Carotenoid pigments in rust fungi: Extraction, separation, quantification and characterisation

Multivariate optimization and comparison between conventional extraction (CE) and ultrasonic-assisted extraction (UAE) of carotenoid extraction from cashew apple

Carotenoids are an essential component of cashew and can be used in pharmaceuticals, cosmetics, natural pigment, food additives, among other applications. The present work focuses on optimizing and comparing conventional and ultrasound-assisted extraction methods. Every optimization step took place with a 1:1 (w:w) mixture of yellow and red cashew apples lyophilized and ground in a cryogenic mill. A Simplex-centroid design was applied for both methods, and the solvents acetone, methanol, ethanol, and petroleum ether were evaluated. After choosing the extractor solvent, a central composite design was applied to optimize the sample mass (59-201 mg) and extraction time (6-34 min). The optimum conditions for the extractor solvent were 38% acetone, 30% ethanol, and 32% petroleum ether for CE and a mixture of 44% acetone and 56% methanol for UAE. The best experimental conditions for UAE were a sonication time of 19 min and a sample mass of 153 mg, while the CE was 23 min and 136 mg. Comparing red and yellow cashews, red cashews showed a higher carotenoid content in both methodologies. The UAE methodology was ca. 21% faster, presented a more straightforward composition of extracting solution, showed an average yield of superior carotenoid content in all samples compared to CE. Therefore, UAE has demonstrated a simple, efficient, fast, low-cost adjustment methodology and a reliable alternative for other applications involving these bioactive compounds in the studied or similar matrix.

Development of Natural Luminescent Powder for the Detection of Latent Fingerprint

<b>Background and Objective:</b> Nowadays, Dyes is widely used to improve fingerprints identification test. Natural dyes are another interesting way that can be used instead of chemical dyes because of its non-toxicity and lower cost. In this research, the development of rust powder from <i>Plumeria</i> tree was applied for fingerprints identification due to its fluorescence property under UV. Rust and Small Particle Reagent (SPR), containing ZnCO<sub>3 </sub>were applied to detect hidden fingerprints on non-porous surfaces in both dried and wet condition. <b>Materials and Methods:</b> Yellowish Rust from <i>Plumeria</i> tree was extracted with ethanol, grinded, dried and then mixed with ZnCO<sub>3</sub>. Powder slurry was sprayed over fingerprint mark on different surfaces and monitored in both dried and wet condition. Visualization of fingerprint under UV was observed. Scanning microscope (SEM), UV-visible spectroscopy (UV-VIS), Fourier-Transform Infrared Spectroscopy (FTIR) and Energy-Dispersive X-ray (EDX) were also used to characterize physical and chemical properties of rust powder. <b>Results:</b> Fingerprints identification by dust technique using <i>Plumeria</i> rust powder as ingredient, provide best quality enhancement of fingerprints under UV light due to its fluorescent property, whereas a conventional technique of Small Particle Reagent technique (SPR) doesn't show fluorescent under UV. Data from SEM and FTIR show slight adhesion between zinc carbonate particles and rust powder. <b>Conclusion:</b> Fluorescence properties of rust powder is still interesting. Further improvement in powder recipe will be further investigated.

Molecular Characterization of Fungal Pigments

The industrial application of pigments of biological origin has been gaining strength over time, which is mainly explained by the increased interest of the consumer for products with few synthetic additives. So, the search for biomolecules from natural origin has challenged food scientists and technologists to identify, develop efficient and less consuming strategies for extraction and characterization of biopigments. In this task, elucidation of molecular structure has become a fundamental requirement, since it is necessary to comply with compound regulatory submissions of industrial sectors such as food, pharmaceutical agrichemicals, and other new chemical entity registrations. Molecular elucidation consists of establishing the chemical structure of a molecule, which allows us to understand the interaction between the natural additive (colorant, flavor, antioxidant, etc) and its use (interaction with the rest of the mixture of compounds). Elucidation of molecular characteristics can be achieved through several techniques, the most common being infrared spectroscopy (IR), spectroscopy or ultraviolet-visible spectrophotometry (UV-VIS), nuclear-resonance spectroscopy (MAGNETIC MRI), and mass spectrometry. This review provides the details that aid for the molecular elucidation of pigments of fungal origin, for a viable and innocuous application of these biopigments by various industries.

Carotenoid biosynthesis and the evolution of carotenogenesis genes in rust fungi

Diseases caused by rust fungi pose a significant threat to global plant production. Although carotenoid pigments are produced in spores of nearly all rust species, the corresponding biosynthesis pathway(s) have not been investigated. Here, candidate genes for carotenoid biosynthesis in Puccinia graminis f. sp. tritici (Pgt) were identified, cloned and functionally complemented using specifically engineered strains of Escherichia coli. A part of the carotenoid biosynthesis pathway in rust fungi was elucidated, with only two genes, CrtYB and CrtI, catalysing the reactions from geranyl-geranyl diphosphate (GGPP) to γ-carotene. The CrtYB gene encodes a bi-functional lycopene cyclase/phytoene synthase, which catalyses the condensation of two GGPP into phytoene, as well as the cyclisation of the ψ-end of lycopene to form γ-carotene. The CrtI gene encodes a phytoene desaturase that carries out four successive desaturations of phytoene, through the intermediates phytofluene and neurosporene to lycopene. The evolution of carotenoid pigmentation in rust fungi, including Pgt, P. graminis avenae, P. graminis secalis (Pgs), P. graminis lolli, P. striiformis f. sp. tritici, P. striiformis f. sp. pseudohordei, P. striiformis f. sp. hordei, the "scabrum" rust (putative hybrids between Pgt and Pgs), P. triticina, and P. hordei, was investigated by phylogenetic analysis. Both CrtYB and CrtI were found to be closely related among rust fungi, other pathogenic fungi, and some aphids. Our results provide a springboard to increase the understanding of the physiological role(s) of carotenoid pigments in rust fungi, to better understand evolution within the Pucciniales, and to develop robust molecular diagnostics for rust fungi.

Ultrasonic-assisted extraction and high-speed counter-current chromatography purification of zeaxanthin dipalmitate from the fruits of Lycium barbarum L

Zeaxanthin dipalmitate (ZDP) is a major non-saponified carotenoid in fully ripe fruits of Lycium barbarum L. In the present study, response surface methodology was used to optimize the ultrasonic-assisted extraction (UAE) conditions of carotenoids from the fruits of L. barbarum, and the optimal extraction conditions were determined as follows: ultrasonic power of 360 W, ultrasonic time of 40 min and the ratio of extraction solvent to sample of 30 mL/g. An actual value of ZDP content of 5.40 mg/g and short extraction time indicated the efficiency of UAE. Furthermore, a promising high-speed counter-current chromatography (HSCCC) method was established for the purification of ZDP from the fruits of L. barbarum. With a developed two-phase solvent system composed of n-hexane/dichloromethane/acetonitrile (10/3/7, v/v/v), ZDP with a purity of higher than 95% was successfully isolated from the crude extract. This is the first report on the purification of ZDP by using HSCCC.

Carotenoid complement of rust spores: Variation among species and pathotype

Rust fungi, which are responsible for some of the world's most destructive plant diseases, are named for the distinctive rusty colour of one or more of their spore forms. Rust spore pigments are thought to provide protection against UV radiation and oxidative stress, and may act as virulence factors. However, with the exception of daisy rust spores, the identity and relative abundance of the carotenoids in the rust spore cytoplasm have not been investigated using modern analytical methods, and little is known about the dependence of the carotenoid complement on species, pathotype, spore-colour mutations and season. We developed and validated a method to separate, identify and quantify rust carotenoids by reversed-phase high-performance liquid chromatography (RP-HPLC) combined with mass spectrometry. The carotenoids identified were lycopene, γ-carotene, β-carotene and phytoene. Rates of carotenoid degradation depended greatly on spore storage conditions, with freezing at -80 °C providing optimal stability. Carotenoid profiles of 103 isolates from 14 rust species were compared, showing that the ratio γ-carotene:β-carotene varied substantially among species. Total carotenoid content was generally lower in spring than in autumn (Sydney, Australia)-possibly due to differences in solar exposure-but the percentage of individual carotenoids was relatively stable. Among the colour mutants tested, chocolate mutants of Puccinia graminis f. sp. tritici (wheat stem rust) contained no carotenoid pigments, while albino mutants of P. striiformis f. sp. tritici (wheat stripe rust) contained only phytoene, a colourless carotenoid. We discuss our results in terms of the biogenesis and biological functions of carotenoids in rust fungi.

Multispectral, Aerial Disease Detection for Myrtle Rust (Austropuccinia psidii) on a Lemon Myrtle Plantation

Disease management in agriculture often assumes that pathogens are spread homogeneously across crops. In practice, pathogens can manifest in patches. Currently, disease detection is predominantly carried out by human assessors, which can be slow and expensive. A remote sensing approach holds promise. Current satellite sensors are not suitable to spatially resolve individual plants or lack temporal resolution to monitor pathogenesis. Here, we used multispectral imaging and unmanned aerial systems (UAS) to explore whether myrtle rust (Austropuccinia psidii) could be detected on a lemon myrtle (Backhousia citriodora) plantation. Multispectral aerial imagery was collected from fungicide treated and untreated tree canopies, the fungicide being used to control myrtle rust. Spectral vegetation indices and single spectral bands were used to train a random forest classifier. Treated and untreated trees could be classified with high accuracy (95%). Important predictors for the classifier were the near-infrared (NIR) and red edge (RE) spectral band. Taking some limitations into account, that are discussedherein, our work suggests potential for mapping myrtle rust-related symptoms from aerial multispectral images. Similar studies could focus on pinpointing disease hotspots to adjust management strategies and to feed epidemiological models.

Spatial Referencing of Hyperspectral Images for Tracing of Plant Disease Symptoms

The characterization of plant disease symptoms by hyperspectral imaging is often limited by the missing ability to investigate early, still invisible states. Automatically tracing the symptom position on the leaf back in time could be a promising approach to overcome this limitation. Therefore we present a method to spatially reference time series of close range hyperspectral images. Based on reference points, a robust method is presented to derive a suitable transformation model for each observation within a time series experiment. A non-linear 2D polynomial transformation model has been selected to cope with the specific structure and growth processes of wheat leaves. The potential of the method is outlined by an improved labeling procedure for very early symptoms and by extracting spectral characteristics of single symptoms represented by Vegetation Indices over time. The characteristics are extracted for brown rust and septoria tritici blotch on wheat, based on time series observations using a VISNIR (400–1000 nm) hyperspectral camera.