UV-B absorbance and UV-B absorbing compounds (para-coumaric acid) in pollen and sporopollenin: the perspective to track historic UV-B levels

Rozema, J.; Broekman, Rob; Blokker, Peter; Meijkamp, B.B.; Bakker, N.V.J. de; Staaij, J. van de; Beem, A. van; Ariese, Freek; Kars, S.

doi:10.1016/s1011-1344(01)00155-5

Cited by 134 publications

(125 citation statements)

References 33 publications

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“…Chemical analysis (Rozema et al, 2001;Bubert et al, 2002;Ahlers et al, 2003) and genetic and biochemical studies (Morant et al, 2007;de Azevedo Souza et al, 2009) have demonstrated the presence of lipidic and phenolic units in the sporopollenin polymer. The isolation of numerous mutants affected in exine synthesis has shown, on the other hand, that a large number of genes expressed in the anther tissues participate in the formation of the pollen cell wall, thus suggesting a high degree of complexity of the underlying processes.…”

Section: Discussion Previously Unknown Gene Functions Required For Pomentioning

confidence: 99%

“…Resulting polyhydroxylated tetraketide compounds may then be exported by ABCG26 and lipid transfer proteins (LTPs) to the locule as sporopollenin building units or further processed before transport and polymerization in the pollen wall. conquest of land by plants (Rozema et al, 2001;Blackmore et al, 2007). Indeed, the widespread occurrence of sporopollenin in pollen grains and spores of land plant lineages indicates the conservation of an ancient biosynthetic pathway during plant evolution.…”

Section: The Sporopollenin Biosynthetic Pathway Is Conserved In Land mentioning

confidence: 99%

“…At this stage, cellulosic primexine and pectocellulosic intine are produced by the developing microspores and constitute the inner layers of the pollen wall. The outer layer of pollen wall, called the exine, is composed primarily of sporopollenin, a polymer of phenylpropanoid and lipidic monomers covalently coupled by ether and ester linkages (Rozema et al, 2001;Bubert et al, 2002;Ahlers et al, 2003). Sporopollenin precursors are produced in the sporophyte tapetal cell layer surrounding the anther locule, then secreted and deposited on the pollen surface.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of TETRAKETIDE α-PYRONE REDUCTASE Function in Arabidopsis thaliana Reveals a Previously Unknown, but Conserved, Biochemical Pathway in Sporopollenin Monomer Biosynthesis

et al. 2010

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The precise structure of the sporopollenin polymer that is the major constituent of exine, the outer pollen wall, remains poorly understood. Recently, characterization of Arabidopsis thaliana genes and corresponding enzymes involved in exine formation has demonstrated the role of fatty acid derivatives as precursors of sporopollenin building units. Fatty acyl-CoA esters synthesized by ACYL-COA SYNTHETASE5 (ACOS5) are condensed with malonyl-CoA by POLYKETIDE SYNTHASE A (PKSA) and PKSB to yield a-pyrone polyketides required for exine formation. Here, we show that two closely related genes encoding oxidoreductases are specifically and transiently expressed in tapetal cells during microspore development in Arabidopsis anthers. Mutants compromised in expression of the reductases displayed a range of pollen exine layer defects, depending on the mutant allele. Phylogenetic studies indicated that the two reductases belong to a large reductase/ dehydrogenase gene family and cluster in two distinct clades with putative orthologs from several angiosperm lineages and the moss Physcomitrella patens. Recombinant proteins produced in bacteria reduced the carbonyl function of tetraketide a-pyrone compounds synthesized by PKSA/B, and the proteins were therefore named TETRAKETIDE a-PYRONE REDUC-TASE1 (TKPR1) and TKPR2 (previously called DRL1 and CCRL6, respectively). TKPR activities, together with those of ACOS5 and PKSA/B, identify a conserved biosynthetic pathway leading to hydroxylated a-pyrone compounds that were previously unknown to be sporopollenin precursors.

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Section: Discussion Previously Unknown Gene Functions Required For Pomentioning

confidence: 99%

Section: The Sporopollenin Biosynthetic Pathway Is Conserved In Land mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of TETRAKETIDE α-PYRONE REDUCTASE Function in Arabidopsis thaliana Reveals a Previously Unknown, but Conserved, Biochemical Pathway in Sporopollenin Monomer Biosynthesis

et al. 2010

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“…The chemical composition of sporopollenin remains poorly characterized because it is extremely resistant to chemical and biological degradation procedures (Bubert et al, 2002;VizcayBarrena and Wilson, 2006). However, available data are consistent with a sporopollenin polymer consisting of phenolic and fatty acid-derived constituents that are covalently coupled by ether and ester linkages (Rozema et al, 2001;Bubert et al, 2002;Ahlers et al, 2003). Progress has been made in identifying genes and enzymes that are involved in sporopollenin biosynthesis and exine formation during pollen development and has revealed that enzymes involved in fatty acid metabolism play key roles in these events.…”

Section: Introductionmentioning

confidence: 90%

LAP6/POLYKETIDE SYNTHASE AandLAP5/POLYKETIDE SYNTHASE BEncode Hydroxyalkyl α-Pyrone Synthases Required for Pollen Development and Sporopollenin Biosynthesis inArabidopsis thaliana

et al. 2010

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Plant type III polyketide synthases (PKSs) catalyze the condensation of malonyl-CoA units with various CoA ester starter molecules to generate a diverse array of natural products. The fatty acyl-CoA esters synthesized by Arabidopsis thaliana ACYL-COA SYNTHETASE5 (ACOS5) are key intermediates in the biosynthesis of sporopollenin, the major constituent of exine in the outer pollen wall. By coexpression analysis, we identified two Arabidopsis PKS genes, POLYKETIDE SYNTHASE A (PKSA) and PKSB (also known as LAP6 and LAP5, respectively) that are tightly coexpressed with ACOS5. Recombinant PKSA and PKSB proteins generated tri-and tetraketide a-pyrone compounds in vitro from a broad range of potential ACOS5-generated fatty acyl-CoA starter substrates by condensation with malonyl-CoA. Furthermore, substrate preference profile and kinetic analyses strongly suggested that in planta substrates for both enzymes are midchain-and v-hydroxylated fatty acyl-CoAs (e.g., 12-hydroxyoctadecanoyl-CoA and 16-hydroxyhexadecanoyl-CoA), which are the products of sequential actions of anther-specific fatty acid hydroxylases and acyl-CoA synthetase. PKSA and PKSB are specifically and transiently expressed in tapetal cells during microspore development in Arabidopsis anthers. Mutants compromised in expression of the PKS genes displayed pollen exine layer defects, and a double pksa pksb mutant was completely male sterile, with no apparent exine. These results show that hydroxylated a-pyrone polyketide compounds generated by the sequential action of ACOS5 and PKSA/B are potential and previously unknown sporopollenin precursors.

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“…The biological role of the exines is to protect and transport the delicate genetic and nutrient payloads as part of the plant replication process. Therefore, the exines have evolved to be light shielding (Rozema et al, 2001;Atkin et al, 2011), antioxidant, elastic, and resilient, both chemically and physically. Such a wide range of properties endowed upon sporopollenin exines has attracted interest toward a wide range of applications, particularly where the raw pollen or spores can be obtained in bulk commercial amounts.…”

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confidence: 99%

Sporopollenin, The Least Known Yet Toughest Natural Biopolymer

et al. 2015

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Sporopollenin is highly cross-linked polymer composed of carbon, hydrogen, and oxygen that is extraordinarily stable and has been found chemically intact in sedimentary rocks some 500 million years old. It makes up the outer shell (exine) of plant spores and pollen and when extracted it is in the form of an empty exine or microcapsule. The exines resemble the spores and pollen from which they are extracted, in size and morphology. Also, from any one plant such characteristics are incredible uniform. The exines can be used as microcapsules or simply as micron-sized particles due to the variety of functional groups on their surfaces. The loading of a material into the chamber of the exine microcapsule is via multi-directional nano-diameter sized channels. The exines can be filled with a variety of polar and non-polar materials. Enzymes can be encapsulated within the shells and still remain active. In vivo studies in humans have shown that an encapsulated active substance can have a substantially increased bioavailability than if it is taken alone. The sporopollenin exine surface possesses phenolic, alkane, alkene, ketone, lactone, and carboxylic acid groups. Therefore, it can be derivatized in a number of ways, which has given rise to applications in areas, such as solid supported for peptide synthesis, catalysis, and ion-exchange chromatography. Also, the presence of the phenolic groups on sporopollenin endows it with antioxidant activity.

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UV-B absorbance and UV-B absorbing compounds (para-coumaric acid) in pollen and sporopollenin: the perspective to track historic UV-B levels

Cited by 134 publications

References 33 publications

Analysis of TETRAKETIDE α-PYRONE REDUCTASE Function in Arabidopsis thaliana Reveals a Previously Unknown, but Conserved, Biochemical Pathway in Sporopollenin Monomer Biosynthesis

Analysis of TETRAKETIDE α-PYRONE REDUCTASE Function in Arabidopsis thaliana Reveals a Previously Unknown, but Conserved, Biochemical Pathway in Sporopollenin Monomer Biosynthesis

LAP6/POLYKETIDE SYNTHASE AandLAP5/POLYKETIDE SYNTHASE BEncode Hydroxyalkyl α-Pyrone Synthases Required for Pollen Development and Sporopollenin Biosynthesis inArabidopsis thaliana

Sporopollenin, The Least Known Yet Toughest Natural Biopolymer

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