Endogenous Trypsin Triggers Free Fluoride Release from Antarctic Krill(Euphausia superba)Cuticle

During postmortem storage,fluoride in Antarctic krill can be enriched in the muscle.Trypsin,as the most important digestive enzyme in Antarctic krill with a high activity in low temperature,plays a potential role in this process.In this study,endogenous trypsin was purified and its properties were investigated.The involvement of trypsin in the generation of free fluoride from Antarctic krill cuticle was explored.Cuticle microstructure before and after hydrolysis was compared with scanning electron microscopy,and the ash samples of the hydrolyzed Antarctic krill cuticle were analyzed with X-ray diffraction,Fourier transform infrared spectroscopy,and electron dispersive spectroscopy,respectively.Mass spectrometry analysis and inhibition tests confirmed that the purified enzyme was endogenous trypsin.Results of the present study indicated that trypsin digestion caused the increases of the concentrations of both fluoride ions and free amino N simultaneously,while the protein coated on the cuticle surface was dissolved too.However,no compositional change was detected in the cuticle inorganic salts.These findings suggest that trypsin triggered free fluoride release from Antarctic krill cuticle.In addition,the kinetics of free fluoride release could be described by the equation C_(W)=(1-0.97^(-0.006t)-0.03e^(0.0558t))×337.53+10.50.The present study improved the understanding of the role of trypsin in free fluoride release from Antarctic krill cuticle,facilitating future studies aimed at reducing the fluoride content in krill protein during Antarctic krill processing.

On Some Dispersed Cordaitean Cuticles from Cathaysian Flora in the Permian of China and Their Significance

Although the research on Cordaites of the Cathaysian Flora in China started early in 1883, the study of the cordaitean cuticles began late in 1991. Up to now, four types of cordaitean cuticles in situ and three types of dispersed ones have been reported from the Cathaysian Flora in China. However compared with the Euramerican Flora, the research work on cordaitean cuticles from the Cathaysian Flora in China is much more insufficient. In this paper, three kinds of dispersed cordaitean cuticles are described in detail from the Permian coal-bearing strata in China. Among these cuticles two kinds are collected from the roof shale of Coal Seam No. A(1) in Shanxi Formation (Lower Permian) in Xinzhuangzhi Coal Mine of Huainan, Anhui Province, southern border of North China Subprovince of the Cathaysian Flora in China. The third one was collected from Coal Seam No. 11 in the top of Longtan Formation (lower Upper Permian) in Dahebian Coal Mine of Shuicheng Mining District, Guizhou Province, South China Subprovince of the Cathaysian Flora in China. Comparison of these three kinds of cordaitean cuticles with the known ones from the Cathaysian Flora in China and from the Euramerican Flora is made. The authors consider that they are all new types of cordaitean cuticles. The significance they bear on palaeobotany is discussed.

Factors impacting nanoindentation testing results of the cuticle of dung beetle Copris ochus Motschulsky

The cuticle of dung beetle is a layered composite material in micro- or nano-scale. Dung beetle can fly, walk and dig. It can shovel and compact dung of mammals into balls. It use foreleg to walk, midleg and hindleg to hold and impel dung ball. Its two foreleges as digging legs are developed. The factors impacting the nanoindentation testing results of the femur cuticle of forelegs of dung beetle Copris ochus Motschulsky were examined. The nanomechanical test instrument used for the tests was Hysitron nanomechanical system. The results shown that the holding time and loading time are important factors im- pacting the accuracy of such indentation properties as reduced modulus (Er) and the harness ( H ) of the femur cuticle of the forelegs of dung beetle Copris ochus Motschulsky in nanoscale. There exists a threshold holding time of 20 s for the reduced modulus of the femur cuticle. The tests of nanoindentation creep property and the regression analysis of relationship between the depth increment at the maximum load and the time further confirmed the correction of the above threshold holding time. There exist visco-elastic-plastic behaviour and creep phenomenon in the femur cuticle during indenting. Its creep property during the holding procedure at maximum load can be regressed by a general logarithmic equation. The equation fitted by the testing data is ? h = 54.83452 ln(0.00723t +1.00486), where, ? h is the depth increment at the maximum load and t is the time.

Cuticles and Spores in Situ of Coniopteris hymenophylloides from the Middle Jurassic in Gansu, Northwestern China

Coniopteris was a ubiquitous plant of the Jurassic and Cretaceous periods and played an important role in the flora of the time. However, its anatomical structure is relatively poorly known. The specimens of Coniopteris hymenophylloides(Brongniart) Seward described here were collected from the Yaojie Formation in Gansu Province, northwestern China. The sterile fronds are characterized as being at least bipinnate with alternate arranged linear pinnae covered by thin cuticles. Fertile fronds are linear-lanceolate, with single sorus at the margin of each fertile pinnule. In situ spores are typically trilete, triangle to subcircular in polar view, cap-shaped in equatorial view, and 37 μm in average diameter. The trilete marking is straight and narrow, generally extends to 4/5 of the spore radius. The spore surface is smooth, and parts of the exine are granulated. The epidermal cells of cuticles are irregular in shape, approximately 40-60μm long and 10-20 μm wide. The elliptical stomatal complexes are paracytic,approximately 30 μm long and 19 μm wide,and irregularly distributed. On the basis of its epidermal structures and comparisons with extant ferns, we consider that Coniopteris displays combined features of the related extant genera.

Possible functions of the microtrichia on the cuticle of Ulomoides dermestoides(Chevrolat)(Coleoptera:Tenebrionidae)

Ulomoides dermestoides （Chevrolat） （Coleop- tera： Tenebrionidae） is one of the most notorious pests in northeastern China. We examined microtrichia on the thorax, elytra and abdomen of U. dermestoides using scanning electron microscopy and recorded their confor- mations （size, shape and insertion method） and distribu- tions （length, width and location）. Possible functions of the microtrichia were （1） stridulation： microtrichia on the inner surface of the elytra interacted with microtrichia on the dorsoventral axis of the thorax or on the costal vein of the hind wing; （2） to increase friction： at the major surface on the middle of the abdominal tergum, hind-wings, inner surface of the medial edge of the elytra and the posterior end of the elytra; （3） protection： the microtrichia covering the posterior face of the abdomen conserved water in the body and protected the body from damage; and （4） sensing organ： the special shape of the microtrichia on the nerva- tion near the vannal fold of the hind wing, the anterio- metapleuron on the metathorax, and the posterior field of the abdomen could perceive the environment. In conclusion, the size and shape of the microtrichia are tightly related to their functions, which may have evolved with the beetles＇ lifestyle.

Leaf Cuticle Microstructure of Machilus maomingensis sp.nov.(Lauraceae) from the Eocene of the Maoming Basin,South China

Machilus maomingensis Jin et Tang,sp.nov.from the Eocene Youganwo Formation of the Maoming Basin,South China,is studied in detail from the perspective of the leaf architecture and the excellently preserved cuticle.The leaf margin is entire,the primary venation is pinnate;6 to 8secondary veins are present and the major secondary venation is eucamptodromous.Stomata are paracytic and occur on the lower epidermis.Trichome bases are unicellular.Oil cells are present in the upper epidermis.The new fossil species described has features of the Lauraceae,particularly of the extant genus Machilus Rumphius ex Nees,and it is most similar to Machilus chinensis（Bentham）Hemsley,an extant species distributed in southern China and Vietnam.Hence,Machilus maomingensis sp.nov.is inferred to live in a warm and humid climate.The discovery of the present fossil indicates that Machilus has existed in South China from at least the Eocene.

Consensus maps of cloned plant cuticle genes

Plant cuticle,which covers the plant surface,consists of waxes and cutins,and is associated with plant drought,cold,and salt resistance.Hitherto,at least 47 genes participating in the formation of plant cuticle have been cloned from Arabidopsis thaliana,Oryza sativa,Zea mays,Ricinus communis,Brassica napus,and Medicago truncatula;and about 85% of them encode proteins sharing above 50% identities with their rice homologous sequences.These cloned cuticle genes were mapped in silico on different chromosomes of rice and Arabidopsis,respectively.The mapping results revealed that plant cuticle genes were not evenly distributed in both genomes.About 40% of the mapped cuticle genes were located on chromosome 1 in Arabidopsis,while 20% of the mapped cuticle genes were located on chromosome 2 but none on chromosome 12 in rice.Some cloned plant cuticle genes have several rice homologous sequences,which might be produced by chromosomal segment duplication.The consensus map of cloned plant cuticle genes will provide important clues for the selection of candidate genes in a positional cloning of an unknown cuticle gene in plants.

Micromorphology and Maturation of the Yellow Granules in the Hornet Gastral Cuticle

The yellow granules in the gastral cuticle of the Oriental hornet Vespa oriental＆ （Hymenoptera, Vespinae） are located in yellow stripes. In the present study, we focus on the micromorphology and formation of the yellow granules from their inception to their spread in the regions which are destined to acquire a yellow color, The cuticle was observed with several methods of electron microscopy. The results showed that the yellow granules comprise a layer which is 20-25 μm thick, within the total cuticular thickness of 40-45 μm. In the mentioned regions one can see, from above, many apertures of about 0.5μm in diameter which extends into a peripheral photoreceptor cell. In each yellow granule, one discerns a myoid envelope inside which there are 9 fibrils arranged in a circle. Yellow granules maturation process involves infiltration of canals that give rise to the incipient ball-shaped primary granules which increase in number （as a result of continues budding off the walls of a canal） as the cuticle matures and transform into secondary barrel shaped granules, becoming elongated and then splitting into shorter barrels that fill up the entire area. Preliminary examinations have suggested liver-like function activity within the layer of yellow granules.

Molecular Cloning and Sequence Analysis of Chitin Synthase cDNA from Mamestra brassicae (L.) (Lepidoptera: Noctuidae) Cuticle

Chitin is the most widespread amino polysaccharide in nature. Chitin synthase （CHS） plays an important role in chitin formation in the cuticle and the peritrophic membrane （PM） lining the midgut. Total RNA was isolated from the cuticle of Mamestra brassicae （L.） fourth instar larva, cDNA sequence was cloned by RT-PCR and Rapid Amplification of cDNA Ends （RACE）. cDNA 5 220 bp in length, contained an open reading frame of 4 704 bp coding for a polypeptide of 1 567 amino acid residues with a predicted molecular weight of 178.3 ku and its pI was 6.42. The deduced amino acid sequence from Mi brassicae （L.） shared the high level of identity with chitin synthase sequences from other insects, especially lepidopteran insects, cDNA sequence has been deposited with GenBank under accession No. GQ281761

Fast genetic mapping in barley:case studies of cuticle mutants using RNA-sequencing

Barley(Hordeum vulgare L.)is one of the earliest domesticated crop species and ranked as the fourth largest cereal production worldwide.Forward genetic studies in barley have greatly advanced plant genetics during the last century;however,most genes are identified by the conventional mapping method.Array genotyping and exome-capture sequencing have also been successfully used to target the causal mutation in barley populations,but these techniques are not widely adopted because of associated costs and partly due to the huge genome size of barley.This review summarizes three mapping cases of barley cuticle mutants in our laboratory with the help of RNA-sequencing.The causal mutations have been successfully identified for two of them and the target genes are located in the pericentromeric regions.Detailed information on the mapping-by-sequencing,mapping-and-sequencing,and RNA-sequencing assisted linkage mapping are presented and some limitations and challenges on the mapping assisted by RNA sequencing are also discussed.The alternative and elegant methods presented in this review may greatly accelerate forward genetics of barley mapping,especially for laboratories without large funding.

Histological Characteristics of the Skin and Cuticle of the Wool Fibers in Dubska Pramenka and the Use in Industry

Microscopic analysis of the skin and cuticle of wool fibers in Dubska pramenka show different qualitative parameters. The research study included different parts of the body and the samples of the wool fibers from different regions of the body. Histological description shows difference in the basic structurers of the skin in Dubska pramenka. A very pronounced thin epidermis, while dermis and hypodermis are more developed on the samples from the shoulder. Cornified flakes-cuticle of the root of the tail was of a fine structure, and comified flakes from the rump showed the features of the rough wool fibers. ＂Transitional form of cuticle＂ was dominant on the shoulder. The qualitative parameters have a significant influence on the overall quality of wool in general, and the research contributes to a greater usability value of the wool and development of livestock farming in areas in a broader sense.

Reduction and Block Staining of Human Hair Shafts and Insect Cuticles by Ammonium Thioglycolate to Enhance Transmission Electron Microscopic Observations

We have developed a method where, after glutaraldehyde fixation, human hair shafts and insect cuticles are treated with ammonium thioglycolate (ATG) to improve ultrastructural staining. Conventional transmission electron microscopic (TEM) preparations do not distinguish the A-layer and the exocuticles of hair shafts. However, after ATG treatment, the A-layer appears in higher contrast. ATG treatment has also been used to observe the fibrillar structure in the cortex. In the cuticle of beetles, the epicuticle is stained by ATG. Although the human hair shaft (keratin) and insect cuticle (chitin) are composed of different materials, both can be reduced by the ATG solution. The ammonium in the ATG solution reacts with hair shafts and insect cuticles, causing a reduction of swelled cuticles. Therefore, ATG not only stains, but also reduces human hair shafts and the cuticles of beetles.

Plant cuticles repress organ initiation and development during skotomorphogenesis in Arabidopsis

After germination in the dark,plants produce a shoot apical hook and closed cotyledons to protect the quiescent shoot apical meristem(SAM),which is critical for seedling survival during skotomorphogenesis.The factors that coordinate these processes,particularly SAM repression,remain enigmatic.Plant cuticles,multilayered structures of lipid components on the outermost surface of the aerial epidermis of all land plants,provide protection against desiccation and external environmental stresses.Whether and how cuticles regulate plant development are still unclear.Here,we demonstrate that mutants of BODYGUARD1(BDG1)and long-chain acyl-CoA synthetase2(LACS2),key genes involved in cutin biosynthesis,produce a short hypocotyl with an opened apical hook and cotyledons in which the SAM is activated during skotomorphogenesis.Light signaling represses expression of BDG1 and LACS2,as well as cutin biosynthesis.Transcriptome analysis revealed that cuticles are critical for skotomorphogenesis,particularly for the development and function of chloroplasts.Genetic and molecular analyses showed that decreased HOOKLESS1 expression results in apical hook opening in the mutants.When hypoxia-induced expression of LITTLE ZIPPER2 at the SAM promotes organ initiation in the mutants,the de-repressed expression of cell-cycle genes and the cytokinin response induce the growth of true leaves.Our results reveal previously unrecognized developmental functions of the plant cuticle during skotomorphogenesis and demonstrate a mechanism by which light initiates photomorphogenesis through dynamic regulation of cuticle synthesis to induce coordinated and systemic changes in organ development and growth during the skotomorphogenesis-to-photomorphogenesis transition.

Myo-inositol accelerates the metamorphosis from megalopa to crablet of Scylla paramamosain by modulating cuticle decomposition and reconstruction

The mud crab Scylla paramamosain is a key species in China due to its high nutritional value and great economic worth and has grown in popularity.Myo-inositol can modulate versatile physiological functions in aquatic animals.In the present study,S.paramamosain megalopa were given graded concentrations of myo-inositol(0,1,2,4,and 8 ppm)by water immersion to explore how their metamorphosis would be affected.The results showed that supplementing with myo-inositol remarkably increased transformation and survival rate from megalopa to crablet by at least 1.16 and 1.26 times,respectively.To decipher the molecular mechanism of how myo-inositol increases metamorphosis and survival rate,we further performed transcriptome-based gene expression profiling of both megalopa and crablet treated with myo-inositol.The integrative transcriptome analyses predicted that the differentially expressed genes(DEGs)were significantly enriched in chitinase activity,structural constituent of cuticle,and chitin binding,which are associated with the decomposition and reconstruction of cuticle.qPCR results confirmed that myo-inositol mediated gene expression levels of the above cuticle-related pathways.Considering the importance of the cuticle in exoskeleton formation and molting,it can be concluded that myo-inositol-induced changes in the cuticle decomposition and reconstruction might have accelerated the transformation from megalopa to crablet of S.paramamosain.Besides,numerous DEGs were significantly enriched in protein digestion and absorption,amino sugar and nucleotide sugar metabolism.It implies that myo-inositol may improve survival by regulating energy or nutrient absorption.Additionally,the accelerated metamorphosis by myo-inositol may improve survival from megalopa to crablet of S.paramamosain.Overall,this study will provide the first insights into the underlying molecular mechanisms by which myo-inositol increases metamorphosis and survival.

Chitin synthase 1 and five cuticle protein genes are involved in serosal cuticle formation during early embryogenesis to enhance eggshells in Nilaparvata lugens

Many holo-and hemimetabolous insects enhance their eggshells during embryogenesis by forming a serosal cuticle(SC).To date,scholarly understanding of the SC composition and SC-related gene functions has been limited,especially for hemimetabolous insects.In this study,we initially performed transmission electron microscopic(TEM)observation and chitin staining of the SC in Nilaparvata lugens,a hemimetabolous rice pest known as the brown planthopper(BPH).We confirmed that the SC was a chitin-rich lamellar structure deposited gradually during the early embryogenesis.Parental RNA interference(RNAi)against Nilaparvata lugens chitin synthase 1(NlCHS1)in newly emerged and matured females resulted in decreases of egg hatchability by 100%and 76%,respectively.Ultrastructural analyses revealed loss of the lamellar structure of the SC in dsNlCHS1-treated eggs.According to temporal expression profiles,five cuticle protein coding genes,NlugCpr1/2/3/8/90,were specifically or highly expressed during the SC formation period,and NlugCpr1/2/3/90 were further detected in 72 h eggshells extract by ultra-performance liquid chromatography-tandem mass spectrometry/mass spectrometry.NlugCpr2/3/90 were likely three SC-specific cuticle proteins.TEM observations of the SC following parental RNAi against NlugCpr1/2/3/8/90 demonstrated that NlugCpr3/8/90 were essential for SC formation.The study provided an understanding of the SC formation process and SC-related cuticle proteins in BPHs,which offer potential targets for pest control in the egg stage as well.

A new method to prepare clean cuticular membrane from fossil leaves with thin and fragile cuticles

Leaf cuticle analysis has long been a powerful tool for fossil plant identification, systematics, and palaeoclimatological recon- struction. In recent decades the application of stomatal frequency data that are relied on precise calculation of stomata on plant fossil cuticles to reconstruct ancient atmospheric CO2 concentration made the preparation of cuticular membrane with sufficient size a critical technique in palaeoclimatological research. However, for plants with originally thin and fragile cuticles, e.g., most deciduous plants, conventional techniques sometimes fail to obtain cuticular membranes with sufficient size, or sometimes unable to recover any. This has largely hampered the usage of fossil cuticle analysis in palaeobotanical and palaeo- climatological research. Here, we describe a new method using clear nail polish as a medium to ＂strengthen＂ the originally thin and fragile cuticles prior to maceration procedures. We demonstrate the method by using middle Eocene Metasequoia fossils that were notorious for the difficulty of recovering large-sized clean cuticular membranes due to their thin and fragile nature. Metasequoia, with well-documented and widely-distributed fossil records since the Late Cretaceous and with a living repre- sentative, 114. glyptostroboides, as a comparative reference, bas been widely used as a model genus for the study of evolution of plants, palaeoclimatological reconstruction, and plant adaptation to climate changes. But its deciduous habit produces thin cuticles and makes the preparation of clean cuticular membranes a tedious process. The new method successfully allows us to recover its delicate cuticular membranes with sufficient sizes for SEM observation and stomatal frequency analysis.

Rice CYP703A3, a cytochrome P450 hydroxylase, is essential for development of anther cuticle and pollen exine

Anther cuticle and pollen exine act as protective envelopes for the male gametophyte or pollen grain, but the mechanism underlying the synthesis of these lipidic polymers remains unclear. Previously, a tapetum‐expressed CYP703A3, a putative cytochrome P450 fatty acid hydroxylase, was shown to be essential for male fertility in rice（Oryza sativa L.）. However,the biochemical and biological roles of CYP703A3 has not been characterized. Here, we observed that cyp703a3‐2 caused by one base insertion in CYP703A3 displays defective pollen exine and anther epicuticular layer, which differs from Arabidopsis cyp703a2 in which only defective pollen exine occurs. Consistently, chemical composition assay showed that levels of cutin monomers and wax components were dramatically reduced in cyp703a3‐2 anthers. Unlike the wide range of substrates of Arabidopsis CYP703A2, CYP703A3 functions as an in‐chain hydroxylase only for a specific substrate, lauric acid, preferably generating 7‐hydroxylated lauric acid. Moreover, chromatin immunoprecipitation and expression analyses revealed that the expression of CYP703A3 is directly regulated by Tapetum Degeneration Retardation, a known regulator of tapetum PCD and pollen exine formation. Collectively, our results suggest that CYP703A3 represents a conserved and diversified biochemical pathway for in‐chain hydroxylation of lauric acid required for the development of male organ in higher plants.

Analysis of expression and chitin-binding activity of the wing disc cuticle protein BmWCP4 in the silkworm, Bombyx moil

The insect exoskeleton is mainly composed of chitin filaments linked by cuticle proteins. When insects molt, the cuticle of the exoskeleton is renewed by degrading the old chitin and cuticle proteins and synthesizing new ones. In this study, chitin-binding activity of the wing disc cuticle protein BmWCP4 in Bombyx mori was studied. Sequence analysis showed that the protein had a conservative hydrophilic ＂R＆R＂ chitin-binding domain （CBD）. Western blotting showed that BmWCP4 was predominately expressed in the wing disc-containing epidermis during the late wandering and early pupal stages. The immunohistochemistry result showed that the BmWCP4 was mainly present in the wing disc tissues containing wing bud and trachea blast during day 2 of wandering stage. Recombinant full-length BmWCP4 protein, ＂R＆R＂ CBD peptide （CBD）, non-CBD peptide （BmWCP4-CBD^-）, four single site-directed mutated peptides （M1, M2, M3 and M4） and four-sites-mutated peptide （MF） were generated and purified, respectively, for in vitro chitin-binding assay. The results indicated that both the full-length protein and the ＂R＆R＂ CBD peptide could bind with chitin, whereas the BmWCP4-CBD- could not bind with chitin. The single residue mutants M1, M2, M3 and M4 reduced but did not completely abolish the chitin-binding activity, while four-sites-mutated protein MF completely lost the chitin-binding activity. These data indicate that BmWCP4 protein plays a critical role by binding to the chitin filaments in the wing during larva-to-pupa transformation. The conserved aromatic amino acids are critical in the interaction between chitin and the cuticle protein.

Chitinase 10 controls chitin amounts and organization in the wing cuticle of Drosophila

Wings are essential for insect fitness.A number of proteins and enzymes have been identified to be involved in wing terminal differentiation,which is characterized by the formation of the wing cuticle.Here,we addressed the question whether chitinase 10(Cht10)may play an important role in chitin organization in the wings of the fruit fly Drosophila melanogaster.Initially,we first found that Cht10 expression coincides with the expression of the chitin synthase coding gene kkv.This suggests that the respective proteins may cooperate during wing differentiation.In tissue-specific RNA interference experiments,we demonstrate that suppression of Cht10 causes an excess in chitin amounts in the wing cuticle.Chitin organization is severely disrupted in these wings.Based on these data,we hypothesize that Cht10 restricts chitin amounts produced by Kkv in order to ensure normal chitin organization and wing cuticle formation.In addition,we found by scanning electron microscopy that Cht10 suppression also affects the cuticle surface.In turn,cuticle inward permeability is enhanced in Cht10 Aess wings.Moreover,flies with reduced Cht 10 function are unable to fly.In conclusion,Cht10 is essential for wing terminal differentiation and function.

Dissecting Abscisic Acid Signaling Pathways Involved in Cuticle Formation

The cuticle is the outer physical barrier of aerial plant surfaces and an important interaction point between plants and the environment. Many environmental stresses affect cuticle formation, yet the regulatory pathways involved remain undefined. We used a genetics and gene expression analysis in Arabidopsis thaliana to define an abscisic acid （ABA） signaling loop that positively regulates cuticle formation via the core ABA signaling pathway, including the PYR/PYL receptors, PP2C phosphatase, and SNF1-Related Protein Kinase （SnRK） 2.21SnRK2.3/SnRK2.6. Downstream of the SnRK2 kinases, cuticle formation was not regulated by the ABA-responsive element-binding transcription factors but rather by DEWAX, MYB16, MYB94, and MYB96. Additionally, low air humidity increased cuticle formation independent of the core ABA pathway and cell death/reactive oxygen species signaling attenuated expression of cuticle-biosynthesis genes. In Physcornitrella patens, exogenous ABA suppressed expression of cuticle- related genes, whose Arabidopsis orthologs were ABA-induced. Hence, the mechanisms regulating cuticle formation are conserved but sophisticated in land plants. Signaling specifically related to cuticle deficiency was identified to play a major role in the adaptation of ABA signaling pathway mutants to increased humidity and in modulating their immunity to Botrytis cinerea in Arabidopsis. These results define a cuticle-specific downstream branch in the ABA signaling pathway that regulates responses to the external environment.