources, suggesting Bet v 1 as a marker for Fagales pollen and related plant food allergies, Ole e 1 as a possible marker for Scrophulariales pollen allergy and Cry j 1 and Cry j 2 as potential markers for allergy to Coniferales pollens. Another work analyzed pollen allergen sequences with respect to protein family membership, taxonomic distribution of protein families, and interspecies variability In botany, an infraspecific name is that corresponding to any taxon below the rank of species. Such names are constructed based in the use of trinomial nomenclature, regulated by the International Code of Botanical Nomenclature (ICBN) (McNeill et al 2006), which includes: genus name, specific epithet, connecting term indicating the rank (not part of the name, but required), and finally the infraspecific epithet. It is habitual to italicize all three parts of the name, but not the connecting term. Five different taxonomical ranks below the species are explicitly allowed in the ICBN:


A **subspecies** is a taxonomical rank formed by individuals of the same species which are capable of interbreeding and producing fertile offspring. However, they often do not interbreed in nature due to geographic isolation or other factors (http://en.wikipedia. org/wiki/Subspecies). The differences between subspecies are usually less distinct than the differences between species, but more distinct than the differences between varieties.

A **botanical variety** is a taxonomic rank below that of species, characterized by differential appearance from other varieties. However, varieties retain the ability to hybridize freely among themselves, providing they become in contact. Usually, varieties are geographically separated. Varieties are named by using the binomial Latin name followed by the term "variety" (usually abbreviated as "var.") and the name of the variety in italics.

**Subvarieties, forms and subforms** constitute taxonomic ranks of "secondary" importance and are more rarely used. For example, a form usually designates a group with a noticeable but minor deviation. Some botanists believe that there is no need to name forms, since there are theoretically countless numbers of forms based on minor genetic differences (http://en.wikipedia.org/wiki/Form\_(botany)).

The term **cultivar** is defined as a plant or group of plants selected for desirable characteristics that can be maintained by propagation (http://en.wikipedia. org/wiki/Cultivar). Most cultivars have been obtained after using agronomical methods, or in some cases, selected from wild populations. Crops and even trees used in forestry are usually cultivars that have been selected for desirable characteristics including improved production, resistance to pests, flavor, timber production etc. Naming of cultivars is recommended by the International Code of Nomenclature for Cultivated Plants (ICNCP) (Brickell et al, 2009), and is formed of the scientific botanical name (Latin) followed by the term "cultivar" (usually abbreviated as "cv.") and a cultivar epithet bounded by single quotation marks, for example: *Olea europaea* cv. 'Picual'.

Pollen Allergenicity is Highly Dependent on the Plant Genetic Background: The "Variety"/"Cultivar" Issues 5

studies have demonstrated significant cross-reactivity between *P. canariensis* and *P.* 

Kwaasi et al (1994) compared pollen crude extracts from ten cultivars of this tree for their antigenic and allergenic potentials. The results of the tests performed on 6 confirmed atopic patients, including skin prick tests, ELISA, IgG and IgE immunoblotting analyses, peripheral blood lymphocyte proliferation and concomitant interleukin-4 (IL-4) production indicated sharp inter-cultivar heterogeneity. One of the cultivars even failed to elicit any skin test reactivity or bind IgE in atopic sera as determined by the indicated assays. The authors therefore suggest that the antigenicity and allergenicity of date palm pollen is more of a cultivar-specific phenomenon than a species-specific phenomenon, which is governed by the number, quantities or both of the major allergen epitopes possessed by that variety or cultivar. Nevertheless, a number of common allergens are responsible for cross-reactivity

It has been later demonstrated that antigens and allergens of date fruits cross-react with date pollen allergens and date fruit-sensitive as well as date pollen-allergic patients' sera recognize the same group of date fruit IgE-binding components (Kwaasi et al 1999). Therefore, the cultivar issue is also tremendously important in selecting date cultivars for

The most relevant allergenic questions regarding this plant are brought together in the following web pages: http://intapp3.phadia.com/en/Allergen-information/ImmunoCAP-Allergens/Tree-Pollens/Allergens/Arizona-cypress-/ (Phadia), and http://www.allergome.

In brief: *Cupressaceae* pollen is characterized by a low protein concentration and high carbohydrate content. Allergens from the Arizona cypress tree have been isolated, characterized, and their diagnostic significance established (Penon 2000). They include Cup a 1, a 43-kDa protein, characterized as a pectate lyase (Di Felice et al1994; 2001; Afferni et al 1999; Aceituno et al 2000; Alisi et al 2001; Mistrello et al 2002; Iacovacci et al 2002; Arilla et al 2004), rCup a 1 (Aceituno et al 2000; Iacovacci et al 2002), Cup a 2, a polygalacturonase (Di Felice et al 2001; de Coana et al 2006), Cup a 3, a thaumatin-like protein (Cortegano et al 2004; Togawa et al 2006; Suarez-Cervera et al 2008) and Cup a 4, a calcium-binding protein (de Coana 2010). *C. arizonica* and *C. sempervirens* extracts are highly cross-reactive at the IgE level and have a number of common epitopes. Two major IgE-reactive components of approximately 43 kDa and 36 kDa have been shown to be present in both (Barletta et al 1996). *C. sempervirens* shows a wider diversity of allergens, whereas *C. arizonica* shows a higher content of the major 43 kDa allergen (Leduc et al 2000). Extensive cross-reactivity also occurs with other family members, which include *Juniperus oxycedrus*, *Chamaecyparis obtusa*

In general, species of the *Cupressaceae* family are a very important cause of allergies in various geographical areas, especially North America, Japan, and Mediterranean countries.

*dactylifera* pollen (Blanco et al 1995).

between the cultivars.

and *Thuja plicata*.

allergen standardization (Kwaasi et al 2000).

**4.2. Arizona cypress (***Cupressus arizonica* **L.)** 

org/ script/dettaglio.php?id\_molecule=1793 (Allergome).

The terms "cultivar" and "variety" are not equivalent. Although different, both terms are often used as synonyms: thus, "grape varieties" are habitually used in viticulture nomenclature to indicate what should be in reality cultivars, according to the International Code of Nomenclature for Cultivated Plants, since grapes are mostly propagated by cuttings. The same applies to "olive varieties", which should be properly named "olive cultivars". In both, and in many other cases, cuttings are the most frequently selected propagation method, as agronomical, physiological and anatomical properties are not maintained in a stable-manner under sexual reproduction. However, usage of the term variety is well fixed in both viticulture and oliviculture, therefore, a change to the correct term (cultivar) is unlikely to occur.

Finally, the term **cultigen** represents to a plant that has been deliberately altered or selected by humans. It is therefore the result of artificial (anthropogenic) selection. Their naming and origin can be very varied, as it is subjected to different rules and criteria (http://en.wikipedia.org/wiki/Cultigen).
