The seed dormancy allele <Emphasis Type="Italic">TaSdr</Emphasis>-<Emphasis Type="Italic">A1a</Emphasis> associated with pre-harvest sprouting tolerance is mainly present in Chinese wheat landraces

Key message

We cloned TaSdr - A1 gene, and developed a gene-specific marker for TaSdr - A1 . A QTL for germination index at the TaSdr - A1 locus was identified in the Yangxiaomai/Zhongyou 9507 RIL population.

Abstract

Pre-harvest sprouting (PHS) affects yield and end-use quality in bread wheat (Triticum aestivum L.). In the present study we found an association between the TaSdr-A1 gene and PHS tolerance in bread wheat. TaSdr-A1 on chromosome 2A was cloned using a homologous cloning approach. Sequence analysis of TaSdr-A1 revealed an SNP at position 643, with the G allele being present in genotypes with lower germination index (GI) values and A in those with higher GI. These alleles were designated as TaSdr-A1a and TaSdr-A1b, respectively. A cleaved amplified polymorphism sequence (CAPS) marker Sdr2A based on the SNP was developed, and linkage mapping and QTL analysis were conducted to confirm the association between TaSdr-A1 and seed dormancy. Sdr2A was located in a 2.9 cM interval between SSR markers Xgwm95 and Xgwm372. A QTL for GI at the TaSdr-A1 locus explained 6.6, 7.3, and 8.2 % of the phenotypic variances in a Yangxiaomai/Zhongyou 9507 RIL population grown at Beijing, Shijiazhuang, and the averaged data from the two environments, respectively. Two sets of Chinese wheat cultivars used for validating the TaSdr-A1 polymorphism and the corresponding gene-specific marker Sdr2A showed that TaSdr-A1 was significantly associated with GI. Among 29 accessions with TaSdr-A1a, 24 (82.8 %) were landraces, indicating the importance of Chinese wheat landraces as sources of PHS tolerance. This study identified a novel PHS resistance allele TaSdr-A1a mainly presented in Chinese landraces and it is likely to be the causal gene for QPhs.ccsu-2A.3, providing new information for an understanding of seed dormancy.

     

Introduction of chromosome segment carrying the seed storage protein genes from chromosome 1V of Dasypyrum villosum showed positive effect on bread-making quality of common wheat

Key message

Development of wheat- D. villosum 1V#4 translocation lines; physically mapping the Glu - V1 and Gli - V1 / Glu - V3 loci; and assess the effects of the introduced Glu - V1 and Gli - V1 / Glu - V3 on wheat bread-making quality.

Abstract

Glu-V1 and Gli-V1/Glu-V3 loci, located in the chromosome 1V of Dasypyrum villosum, were proved to have positive effects on grain quality. However, there are very few reports about the transfer of the D. villosum-derived seed storage protein genes into wheat background by chromosome manipulation. In the present study, a total of six CS-1V#4 introgression lines with different alien-fragment sizes were developed through ionizing radiation of the mature female gametes of CS––D. villosum 1V#4 disomic addition line and confirmed by cytogenetic analysis. Genomic in situ hybridization (GISH), chromosome C-banding, twelve 1V#4-specific EST–STS markers and seed storage protein analysis enabled the cytological physical mapping of Glu-V1 and Gli-V1/Glu-V3 loci to the region of FL 0.50–1.00 of 1V#4S of D. villosum. The Glu-V1 allele of D. villosum was Glu-V1a and its coded protein was V71 subunit. Quality analysis indicated that Glu-V1a together with Gli-V1/Glu-V3 loci showed a positive effect on protein content, Zeleny sedimentation value and the rheological characteristics of wheat flour dough. In addition, the positive effect could be maintained when specific Glu-V1 and Gli-V1/Glu-V3 loci were transferred to the wheat genetic background as in the case of T1V#4S-6BS·6BL, T1V#4S·1BL and T1V#4S·1DS translocation lines. These results showed that the chromosome segment carrying the Glu-V1 and Gli-V1/Glu-V3 loci in 1V#4S of D. villosum had positive effect on bread-making quality, and the T1V#4S-6BS·6BL and T1V#4S·1BL translocation lines could be useful germplasms for bread wheat improvement. The developed 1V#4S-specific molecular markers could be used to rapidly identify and trace the alien chromatin of 1V#4S in wheat background.     

Genetic mapping of a putative Thinopyrum intermedium-derived stripe rust resistance gene on wheat chromosome 1B

Key message

Stripe rust resistance transferred from Thinopyrum intermedium into common wheat was controlled by a single dominant gene, which mapped to chromosome 1B near Yr26 and was designated YrL693.

Abstract

Stripe rust caused by Puccinia striiformis f. sp. tritici (Pst) is a highly destructive disease of wheat (Triticum aestivum). Stripe rust resistance was transferred from Thinopyrum intermedium to common wheat, and the resulting introgression line (L693) exhibited all-stage resistance to the widely virulent and predominant Chinese pathotypes CYR32 and CYR33 and to the new virulent pathotype V26. There was no cytological evidence that L693 had alien chromosomal segments from Th. intermedium. Genetic analysis of stripe rust resistance was performed by crossing L693 with the susceptible line L661. F₁, F₂, and F_2:3 populations from reciprocal crosses showed that resistance was controlled by a single dominant gene. A total 479 F_2:3 lines and 781 pairs of genomic simple sequence repeat (SSR) primers were employed to determine the chromosomal location of the resistance gene. The gene was linked to six publicly available and three recently developed wheat genomic SSR markers. The linked markers were localized to wheat chromosome 1B using Chinese Spring nulli-tetrasomic lines, and the resistance gene was localized to chromosome 1B based on SSR and wheat genomic information. A high-density genetic map was also produced. The pedigree, molecular marker data, and resistance response indicated that the stripe rust resistance gene in L693 is a novel gene, which was temporarily designated YrL693. The SSR markers that co-segregate with this gene (Xbarc187-1B, Xbarc187-1B-1, Xgwm18-1B, and Xgwm11-1B) have potential application in marker-assisted breeding of wheat, and YrL693 will be useful for broadening the genetic basis of stripe rust resistance in wheat.     

Application of gliadin polymorphism for pedigree analysis in common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) from Northern Kazakhstan

Gliadins, seed storage proteins, are popular markers effectively employed for the analysis of common wheat. Gliadin electrophoretic patterns are genotype-specific, reproducible, not dependent on growing conditions and are suitable for germplasm identification complementary to molecular markers. Gliadins have been identified and used in wheat from various countries, but prior to this study little was known about gliadin polymorphism in wheat from Kazakhstan. In this study, 48 alleles of six gliadin-coding loci were identified in 43 cultivars of spring wheat from Northern Kazakhstan. The alleles Gli-A1 f , Gli-B1 e , Gli-D1 a , Gli-A2 p , Gli-B2 d and Gli-D2 e had maximal frequencies in each of the six loci. Identified Gli alleles in the loci formed ‘Gliadin Genetic Formula’ unique for each studied variety, and these were compared to the published data from previously analyzed wheat varieties. Pedigree analysis of 43 varieties studied for gliadin polymorphisms indicated that some Gli alleles were conserved and inherited from the progenitor cultivar Akmolinka 1. In contrast, other Gli alleles were replaced by those from modern germplasms. It is assumed that a higher frequency of gliadin alleles can be associated with the selection of genotypes with improved traits for yield and seed quality in the studied wheat cultivars from Northern Kazakhstan.     

Development of wheat–Aegilops speltoides recombinants and simple PCR-based markers for Sr32 and a new stem rust resistance gene on the 2S#1 chromosome

Key message

Wheat– Aegilops speltoides recombinants carrying stem rust resistance genes Sr32 and SrAes1t effective against Ug99 and PCR markers for marker-assisted selection.

Abstract

Wild relatives of wheat are important resources for new rust resistance genes but underutilized because the valuable resistances are often linked to negative traits that prevent deployment of these genes in commercial wheats. Here, we report ph1b-induced recombinants with reduced alien chromatin derived from E.R. Sears’ wheat–Aegilops speltoides 2D-2S#1 translocation line C82.2, which carries the widely effective stem rust resistance gene Sr32. Infection type assessments of the recombinants showed that the original translocation in fact carries two stem rust resistance genes, Sr32 on the short arm and a previously undescribed gene SrAes1t on the long arm of chromosome 2S#1. Recombinants with substantially shortened alien chromatin were produced for both genes, which confer resistance to stem rust races in the TTKSK (Ug99) lineage and representative races of all Australian stem rust lineages. Selected recombinants were back crossed into adapted Australian cultivars and PCR markers were developed to facilitate the incorporation of these genes into future wheat varieties. Our recombinants and those from several other labs now show that Sr32, Sr39, and SrAes7t on the short arm and Sr47 and SrAes1t on the long arm of 2S#1 form two linkage groups and at present no rust races are described that can distinguish these resistance specificities.     

Efficient isolation of ion beam-induced mutants for homoeologous loci in common wheat and comparison of the contributions of Glu-1 loci to gluten functionality

Key message

Ion beam mutations can be efficiently isolated and deployed for functional comparison of homoeologous loci in polyploid plants, and Glu - 1 loci differ substantially in their contribution to wheat gluten functionality.

Abstract

To efficiently conduct genetic analysis, it is beneficial to have multiple types of mutants for the genes under investigation. Here, we demonstrate that ion beam-induced deletion mutants can be efficiently isolated for comparing the function of homoeologous loci of common wheat (Triticum aestivum). Through fragment analysis of PCR products from M₂ plants, ion beam mutants lacking homoeologous Glu-A1, Glu-B1 or Glu-D1 loci, which encode high molecular weight glutenin subunits (HMW-GSs) and affect gluten functionality and end-use quality of common wheat, could be isolated simultaneously. Three deletion lines missing Glu-A1, Glu-B1 or Glu-D1 were developed from the original mutants, with the Glu-1 genomic regions deleted in these lines estimated using newly developed DNA markers. Apart from lacking the target HMW-GSs, the three lines all showed decreased accumulation of low molecular weight glutenin subunits (LMW-GSs) and increased amounts of gliadins. Based on the test data of five gluten and glutenin macropolymer (GMP) parameters obtained with grain samples harvested from two environments, we conclude that the genetic effects of Glu-1 loci on gluten functionality can be ranked as Glu-D1 > Glu-B1 > Glu-A1. Furthermore, it is suggested that Glu-1 loci contribute to gluten functionality both directly (by promoting the formation of GMP) and indirectly (through keeping the balance among HMW-GSs, LMW-GSs and gliadins). Finally, the efficient isolation of ion beam mutations for functional comparison of homoeologous loci in polyploid plants and the usefulness of Glu-1 deletion lines for further studying the contribution of Glu-1 loci to gluten functionality are discussed.     

Mono- and digalactosyldiacylglycerols: potent nitric oxide inhibitors from the marine microalga Nannochloropsis granulata

Chemical investigation of a marine microalga, Nannochloropsis granulata, led to the isolation of four digalactosyldiacylglycerols namely, (2S)-1-O-eicosapentaenoyl-2-O-palmitoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (1), (2S)-1-O-eicosapentaenoyl-2-O-palmitoleoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (2), (2S)-1-O-eicosapentaenoyl-2-O-myristoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (3), and (2S)-1,2-bis-O-eicosapentaenoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (4), together with their monogalactosyl analogs (5–8). Among the isolated galactolipids 2 and 3 were new natural products. Complete stereochemistry of 1, 4, 5, 7, and 8 was determined for the first time by both spectroscopic techniques and classical degradation methods. Both mono- and digalactosyldiacylglycerols isolated from N. granulata possessed strong nitric oxide (NO) inhibitory activity against lipopolysaccharide-induced NO production in RAW264.7 macrophage cells through downregulation of inducible nitric oxide synthase expression indicating the possible use as anti-inflammatory agents.     

Density functional studies on photophysical properties and chemical reactivities of the triarylboranes: effect of the constraint of planarity

The geometric and electronic structures, absorption spectra, transporting properties, chemical reactivity indices and electrostatic potentials of the planar three-coordinate organoboron compounds 1-2 and twisted reference compound Mes ₃ B, have been investigated by employing density functional theory (DFT) and conceptual DFT methods to shed light on the planarity effects on the photophysical properties and the chemical reactivity. The results show that the planar compounds 1-2 exhibit significantly lower HOMO level than Mes ₃ B, owing to the stronger electronic induction effect of boron centers. This feature conspicuously induces a blue shifted absorption for 1, although 1 seemingly possesses more extended conjugation framework than Mes ₃ B. Importantly, the reactivity strength of the boron atoms in 1-2 is much lower than that in Mes ₃ B, despite the fact that the tri-coordinate boron centers of 1-2 are completely naked. The interesting and abnormal phenomenon is caused by the strong p-π electronic interactions, that is, the empty p-orbital of boron center is partly filled by π-electron of the neighbor carbon atoms in 1-2, which are confirmed by the analysis of Laplacian of the electron density and natural bond orbitals. Furthermore, the negative electrostatic potentials of the boron centers in 1-2 also interpret that they are not the most preferred sites for incoming nucleophiles. Moreover, it is also found that the planar compounds 1-2 can act as promising electron transporting materials since the internal reorganization energies for electron are really small.

Genome-wide association study reveals genetic architecture of coleoptile length in wheat

Key message

Eight QTL for coleoptile length were identified in a genome-wide association study on a set of 893 wheat accessions, four of which are novel loci.

Abstract

Wheat cultivars with long coleoptiles are preferred in wheat-growing regions where deep planting is practiced. However, the wide use of gibberellic acid (GA)-insensitive dwarfing genes, Rht-B1b and Rht-D1b, makes it challenging to breed dwarf wheat cultivars with long coleoptiles. To understand the genetic basis of coleoptile length, we performed a genome-wide association study on a set of 893 landraces and historical cultivars using 5011 single nucleotide polymorphism (SNP) markers. Structure analysis revealed four subgroups in the association panel. Association analysis results suggested that Rht-B1b and Rht-D1b genes significantly reduced coleoptile length, and eight additional quantitative trait loci (QTL) for coleoptile length were also identified. These QTL explained 1.45–3.18 and 1.36–3.11% of the phenotypic variation in 2015 and 2016, respectively, and their allelic substitution effects ranged from 0.31 to 1.75 cm in 2015, and 0.63–1.55 cm in 2016. Of the eight QTL, QCL.stars-1BS1, QCL.stars-2DS1, QCL.stars-4BS2, and QCL.stars-5BL1 are likely novel loci for coleoptile length. The favorable alleles in each accession ranged from two to eight with an average of 5.8 at eight loci in the panel, and more favorable alleles were significantly associated with longer coleoptile, suggesting that QTL pyramiding is an effective approach to increase wheat coleoptile length.

     

Molecular mapping of an adult plant stem rust resistance gene Sr56 in winter wheat cultivar Arina

Key message

This article covers detailed characterization and naming of QSr.sun - 5BL as Sr56 . Molecular markers linked with adult plant stem rust resistance gene Sr56 were identified and validated for marker-assisted selection.

Abstract

The identification of new sources of adult plant resistance (APR) and effective combinations of major and minor genes is well appreciated in breeding for durable rust resistance in wheat. A QTL, QSr.sun-5BL, contributed by winter wheat cultivar Arina providing 12–15 % reduction in stem rust severity, was reported in an Arina/Forno recombinant inbred line (RIL) population. Following the demonstration of monogenic segregation for APR in the Arina/Yitpi RIL population, the resistance locus was formally named Sr56. Saturation mapping of the Sr56 region using STS (from EST and DArT clones), SNP (9 K) and SSR markers from wheat chromosome survey sequences that were ordered based on synteny with Brachypodium distachyon genes in chromosome 1 resulted in the flanking of Sr56 by sun209 (SSR) and sun320 (STS) at 2.6 and 1.2 cM on the proximal and distal ends, respectively. Investigation of conservation of gene order between the Sr56 region in wheat and B. distachyon showed that the syntenic region defined by SSR marker interval sun209-sun215 corresponded to approximately 192 kb in B. distachyon, which contains five predicted genes. Conservation of gene order for the Sr56 region between wheat and Brachypodium, except for two inversions, provides a starting point for future map-based cloning of Sr56. The Arina/Forno RILs carrying both Sr56 and Sr57 exhibited low disease severity compared to those RILs carrying these genes singly. Markers linked with Sr56 would be useful for marker-assisted pyramiding of this gene with other major and APR genes for which closely linked markers are available.     

Identification of major loci for seed dormancy at different post-ripening stages after harvest and validation of a novel locus on chromosome 2AL in common wheat

A long-period duration of seed dormancy helps to reduce pre-harvest sprouting (PHS) damage in common wheat when a long period of rainfall or high humidity occurs. Identification of genes or loci underlying seed dormancy duration is of high importance for investigating genetic mechanism of PHS tolerance of wheat. In the present study, the germination index (GI) of different mapping populations at 5 days (GI5), 15 days (GI15), and 30 days (GI30) after harvest (DAH) was recorded during the 2011–2012, 2012–2013, 2013–2014, and 2014–2015 cropping seasons. Field sprouting (FS) values were also determined in 2012–2013 and 2014–2015 cropping seasons. Association analysis was performed in 260 wheat varieties and advanced lines differing in seed dormancy (SD) using 557 SSR and 14 gene-specific markers for PHS/SD-related genes. The result indicated that a total of 47 loci were significantly (P < 0.01) associated with SD using both the general linear model (GLM) and mixed linear model (MLM). Five major loci were consistently detected at different post-ripening stages after harvest, including four for GI5 and GI15 on chromosomes 3AS, 3BL, 5AL, and 5BL responsible for middle-duration SD, and one for GI5, GI15, and GI30 on 2AL associated with longer-duration SD. The major locus on 2AL (designated Qsd.ahau-2AL) is likely to be a novel QTL, which was linked to Xwmc658 by mapping analysis in 165 recombinant inbred lines (RILs) derived from the Jing 411 × Wanxianbaimaizi cross and 728 F₂ plants from Jimai 20 × Suiningtuotuomai. Furthermore, a CAPS marker CAPS-2AL was developed for Qsd.ahau-2AL locus and was validated using the 728 F₂ plants and 201 accessions of the Chinese mini-core collection. Our results also revealed that the TaMFT-like gene on 3AS had a more significant association with dormancy duration than the other six genes underlying SD/PHS resistance in Chinese wheat germplasm. This study provides useful information for marker-assisted selection in wheat breeding and enhances our understanding of molecular genetics of SD in wheat.     

Epistatic determinism of durum wheat resistance to the wheat spindle streak mosaic virus

Key message

The resistance of durum wheat to the Wheat spindle streak mosaic virus (WSSMV) is controlled by two main QTLs on chromosomes 7A and 7B, with a huge epistatic effect.

Abstract

Wheat spindle streak mosaic virus (WSSMV) is a major disease of durum wheat in Europe and North America. Breeding WSSMV-resistant cultivars is currently the only way to control the virus since no treatment is available. This paper reports studies of the inheritance of WSSMV resistance using two related durum wheat populations obtained by crossing two elite cultivars with a WSSMV-resistant emmer cultivar. In 2012 and 2015, 354 recombinant inbred lines (RIL) were phenotyped using visual notations, ELISA and qPCR and genotyped using locus targeted capture and sequencing. This allowed us to build a consensus genetic map of 8568 markers and identify three chromosomal regions involved in WSSMV resistance. Two major regions (located on chromosomes 7A and 7B) jointly explain, on the basis of epistatic interactions, up to 43% of the phenotypic variation. Flanking sequences of our genetic markers are provided to facilitate future marker-assisted selection of WSSMV-resistant cultivars.

     

New phenotypic characteristics of three tmm alleles in Arabidopsis thaliana

Key message

Three new tmm mutants were isolated and showed differential phenotypes from tmm - 1 , and TMM overexpression led to abnormal leaf trichomes.

Abstract

TOO MANY MOUTH (TMM) plays a significant role in the stomatal signal transduction pathway, which involves in the regulation of stomatal distribution and patterning. Three mutants with clustered stomata were isolated and identified as new alleles of tmm. tmm-4 mutation included a base transversion from adenine to thymidine in position 1,033 of the TMM coding region and resulted in premature termination of translation at position 345 of TMM. tmm-5 had a base transition from cytosine to thymidine in 244 of TMM and translated 82 amino acids before premature termination. tmm-6 mutation took a base transition from guanine to adenine in 463 of TMM and changed a glycine (Gly) to an arginine (Arg) in position 155 of the protein. tmm-6 had an evident reduction of stomatal clusters and fewer stomata in cluster compared with other tmm alleles, possibly due to decreased level of entry divisions in cells next to two stomata or their precursors. tmm-5 and tmm-6 were hypersensitive to abscisic acid (ABA) in seedling growth and seed germination, while tmm-4 was defective in response to ABA during seed dormancy, suggesting that TMM was involved in ABA signaling transduction. Interestingly, overexpression of TMM resulted in the reduction of leaf trichomes and their branches, and this might reveal a new function of TMM in trichome development.     

QTL for resistance to root lesion nematode (Pratylenchus thornei) from a synthetic hexaploid wheat source

Key message

A whole genome average interval mapping approach identified eight QTL associated with P. thornei resistance in a DH population from a cross between the synthetic-derived wheat Sokoll and cultivar Krichauff.

Abstract

Pratylenchus thornei are migratory nematodes that feed and reproduce within the wheat root cortex, causing cell death (lesions) resulting in severe yield reductions globally. Genotypic selection using molecular markers closely linked to Pratylenchus resistance genes will accelerate the development of new resistant cultivars by reducing the need for laborious and expensive resistance phenotyping. A doubled haploid wheat population (150 lines) from a cross between the synthetic-derived cultivar Sokoll (P. thornei resistant) and cultivar Krichauff (P. thornei moderately susceptible) was used to identify quantitative trait loci (QTL) associated with P. thornei resistance. The resistance identified in the glasshouse was validated in a field trial. A genetic map was constructed using Diversity Array Technology and the QTL regions identified were further targeted with simple sequence repeat (SSR) and single-nucleotide polymorphism (SNP) markers. Six significant and two suggestive P. thornei resistance QTL were detected using a whole genome average interval mapping approach. Three QTL were identified on chromosome 2B, two on chromosome 6D, and a single QTL on each of chromosomes 2A, 2D and 5D. The QTL on chromosomes 2BS and 6DS mapped to locations previously identified to be associated with Pratylenchus resistance. Together, the QTL on 2B (QRlnt.sk-2B.1–2B.3) and 6D (QRlnt.sk-6D.1 and 6D.2) explained 30 and 48 % of the genotypic variation, respectively. Flanking PCR-based markers based on SSRs and SNPs were developed for the major QTL on 2B and 6D and provide a cost-effective high-throughput tool for marker-assisted breeding of wheat with improved P. thornei resistance.     

Characterization of Sr9h,a wheat stem rust resistance allele effective to Ug99

Key message

Wheat stem rust resistance gene SrWeb is an allele at the Sr9 locus that confers resistance to Ug99.

Abstract

Race TTKSK (Ug99) of Puccinia graminis f. sp. tritici, the causal fungus of stem rust, threatens global wheat production because of its broad virulence to current wheat cultivars. A recently identified Ug99 resistance gene from cultivar Webster, temporarily designated as SrWeb, mapped near the stem rust resistance gene locus Sr9. We determined that SrWeb is also present in Ug99 resistant cultivar Gabo 56 by comparative mapping and an allelism test. Analysis of resistance in a population segregating for both Sr9e and SrWeb demonstrated that SrWeb is an allele at the Sr9 locus, which subsequently was designated as Sr9h. Webster and Gabo 56 were susceptible to the Ug99-related race TTKSF+ from South Africa. Race TTKSF+ possesses unique virulence to uncharacterized Ug99 resistance in cultivar Matlabas. This result validated that resistance to Ug99 in Webster and Gabo 56 is conferred by the same gene: Sr9h. The emergence of pathogen virulence to several resistance genes that are effective to the original Ug99 race TTKSK, including Sr9h, suggests that resistance genes should be used in combinations in order to increase resistance durability.     

Lipids isolated from the cultivated red alga Chondrus crispus inhibit nitric oxide production

A MeOH extract of cultivated Chondrus crispus showed dose-dependent nitric oxide (NO) inhibition of lipopolysaccharide-induced NO production in macrophage RAW264.7 cells. NO inhibition-guided fractionation of the extract led to identification of eicosapentaenoic acid (EPA, 1), arachidonic acid (AA, 2), lutein (3), and eight galactolipids as active components. Based on spectral analysis, the isolated galactolipids were identified as (2S)-1,2-bis-O-eicosapentaenoyl-3-O-β-d-galactopyranosylglycerol (4), (2S)-1-O-eicosapentaenoyl-2-O-arachidonoyl-3-O-β-d-galactopyranosylglycerol (5), (2S)-1-O-(6Z,9Z,12Z,15Z-octadecatetranoyl)-2-O-palmitoyl-3-O-β-d-galactopyranosylglycerol (6), (2S)-1-O-eicosapentaenoyl-2-O-palmitoyl-3-O-β-d-galactopyranosylglycerol (7), (2S)-1,2-bis-O-arachidonoyl-3-O-β-d-galactopyranosylglycerol (8), (2S)-1-O-arachidonoyl-2-O-palmitoyl-3-O-β-d-galactopyranosylglycerol (9), (2S)-1-O-eicosapentaenoyl-2-O-palmitoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (10), and (2S)-1-O-arachidonoyl-2-O-palmitoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (11). All the isolated compounds showed significant NO inhibitory activity. This is the first report of the isolation and identification of individual galactolipids from C. crispus. Moreover, (2S)-1,2-bis-O-arachidonoyl ?3-O-β-d-galactopyranosylglycerol (8) is a novel compound.     

Synthesis of Pyrrolo[2′,3′:4,5]Furo[3,2-c]Pyridine-2-Carboxylic Acids

1H-Pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylic acid (6a) and its 1-methyl (6b) and 1-benzyl (6c) derivatives were synthesized. 3-(5-Methoxycarbonyl-4H-furo[3,2-b]-pyrrole-2-yl)propenoic acid (1) was converted to the corresponding azide 2, which in turn was cyclized to give 3 by heating in diphenylether. The pyridone 3 obtained was aromatized with phosphorus oxychloride, then reduced with zinc in acetic acid to give methyl 1H-pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylate (5), which by hydrolysis gave the corresponding carboxylic acid 6a.     

Photophysics of novel coumarin-labeled depsipeptides in solution: sensing interactions with SDS micelle via TICT model

N-Acylbenzotriazoles enable the synthesis (69–92 % yield) of blue to green fluorescent coumarin-labeled depsidipeptides 8a–f (quantum yields 0.004–0.97) and depsitripeptides 12a–d (quantum yields 0.02–0.96). Detailed photophysical studies of fluorescent coumarin-labeled depsipeptides 8a–f and 12a–d are reported for both polar protic and polar aprotic solvents. 7-Methoxy and 7-diethylaminocoumarin-3-ylcarbonyl depsipeptides 8c,f and 12d are highly solvent sensitive. These highly fluorescent compounds could be useful for peptide assays. Further photophysical studies of 7-diethylaminocoumarin-labeled depsipeptides 8c,12d within the micellar microenvironment of SDS reflect their ability to bind with the biological membrane, suggesting potential applications in the fields of bio- and medicinal chemistry.     

Five new galactolipids from the freshwater microalga Porphyridium aerugineum and their nitric oxide inhibitory activity

Chemical investigation of the freshwater rhodophyte microalga Porphyridium aerugineum led to the isolation of five new galactolipids, namely, (2S)-1-O-eicosapentaenoyl-2-O-arachidonoyl-3-O-β-d-galactopyranosylglycerol (1), (2S)-1-O-eicosapentaenoyl-2-O-linoleoyl-3-O-β-d-galactopyranosylglycerol (2), (2S)-1-O-arachidoyl-2-O-palmitoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (6), (2S)-1-O-eicosapentaenoyl-2-O-arachidoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (7), and (2S)-1-O-eicosapentaenoyl-2-O-linoleoyl-3-O-(β-d-galactopyranosyl-6-1α-d-galactopyranosyl)-glycerol (8) together with five known galactolipids. The stereo-structures of all new galactolipids were elucidated by spectroscopic analyses and both enzymatic and chemical degradation methods. This is the first report of galactolipids from P. aerugineum. The newly isolated galactolipids showed strong and dose-dependent nitric oxide (NO) inhibitory activity against lipopolysaccharide-induced NO production in RAW264.7 macrophage cells. Both galactolipids 1 and 2 possessed stronger NO inhibitory activity than N ^G-methyl-l-arginine acetate salt, a well-known NO inhibitor used as a positive control. Further study suggested that these galactolipids inhibit NO production through downregulation of inducible nitric oxide synthase expression.