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Article

Effects of Different Shade Treatments on the Epidermal Wax Deposition of Hosta Genotypes with Different Glaucousness of Leaf Surface

by
Ping Guan
1,
Siyu Chen
1,2,
Jiaying Sun
1,2,
Shuyi Zhao
1,2,
Ren Fan
1,
Yufeng Xu
1,* and
Bo Qu
1,*
1
College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang 110866, China
2
College of Forestry, Shenyang Agricultural University, Shenyang 110866, China
*
Authors to whom correspondence should be addressed.
Horticulturae 2024, 10(9), 981; https://doi.org/10.3390/horticulturae10090981
Submission received: 4 July 2024 / Revised: 12 September 2024 / Accepted: 13 September 2024 / Published: 17 September 2024
(This article belongs to the Special Issue New Insights into Protected Horticulture Stress)
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Abstract

:
Epidermal wax is strategically situated at the interface between plants and air; therefore, it plays a key role in plants’ interactions with their surroundings. It is also unstable and susceptible to light intensity. Hosta plants are shade-loving herbs with admirable flowers and leaves. Hosta ‘Halcyon’ and Hosta ensata F. Maek. are two species of Hosta with a glaucous and a glossy appearance, respectively. Light intensity can affect the composition of epicuticular wax on the leaf surface, which influences the leaf color phenotype and ornamental value. In this paper, the crystal micromorphology, content, and components of epicuticular wax on the leaves of two species of Hosta under different light conditions (10%-, 30%-, 50%-, 70%-, and 100%-intensity sunlight, relative light intensity (RLI)) have been studied using pot experiments. The results indicate that the epicuticular wax crystals of H. ‘Halcyon’ and H. ensata are tubular and platelet-like, respectively. The wax crystals of H. ‘Halcyon’ melted and formed a thick crust under 100% RLI, and those of H. ensata melted and formed a thick crust under 70% and 100% RLI conditions. The primary ingredients of the epicuticular wax of the two species of Hosta contained primary alcohols, alkanes, fatty acids, and esters; β-diketones were only detected in H. ‘Halcyon’. The quantity of epicuticular wax of H. ‘Halcyon’ reduced at first and then increased with an RLI increase, achieving its lowest value at 50% RLI, but that of H. ensata declined little by little. The amounts of C28 primary alcohols, C31 alkanes, and C18 fatty acids were significantly higher than those of other carbon atoms in the two genotypes of Hosta. The C31β-diketones content decreased with the increase in light intensity, which caused the white frost phenotype to gradually weaken in H. ‘Halcyon’.

1. Introduction

In the course of the evolution from aquatic to terrestrial circumstances, land plants developed a cuticle to protect against environmental stress. The cuticle layer comprises a matrix of cutin polyester, which is saturated with intracuticular wax and coated with epicuticular wax [1]. The epicuticular waxes are strategically situated at the interface between plant and air; therefore, they play a key role in plants’ interactions with their environment, such as by preventing non-stomatal dehydration, reducing ultraviolet (UV) damage, reflecting strong sunlight, influencing the feeding of herbivorous insects, and resisting bacterial and fungal invasion [2,3,4,5,6,7]. The epicuticular waxes usually crystallize on the outermost part of the leaf epidermis, and the micromorphology can be divided into 26 types [8]. The epicuticular wax mixture is mainly composed of aliphatic components, including alkanes, aldehydes, ketones, alcohols, fatty acids, alkylacetic acid, etc. [9,10,11]. The chemical composition of epicuticular wax is directly related to its crystal morphology [12,13]. Primary alcohols mainly form platelet crystals, and more abundant secondary alcohols and diketones mainly form tube or rodlet crystals. Alkanes, on the other hand, do not form a clear crystal structure and, therefore, exhibit a smooth film under scanning electron microscopy [8]. The biosynthesis pathway of cuticular wax can be divided into the following three steps: the first step is the formation of C16 or C18 fatty acids from acetyl-CoA, catalyzed by fatty acid synthases; the second step is the formation of very long chain fatty acids from C16 or C18 fatty acids in the endoplasmic reticulum; and the third step is the synthesis of wax components, such as alkanes, primary alcohols, secondary alcohols, wax esters, ketones, etc., from long-chain fatty acids through two pathways (the decarbonylation pathway and the acyl reduction pathway).
The content, composition, and micromorphology of epicuticular wax change widely between genotypes and are affected by the plant growth period and environmental conditions such as heat, water, and light [14,15,16,17]. Some previous research results showed that a plant’s wax content and its capacity for drought tolerance were directly proportional. The wax content increased as the temperature increased. The change in temperature could induce the reorganization of the plant’s wax crystal structure. The crystal morphology was mostly horizontal, such as plate-shaped or flaky, in high temperatures; the wax morphology tended to be vertical, such as rod-shaped, tubular, etc., in low temperatures. Ultraviolet radiation can affect the epicuticular waxes of plants by changing the chemical composition and content. After UV-B irradiation, the epicuticular wax content in the leaves of cucumber and barley increased by 25%, and aldehydes increased two-fold [18]. Light intensity did not affect the deposition of the epicuticular wax on the leaf surface of Abutilon theophrasti Medicus, but the content of lipids decreased, and that of secondary alcohols increased with the increase in light intensity [19].
The epidermal waxes on the organs of some ornamental plants contribute to their ornamental value. The epicuticular wax crystals make the needles of Colorado blue spruce appear as an attractive grayish-blue color. The non-crystalline form of epicuticular wax can also make the leaves of Japanese cleyera shiny and charming [20]. Hosta genus (Asparagaceae) plants are perennial herbaceous flowers that thrive under shade environments. The leaves of Hosta ‘Halcyon’ have a white frost-like wax powder, but those of Hosta ensata F. Maek. do not.
Light, as an environmental factor, is crucial for the growth and development of plants. The leaf tissues of H. ensata were damaged by photooxidation when the relative light intensity (RLI) was higher than (and at) 70%, while photooxidative damage did not occur in the leaf tissues of H. ‘Halcyon’ under full sunlight conditions. At the same time, the frosty phenotype of H. ‘Halcyon’ gradually weakened or even disappeared with RLI increase [21,22,23]. It is speculated that light intensity changes the micromorphology and composition of epicuticular wax, which influences the leaf color phenotype and ornamental value. The differences in responses to light intensity may be related to plants’ waxy phenotypes. Knowledge of changes in epicuticular wax with light intensity may be vital to explain the response of plants to environmental factors. So far, studies on the responses of epicuticular wax to the environment have mainly focused on drought stress; the few studies published on plants’ responses to light conditions mainly concentrated on sun-loving plants. The aims of this current study were to provide detailed knowledge about the differences between H. ‘Halcyon’ (glaucous species) and H. ensata (glossy species) in terms of the changes in their epidermal wax properties including crystal micromorphology, content, and composition in response to different light intensities, to explore their potential wax biosynthesis pathways and their adaptive changes to light conditions, and to fill a gap in our knowledge about the responses of the epicuticular waxes of shade-loving plants to changing light conditions.

2. Materials and Methods

2.1. Plant Materials and Shading Treatments

The test was conducted at the Experimental Base of Shenyang Agricultural University. The climate of this region is part of the temperate semi-humid continental climate; the annual average temperature and precipitation are 8 °C and 600~800 mm, respectively. During May 2021, uniform sprouting seedlings of H. ‘Halcyon’ and H. ensata were selected and grown in flowerpots (diameter/height: 29 cm/26 cm). Each pot was filled with 7.0 kg of soil. The physicochemical properties of the soil were as follows: pH 7.05 ± 0.12, organic matter 1.96 ± 0.07 (g kg−1), total nitrogen 0.89 ± 0.05 (g kg−1), total phosphorus 0.45 ± 0.03 (g kg−1), total potassium 9.92 ± 0.16 (g kg−1), alkali hydrolyzable nitrogen 9.93 ± 0.24 (mg kg−1), available phosphorus 62.83 ± 1.84 (mg kg−1), and available potassium 50.35 ± 1.54 (mg kg−1). There were five shading treatments (10%, 30%, 50%, 70%, and 100% of sunlight, RLI) using black nets, and light intensities were checked using an illuminometer (Testo 540, Testo Instruments Co., Ltd., Shenzhen, China). The highest light intensities measured during the experiment were about 141, 446, 740, 1048, and 1485 μmol m−2 s−1, respectively. Three seedlings were cultivated in one pot, and each treatment had 5 replicates. The flowerpots were moved into a canopy on rainy days to avoid rainwater washing away the wax powder on the leaves. The crystal micromorphology and composition of epicuticular wax were determined after two months of shading treatment. The leaf samples were all mature leaves developed after shading.

2.2. Micromorphology of Epicuticular Wax Crystals by SEM

To examine the micromorphology of epidermal wax crystals using scanning electron microscopy (SEM), fresh leaf samples selected carefully from two genotypes of Hosta in different shade treatments were cut into small pieces of 5 mm × 5 mm, while avoiding touching them by hand or mechanically altering any of the samples. At first, fresh samples were fastened on a stub using a tissue freezing agent of TBS, frozen in slush nitrogen, and then stuck to the specimen holder of a Quorum PP3010T Cryo-transfer system (Hitachi Scientific Instruments Co., Ltd., Beijing, China) interfaced with a HITACHI regulus 8100 SEM (Hitachi, Shanghai Bahens Instrument Technology Co., Ltd., Shanghai, China). Next, the specimens were bent from the cryostage to the microscope sample stage. Finally, they were moved to the cryostage for gold plating. In the end, the specimens were returned to the microscope sample stage to be observed and photographed at an accelerating voltage of 15 keV by a cold field scanning electron microscope [24].

2.3. Total Epicuticular Wax Determination and Composition Analysis

Leaf samples were submerged in a beaker with 30 mL of GC-grade trichloromethane at an ordinary temperature and were taken out after 30 s. There were three replicates per light treatment. Then, 20 μL of C24 alkane as an internal standard was added to the extracting solution of the epicuticular wax. The extracts were mixed equally, filtered, evaporated, concentrated, and dried under a nitrogen stream successively. The dried residue was prepared for gas chromatography by derivatization with pyridine and BSTFA [N, O-bis (trimethylsilyl) trifluoroacetamide] for 1 h at 70 °C. After residual BSTFA was vapored under nitrogen, the samples were dissolved in chloroform for the analysis of epicuticular wax composition using a gas chromatograph mass spectrometer (GC-MS, QP-2020, Shimadzu Corporation, Japan) [25].
The figures of all experimental data were drawn using Microsoft Office Excel 2010. A single-factor ANOVA was used with SPSS 22.0, and significant differences were evaluated with Duncan’s test.

3. Results

3.1. The Micromorphology of Epicuticular Wax Crystals in Different Shade Treatments

As shown in Figure 1, the adaxial and abaxial leaf surfaces of H. ‘Halcyon’ were coated with dense tubular crystals, the abundance of which declined gradually with the increase in light intensity. The wax crystals on the adaxial and abaxial leaf surfaces presented a thick crust under 100% RLI, which was more obvious in the abaxial than the adaxial. Unlike H. ‘Halcyon’, the abaxial and adaxial leaf surfaces of H. ensata were covered with platelet crystals, the abundance of which also declined gradually with the increase in light intensity. The wax crystals presented a thick crust under 70% RLI on the adaxial surface and 100% RLI on the adaxial and abaxial surfaces. Meanwhile, it was observed that wax crystals on the leaf surfaces of H. ‘Halcyon’ were denser than those on the leaf surface of H. ensata.

3.2. Effect of Different Shade Treatments on the Chemical Composition and the Content of Epidermal Wax

As shown in Table 1, the epicuticular wax content on the leaf surface of H. ‘Halcyon’ reduced gradually and reached the lowest level under 50% RLI and then rose with the increase in light intensity. The epicuticular wax components of H. ‘Halcyon’ contained β-diketones, alkanes, primary alcohols, free fatty acids, and aliphatic esters. β-diketones were the major compounds for the ratios of 49.53%, 42.77%, and 43.08% under 10~50% RLI, respectively, and β-diketones decreased to 21.04% and 12.94% under 70~100% RLI, respectively. The amount of β-diketones decreased from 47.1 mg·dm−2 to 9.1 mg·dm−2 with the increase in light intensity; there were significant differences between different RLIs (p < 0.05). The amount of primary alcohols decreased at first and then increased, reaching the minimum value of 10.3 mg·dm−2 at 50% RLI. The amount of alkanes showed the same trend as primary alcohols and reached the minimum value of 5.6 mg·dm−2 and the maximum value of 16.2 mg·dm−2 at 50% and 100% RLI, respectively. Compared with H. ‘Halcyon’, β-diketones were not checked in the epidermal wax mixture on the leaf of H. ensata. Primary alcohols were the principal wax constitutions, followed by alkanes, and free fatty acids were less present. The amounts of alkanes, primary alcohols, and free fatty acids declined gradually with the increase in light intensity.

3.3. The Carbon Chain Length of Epicuticular Wax under Different Light Intensities

The primary alcohols of the epidermal wax constitution on the leaves of two species of Hosta were composed of a homologous series with even numbers of carbon atoms from C22 to C30, and the amount of C28 primary alcohols was significantly higher than that of other carbon atoms under different RLI conditions (p < 0.05). Moreover, most carbon atoms of primary alcohols on the leaf of H. ensata declined gradually with the increase in light intensity, which in H. ‘Halcyon’ showed the trend of reducing at first and then increasing with an RLI increase, achieving the lowest level at 70% RLI (Figure 2A). The alkanes of epidermal wax on the leaves of two species of Hosta were composed of a homologous series with odd numbers of carbon atoms from C23 to C31, and the C31 alkanes were the dominant wax compounds and were significantly higher than those of other carbon atoms (p < 0.05). The amount of C31 alkanes on the leaf surface of H. ensata declined gradually with the increase in light intensity, but those of H. ‘Halcyon’ showed the tendency to reduce at first and then enhance with an RLI increase, reaching the lowest level at 50% RLI (Figure 2B). The fatty acids contained carbon atoms of C16 and C18, and the C18 fatty acids were dominant under different RLI conditions (Figure 2C). The epicuticular waxes on the leaf surface of H. ‘Halcyon’ included large amounts of β-diketones identified as the carbon atoms of C31, which decreased gradually with the increase in light intensity and were not detected on the leaf surface of H. ensata (Figure 2D).

4. Discussion

Light, as a major environmental factor, influences plant survival and growth. The relationship between plants and light has always been a core component of the fields of plant physiological and ecological research [26,27]. Epicuticular waxes coated at the outermost layer of the epidermis play a significant role in plant adaptation to light conditions [28,29,30]. Barthlott et al. observed 13,000 epidermis samples belonging to different plant species through scanning electron microscopy and classified the micromorphology of wax into 26 types: filament, rodlet, platelet, tubular, and chimney, etc. Platelet and tubular were the most important types of wax crystal [8]. There are differences in the morphology of wax crystals on the leaf surfaces of different plant species. Moreover, the morphology of wax crystals varies with changes in environmental conditions. The abundance of tubular epidermal wax crystals on the adaxial leaf surface of Tragopogon pratensis L. reduced with the increase in light intensity [31]. Under UV-B stress, the wax content of Arabidopsis increased significantly; the wax crystals changed from rodlet to parallel flake, which could increase the coverage area of epicuticular wax for reducing transpiration and increasing leaf reflectance [32]. The wax crystals of the adaxial and abaxial of H. ‘Halcyon’ were tubular and very densely distributed, while those of H. ensata were platelet-like, and the distribution was sparse. With the increase in light intensity, the crystals of the epidermal wax of two species of Hosta gradually changed from dense to thin and melted to form crusts and fissured layers under high light intensity conditions. It is speculated that this is for the purpose of reducing transpiration and increasing reflectance. This plasticity of the micromorphology of the leaf epidermis is considered to be an acclimation of plants to light conditions.
Epicuticular wax morphology is related to the content and the composition of wax. The wax crystal morphology of plants with a higher wax content is usually tubular or plate-like, while that of plants with a lower wax content is smooth. Wax layers mainly composed of primary alcohols were more prone to forming flake crystals, while the waxy layers dominated by β-diketones were more prone to forming tubular crystals [8,33,34]. The wax crystal morphology of H. ‘Halcyon’ was tubular due to the large amount of β-diketones. The amount of β-diketones declined gradually with the increase in light intensity, which was consistent with the phenotype of gradually thinning crystals. The wax crystal morphology of H. ensata was platelet-like, which was closely related to the components of alkanes and primary alcohol.
Light intensity affects the accumulation of epidermal wax on the leaves of plants. Enhanced UV-B radiation improved epidermal wax deposition on the leaf [8,20,35,36]. Sunny leaves had higher wax accumulation to cope with UV-B radiation [37]. High light intensity promoted the epidermal wax accumulation on the leaf surfaces of green gram, soybean, canola (Brassica napus L.), and Tilia platyphyllos Scop. [38,39,40]. These studies indicated that epicuticular wax content on the plant epidermis increased with the increase in light intensity, probably with the aim of reducing the damage to leaf tissues caused by strong light. In the present research, with increasing RLI, the epidermal wax content of H. ensata declined progressively; that of H. ‘Halcyon’ reduced at first and achieved the lowest value at 50% RLI and then rose, which was not consistent with previous studies finding that the epicuticular wax content increased with increasing light intensity. Until now, the research on the response of plant epidermal wax to light intensity has principally concentrated on sun-loving plants. In contrast, Hosta are shade-loving plants and Pn reached its maximum value at 50% RLI [21,22]. When light intensity was more than 50% RLI, the content of epidermal wax on the leaf surface of H. ‘Halcyon’ increased progressively, which seemed to afford enough photoprotection in the leaves. On the contrary, epicuticular wax content on the leaf of H. ensata decreased gradually with the increase in light intensity and developed tissue necrosis, which was probably owing to light-induced photooxidative damage. The changes in the epicuticular wax content were related to the acclimation ability of the light environment and the allocation of energy and resources in the plants [41,42].
Plants have evolved complex physical and chemical defense strategies in response to the damage caused by herbivorous insects [43,44]. Epicuticular wax is considered an important physical barrier affecting herbivorous insects’ attachment, feeding, and oviposition and reducing the invasion of plant tissues by pathogens [45,46,47]. Hosta plants like to grow in humid and low-light environments, where their leaves are susceptible to damage from fungi (which commonly cause diseases such as anthrax disease, leaf mold spot disease, black spot disease, and white silk disease), slugs, nematodes, and foliar feeding insects [48,49,50]. The increase of epidermal wax on the leaf of Hosta in spring was supposed to enhance its protection against biotic and abiotic stress, such as by reducing damage from foliar-feeding insects [25]. So, it was speculated that the epicuticular wax content of Hosta increased under low light conditions for the purpose of reducing the damage caused by herbivorous insects and invasion by pathogens.
The main components of epicuticular wax on the surface of higher plants vary with plant species, varieties, organs, and even environmental conditions [51,52]. UV-B radiation led to a change of wax constitution on the leaf surface of pea lines from alcohols to esters and hydrocarbons [53]. UV-B irradiation increased the content of alkanes in all studied plants; the content of primary alcohols and esters in beans and barley leaves had been influenced by enhanced UV-B radiation, but that in cucumber leaves had not, indicating that different plants had different responses to environmental stress [18]. The enhanced light intensity increased the content of secondary alcohols on the leaf surface and reduced the content of the esters [19]. The composition of epicuticular wax on the leaf surface of Tilia platyphyllos had a substantial increase of very long-chain n-alkanes and a sharp decrease of the fatty acid under illumination conditions [40]. A similar result has been stated by Gonzalez et al. for the alkyl ester composition of pea wax, as well as by Steinmüller and Tevini for the alkane composition of cucumber leaf wax [18,53]. Under high light conditions, plants tend to synthesize more decarbonylation pathway products [54]. Wax chemical composition has been shown to be altered by enhanced UV-B in varieties of crops such as beans, tobacco, cucumber, peas, and barley [55]. The chemical composition of the epicuticular wax of H. ‘Halcyon’ is dominated by β-diketones, alkanes, primary alcohols, and fatty acids; that of H. ensata is dominated by alkanes, primary alcohols, and fatty acids. β-diketones were not detected in H. ensata. The compound of aldehydes and secondary alcohols were not found in the components of epicuticular wax on the leaf surface of Hosta. This result was consistent with Jenks’ report [25], and was also in line with their crystal phenotypes. With the increase in light intensity, the β-diketones content of H. ‘Halcyon’ reduced significantly; the amounts of alkanes and primary alcohols decreased at first and then increased gradually. However, the amounts of alkanes and primary alcohols of H. ensata decreased gradually. Two major branches of the wax synthesis pathway are currently hypothesized, one of which is called the decarbonylation pathway, producing alkanes and aldehydes, and another is called the acyl reduction pathway, producing primary alcohols and esters. Both the decarbonylation pathway and the acyl reduction pathway were equal in H. ‘Halcyon’, but the acyl reduction pathway was the major one in H. ensata. Light intensity affected the synthesis of the epicuticular wax of Hosta.
The epicuticular waxes on the leaf surface of plants are mainly composed of very long-chain fatty acids (VLCFAs, C20~C36). The carbon chains of primary alcohol are mainly concentrated between C20 and C36 with even numbers of carbon atoms, and C24~C30 primary alcohols are dominant. Alkanes are mainly distributed from C21 to C35 with odd numbers of carbon atoms, and alkanes C27~C33 are dominant. The carbon atom numbers of fatty acids are lower, and their distributions range from C12 to C20; C16 and C18 fatty acids are dominant [56,57,58,59]. In the current study, the primary alcohols of two genotypes of Hosta dominated with even-numbered carbon atoms of C22~C32 under different light intensities, and primary alcohol C28 was the major component. The alkanes were composed of C23~C31 odd-numbered carbon atoms, with alkane C31 as the main composition. The carbon atoms of fatty acids were mainly distributed from C16 to C18, and C18 fatty acid dominated. The results were consistent with the previous studies of Jenks et al. [25]. Fukuda et al. found that the quantities of alkanes and primary alcohols increased more than two-fold after the exposure of cotyledons to a medium level of UV-B; the amount of shorter alkyl chain lengths of alkanes and primary alcohols increased, and their longer alkyl chain lengths reduced. The homologs for the alkane and primary alcohol transformed to longer alkyl chain lengths in the control during the course of growth [60]. UV-B irradiation suppressed these shifts, indicating that UV-B had effects on epicuticular wax biosynthetic pathways. However, Mohammadian et al. found that there was no difference in wax deposition and wax chain length between the shade leaves and sun leaves [61]. In the present research, the C32 chain length of primary alcohol was not detected under 100% sunlight conditions; thus, it was speculated that strong sunlight suppressed the pathway leading to the extension of the C30 carbon chain.

5. Conclusions

H. ‘Halcyon’ and H. ensata are two species of Hosta differing in the white frost wax phenotype of their leaves. The epidermal wax crystals of H. ‘Halcyon’ were tubular and very densely distributed, while those of H. ensata were platelet-like and very sparsely distributed. With the increase in light intensity, the epidermal wax crystals of two genotypes of Hosta gradually transformed from dense to thin and changed from rodlet to parallel flake under strong light conditions. With the increase in light intensity, the epidermal wax content of H. ‘Halcyon’ reduced at first and then increased, but that of H. ensata reduced. The main components of the epicuticular wax include primary alcohols, alkanes, fatty acids, and esters. β-diketones were only detected in H. ‘Halcyon’. Strong sunlight blocked the extension of the C30 carbon chain. The content of β-diketones declined under strong light conditions, which caused the white frost phenotype to weaken.

Author Contributions

Writing—original draft, P.G.; Data curation, Formal analysis, S.C.; Software, Validation, J.S.; Conceptualization, Investigation, S.Z.; Investigation, Methodology, R.F.; Funding acquisition, Writing—original draft, Writing—review & editing, Supervision, Y.X.; Writing—review & editing, B.Q. All authors have read and agreed to the published version of the manuscript.

Funding

This work received fund support from the Project of Liaoning Provincial Department of Education (No. JYTMS20231275).

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding authors.

Conflicts of Interest

The authors declare no conflicts of interest.

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Horticulturae 10 00981 g001aHorticulturae 10 00981 g001b
Figure 1. Effects of light intensity on the micromorphology of the epicuticular wax crystals on the leaf surfaces. (A) H. ‘Halcyon’; (B) H. ensata.
Figure 1. Effects of light intensity on the micromorphology of the epicuticular wax crystals on the leaf surfaces. (A) H. ‘Halcyon’; (B) H. ensata.
Horticulturae 10 00981 g001aHorticulturae 10 00981 g001b
Horticulturae 10 00981 g002aHorticulturae 10 00981 g002b
Figure 2. Effect of light intensity on the amount of epicuticular waxes in each wax class of two genotypes of Hosta. (A) Primary alcohol; (B) alkanes; (C) fatty acids; (D) diketones. Note: Data are mean ± SD (n = 3). Different letters (a–e) stand for obvious differences between the shade treatments at the level of p < 0.05. Different letters with an apostrophe (a′–e′) stand for obvious differences between the carbon chain lengths at the level of p < 0.05.
Figure 2. Effect of light intensity on the amount of epicuticular waxes in each wax class of two genotypes of Hosta. (A) Primary alcohol; (B) alkanes; (C) fatty acids; (D) diketones. Note: Data are mean ± SD (n = 3). Different letters (a–e) stand for obvious differences between the shade treatments at the level of p < 0.05. Different letters with an apostrophe (a′–e′) stand for obvious differences between the carbon chain lengths at the level of p < 0.05.
Horticulturae 10 00981 g002aHorticulturae 10 00981 g002b
Table 1. Effect of RLI on the epicuticular wax composition of two species of Hosta (mg·dm−2).
Table 1. Effect of RLI on the epicuticular wax composition of two species of Hosta (mg·dm−2).
Hosta
Genotype		RLIAlkanesPrimary
Alcohols		Fatty Acidsβ-DiketonesAliphatic
Esters		UnknownsTotal
Content
10%14.5 ± 0.6 b25.4 ± 1.0 a3.1 ± 0.1 b47.1 ± 1.8 a1.0 ± 0.0 b4.0 ± 0.2 c95.1 ± 3.6 a
H. ‘Halcyon’30%9.1 ± 0.7 d19.6 ± 1.6 c4.7 ± 0.4 a29.0 ± 2.3 b1.5 ± 0.01 a3.8 ± 0.3 c67.8 ± 5.4 b
50%5.6 ± 0.6 e10.3 ± 1.2 d4.6 ± 0.5 a16.5 ± 1.9 c0.1 ± 0.00 c1.3 ± 0.2 d38.3 ± 4.7 c
70%10.3 ± 0.1 c11.2 ± 0.1 d1.9 ± 0.0 c9.3 ± 0.1 d0.9 ± 0.0 b10.6 ± 0.1 b44.2 ± 0.4 c
100%16.2 ± 0.1 a22.5 ± 0.2 b4.3 ± 0.0 a9.1 ± 0.1 d1.4 ± 0.0 a16.3 ± 0.1 a70.3 ± 0.6 b
10%10.1 ± 0.0 a30.5 ± 0.1 a3.4 ± 0.0 and0.9 ± 0.0 b5.2 ± 0.0 b50.1 ± 0.1 a
H. ensata30%10.2 ± 0.4 a21.3 ± 0.7 b3.3 ± 0.1 and01.1 ± 0.0 a3.1 ± 0.1 c39.0 ± 1.4 b
50%10.4 ± 01.8 a14.1 ± 2.4 c2.7 ± 0.5 bnd0.8 ± 0.1 c10.5 ± 1.7 a38.4 ± 6.5 bc
70%6.3 ± 1.2 b14.1 ± 1.6 c1.2 ± 0.1 cnd0.6 ± 0.1 d9.7 ± 0.9 a32.0 ± 3.9 c
100%4.8 ± 0.1 b8.9 ± 0.3 d1.2 ± 0.0 cnd0.2 ± 0.0 e5.7 ± 0.1 b20.8 ± 3.4 d
Note: Data are mean ± SD (n = 3). Different letters stands for obvious differences between the treatments at the level of p < 0.05. nd—Not detected.
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Guan, P.; Chen, S.; Sun, J.; Zhao, S.; Fan, R.; Xu, Y.; Qu, B. Effects of Different Shade Treatments on the Epidermal Wax Deposition of Hosta Genotypes with Different Glaucousness of Leaf Surface. Horticulturae 2024, 10, 981. https://doi.org/10.3390/horticulturae10090981

AMA Style

Guan P, Chen S, Sun J, Zhao S, Fan R, Xu Y, Qu B. Effects of Different Shade Treatments on the Epidermal Wax Deposition of Hosta Genotypes with Different Glaucousness of Leaf Surface. Horticulturae. 2024; 10(9):981. https://doi.org/10.3390/horticulturae10090981

Chicago/Turabian Style

Guan, Ping, Siyu Chen, Jiaying Sun, Shuyi Zhao, Ren Fan, Yufeng Xu, and Bo Qu. 2024. "Effects of Different Shade Treatments on the Epidermal Wax Deposition of Hosta Genotypes with Different Glaucousness of Leaf Surface" Horticulturae 10, no. 9: 981. https://doi.org/10.3390/horticulturae10090981

APA Style

Guan, P., Chen, S., Sun, J., Zhao, S., Fan, R., Xu, Y., & Qu, B. (2024). Effects of Different Shade Treatments on the Epidermal Wax Deposition of Hosta Genotypes with Different Glaucousness of Leaf Surface. Horticulturae, 10(9), 981. https://doi.org/10.3390/horticulturae10090981

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