Journal of Species Research 4(2):159­168, 2015 Morphological characteristics of major airborne pollen in Korea peninsula Hye­Kyoung Moon1, Min­Jung Kong1, Jun­Ho Song1, Sun­Yu Kim2, Jin­Suk Kim2, Eun­Hee Jung2, Chan­Ho Park2, Byoung­Yoon Lee2 and Suk­Pyo Hong1,* 1Laboratory of Plant Systematics, Department of Biology and Institute of Basic Sciences, Kyung Hee University, Seoul 130-701, Korea 2National Institute of Biological Resources, Plant Resources Division 42 Nanji-ro, Seo-gu, Incheon 404-708, Korea *Correspondent: [email protected] Although airborne pollen is invisible to the eye, it has been known as a major source to respiratory aller­ gic reactions. For this reason, airborne pollen is monitoring in many countries to predict pollen concentra­ tion based on locality and season. However, the morphological characteristics of airborne pollen and their potential tendency as an allergen are still obscure. In the present study, we selected 52 airborne pollen sam­ ples based on previously reported data and investigated their detail pollen characteristics using LM and SEM. Major airborne pollen in Korea has sorted in 19 families (most angiosperms except four gymno sperm families), and all pollen grains are small to medium in size (P=17.34 ­ 49.86 μm) apart from the bisac cate pollen grains of Pinaceae (P=46.49­106.20 μm). The aperture number and shape vary from sulcate to poly­ porate. While the inaperture pollen has found only in gymnosperm (Cupressaceae and Taxaceae), triporate or polyporate is common pollen type in angiosperm. The sexine ornamentations could divide into several types, but the most sculpturing types are inconspicuous like psilate, rugulate and granulate. Reticulate pol­ len grains as a semitectum have occurred the species of genera Platanus and Fraxinus only. To estimate the possible relationships between pollen features and allergen, the results are discussed in botanical context. Keywords: airborne pollen, botany, morphological features Ⓒ 2015 National Institute of Biological Resources DOI:10.12651/JSR.2015.4.2.159 among the countries. Certain plants groups like genera INTRODUCTION Alnus, Ambrosia, Artemisia, Betula, Humulus, Pinus, and Quercus are well known as airborne pollen in the Airborne pollen has been assessed as the subject of al­ world (Anderson et al., 1978; Mardones et al., 2013). lergy research over the past two decades (Raynor et al., However, Olea europaea is one of the main causes of 1976; Anderson et al., 1978; Irani et al., 2013; Mardones allergy in Mediterranean countries and some areas of et al., 2013). Since the pollinosis has become serious al­ North America (Bousquet et al., 1985; Wheller, 1992) lergic disease, most studies about airborne pollen have and Cryptomeria japonica is the most popular pollinosis been accomplished for the clinical reason. Thus, many in Japan (Wang et al., 2013). Thus, the constant research researches were carried out to monitor and count the air­ of airborne pollen is necessary at the regional range (Puc borne pollen to predict pollen concentration exactly (Jung and Kasprzyk, 2013; Velasco­Jiménez et al., 2013). In and Choi, 2013; Velasco­Jiménez et al., 2013). However, Korea major airborne pollen was captured from 20 to the pollen concentrations are not always related with al­ 30 plants group, in which Pinus, Quercus and Humulus lergen reaction, furthermore the pollinosis is not the spe­ showed high pollen concentration (Oh and Lee, 1997; cies specific response. For example, the pollen grains Oh et al., 2006; Jung and Choi, 2013). In particular, the of Pinus group have rather lower allergenicity in Korea weed plants like Ambrosia and Humulus are focused albeit to high concentration during spring time (Oh and as severe airborne pollen since the patients at autumn Lee, 1997). gradually increased from the year 2,000 in Korea (Oh et In fact, the pollinosis is affected by various biotic and al., 2009). Since the airborne pollen has been observed abiotic factor and the major pollinosis plants are different mainly by light microscope, the identification of plants 160 JOURNAL OF SPECIES RESEARCH Vol. 4, No. 2 is rather restricted at higher plants group. Thus, we carry Table 1. The character states of main pollinosis plants accord­ out the detail palynological study based on common air­ ing to their growth form in Korea. ­ The numbers are not exactly matched with species by overlapping counts. borne pollen in Korea to provide the pollen characteris­ tics of airborne pollen which may help to identify plants Gymnosperm Angiosperm at species level, and to figure out the possible link bet­ 12 spp 28 spp (tree) 12 spp (herb) ween morphological features and allergen. Floral sexuality: Hermaphrodite 0 3 5 Unisexual 12 27 7 MATERIALS AND METHODS Sexual system: Cosexual 10 25 9 To observe morphological characteristics of airborne Dioecious 3 4 3 pollen in Korea, we selected 52 species of 35 genera from Anthersis time: 19 families based on previously reported data (Table 2; March­May 11 28 0 Oh et al., 2006; Mardones et al., 2013). Most materials June­August 0 0 10 were taken from the dried specimen from the following September­November 1 0 6 herbaria: KB, KH, and KHUS (acronyms follow Thiers, Pollination type 2011), and some plants were collected in natural popula­ Abiotic (wind) 12 27 12 tions of Korea by the authors. For pollen measurements Biotic (insect) 0 1 0 (polar axis=P, equatorial diameter=E), all materials were prepared by standard acetolysis method (Erdtman, 1960). The permanent glycerin jelly slides were observed (Table 1). All pollen grains were dispersed as monad under light microscopy (LM, BX41 Laboratory Micro­ and the pollen size varied from small to large (P=17.34­ scope, Olympus, Melville, USA) and measured the pol­ 106.20 μm; Walker and Doyle, 1975) with peroblate to len size like polar axis, equatorial diameter, and aperture prolate shape (P/E ratio=0.38­1.70). Reasonably, the length using captured images with ×400 or ×1,000 mag­ pollen characteristics could be analyzed according to nifications by a digital camera for microscopes (MDX­ their classification. So, here we described detail pollen 30, Shinwoo Optics, Anyang, Korea) and the image ana­ morphological features with following plants categories: lysis software (I­Works Lite, Saramsoft, Anyang, Korea). gymnosperm and angiosperm. For scanning electron microscopic observation, some acetolysed pollen grains were suspended in ethanol, air Gymnosperm dried on a stub and coated with plati num prior to obser­ In total, 12 species are belong to the gymnosperm. All vation with a field emission scanning electron micro­ species are trees and wind pollinated (Table 1). The com­ scope (FE­SEM, S­4700, Hitachi Ltd., To kyo, Japan) at mon sexual system within gymnosperm is monoecy ex­ an accelerating voltage of 10 kV with 10­13 mm work­ cept dioecious plants of Ginkgo, Juniperus, and Taxus. ing distance. The fragile pollen like gymnosperm group The pollen size varied from small to large (P=22.78­ was prepared with critical point­dried technique to ob­ 106.20 μm) with peroblate to prolate shape (P/E ratio= serve natural shape and ornamentation of pollen using 0.38­1.27). Ginkgo biloba is easy to recognize with boat FE­SEM (Moon et al., 2008; see also Table 1). For cri­ shape and sulcate pollen grains, the family Pinaceae tical point­dried, the collected anthers were rehydrated are distinct from other taxa by having bisaccate pollen with Agepon® (Agfa Gevaert, Leverkusen, Germ any; grains. In fact, the pollen size of gymnosperm other than Agepon wetting agent : distilled water, 1 : 200) before Pinaceae could be interpreted as small to medium (P= dehydrated through an acetone series (in 50%, 70%, 90%, 22.78­38.55 μm). Juniperus chinensis has ulcerate pollen and absolute acetone 30 min in each solution). The com­ grains while other taxa of Cupressaceae have inaperture pletely dehydrated materials were dried with carbon di­ pollen grains (Table 2). The pollen surface ornamenta­ oxide (SPI­13200J­AB) and observed using FE­SEM tion was unnoted but additional projection on the surface after following same steps which described above. could be defined as granulate, verrucate, gemmate, and The pollen terminology follows the online edition of papillate (Fig. 1). the Glossary of Pollen and Spore Terminology (Punt et al., 2007). Angiosperm Dicotyledon: Most airborne pollens (37 taxa, 21 gen­ RESULTS era of 12 families) are included and their major sexual system is monoecious (Table 1). Andromonoecy (male In total 52 taxa out of 19 families were investigated and hermaphrodite flowers in same individual) found August 2015 Table 2. Overview of morphological characteristics of major airborne pollen in Korea. Scientific name Polar axis Equatorial diameter P/E ratio Aperture Surface ornamentation Voucher information Gymnosperms Ginkgoales: Ginkgoaceae Ginkgo biloba L. 22.78±1.74 42.69±4.15 0.45­0.67 sulcate psilate Hong & Oh, HOH980414 (KHUS) Pinales: Cupressaceae Cryptomeria japonica (Thunb. ex 38.55±2.55 35.27±2.78 0.97­1.27 inaperture papillate Yang & Kim, KKS100003 (KH) L.f.) D.Don Juniperus chinensis L. 31.60±3.42 30.87±3.21 0.90­1.16 ulcerate granulate Yang & Kim, KKS100032 (KH) Metasequoia glyptostroboides 26.51±1.49 36.03±1.92 0.95­1.14 inaperture granulate Yang & Kim, KKS100007 (KH) M Hu & W.C.Cheng OON Taxodium dicstichum (L.) Rich. 27.17±2.28 27.76±2.57 0.94­1.07 inaperture psilate Yang & Kim, KKS100025 (KH) E Platycladus orientailis (L.) 30.49±1.80 29.54±1.54 0.93­1.16 inaperture granulate­psilate­perforate Yang & Kim, KKS10017 (KH) T Franco AL . ­ Pinales: Pinaceae M Cedrus deodara (Roxb.) G.Don 46.49±8.32 64.40±7.45 0.62­0.82 leptoma rugulate Nam et al., SHY2-1854 (KB) ORPHOLOGY Picea abies (L.) H.Karst.