BrrTCP4b interacts with BrrTTG1 to suppress the development of trichomes in Brassica rapa var. rapa

The number of trichomes significantly increased in CRISPR/Cas9-edited BrrTCP4b turnip(Brassica rapa var.rapa)plants.However,the underlying molecular mechanism remains to be uncovered.In this study,we performed the Y2H screen using BrrTCP4b as the bait,which unveiled an interaction between BrrTCP4b and BrrTTG1,a pivotal WD40-repeat protein transcription factor in the MYB-bHLH-WD40(MBW)complex.This physical interaction was further validated through bimolecular luciferase complementation and co-immunoprecipitation.Furthermore,it was found that the interaction between BrrTCP4b and BrrTTG1 could inhibit the activity of MBW complex,resulting in decreased expression of BrrGL2,a positive regulator of trichomes development.In contrast,AtTCP4 is known to regulate trichomes development by interacting with AtGL3 in Arabidopsis thaliana.Overall,this study revealed that BrrTCP4b is involved in trichome development by interacting with BrrTTG1 in turnip,indicating a divergence from the mechanisms observed in model plant A.thaliana.The findings contribute to our understanding of the regulatory mechanisms governing trichome development in the non-model plants turnip.

Less hairy leaf 1,an RNaseH-like protein,regulates trichome formation in rice through auxin

The trichomes of rice leaves are formed by the differentiation and development of epidermal cells.Plant trichomes play an important role in stress resistance and protection against direct ultraviolet irradiation.However,the development of rice trichomes remains poorly understood.In this study,we conducted ethylmethane sulfonate(EMS)-mediated mutagenesis on the wild-type(WT)indica rice‘Xida 1B’.Phenotypic analysis led to the screening of a mutant that is defective in trichome development,designated lhl1(less hairy leaf 1).We performed map-based cloning and localized the mutated gene to the 70-kb interval between the molecular markers V-9 and V-10 on chromosome 2.The locus LOC_Os02g25230 was identified as the candidate gene by sequencing.We constructed RNA interference(LHL1-RNAi)and overexpression lines(LHL1-OE)to verity the candidate gene.The leaves of the LHL1-RNAi lines showed the same trichome developmental defects as the lhl1 mutant,whereas the trichome morphology on the leaf surface of the LHL1-OE lines was similar to that of the WT,although the number of trichomes was significantly higher.Quantitative real-time PCR(RT-qPCR)analysis revealed that the expression levels of auxin-related genes and positive regulators of trichome development in the lhl1 mutant were down-regulated compared with the WT.Hormone response analysis revealed that LHL1 expression was affected by auxin.The results indicate that the influence of LHL1 on trichome development in rice leaves may be associated with an auxin pathway.

OsSPL10 controls trichome development by interacting with OsWOX3B at both transcription and protein levels in rice(Oryza sativa L.)

Plant trichomes are a specialized cellular tissue that functions in resistance to biotic and abiotic stresses.In rice,three transcription-factor genes:OsWOX3B,HL6,and OsSPL10,have been found to control trichome development.Although studies have shown interactions between the three genes,their full relationship in trichome development is unclear.We found that the expression levels of OsWOX3B and HL6 were both reduced in OsSPL10-knockout plants but increased in OsSPL10-overexpression plants,suggesting that OsSPL10 positively regulates their expression.Physical interaction between OsSPL10 and OsWOX3B was found both in vivo and in vitro and attenuated their abilities to bind to the promoter of HL6 to activate its transcription.This mechanism may regulate trichome length by adjusting the expression of HL6.A rice gene network regulating trichome development is proposed.

Protective and defensive roles of non-glandular trichomes against multiple stresses:structure-function coordination

As superficial structures,non-glandular trichomes,protect plant organs against multiple biotic and abiotic stresses.The protective and defensive roles of these epidermal appendages are crucial to developing organs and can be attributed to the excellent combination of suitable structural traits and chemical reinforcement in the form of phenolic compounds,primarily fl avonoids.Both the formation of trichomes and the accumulation of phenolics are interrelated at the molecular level.During the early stages of development,non-glandular trichomes show strong morphological similarities to glandular ones such as the balloon-like apical cells with numerous phenolics.At later developmental stages,and during secondary wall thickening,phenolics are transferred to the cell walls of the trichomes.Due to the diff use deposition of phenolics in the cell walls,trichomes provide protection against UV-B radiation by behaving as optical fi lters,screening out wavelengths that could damage sensitive tissues.Protection from strong visible radiation is also aff orded by increased surface light refl ectance.Moreover,the mixtures of trichome phenolics represent a superfi-cial chemical barrier that provides protection against biotic stress factors such as herbivores and pathogens.Although the cells of some trichomes die at maturity,they can modulate their quantitative and qualitative characteristics during development,depending on the prevailing conditions of the external biotic or abiotic environment.In fact,the structure and chemical constituents of trichomes may change due to the particular light regime,herbivore damage,wounding,water stress,salinity and the presence of heavy metals.Hence,trichomes represent dynamic protective structures that may greatly aff ect the outcome of many plant–environment interactions.

Disruption of the 1-deoxy-D-xylulose-5-phosphate reductoisomerase （DXR） gene results in albino, dwarf and defects in trichome initiation and stomata closure in Arabidopsis

1-Deoxy-D-xylulose-5-phosphate reductoisomerase (DXR ) 是涉及 2-C-methyl-D-erythritol-4-phosphate (MEP ) 的重要的酶为 isoprenoid 生合成提供基本五碳的单位的小径。在植物开发和新陈代谢调查 MEP 小径的角色，我们在 dxr 异种(GK_215C01 ) 和二根 DXR 转基因的合作抑制线上执行了详细分析， OX-DXR-L2 和 OX-DXR-L7。我们发现 dxr 异种是白化体和矮子。它从来没跑，显著地减少了毛状体的数字，大多数 stomata 不能在叶子通常关门。二根合作抑制线没有毛状体生产了更黄的开花期和白化体萼片。涉及毛状体开始的基因的抄写层次被发现强烈被假装，包括 GLABRA1，透明种皮光洁 1， TRIPTYCHON 并且细长纤弱，哪个被 gibberellic 酸(气体) 调整的表示。而 abscisic 酸(骆驼毛的织物) 的外长的申请能救 stomata 闭合缺点， GA3 的外长的申请能部分救矮子显型和 dxr 的毛状体开始，建议 GA 和骆驼毛的织物的底层贡献在 dxr 异种的显型。我们进一步发现涉及 GA 和骆驼毛的织物的 biosynthetic 小径的基因并列地被调整。这些结果显示 plastidial MEP 小径的那混乱导致光合的颜料，气体和骆驼毛的织物的 biosynthetic 缺乏，并且这样发展畸形，并且从细胞质的 mevalonate 小径的流动不是足够的救缺乏，这由 plastidial MEP 小径的阻塞引起了。这些结果在控制 isoprenoids 的生合成为 MEP biosynthetic 小径揭示一个关键角色。

Up-regulation of a homeodomain-leucine zipper gene HD-1 contributes to trichome initiation and development in cotton

Plant trichomes originate from epidermal cells.In this work,we demonstrated that a homeodomain-leucine zipper(HD-Zip)gene,Gh_A06G1283(Gh HD-1A),was related to the leaf trichome trait in allotetraploid cotton and could be a candidate gene for the T_1 locus.The ortholog of GhHD-1A in the hairless accession Gossypium barbadense cv.Hai7124 was interrupted by a long terminal repeat(LTR)retrotransposon,while GhHD-1A worked well in the hairy accession Gossypium hirsutum acc.T586.Sequence and phylogenetic analysis showed that GhHD-1A belonged to the HD-Zip IV gene family,which mainly regulated epidermis hair development in plants.Silencing of GhHD-1A and its homoeologs GhHD-1D in allotetraploid T586and Hai7124 could significantly reduce the density of leaf hairs and affect the expression levels of other genes related to leaf trichome formation.Further analysis found that GhHD-1A mainly regulated trichome initiation on the upper epidermal hairs of leaves in cotton,while the up-regulated expression of GhHD-1A in different organs/tissues also altered epidermal trichome development.This study not only helps to unravel the important roles of GhHD-1A in regulating trichome initiation in cotton,but also provides a reference for exploring the different forms of trichome development in plants.

Pollen morphology and trichome types of Betula spp. in the Hyrcanian forests of northern Iran

Pollen and trichome morphology of the genus Betula were evaluated from three main habitats in Iran using light and electron microscopy.Pollen types were identical and tri-porate;however,in terms of quantitative data,some differences were observed in exine(outside)wall thickness,length of polar axis and length of equatorial axis,possibly due to the environment.Pollen alone is insufficient to separate species of Iranian birch.Investigation of the trichome trait(small hairs or other outgrowths)revealed that birch species in Iran belong to:(1)Betula litwinowii Doluch.according to the low density of trichomes on the adaxial surface of the leaves and the lack of trichomes on the abaxial surface and many trichomes on the petioles;(2)Betula pendula Roth.due to the absence of trichomes on the adaxial surface and the low density of trichomes on the abaxial surface;and,(3)in the adaxial and abaxial surfaces of leaves and petioles,the trichomes had different types of pilose(long,soft hairs),and this strengthens the possibility of a different species or more likely a hybrid of B.pendula.

Cloning and Expression Analysis of <i>TTG</i>1 Gene Related to <i>Rosa rugosa</i>Trichomes Formation

The TTG1 transcription factor plays an important role in the formation of plant trichomes. Based on the R. rugosa transcriptome data, this study cloned a R. rugosa TTG1 gene, named RrTTG1, and carried out bioinformatics analysis and fluorescence quantitative analysis to explore the relationship between TTG1 gene and R. rugosa trichomes formation, in order to lay a good foundation to cultivate a thornless plant in the family Rosaceae. In this experiment, six hybrid cultivars of R. rugosa “Zizhi”, R. rugosa “Xizi”, R. rugosa “Tang fen”, R. rugosa “Hun chun”, R. rugosa “Zi long wo chi” and R. rugosa “Tian e huang” were used as experimental materials, and the cDNA full length of this gene was obtained by RT-PCR and RACE, and the full length of the cDNA was 1348 bp. After bioinformatics analysis, it is predicted that its molecular formula is C1723H2661N465O529S12, the molecular weight is 38.71 KB, and the isoelectric point is 5.00. Its instability index is 54.30, which belongs to unstable protein;and its hydrophilic amino acid distribution is relatively uniform, and the amount is larger than hydrophobic amino acid, which belongs to hydrophilic protein. Phylogenetic tree was constructed for the TTG1 gene. Evolutionary analysis indicated that RrTTG1 is closely related to the TTG1 protein of Rosaceae family, and has a close relationship with other families. The expression analysis showed that the expression of RrTTG1 protein was negatively correlated with the trichome content of R. rugosa stems and leaves. The expression levels of the three spiny varieties of R. rugosa “Hun chun”, R. rugosa “Xizi” and R. rugosa “Zi long wo chi” were lower, and the expressions of the three less thorn varieties of R. rugosa “Zizhi”, R. rugosa “Tian e huang” and R. rugosa “Tang fen” were higher. According to the above results, it was speculated that RrTTG1 is involved in the synthesis of R. rugosa trichomes and belongs to the negative regulation mechanism.

Leaf Traits and Histochemistry of Trichomes of Conocarpus lancifolius a Combretaceae in Semi-Arid Conditions

Leaf traits, structure and water status of Conocarpus lancifolius, a Combretaceae were investigated under semi-arid conditions. The leaf traits examined included leaf area and thickness, stomatal distribution, sclerophylly, succulence and relative water content. Additionally, the types of secretory structures, histochemistry of trichomes, and chemical nature of the cuticlular waxes were evaluated. Leaves showed xerophytic characteristics including a high degree of sclerophylly, thick cuticle and outer epidermal cell wall, low relative water content and high trichome density on younger leaves. The species has two types of trichomes;a secretory, short-stalked capitate trichome and a non-secretory trichome with a bulbous base and a pointed tip. The leaves also have a pair of extrafloral nectaries on both sides of the distal end of the petiole, 3-4 pairs near the leaf apex and two secretory ducts or cavities on mature leaves that secreted polysaccharides, epicuticlar waxes and polyphenols. Compared to young leaves mature leaves had almost 3 times total cuticular wax deposit or load. The most abundant fatty acids were palmitic, stearic, nondecanoic, behenic and arachidic acids. The leaf traits and structures are discussed in relation to semi-arid habitat.

Localization of a defensive volatile 4-hydroxy-4-methylpentan-2-one in the capitate glandular trichomes of Oenothera glazioviana

Glandular trichomes of plants produce a wide variety of secondary metabolites which are considered as major defensive chemicals. The capitate glandular trichomes of Oenothera glazioviana(Onagraceae) were collected with laser microdissection and analyzed by gas chromatography-mass spectrometry. The volatile compound 4-hydroxy-4-methylpentan-2-one(1) was identified. We found that compound 1 displays antimicrobial, insecticidal, and phytotoxic activities. These results suggest that compound 1 might function as a defensive compound in the capitate glandular trichomes of O. glazioviana against pathogens, insect herbivores, and presumably competitive plants as well.

A Systematic Revision of the Genus Plectranthus L. (Lamiaceae) in Saudi Arabia Based on Morphological, Palynological, and Micromorphological Characters of Trichomes

This study aims to investigate the morphology and ultrastructure characters of pollen grains and trichomes in order to evaluate their systematic value of these characters in specific and intraspecific separation of the Saudi Arabian Plectranthus species. A critical systematic revision of 7 species of Plectranthus (Lamiaceae) in Saudi Arabia was conducted by means of numerical analyses based on thirty-one morphological characters, including vegetative parts, seeds, pollen grains, and trichomes. Macro- and micro-morphological characters, including seed and pollen shape, size, coat sculpture, trichome structure, were studied. It reveals the presence of seven species, including two endemic species. The pollen grains were zonocolpate, hexacolpate, prolate to subprolate. Three types of exine ornamentation were recognized. Also, two trichome types could be distinguished and classified into glandular and non-glandular. The glandular trichomes could be distinguished as peltate, capitate and digitiform. The eglandular trichomes were single, uniseriate, multicellular. Pollen and trichome characters were found to be valuable, while seed characters presented only minor taxonomic value. On the basis of UPGMA clustering analysis four branches and clusters were distinguished. The results offer useful data for evaluating the taxonomy of Plectranthus both at subgeneric and sectional levels. Our results indicated some degree of similarity among the species of subgenus Burnatastrum. Plectranthus arabicus is considered as a separate group and may be treated as separate subgenus. Furthermore, the endemic species Plectranthus asirensis and Plectranthus hijazensis constitute a monophyletic group and there are close relationships between this group and Plectranthus tenuiflorus. A key for the identification of the investigated taxa based on studied characters is provided.

Identifying candidate genes involved in trichome formation on carrot stems by transcriptome profiling and resequencing

Trichomes are specialized structures developed from epidermal cells and can protect plants against biotic and abiotic stresses.Trichomes cover carrots during the generative phase.However,the morphology of the carrot trichomes and candidate genes controlling the formation of trichomes are still unclear.This study found that carrot trichomes were nonglandular and unbranched hairs distributed on the stem,leaf,petiole,pedicel,and seed of carrot.Resequencing analysis of a trichome mutant with sparse and short trichomes(sst)and a wild type(wt)with long and dense trichomes on carrot stems was conducted.A total of 15396 genes containing nonsynonymous mutations in sst were obtained,including 42 trichomerelated genes.We also analyzed the transcriptome of the trichomes on secondary branches when these secondary branches were 10 cm long between wt and sst and obtained 6576 differentially expressed genes(DEGs),including 24 trichome-related genes.qRT-PCR validation exhibited three significantly up-regulated DEGs,20 significantly downregulated,and one with no difference.We considered both the resequencing and transcriptome sequencing analyses and found that 12 trichome-related genes that were grouped into five transcription factor families containing nonsynonymous mutations and significantly down-regulated in sst.Therefore,these genes are potentially promising candidate genes whose nonsynonymous mutations and down-regulation may result in scarce and short trichomes mutation on carrot stems in sst.

New Allele of HL6 Regulates Trichome Elongation in Rice

Trichomes are specialized epidermal cells that plav multiple roles in plant development.However,knowledge about the molecular mechanism of trichome development in rice is limited.In this study,a hairy leaf locus HL6SWWR of rice variety Suwangwanger(SWWR)was identified by map-based cloning.Transgenic complementation and knock-out mutation demonstrated that HL6SWWR regulated trichomes on leaves and expression levels of HL6SWWR affected trichome elongation.Transgenic experiments of PROswwr:HL6nipand PROnip:HL6swwr indicated that the promoter and coding sequences of HL6swwr were indispensable for trichome regulation.Sequencing alignment of the promoter and coding regions of HL6 in 22 varieties showed that some c/s-binding elements in the promoter region may be related to trichome development,while no decisive variation was found in the coding sequence.Furthermore,RNA-sequencing analysis revealed that 1415 differential expression genes(DEGs)were detected in hl6SWWR mutant vs wild type and that 1010 DEGs were found in HL6SWWR complementary transgenic line vs wild type.Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis showed that most of the DEGs were involved in metabolite pathway,secondary metabolite biosynthesis,plant pathogen interaction and phytohormone signal transduction in both the two groups.The results indicated that these enhanced pathways are critical during trichome development in rice.Taken together,our results provided new views into the regulatory mechanism of trichome formation in rice.

Comparative transcriptomic analysis of Rosa sterilis inflorescence branches with different trichome types reveals an R3-MYB transcription factor that negatively regulates trichome formation

Rosa sterilis S.D.Shi is an important economic tree in China that produces fruits with high nutritional and medicinal value.Many of R.sterills’organs are covered with different types of trichomes or prickles that directly affect fruit appearance and plant management.This study used RNA sequencing technology to analyze the transcriptomes of two parts of the inflorescence branch,namely inflorescence stems with flagellated trichomes and pedicels with both flagellated and glandular trichomes.Comparative transcriptomic analysis showed that many transcription factors(TFs)are potentially involved in the formation and development of trichomes.The accumulation of RsETC1,a TF of the R3-MYB family,was significantly higher in inflorescence stems than in pedicels;quantitative reverse transcription PCR(qRTPCR)verified that its expression was significantly higher in inflorescence stems than in pedicels during the first three development stages,indicating its inhibitory action on the initiation of glandular trichomes in R.sterilis.The mRNA level of RsETC1 accumulated to significantly higher levels in trichomeless tissues than in tissues with trichromes,suggesting that this gene may inhibit the formation of trichomes in R.sterilis.Over-expression of RsETC1 in Arabidopsis resulted in glabrous phenotypes,and the expression of trichome-related endogenous genes,except for TTG1,was markedly reduced.In addition,the contents of the phytohormones jasmonic acid(JA),gibberellin A3(GA_(3)),and cytokinins(CKs)in pedicels were significantly higher than those in inflorescence stems,and the expression patterns of the genes related to hormone biosynthesis and signal transduction presented consistent responses,suggesting that the transduction of these hormones might be crucial for trichome initiation and development.These data provide a new perspective for revealing the molecular mechanism of trichome formation in R.sterilis.

Silicon Deposition in Leaf Trichomes of Cucurbitaceae Horticultural Plants: A Short Report

Silicon deposition in leaf trichome of six horticultural Cucurbitaceae species, cucumber (Cucumis sativus), pumpkin (Cucurbita maxima), melon (Cucumis melo), watermelon (Citrullus lanatus), sponge gourd (Luffa cylindrica) and bottle gourd (Lagenaria siceraria var. hispida) was observed by an X-ray microanalyzer coupled with an environmental scanning electron microscope. The elements that presented in the surface of three or four leaves of the individual species were detected and mapped by the X-ray microanalyzer. In leaves of cucumber, pumpkin, and melon, high accumulation of silicon was detected in cells surrounding the bases of the trichome hair and the hair itself deposited calcium. On the other hand, in sponge gourd and bottle gourd, high accumulation of silicon was detected only in the hair. In watermelon leaves, silicon deposited both in the hair and in cells surrounding the bases of the hair. Thus, horticultural Cucurbitaceae plants have interspecific variation in the pattern of silicon deposition in leaf trichomes.

植物腺毛分泌物研究进展

植物腺毛(Plant glandular trichomes,GTs)是具有分泌能力的植物表皮毛,分布在茎、叶、花器官甚至果实的表面,可产生具有抗生物胁迫和非生物胁迫能力的腺毛分泌物(Glandular trichomes secretions),被誉为“生物合成工厂”。植物腺毛分泌物属于次生代谢产物,在医疗保健、植物源农药及食品工业等行业具有重要的应用价值。本文主要综述了植物腺毛结构、腺毛分泌物种类、提取分离及其功能活性等方面的研究进展,并对存在的问题和应用前景进行了分析与展望,以期为植物腺毛分泌物在医药、农业及食品领域的开发与利用提供参考。

中国杨属叶表皮毛状体微形态特征

为讨论叶表皮毛状体特征的分类学价值和系统学意义,借助体视显微镜和扫描电镜对中国杨属(Populus)33个物种的叶表皮毛状体进行了观察和分析。结果表明:杨属物种叶片毛状体整体上是非腺状的、简单的、基底固定的;除胡杨(P.euphratica)叶表皮没有毛状体外,其余物种叶表皮均被有毛状体,但毛状体的分布、形态、长度等在物种间存在不同程度差异。毛状体外形(圆柱状至条带状)、弯曲程度(直立至曲卷)、相对于叶表皮表面的方向(伏贴或不伏贴)及毛状体长度具有一定的分类学意义。结合分子系统发育研究提供的进化框架,本研究认为杨属叶表皮毛状体特征在亚属水平难以区分,但胡杨亚属(subg.Turanga)和白杨亚属(subg.Populus)在种间水平可区分很多物种,尤其是白杨亚属内的物种毛状体差异大;脂杨亚属(subg.Tacamahaca)内叶片毛状体相似且稳定,但不同分支上的叶片毛状体在长度上有差异。毛状体特征整合后可划分为以下类型:无毛、毡毛、绢毛、短柔毛和长柔毛。

烟草NtJAZ15基因对腺毛发生的影响

为验证NtJAZ15对烟草腺毛发生的影响,探究NtJAZ15调控腺毛发生的分子机制,本研究从K326中克隆了NtJAZ15基因,并对其进行了生物信息学和组织表达模式分析,通过创制NtJAZ15敲除和过表达突变体,分析其对腺毛发生的调控作用。结果表明,NtJAZ15-1和NtJAZ15-2在不同烟草品种中高度保守,具有典型的TIFY和Jas结构域,属于JAZ家族。NtJAZ15在各组织中均表达,且各组织中NtJAZ15-2表达量均高于NtJAZ15-1。NtJAZ15基因敲除突变体烟叶长柄和短柄腺毛密度增加,过表达突变体则相反。qRT-PCR结果表明NtJAZ15可显著影响NtWo、NtCycB2、NtHD9、NtHD12的表达,但对NtMIXTA的表达影响不显著。因此,NtJAZ15负调控烟草长柄和短柄腺毛发生,NtWo、NtCycB2、NtHD9、NtHD12可能参与NtJAZ15调控烟草腺毛发生。

Profiles of the Headspace Volatile Organic and Essential Oil Compounds from the Tunisian Cardaria draba (L.) Desv. and Its Leaf and Stem Epidermal Micromorphology

In this work, we investigated aroma volatiles emanated by dry roots, stems, leaves, flowers, and fruits of Cardariadraba (L.) Desv. growing wild in Tunisia and its aerial part essential oils (EOs) composition. A total of 37 volatileorganic compounds (96.7%–98.9%) were identified;4 esters, 4 alcohols, 7 hydrocarbons, 12 aldehydes, 5 ketones,1 lactone, 1 organosulfur compound, 2 organonitrogen compounds, and 1 acid. The hydrocarbons form the maingroup, representing 49.5%–84.6% of the total detected volatiles. The main constituent was 2,2,4,6,6-pentamethylheptane(44.5%–76.2%) reaching the highest relative percentages. Forty-two compounds were determined in thetwo fractions of EOs, representing 98.8% and 97.2% of the total oil composition, respectively. The principal componentswere hexadecanoic acid (34.6%), 6-methyl-5-hepten-2-one (18.3%), decanal (15.0%), 6,10,14-trimethyl-2-pentadecanone (13.2%), and n-pentacosane (13%). Micromorphological details of the leaf and stem epidermisusing light microscopy revealed polygonal cells with sinuous walls in the adaxial and abaxial leaf surfaces andnearly rectangular and long ones with linear and thick walls for the stem epidermis. The stomata complexes wereanisocytic in the leaf epidermis and mainly anisocytic and rarely paracytic in the stem epidermis. Non-glandulartrichomes were unbranched and long with an acute apex or short with a convex apex. The glandular ones wereidentified for the first time in this species. They were short-stalked with a large secretory head. The highest stomatalindex (17.02%) was recorded in the abaxial leaf surface. The identification of headspace volatiles and essentialoil compounds can be used to characterize this species, and the various epidermis micromorphologicalfeatures are very useful for biosystematics taxonomic studies within Brassicaceae.