Zygospore development of Spirogyra (Charophyta) investigated by serial block-face scanning electron microscopy and 3D reconstructions.

Sexual reproduction of Zygnematophyceae by conjugation is a less investigated topic due to the difficulties of the induction of this process and zygospore ripening under laboratory conditions. For this study, we collected field sampled zygospores of Spirogyra mirabilis and three additional Spirogyra strains in Austria and Greece. Serial block-face scanning electron microscopy was performed on high pressure frozen and freeze substituted zygospores and 3D reconstructions were generated, allowing a comprehensive insight into the process of zygospore maturation, involving storage compound and organelle rearrangements. Chloroplasts are drastically changed, while young stages contain both parental chloroplasts, the male chloroplasts are aborted and reorganised as 'secondary vacuoles' which initially contain plastoglobules and remnants of thylakoid membranes. The originally large pyrenoids and the volume of starch granules is significantly reduced during maturation (young: 8 ± 5 µm³, mature: 0.2 ± 0.2 µm³). In contrast, lipid droplets (LDs) increase significantly in number upon zygospore maturation, while simultaneously getting smaller (young: 21 ± 18 µm³, mature: 0.1 ± 0.2 and 0.5 ± 0.9 µm³). Only in S. mirabilis the LD volume increases (34 ± 29 µm³), occupying ~50% of the zygospore volume. Mature zygospores contain barite crystals as confirmed by Raman spectroscopy with a size of 0.02 - 0.05 µm³. The initially thin zygospore cell wall (~0.5 µm endospore, ~0.8 µm exospore) increases in thickness and develops a distinct, electron dense mesospore, which has a reticulate appearance (~1.4 µm) in Spirogyra sp. from Greece. The exo- and endospore show cellulose microfibrils in a helicoidal pattern. In the denser endospore, pitch angles of the microfibril layers were calculated: ~18 ± 3° in S. mirabilis, ~20 ± 3° in Spirogyra sp. from Austria and ~38 ± 8° in Spirogyra sp. from Greece. Overall this study gives new insights into Spirogyra sp. zygospore development, crucial for survival during dry periods and dispersal of this genus.

Sporopollenin Capsules as Biomimetic Templates for the Synthesis of Hydroxyapatite and ß-TCP.

Pollen grains, with their resilient sporopollenin exine and defined morphologies, have been explored as bio-templates for the synthesis of calcium phosphate minerals, particularly hydroxyapatite (HAp) and ß-tricalcium phosphate (TCP). Various pollen morphologies from different plant species (black alder, dandelion, lamb's quarters, ragweed, and stargazer lily) were evaluated. Pollen grains underwent acid washing to remove allergenic material and facilitate subsequent calcification. Ragweed and lamb's quarter pollen grains were chosen as templates for calcium phosphate salts deposition due to their distinct morphologies. The calcification process yielded well-defined spherical hollow particles. The washing step, intended to reduce the protein content, did not significantly affect the final product; thus, justifying the removal of this low-yield step from the synthesis process. Characterisation techniques, including X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermal gravimetric analysis, confirmed the successful calcification of pollen-derived materials, revealing that calcified grains were principally composed of calcium deficient HAp. After calcination, biphasic calcium phosphate composed of HAp and TPC was obtained. This study demonstrated the feasibility of using pollen grains as green and sustainable bio-templates for synthesizing biomaterials with controlled morphology, showcasing their potential in biomedical applications such as drug delivery and bone regeneration.

A subclass II bHLH transcription factor in Marchantia polymorpha gives insight into the ancestral land plant trait of spore formation.

Sporopollenin is often said to be one of the toughest biopolymers known to man. The shift in dormancy cell wall deposition from around the diploid zygotes of charophycean algae to sporopollenin around the haploid spores of land plants essentially imparted onto land plants the gift of passive motility, a key acquisition that contributed to their vast and successful colonization across terrestrial habitats.1,2 A putative transcription factor controlling the land plant mode of sporopollenin deposition is the subclass II bHLHs, which are conserved and novel to land plants, with mutants of genes in angiosperms and mosses divulging roles relating to tapetum degeneration and spore development.3,4,5,6,7 We demonstrate that a subclass II bHLH gene, MpbHLH37, regulates sporopollenin biosynthesis and deposition in the model liverwort Marchantia polymorpha. Mpbhlh37 sporophytes show a striking loss of secondary wall deposits of the capsule wall, the elaters, and the spore exine, all while maintaining spore viability, identifying MpbHLH37 as a master regulator of secondary wall deposits of the sporophyte. Localization of MpbHLH37 to the capsule wall and elaters of the sporophyte directly designates these tissue types as a bona fide tapetum in liverworts, giving support to the notion that the presence of a tapetum is an ancestral land plant trait. Finally, as early land plant spore walls exhibit evidence of tapetal deposition,8,9,10,11,12 a tapetal capsule wall could have provided these plants with a developmental mechanism for sporopollenin deposition.

A new bodipy/pillar[5]arene functionalized magnetic sporopollenin for the detection of Cu(II) and Hg(II) ions in aqueous solution.

In this study, a new bodipy/pillar[5]arene functionalized magnetic MS-Sp-P[5]-bodipy microcapsule sensor was prepared based on the use of environmentally friendly for the selective and sensitive detection of Cu(II) and Hg(II) ions in aqueous media. SEM results used in the characterization process of the materials synthesized at each stage confirmed the structural and morphological changes in the pore structure, while other characterization results (FT-IR and XRD) elucidated the role of pillar[5]arene compound and bodipy dye in the synthesis of magnetic microcapsule sensors. The colloidal solution of MS-Sp-P[5]-bodipy (water/ethanol)) showed two fluorescence bands centered at 402 and 540 nm. The detection limits of MS-Sp-P[5]-bodipy for Hg(II) and Cu(II) were calculated to be 0.06 µM and 2.27 µM, respectively (at 540 nm). The linear range of the magnetic sensor for Hg(II) and Cu(II) was found to be in the range of 1-150 µM and 10-150 µM, respectively. The experimental results (response time, pH, temperature, sensitivity and selectivity) demonstrated the applicability and potential of the prepared magnetic microcapsule sensor for the detection of Cu(II) and Hg(II) in water and tap water samples containing heavy metal ions.

CRISPR/Cas9-based genome editing of 14 lipid metabolic genes reveals a sporopollenin metabolon ZmPKSB-ZmTKPR1-1/-2 required for pollen exine formation in maize.

Lipid biosynthesis and transport are essential for plant male reproduction. Compared with Arabidopsis and rice, relatively fewer maize lipid metabolic genic male-sterility (GMS) genes have been identified, and the sporopollenin metabolon in maize anther remains unknown. Here, we identified two maize GMS genes, ZmTKPR1-1 and ZmTKPR1-2, by CRISPR/Cas9 mutagenesis of 14 lipid metabolic genes with anther stage-specific expression patterns. Among them, tkpr1-1/-2 double mutants displayed complete male sterility with delayed tapetum degradation and abortive pollen. ZmTKPR1-1 and ZmTKPR1-2 encode tetraketide α-pyrone reductases and have catalytic activities in reducing tetraketide α-pyrone produced by ZmPKSB (polyketide synthase B). Several conserved catalytic sites (S128/130, Y164/166 and K168/170 in ZmTKPR1-1/-2) are essential for their enzymatic activities. Both ZmTKPR1-1 and ZmTKPR1-2 are directly activated by ZmMYB84, and their encoded proteins are localized in both the endoplasmic reticulum and nuclei. Based on protein structure prediction, molecular docking, site-directed mutagenesis and biochemical assays, the sporopollenin biosynthetic metabolon ZmPKSB-ZmTKPR1-1/-2 was identified to control pollen exine formation in maize anther. Although ZmTKPR1-1/-2 and ZmPKSB formed a protein complex, their mutants showed different, even opposite, defective phenotypes of anther cuticle and pollen exine. Our findings discover new maize GMS genes that can contribute to male-sterility line-assisted maize breeding and also provide new insights into the metabolon-regulated sporopollenin biosynthesis in maize anther.

Adsorption behavior and mechanism of modified Pinus massoniana pollen microcarriers for extremely efficient and rapid adsorption of cationic methylene blue dye.

Herein, a novel biosorbent was successfully fabricated through a two-step process employing Pinus massoniana pollen as raw material. The efficacy of this biosorbent in eliminating methylene blue (MB), a typical organic cationic dye, from highly concentrated industrial wastewater was investigated. The results demonstrated that by adjusting the wettability of pollen microcarriers, it is possible to significantly increase their adsorption capacity for cationic dyes, resulting in a remarkable 25-fold improvement. The modified Pinus massoniana pollen microcarriers (MPPMC) exhibited an optimal adsorption capacity (585 mg/g) under specific conditions and a rapid equilibrium (97.6% in 5 min, uptake 487.8 mg/g) even at room temperature, showing excellent performance in removing MB efficiently and quickly. It is worth noting that the modified microcarriers could be regenerated via a simple pH-controlled adsorption-desorption cycle, maintaining their superior efficiency (> 99%) even after undergoing five cycles, indicating their excellent reproducibility. The MB adsorption process on MPPMC obeyed the pseudo-second-order kinetic model and followed the Langmuir model. Through the introduced modifications, the substantial deprotonation of carboxyl groups notably augmented electrostatic and hydrogen bonding interactions between MPPMC and MB. Overall, this study offers a sustainable, eco-friendly biological adsorbent, and the MPPMC exhibit the considerable potential for efficient and rapid removal of organic cationic dyes in wastewater.

Characterization and expression analysis of chalcone synthase gene family members suggested their roles in the male sterility of a wheat temperature-sensitive genic male sterile (TGMS) line.

Chalcone synthase (CHS), also known as the plants-specific type III polyketide synthases (PKSs), catalyzes the first key step in the biosynthesis of plant flavonoids. Flavonoids are one of the most important secondary metabolites which participate in flower pigmentation and pollen fertility. Recent reports have demonstrated the role of the CHS family in plant pollen exine formation. This study focused on the potential roles of CHS in the pollen exine formation of wheat. In the present study, a genome-wide investigation of the CHS family was carried out, and 87 CHS genes were identified in wheat. TaCHS3, TaCHS10, and TaCHS13 are wheat orthologs of Arabidopsis LESS ADHESIVE POLLEN (LAP5); TaCHS58, TaCHS64, and TaCHS67 are wheat orthologs of AtLAP6. TaCHS3, TaCHS10, and TaCHS67 showed anther-specific patterns. The expression of TaCHS3, TaCHS10, and TaCHS67 was positively co-expressed with sporopollenin biosynthetic genes, including TaCYP703A2, TaCYP704B1, TaDRL1, TaTKPR2, and TaMS2. Coincidently, the expression of TaCHS3, TaCHS10, and TaCHS67, together with those sporopollenin biosynthetic genes, were repressed at the tetrads and uninucleate stages in the temperature-sensitive genic male-sterile (TGMS) line BS366 under sterile conditions. Wheat anther-specific CHS genes might participate in the exine formation of BS366 through co-expressing with sporopollenin biosynthetic genes, which will undoubtedly provide knowledge of the roles of CHS in wheat pollen development.

VAMP726 from maize and Arabidopsis confers pollen resistance to heat and UV radiation by influencing lignin content of sporopollenin.

Sporopollenin in the pollen cell wall protects male gametophytes from stresses. Phenylpropanoid derivatives, including guaiacyl (G) lignin units, are known to be structural components of sporopollenin, but the exact composition of sporopollenin remains to be fully resolved. We analyzed the phenylpropanoid derivatives in sporopollenin from maize and Arabidopsis by thioacidolysis coupled with nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS). The NMR and GC-MS results confirmed the presence of p-hydroxyphenyl (H), G, and syringyl (S) lignin units in sporopollenin from maize and Arabidopsis. Strikingly, H units account for the majority of lignin monomers in sporopollenin from these species. We next performed a genome-wide association study to explore the genetic basis of maize sporopollenin composition and identified a vesicle-associated membrane protein (ZmVAMP726) that is strongly associated with lignin monomer composition of maize sporopollenin. Genetic manipulation of VAMP726 affected not only lignin monomer composition in sporopollenin but also pollen resistance to heat and UV radiation in maize and Arabidopsis, indicating that VAMP726 is functionally conserved in monocot and dicot plants. Our work provides new insight into the lignin monomers that serve as structural components of sporopollenin and characterizes VAMP726, which affects sporopollenin composition and stress resistance in pollen.

OsTKPR1 proteins with a single amino acid substitution fail the synthesis of a specific sporopollenin precursor and cause abnormal exine and pollen development in rice.

Fatty acid derivatives are key components of rice pollen exine. The synthesis of aliphatic sporopollenin precursors are initiated in the plastids of the tapetal cells, followed by multiple-step reactions conducted in the endoplasmic reticulum (ER). However, the relative contribution of different precursors to the precise structure of sporopollenin remains largely elusive, let alone the underlying mechanism. Here, we report that two complete male sterile mutants ostkpr1-3 (Tetraketide α-pyrone reductase 1-3, with OsTKPR1P124S substitution) and ostkpr1-4 (with truncated OsTKPR1stop) are defective in pollen exine, Ubisch body and anther cuticle development where ostkpr1-4 display severer phenotypes. Remarkably, OsTKPR1 could produce reduced hydroxylated tetraketide α-pyrone and reduced tetraketide α-pyrone, whereas OsTKPR1P124S fails to produce the latter. Pairwise interaction assays show that mutated OsTKPR1P124S is able to integrate into a recently characterized metabolon, thus its altered catalytic activity is not due to dis-integrity of the metabolon. In short, we find that reduced tetraketide α-pyrone is a key sporopollenin precursor required for normal exine formation, and the conserved 124th proline of OsTKPR1 is essential for the reduction activity. Therefore, this study provided new insights into the sporopollenin precursor constitution critical for exine formation.

Multifaceted roles of pollen in the management of cancer.

Oral drug delivery of microparticles demonstrates shortcomings like aggregation, decreased loading capacity and batch-to-batch variation, which limits its scale-up. Later, porous structures gained attention because of their large surface-to-volume ratio, high loading capacity and ability to carry biomacromolecules, which undergo degradation in GIT. But there are pitfalls like non-uniform particle size distribution, the impact of porogen properties, and harsh chemicals. To circumvent these drawbacks, natural carriers like pollen are explored in drug delivery, which withstands harsh environments. This property helps to subdue the acid-sensitive drug in GIT. It shows uniform particle size distribution within the species. On the other side, they contain phytoconstituents like flavonoids and polysaccharides, which possess various pharmacological applications. Therefore, pollen has the capability as a carrier system and therapeutic agent. This review focuses on pollen's microstructure, composition and utility in cancer management. The extraction strategies, characterisation techniques and chemical structure of sporopollenin exine capsule, its use in the oral delivery of antineoplastic drugs, and emerging cancer treatments like photothermal therapy, immunotherapy and microrobots have been highlighted. We have mentioned a note on the anticancer activity of pollen extract. Further, we have summarised the regulatory perspective, bottlenecks and way forward associated with pollen.

Ultrasonic-assisted photocatalytic degradation of various organic contaminants using ZnO supported on a natural polymer of sporopollenin.

Water resource pollution by organic contaminants is an environmental issue of increasing concern. Here, sporopollenin/zinc oxide (SP/ZnO) was used as an environmentally friendly and durable catalyst for sonophotocatalytic treatment of three organic compounds: direct blue 25 (DB 25), levofloxacin (LEV), and dimethylphtalate (DMPh). The resulting catalyst had a 2.65 eV bandgap value and 9.81 m2/g surface area. The crystalline structure and functional groups of SP/ZnO were confirmed by X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR) analyses. After 120 min of the sonophotocatalysis, the degradation efficiencies of DB 25, LEV, and DMPh by SP/ZnO were 86.41, 75.88, and 62.54%, respectively, which were higher than that of the other investigated processes. The role of reactive oxygen species were investigated using various scavengers, enhancers, photoluminescence, and o-phenylenediamine. Owing to its stability, the catalyst exhibited good reusability after four consecutive cycles. In addition, the high integrity of the catalyst was confirmed by scanning electron microscopy (SEM), XRD, and FTIR analyses. After four consecutive examinations, the leaching of zinc in the aqueous phase was < 3 mg/L. Moreover, gas chromatography-mass spectrometry (GC-MS) analyses indicated that the contaminants were initially converted into cyclic compounds and then into aliphatic compounds, including carboxylic acids and animated products. Thus, this study synthesized an environmentally friendly and reusable SP/ZnO composite for the degradation of various organic pollutants using a sonophotocatalytic process.

Magnetic sporopollenin supported magnesium nanoparticles for removal of tetracycline as an emerging contaminant from water.

Since the release of antibiotics as emerging contaminants into the environmental water can cause severe difficulties for human health, their removal from the water is necessary. In this regard, a novel environmentally friendly adsorbent was developed based on green sporopollenin, which was magnetized and modified with magnesium oxide nanoparticles to produce MSP@MgO nanocomposite. The newly developed adsorbent was applied to remove tetracycline antibiotic (TC) from aqueous media. The surface morphology of the MSP@MgO nanocomposite was characterized using FTIR, XRD, EDX, and SEM techniques. The effective parameters of the removal process were studied, and it was confirmed that the chemical structure of TC was highly affected by changes in pH solution due to different pKa; therefore, the results showed that pH 5 was the optimum. Also, the maximum sorption capacity of MSP@MgO for TC for adsorption was obtained at 109.89 mg.g-1. In addition, the adsorption models were investigated, and the process was fitted with the Langmuir model. Thermodynamic parameters showed that the process was spontaneous (ΔG < 0), endothermic (ΔH > 0) and the adsorption mechanism was following the physisorption mechanism at room temperature.

Microspore-expressed SCULP1 is required for p-coumaroylation of sporopollenin, exine integrity, and pollen development in wheat.

Sporopollenin is one of the most structurally sophisticated and chemically recalcitrant biopolymers. In higher plants, sporopollenin is the dominant component of exine, the outer wall of pollen grains, and contains covalently linked phenolics that protect the male gametes from harsh environments. Although much has been learned about the biosynthesis of sporopollenin precursors in the tapetum, the nutritive cell layer surrounding developing microspores, little is known about how the biopolymer is assembled on the microspore surface. We identified SCULP1 (SKS clade universal in pollen) as a seed plant conserved clade of the multicopper oxidase family. We showed that SCULP1 in common wheat (Triticum aestivum) is specifically expressed in the microspore when sporopollenin assembly takes place, localized to the developing exine, and binds p-coumaric acid in vitro. Through genetic, biochemical, and 3D reconstruction analyses, we demonstrated that SCULP1 is required for p-coumaroylation of sporopollenin, exine integrity, and pollen viability. Moreover, we found that SCULP1 accumulation is compromised in thermosensitive genic male sterile wheat lines and its expression partially restored exine integrity and male fertility. These findings identified a key microspore protein in autonomous sporopollenin polymer assembly, thereby laying the foundation for elucidating and engineering sporopollenin biosynthesis.

Chrysanthemum sporopollenin: A novel vaccine delivery system for nasal mucosal immunity.

Objective: Mucosal immunization was an effective defender against pathogens. Nasal vaccines could activate both systemic and mucosal immunity to trigger protective immune responses. However, due to the weak immunogenicity of nasal vaccines and the lack of appropriate antigen carriers, very few nasal vaccines have been clinically approved for human use, which was a major barrier to the development of nasal vaccines. Plant-derived adjuvants are promising candidates for vaccine delivery systems due to their relatively safe immunogenic properties. In particular, the distinctive structure of pollen was beneficial to the stability and retention of antigen in the nasal mucosa. Methods: Herein, a novel wild-type chrysanthemum sporopollenin vaccine delivery system loaded with a w/o/w emulsion containing squalane and protein antigen was fabricated. The unique internal cavities and the rigid external walls within the sporopollenin skeleton construction could preserve and stabilize the inner proteins. The external morphological characteristics were suitable for nasal mucosal administration with high adhesion and retention. Results: Secretory IgA antibodies in the nasal mucosa can be induced by the w/o/w emulsion with the chrysanthemum sporopollenin vaccine delivery system. Moreover, the nasal adjuvants produce a stronger humoral response (IgA and IgG) compared to squalene emulsion adjuvant. Mucosal adjuvant benefited primarily from prolongation of antigens in the nasal cavity, improvement of antigen penetration in the submucosa and promotion of CD8+ T cells in spleen. Disccusion: Based on effective delivering both the adjuvant and the antigen, the increase of protein antigen stability and the realization of mucosal retention, the chrysanthemum sporopollenin vaccine delivery system has the potential to be a promising adjuvant platform. This work provide a novel idea for the fabrication of protein-mucosal delivery vaccine.

OsTKPR2 is part of a sporopollenin-producing metabolon required for exine formation in rice.

The sporopollenin polymer is a major component of the pollen exine. Fatty acid derivatives synthesized in the tapetum are among the precursors of sporopollenin. Progress has been made to understand sporopollenin metabolism in rice; however, the underlying molecular mechanisms remain elusive. We found that OsTKPR2 and OsTKPR1 share a similar expression pattern, and their coding proteins have a similar subcellular localization and enzyme activities towards reduced tetraketide α-pyrone and hydroxylated tetraketide α-pyrone. Unexpectedly, OsTKPR1pro:OsTKPR2-eGFP could not rescue the phenotype of ostkpr1-4. Three independent ostkpr2 mutant lines generated by CRISPR/Cas9 displayed reduced male fertility to various extents which were correlated with the severity of gene disruptions. Notably, the anther cuticle, Ubisch bodies, and pollen development were affected in the ostkpr2-1 mutant, where a thinner pollen exine was noticed. OsTKPR1 and OsTKPR2 were integrated into a metabolon including OsACOS12 and OsPKS2, which resulted in a significant increased enzymatic efficiency when both OsTKPR1 and OsTKPR2 were present, indicating the mutual dependence of OsTKPR2 and OsTKPR1 for their full biochemical activities. Thus, our results demonstrated that OsTKPR2 is required for anther and pollen development where an OsTKPR2-containing metabolon is functional during rice sporopollenin synthesis. Furthermore, the cooperation and possible functional divergence between OsTKPR2 and OsTKPR1 is also discussed.

A novel biosorbent functionalized pillar[5]arene: Synthesis, characterization and effective biosorption of Cr(VI).

Among toxic chemicals, hexavalent chromium (Cr(VI)) is one of the most carcinogenic and toxic pollutants that hostiles to the health of both humans and other living things. Therefore, the removal of Cr(VI) is of great importance to keep our environment clean and tidy. In this study, an easy-make, inexpensive, and natural biosorbent material (Sp-P[5]) was prepared to preserve our environment using a pillar[5]arene based-on sporopollenin microcapsule. The prepared biosorbent was successfully characterized by some techniques such as FTIR, XRD, and SEM. The biosorbent, Sp-P[5], exhibited an open mesoporous structure richly decorated with multi-amine-containing moieties resulting in enhanced Cr(VI) sorption. The sorption behavior of Cr(VI) ions is satisfactorily adapted from the sorption kinetics pseudo-second-order law and the isotherm models to the Langmuir model at different temperatures. The Langmuir model fits at different temperatures (298-328 K) and the maximum sorption capacities of the Cr(VI) ion ranged from 106.38 to 117.26 mg/g. The thermodynamic calculations reveal that the sorption of Cr(VI) ions on the Sp-P[5] is entropy-driven, endothermic, and spontaneous. The prepared biosorbent was also applied to the natural wastewater samples and different ions (chromate and dichromate). The sorption and desorption experiments showed that the sorption efficiency for Cr(VI) ions of the Sp-P[5] decreased to 70.88 % after 8 cycles. As result, the synthesized biosorbent, Sp-P[5], has outstanding potential in the removal of Cr(VI) ions from water bodies and natural wastewater systems.

Rice anther tapetum: a vital reproductive cell layer for sporopollenin biosynthesis and pollen exine patterning.

The tapetum is the innermost layer of the four layers of the rice anther that provides protection and essential nutrients to pollen grain development and delivers precursors for pollen exine formation. The tapetum has a key role in the normal development of pollen grains and tapetal programmed cell death (PCD) that is linked with sporopollenin biosynthesis and transport. Recently, many genes have been identified that are involved in tapetum formation in rice and Arabidopsis. Genetic mutation in PCD-associated genes could affect normal tapetal PCD, which finally leads to aborted pollen grains and male sterility in rice. In this review, we discuss the most recent research on rice tapetum development, including genomic, transcriptomic and proteomic studies. Furthermore, tapetal PCD, sporopollenin biosynthesis, ROS activity for tapetum function and its role in male reproductive development are discussed in detail. This will improve our understanding of the role of the tapetum in male fertility using rice as a model system, and provide information that can be applied in rice hybridization and that of other major crops.

The Plant Fatty Acyl Reductases.

Fatty acyl reductase (FAR) is a crucial enzyme that catalyzes the NADPH-dependent reduction of fatty acyl-CoA or acyl-ACP substrates to primary fatty alcohols, which in turn acts as intermediate metabolites or metabolic end products to participate in the formation of plant extracellular lipid protective barriers (e.g., cuticular wax, sporopollenin, suberin, and taproot wax). FARs are widely present across plant evolution processes and play conserved roles during lipid synthesis. In this review, we provide a comprehensive view of FAR family enzymes, including phylogenetic analysis, conserved structural domains, substrate specificity, subcellular localization, tissue-specific expression patterns, their varied functions in lipid biosynthesis, and the regulation mechanism of FAR activity. Finally, we pose several questions to be addressed, such as the roles of FARs in tryphine, the interactions between transcription factors (TFs) and FARs in various environments, and the identification of post-transcriptional, translational, and post-translational regulators.

Sporopollenin Microcapsule: Sunscreen Delivery System with Photoprotective Properties.

In recent years, the demand for high-quality solar products that combine high efficacy with environmentally friendly characteristics has increased. Among the coral-safe sunscreens, ethylhexyl triazone (Uvinul® T150) is an effective organic UVB filter, photostable and practically insoluble in water, therefore difficult to be formulated in water-based products. Oil-free sunscreens are considered ideal for most skin types, as they are not comedogenic and do not leave the skin feeling greasy. Recent studies reported that pollen grains might represent innovative drug delivery systems for their ability to encapsulate and release active ingredients in a controlled manner. Before being used, the pollen grains must be treated to remove cellular material and biomolecules, which could cause allergic reactions in predisposed subjects; the obtained hollow structures possess uniform diameter and a rigid wall with openings that allow them to be filled with bioactive substances. In the present work, pollen from Lycopodium clavatum has been investigated both as a delivery system for ethylhexyl triazone and as an active ingredient by evaluating its photoprotective capacity. The goal is to obtain environmentally friendly solar aqueous formulations that take advantage of both sunscreen and sporopollenin microcapsules' UV protection with a relatively low cost, as these pollen grains are widely available.

Sporopollenin - Invincible biopolymer for sustainable biomedical applications.

The objective of this review article is to present the utility of Sporopollenin, a natural biopolymer, for a wide range of applications. Sporopollenin is a ubiquitous natural polymer and chief ingredient of plant pollen grains, spores and it is chemically inert. Sporopollenin has a beautifully sculpted, decorated, and nano porous surface that is species unique. In both organic and aqueous solutions, it is stable. Purified sporopollenin keeps its spore or pollen particle shape, size, and surface properties while remaining an empty shell (sporopollenin microcapsules). Sporopollenin microcapsules and Sporopollenin Exine Shells (SEC) from pollen grains of plants (Angiosperms), spores of Bryophytes, Pteridophytes Gymnosperms and fungi have been developed as new biomaterials for drug/vaccine delivery, catalyst support, and heavy metal removal, among other sustainable applications. This review paper could pave the way for further research into sporopollenin production and the development of novel biomimetic polymers with desirable inert characteristics. The authors anticipate that this unique renewable polymer, which is abundant in nature and can be made from a variety of plants and fungal sources, will have biomedical applications contributing to sustainability in the future.