Cuticular Wax Research Articles

Pathway elucidation and heterologous reconstitution of the long‐chain alkane pentadecane biosynthesis from Pogostemon cablin

SummaryVery‐long‐chain (VLC) alkanes are major components of hydrophobic cuticular waxes that cover the aerial epidermis of land plants, serving as a waterproofing barrier to protect the plant against environmental stresses. The mechanism of VLC‐alkane biosynthesis has been extensively elucidated in plants. However, little is known about the biosynthesis of long‐chain alkanes (LC, C13 ~ C19) such as pentadecane in plants. Alkanes with different chain lengths are also major constituents of fossil fuels and thus the discovery of the alkane biosynthetic machinery in plants would provide a toolbox of enzymes for the production of renewable hydrocarbon sources and next generations of biofuels. The top leaves of Pogostemon cablin at young stage accumulate large amounts of LC‐alkane pentadecane, making this plant an excellent system for the elucidation of LC‐alkane biosynthetic machinery in plant. We show here that LC‐alkane pentadecane biosynthesis in P. cablin involves an endoplasmic reticulum (ER)‐localized complex made of PcCER1‐LIKE3 and PcCER3, homologues of Arabidopsis ECERIFERUM1 (AtCER1) and AtCER3 proteins that are involved in Arabidopsis VLC‐alkane biosynthesis. We reconstitute the biosynthesis of pentadecane in Nicotiana benthamiana by co‐expression of PcCER1‐LIKE3 and PcCER3 and further improve its production by silencing multifunctional acetyl‐CoA carboxylases involved in fatty acid elongation pathway. Taken together, we uncovered the key biosynthetic machinery of LC‐alkane pentadecane in P. cablin and demonstrated that using these newly identified enzymes to engineer this LC‐alkane for liquid biofuel production in a heterologous plant host is possible.

Wheat Topoisomerase VI Positively Regulates the Biosynthesis of Cuticular Wax and Cutin.

Lipophilic cuticles mainly composed of wax mixtures and cutin matrices seal the plant epidermis and control plant development and environmental adaptation. Although cuticle-associated traits have been selected in the breeding of agronomically important cereal bread wheat, the biosynthesis of wheat cuticular wax and cutin remains poorly understood. Herein, wheat topoisomerase VI was characterized as an essential activator of cuticular wax and cutin biosynthesis. Knock-down of wheat TaTOP6A, TaTOP6B, TaRHL1, or TaBIN4 gene encoding component of topoisomerase VI resulted in decreased loads of leaf cuticular wax and cutin, as well as increased leaf cuticle permeability. Moreover, TaCYP86A2 was identified as a key component of the wheat cutin biosynthetic machinery. Reduction of wheat TaCYP86A2 expression led to decreased cutin accumulation and enhanced cuticle permeability. In addition, TaTOP6A, TaTOP6B, TaRHL1, or TaBIN4 was shown to enrich at the promoter regions of the wax biosynthesis gene TaKCS1 and the cutin biosynthesis gene TaCYP86A2. Importantly, chromatin at TaKCS1 and TaCYP86A2 promoters is marked by high nucleosome occupancy and low histone acetylation in TaTOP6A-, TaTOP6B-, TaRHL1-, or TaBIN4-silenced wheat leaves. These results collectively support that wheat topoisomerase VI positively regulates the biosynthesis of cuticular wax and cutin probably via maintaining a permissive chromatin state at TaKCS1 and TaCYP86A2 genes.

BoaCRTISO regulates the color and glossiness of Chinese kale through its effects on pigment, abscisic acid, and cuticular wax biosynthesis

Carotenoid isomerase (CRTISO) is an important enzyme in carotenoid biosynthesis, and it catalyzes the conversion of lycopene precursors to lycopene in several plant species. However, the role of CRTISO in other biochemical processes during plant growth and development remains unclear. Here, we showed that Chinese kale boacrtiso mutants have distinctive characteristics, including a yellow-green hue and glossy appearance, and this contrasts with the dark green and glaucous traits observed in wild-type (WT) plants. Analysis of pigments in mutants revealed that the reduction in the content of carotenoids and chlorophylls contributed to the yellow-green coloration observed in mutants. An examination of cuticular waxes in Chinese kale indicated that there was a decrease in both the total wax content and the content of individual waxes in boacrtiso mutants (bearing a mutation of BoaCRTISO), which may be caused by the decrease of abscisic acid (ABA) content. The expression of carotenoid, chlorophyll, ABA, and wax biosynthesis genes was down-regulated in boacrtiso mutants. This finding confirms that BoaCRTISO regulates the biosynthesis of pigments, ABA, and cuticular waxes in Chinese kale. Our results provide new insights into the interplay between plant pigment and cuticular wax metabolic pathways in Brassica vegetables.

Advanced technology in fruit preservation: Effects of nanoscale charged water particles on storage quality and reactive oxygen species in blueberries

During the postharvest period, blueberries with a short shelf life due to microbial activity and an overload of reactive oxygen species (ROS) were still a major unresolved problem. In this study, the effect of nanoscale charged water particles (NCWP) treatment on the postharvest characteristics and ROS metabolism in blueberries (Vaccinium ashei Reade) were investigated. The results showed that NCWP treatment significantly inhibited microbial growth, maintained high firmness and commercial acceptability, and extended the storage period of blueberries. The nutrient of blueberries was retained and elevated after NCWP treatment, especially in the 6 d of NCWP-9 h treatment, the total phenol and anthocyanin content reached the peak at 565.1 mg/L and 5.26 mg/g, which contribute to the total antioxidant capacity of blueberries increased. SEM showed that NCWP-9 h treatment maintained the integrity of the cuticular wax of the blueberry peel, which indirectly decelerated the decline of blueberry firmness. The NCWP treatment significantly enhanced the antioxidant enzyme system of blueberry peel. On days 2, 4 and 6 after NCWP-9 h treatment, the CAT, SOD and APX activities were significantly different from the control group (P < 0. 05), with 585.09 ΔA/min/g, 79.34 U/g and 3.32 umol/min/g, respectively, which effectively scavenged the oxidative stress markers (H2O2, O2−) accumulated in the blueberry peels, and slowed down the aging and deteriorated of the blueberry process. This finding demonstrates that NCWP is an effective postharvest preservation method for blueberries and provides a viable strategy for quality maintenance in the postharvest fruit and vegetable sector.

Arabidopsis DREB26/ERF12 and its close relatives regulate cuticular wax biosynthesis under drought stress condition.

Land plants have evolved a hydrophobic cuticle on the surface of aerial organs as an adaptation to ensure survival in terrestrial environments. Cuticle is mainly composed of lipids, namely cutin and intracuticular wax, with epicuticular wax deposited on plant surface. The composition and permeability of cuticle have a large influence on its ability to protect plants against drought stress. However, the regulatory mechanisms underlying cuticular wax biosynthesis in response to drought stress have not been fully elucidated. Here, we identified three AP2/ERF transcription factors (DREB26/ERF12, ERF13 and ERF14) involved in the regulation of water permeability of the plant surface. Transmission electron microscopy revealed thicker cuticle on the leaves of DREB26-overexpressing (DREB26OX) plants, and thinner cuticle on the leaves of transgenic plants expressing SRDX repression domain-fused DREB26 (DREB26SR). Genes involved in cuticular wax formation were upregulated in DREB26OX and downregulated in DREB26SR. The levels of very-long chain (VLC) alkanes, which are a major wax component, increased in DREB26OX leaves and decreased in DREB26SR leaves. Under dehydration stress, water loss was reduced in DREB26OX and increased in DREB26SR. The erf12/13/14 triple mutant showed delayed growth, decreased leaf water content, and reduced drought-inducible VLC alkane accumulation. Taken together, our results indicate that the DREB26/ERF12 and its closed family members, ERF13 and ERF14, play an important role in cuticular wax biosynthesis in response to drought stress. The complex transcriptional cascade involved in the regulation of cuticular wax biosynthesis under drought stress conditions is discussed.

Integrative multi-omic analysis identifies genes associated with cuticular wax biogenesis in adult maize leaves.

Studying the genetic basis of leaf wax composition and its correlation with leaf cuticular conductance (gc) is crucial for improving crop productivity. The leaf cuticle, which comprises a cutin matrix and various waxes, functions as an extracellular hydrophobic layer, protecting against water loss upon stomatal closure. To address the limited understanding of genes associated with the natural variation of adult leaf cuticular waxes and their connection to gc, we conducted statistical genetic analyses using leaf transcriptomic, metabolomic, and physiological data sets collected from a maize (Zea mays L.) panel of ∼300 inbred lines. Through a random forest analysis with 60 cuticular wax traits, it was shown that high molecular weight wax esters play an important role in predicting gc. Integrating results from genome-wide and transcriptome-wide studies (GWAS and TWAS) via a Fisher's combined test revealed 231 candidate genes detected by all three association tests. Among these, 11 genes exhibit known or predicted roles in cuticle-related processes. Throughout the genome, multiple hotspots consisting of GWAS signals for several traits from one or more wax classes were discovered, identifying four additional plausible candidate genes and providing insights into the genetic basis of correlated wax traits. Establishing a partially shared genetic architecture, we identified 35 genes for both gc and at least one wax trait, with four considered plausible candidates. Our study enhances the understanding of how adult leaf cuticle wax composition relates to gc and implicates both known and novel candidate genes as potential targets for optimizing productivity in maize.

Wheat Transcription Factor TaMYB60 Modulates Cuticular Wax Biosynthesis by Activating TaFATB and TaCER1 Expression.

Cuticular wax mixtures cover the epidermis of land plants and shield plant tissues from abiotic and biotic stresses. Although cuticular wax-associated traits are employed to improve the production of bread wheat, regulatory mechanisms underlying wheat cuticular wax biosynthesis remain poorly understood. In this research, partially redundant transcription factors TaMYB60-1 and TaMYB60-2 were identified as positive regulators of wheat cuticular wax biosynthesis. Knock-down of wheat TaMYB60-1 and TaMYB60-2 genes by virus-induced gene silencing resulted in attenuated wax accumulation and enhanced cuticle permeability. The roles of wheat fatty acyl-ACP thioesterase genes TaFATB1 and TaFATB2 in cuticular wax biosynthesis were characterized. Silencing wheat TaFATB1 and TaFATB2 genes led to reduced wax accumulation and increased cuticle permeability, suggesting that TaFATB1 and TaFATB2 genes positively contribute to wheat cuticular wax biosynthesis. Importantly, transcription factors TaMYB60-1 and TaMYB60-2 exhibit transcriptional activation ability and could stimulate the expression of wax biosynthesis genes TaFATB1, TaFATB2, and ECERIFERUM 1 (TaCER1). These findings support that transcription factor TaMYB60 positively regulates wheat cuticular wax biosynthesis probably by activating transcription of TaFATB1, TaFATB2, and TaCER1 genes.

Composition and micromorphological determination of blue honeysuckle fruit (Lonicera caerulea L.) cuticular wax and its effects on fruit post-harvest quality

The chemical composition and structure of the cuticular wax in blue honeysuckle fruit were investigated using gas chromatography–mass spectrometry (GC–MS) and scanning electron microscopy (SEM). The results revealed that the cuticular wax was dense and uniform, taking on a tubular form. A total of 158 wax components were identified, including alkanes, terpenes, ketones, alcohols, fatty acids, and esters. The wax was found to be particularly rich in alkanes. After storage, the wax content decreased, whereas an increase in 1-undecanol. The destruction or reduction of cuticular wax resulted in a more rapid decline in storage quality, loss of nutrients, and a decrease in antioxidant phytochemicals. Meanwhile, wax metabolizing enzyme activity and gene expression increased. This study presents a deeper understanding of blue honeysuckle fruit cuticular wax composition and aids to developing effective measures to delay its postharvest fruit quality deterioration.

ACL1-ROC4/5 complex reveals a common mechanism in rice response to brown planthopper infestation and drought

Brown planthopper (BPH) is the most destructive insect pest of rice. Drought is the most detrimental environmental stress. BPH infestation causes adaxial leaf-rolling and bulliform cells (BCs) shrinkage similar to drought. The BC-related abaxially curled leaf1 (ACL1) gene negatively regulates BPH resistance and drought tolerance, with decreased cuticular wax in the gain-of-function mutant ACL1-D. ACL1 shows an epidermis-specific expression. The TurboID system and multiple biochemical assays reveal that ACL1 interacts with the epidermal-characteristic rice outermost cell-specific (ROC) proteins. ROC4 and ROC5 positively regulate BPH resistance and drought tolerance through modulating cuticular wax and BCs, respectively. Overexpression of ROC4 and ROC5 both rescue ACL1-D mutant in various related phenotypes. ACL1 competes with ROC4/ROC5 in homo-dimer and hetero-dimer formation, and interacts with the repressive TOPLESS-related proteins. Altogether, we illustrate that ACL1–ROC4/5 complexes synergistically mediate drought tolerance and BPH resistance through regulating cuticular wax content and BC development in rice, a mechanism that might facilitate BPH-resistant breeding.

Comparative physiological and transcriptomic analyses reveal genotype specific response to drought stress in Siberian wildrye (Elymus sibiricus)

Siberian wildrye (Elymus sibiricus) is a xero-mesophytic forage grass with high nutritional quality and stress tolerance. Among its numerous germplasm resources, some possess superior drought resistance. In this study, we firstly investigated the physiological differences between the leaves of drought-tolerant (DT) and drought-sensitive (DS) genotypes under different field water contents (FWC) in soil culture. The results showed that, under drought stress, DT maintained a lower leaf water potential for water absorption, sustained higher photosynthetic efficiency, and reduced oxidative damage in leaves by efficiently maintaining the ascorbic acid-glutathione (ASA-GSH) cycle to scavenge reactive oxygen species (ROS) compared to DS. Secondly, using RNA sequencing (RNA-seq), we analyzed the gene expression profiles of DT and DS leaves under osmotic stress of hydroponics induced by PEG-6000. Through differential analysis, we identified 1226 candidate unigenes, from which we subsequently screened out 115/212 differentially expressed genes (DEGs) that were more quickly induced/reduced in DT than in DS under osmotic stress. Among them, Unigene0005863 (EsSnRK2), Unigene0053902 (EsLRK10) and Unigene0031985 (EsCIPK5) may be involved in stomatal closure induced by abscisic acid (ABA) signaling pathway. Unigene0047636 (EsCER1) may positively regulates the synthesis of very-long-chain (VLC) alkanes in cuticular wax biosynthesis, influencing plant responses to abiotic stresses. Finally, the contents of wax and cutin were measured by GC–MS under osmotic stress of hydroponics induced by PEG-6000. Corresponding to RNA-seq, contents of wax monomers, especially alkanes and alcohols, showed significant induction by osmotic stress in DT but not in DS. It is suggested that limiting stomatal and cuticle transpiration under drought stress to maintain higher photosynthetic efficiency and water use efficiency (WUE) is one of the critical mechanisms that confer stronger drought resistance to DT. This study provides some insights into the molecular mechanisms underlying drought tolerance in E. sibiricus. The identified genes may provide a foundation for the selection and breeding of drought-tolerant crops.

Polar-localized OsLTPG22 regulates rice leaf cuticle deposition and drought response

The cuticle serves as a crucial protective barrier for plant survival, and recent studies have highlighted the essential roles of nonspecific lipid transfer proteins (nsLTPs) in cuticle formation. However, the specific function of nsLTPs in the rice leaf cuticle remains unclear. In this study, we functionally characterized OsLTPG22, a G-type nsLTP with a signal peptide (SP) domain and a glycosylphosphatidylinositol (GPI) anchor region. Mutation in OsLTPG22 led to a reduction in cuticular wax abundance, increased leaf epidermal permeability, and higher drought sensitivity in seedlings. OsLTPG22 was widely expressed in various tissues and exhibited distinct polar localization to the aerial surface of epidermal cells in expanding leaves. OsLTPG22 binds lipids and localizes to the plasma membrane. Protein truncation experiments demonstrated that OsLTPG22’s polar localization was regulated by the SP domain, while both the SP domain and GPI anchor region regulated OsLTPG22’s plasma membrane localization. This work provides genetic and cytological evidence for OsLTPG22’s role in leaf cuticle formation and drought response, enhancing our understanding of nsLTP function and offering insights for breeding drought-resistant crops.

The yellowhorn MYB transcription factor MYB30 is required for wax accumulation and drought tolerance.

Yellowhorn (Xanthoceras sorbifolium Bunge) is an economically important tree species in northern China, mainly distributed in arid and semi-arid areas where water resources are scarce. Drought affects its yield and the expansion of its suitable growth area. It was found that the wax content in yellowhorn leaves varied significantly among different germplasms, which had a strong correlation with the drought resistance of yellowhorn. In this study, XsMYB30 was isolated from 'Zhongshi 4' of yellowhorn, a new highly waxy variety. DAP-Seq technology revealed that the pathways associated with fatty acids were significantly enriched in the target genes of XsMYB30. Moreover, the results of electrophoretic mobility shift assay, yeast one hybrid assay and dual-luciferase assay demonstrated that XsMYB30 could directly and specifically bind with the promoters of genes involved in wax biosynthesis (XsFAR4, XsCER1 and XsKCS1), lipid transfer (XsLTPG1 and XsLTP1) and fatty acid synthesis (XsKASIII), thus enhancing their expression. In addition, the overexpression of XsMYB30 in poplar promoted the expression levels of these target genes and increased the wax deposition on poplar leaves leading to a notable improvement in the plant's ability to withstand drought. These findings indicate that XsMYB30 is an important regulatory factor in cuticular wax biosynthesis and the drought resistance of yellowhorn.

First line of defence: Eucalyptus leaf waxes influence infection by an aggressive fungal leaf pathogen.

Leaf epicuticular waxes provide important anatomical and chemical defences against fungi that infect leaves. In this study we analysed the leaf wax composition of Eucalyptus grandis × Eucalyptus urophylla hybrids with contrasting susceptibilities to Teratosphaeria leaf blight (TLB) caused by Teratosphaeria destructans, one of the most important foliar diseases of Eucalyptus. The Eucalyptus cuticular wax was extracted from non-inoculated and inoculated genotypes with different levels of susceptibility to TLB and analysed by gas chromatography-mass spectrometry. The results showed that a triterpenoid, cycloartenol (CAS), was abundant in a resistant genotype and that hexanedioic acid content increased in the resistant genotypes in response to T. destructans infection. In contrast, palmitic acid was significantly more abundant in the inoculated highly susceptible genotype. In-vitro and in-planta T.destructans spore germination assays with pure compounds, showed that CAS and hexanedioic acid significantly inhibited spore germination. Application of these two compounds to the leaves of a susceptible host also significantly increased resistance to infection. In contrast, palmitic acid promoted spore germination and, when applied to the leaves of a resistant genotype, increased colonization by the pathogen. This is the first study providing insights into differences in the leaf wax composition of hosts with different levels of susceptibility to T. destructans. It also showed that leaf wax compounds can modulate spore germination and, ultimately, host resistance to infection.

PpyLTP36 and PpyLTP39 are involved in the transmembrane transport of cuticular wax and are associated with the occurrence of pear fruit russeting

Non-specific lipid-transfer proteins (nsLTPs) are a group of small, cysteine-rich proteins that are involved in the transport of cuticular wax and other lipid compounds. Accumulating evidence suggests that dynamic changes in cuticular waxes are strongly associated with fruit russeting, an undesirable visual quality that negatively affects consumer appeal in pears. Currently, the regulatory role of nsLTPs in cuticular wax deposition and pear fruit skin russeting remains unclear. Here, we characterized the variations of cuticular waxes in non-treated (russeted) and preharvest bagging treated (non-russeted) pear fruits throughout fruit development and confirmed that the contents of cuticular waxes were significantly negatively correlated with the occurrence of pear fruit russeting. Based on RNA-Sequencing (RNA-Seq) and quantitative real-time PCR (qRT-PCR) analyses, two nsLTP genes (PpyLTP36 and PpyLTP39) were identified, which exhibited high expression levels in non-russeted pear fruit skins and were significantly repressed during fruit skin russeting. Subcellular localization analysis demonstrated that PpyLTP36 and PpyLTP39 were localized to the plasma membrane (PM). Further, transient Virus-Induced Gene Silencing (VIGS) analyses of PpyLTP36 and PpyLTP39 in pear fruits significantly reduced cuticular wax deposition. In conclusion, PpyLTP36 and PpyLTP39 are involved in the transmembrane transport of cuticular wax and are associated with pear fruit skin russeting.

From the archives: Epidermal affairs-EVER links floral scent with cuticular waxes, while SPL9 and DEWAX connect them to diurnal regulation, and FIDDLEHEAD takes on a function in the epidermis.

From the archives: Epidermal affairs-EVER links floral scent with cuticular waxes, while SPL9 and DEWAX connect them to diurnal regulation, and FIDDLEHEAD takes on a function in the epidermis.

Identification of long-chain acyl-CoA synthetase gene family reveals that SlLACS1 is essential for cuticular wax biosynthesis in tomato

Long-chain acyl-CoA synthetases (LACSs), belonging to the acyl-activating enzyme superfamily, play crucial roles in lipid biosynthesis and fatty acid catabolism. Here, we identified 11 LACS genes in the tomato reference genome, and these genes were clustered into six subfamilies. Gene structure and conserved motif analyses indicated that LACSs from the same subfamily shared conserved gene and protein structures. Expression analysis revealed that SlLACS1 was highly expressed in the outer epidermis of tomato fruits and leaves. Subcellular localization assay results showed that SlLACS1 was located in the endoplasmic reticulum. Compared with wild-type plants, the wax content on leaves and fruits decreased by 22.5–34.2 % in SlLACS1 knockout lines, confirming that SlLACS1 was involved in wax biosynthesis in both leaves and fruits. Water loss, chlorophyll extraction, water-deficit, and toluidine blue assays suggested that cuticle permeability was elevated in SlLACS1 knockout lines, resulting in reduction in both drought stress resistance and fruit shelf-life. Overall, our analysis of the LACSs in tomato, coupled with investigations of SlLACS1 function, yielded a deeper understanding of the evolutionary patterns of LACS members and revealed the involvement of SlLACS1 in wax accumulation contribute to drought resistance and extended fruit shelf-life in tomato.

BrWax1 function in wax biosynthesis was verified by allelic mutations in Chinese cabbage

The primary function of cuticular wax is to prevent non-stomatal water loss, while the wax deficiency conferring a glossy appearance on plants is conductive to crop commodity qualities. We previously mapped a wax-deficient gene BrWax1 in a natural mutant ‘08A235-2’ by SSR marker, and predicted Bra013809 (BrWax1) as the candidate gene in Chinese cabbage (Brassica rapa L. ssp. pekinensis). In order to verifying the function of BrWax1, two allelic wax-crystal deficiency mutants wdm4 and wdm8 from an EMS mutagenesis population of Chinese cabbage were screened. wdm4 was applied to identify the mutant gene, with the finding that BraA01g015290.3C, the homologous of AT4G24510 (AtCER2), was the candidate gene. Bra013809 in Brara_Chiifu_V1.5 and BraA01g015290.3C in Brara_Chiifu_V3.0 were annotated as the same gene in Brassicaceae Database. A SNP (C to T) on BrWax1 in wdm4 resulted in a stopgain, and a SNP (G to A) on BrWax1 in wdm8 led to the deletion of 38 bases which caused a stopgain at the 190th amino acid. These results finally verified the function of BrWax1 in the wax biosynthesis. Our findings emphasize the crucial role of the BrWax1 gene in cuticular wax biosynthesis in Chinese cabbage and suggest its potential as a valuable genetic resource for breeding for glossy appearance.

A high-quality genome assembly reveals adaptations underlying glossy, wax-coated leaves in the heat-tolerant wild raspberry Rubus leucanthus.

With glossy, wax-coated leaves, Rubus leucanthus is one of the few heat-tolerant wild raspberry trees. To ascertain the underlying mechanism of heat tolerance, we generated a high-quality genome assembly with a genome size of 230.9 Mb and 24,918 protein-coding genes. Significantly expanded gene families were enriched in the flavonoid biosynthesis pathway and the circadian rhythm-plant pathway, enabling survival in subtropical areas by accumulating protective flavonoids and modifying photoperiodic responses. In contrast, plant-pathogen interaction and MAPK signaling involved in response to pathogens were significantly contracted. The well-known heat response elements (HSP70, HSP90, and HSFs) were reduced in R. leucanthus compared to two other heat-intolerant species, R. chingii and R. occidentalis, with transcriptome profiles further demonstrating their dispensable roles in heat stress response. At the same time, three significantly positively selected genes in the pathway of cuticular wax biosynthesis were identified, and may contribute to the glossy, wax-coated leaves of R. leucanthus. The thick, leathery, waxy leaves protect R. leucanthus against pathogens and herbivores, supported by the reduced R gene repertoire in R. leucanthus (355) compared to R. chingii (376) and R. occidentalis (449). Our study provides some insights into adaptive divergence between R. leucanthus and other raspberry species on heat tolerance.

Identification of Biomarkers Associated with Phyllosticta citricarpa Tolerance.

Citrus black spot (CBS) is a fungal disease caused by Phyllosticta citricarpa Kiely, (McAlpine Van der Aa), with most cultivars being susceptible to infection. Currently, disease control is based on the application of protective fungicides, which is restricted due to resistance, health and environmental concerns. Although using natural products for disease management is gaining momentum, more advances are required. This study obtained the metabolic profiles of the essential oil and cuticular waxes of two citrus cultivars with a varying susceptibility to CBS infection using gas chromatography-mass spectrometry. A multivariate data analysis identified possible biomarker compounds that contributed to the difference in susceptibility between the two cultivars. Several identified biomarkers were tested in vitro for their antifungal properties against P. citricarpa. Two biomarkers, propanoic acid and linalool, were able to completely inhibit pathogen growth at 750 mg/L and 2000 mg/L, respectively.

Compositional analysis of tuberose floral cuticle sheds light on scent volatile emission and cuticle deposition

The plant cuticle acts as a vital shield, safeguarding against environmental and biological stresses. Tuberose flowers, specifically the ‘Calcutta Single’ and ‘Calcutta Double’ cultivars of Agave amica (syn. Polianthes tuberosa), are highly prized in India for their aromatic and aesthetic appeal. This research examines the tuberose floral cuticle using GC-MS to identify key chemical components and their characteristics. The analysis uncovered six major chemical classes viz. fatty acids, fatty alcohols, esters, alkanes, alkenes, and aldehydes as the primary constituents of the cuticular wax. Fatty acids and fatty alcohols are dominant in both cultivars, with ‘Calcutta Single’ displaying a higher ester content than ‘Calcutta Double’. This study represents the inaugural in-depth exploration of cuticular wax in tuberose flowers, presenting a comparative investigation into these prominent cultivars.