Amyloid Form of Ovalbumin Evokes Native Antigen-specific Immune Response in the Host: PROSPECTIVE IMMUNO-PROPHYLACTIC POTENTIAL

Amyloids are highly organized protein aggregates that arise from inappropriately folded versions of proteins or polypeptides under both physiological as well as simulated ambiences. Once thought to be irreversible assemblies, amyloids have begun to expose their more dynamic and reversible attributes depending upon the intrinsic properties of the precursor protein/peptide and experimental conditions such as temperature, pressure, structural modifications in proteins, or presence of chemicals in the reaction mixture. It has been repeatedly proposed that amyloids undergo transformation to the bioactive peptide/protein forms under specific conditions. In the present study, amyloids assembled from the model protein ovalbumin (OVA) were found to release the precursor protein in a slow and steady manner over an extended time period. Interestingly, the released OVA from amyloid depot was found to exhibit biophysical characteristics of native protein and reacted with native-OVA specific monoclonal as well as polyclonal antibodies. Moreover, antibodies generated upon immunization of OVA amyloidal aggregates or fibrils were found to recognize the native form of OVA. The study suggests that amyloids may act as depots for the native form of the protein and therefore can be exploited as vaccine candidates, where slow antigen release over extended time periods is a pre-requisite for the development of desired immune response.     

Identification of a microsatellite on chromosomes 6B and a STS on 7D of bread wheat showing an association with preharvest sprouting tolerance

 In bread wheat, the transfer of tolerance to preharvest sprouting (PHS) that is associated with genotypes having red kernel colour to genotypes with amber kernels is difficult using conventional methods of plant breeding. The study here was undertaken to identify DNA markers linked with tolerance to PHS as these would allow indirect marker-assisted selection of PHS-tolerant genotypes with amber kernels. For this purpose, a set of 100 recombinant inbred lines (RILs) was developed using a cross between a PHS-tolerant genotype, SPR8198, with red kernels and a PHS-susceptible cultivar, ‘HD2329’, with white kernels. The two parents were analysed with 232 STMS (sequence-tagged microsatellite site) and 138 STS (sequence-tagged site) primer pairs. A total of 300 (167 STMSs and 133 STSs) primer pairs proved functional by giving scorable PCR products. Of these, 57 (34%) STMS and 30 (23%) STS primer pairs detected reproducible polymorphism between the parent genotypes. Using these primer pairs, we carried out bulked segregant analysis on two bulked DNAs, one obtained by pooling DNA from 5 PHS-tolerant RILs and the other similarly derived by pooling DNA from 5 PHS-susceptible RILs. Two molecular markers, 1 STMS primer pair for the locus wmc104 anda STS primer pair for the locus MST101, showed apparent linkage with tolerance to PHS. This was confirmed following selective genotyping of individual RILs included in the bulks. Chi-square contingency tests for independence were conducted on the cosegregation data collected on 100 RILs involving each of the two molecular markers (wmc104 and MST101) and PHS. The tests revealed a strong association between each of the markers and tolerance to PHS. Using nullisomic-tetrasomic lines, we were able to assign wmc104 and MST101 to chromosomes 6B and 7D, respectively. The results also indicated that the tolerance to PHS in SPR8198 is perhaps governed by two genes (linked with two molecular markers) exhibiting complementary interaction. Received: 15 October 1998 / Accepted: 19 December 1998     

Physical molecular maps of wheat chromosomes

In bread wheat, a set of 527 simple sequence repeats (SSRs) were tried on 164 deletion lines, leading to a successful mapping of 270 SSRs on 313 loci covering all 21 chromosomes. A maximum of 119 loci (38%) were located on B subgenome, and a minimum of 90 loci (29%) mapped on D subgenome. Similarly, homoeologous group 7 carried a maximum of 61 loci (19%), and group 4 carried a minimum of 22 loci (7%). Of the cited 270 SSRs, 39 had multiple loci, but only eight of these detected homoeologous loci. Linear order of loci in physical maps largely corresponded with those in the genetic maps. Apparently, distances between each of only 26 pairs of loci significantly differed from the corresponding distances on genetic maps. Some loci, which were genetically mapped close to the centromere, were physically located distally, while other loci that were mapped distally in the genetic maps were located in the proximal bins in the physical maps. This suggested that although the linear order of the loci was largely conserved, variation does exist between genetic and physical distances.Electronic Supplementary Material Supplementary material is available for this article at .     

Mapping of a major QTL for pre-harvest sprouting tolerance on chromosome 3A in bread wheat

Quantitative trait loci (QTL) analysis was conducted for pre-harvest sprouting tolerance (PHST) in bread wheat for a solitary chromosome 3A, which was shown to be important for this trait in earlier studies. An intervarietal mapping population in the form of recombinant inbred lines (RILs) developed from a cross between SPR8198 (a PHS tolerant genotype) and HD2329 (a PHS susceptible cultivar) was used for this purpose. The parents and the RIL population were grown in six different environments and the data on PHS were collected in each case. A framework linkage map of chromosome 3A with 13 markers was prepared and used for QTL analysis. A major QTL (QPhs.ccsu-3A.1) was detected on 3AL at a genetic distance of ∼183 cM from centromere, the length of the map being 279.1 cM. The QTL explained 24.68% to 35.21% variation in individual environments and 78.03% of the variation across the environments (pooled data). The results of the present study are significant on two counts. Firstly, the detected QTL is a major QTL, explaining up to 78.03% of the variation and, secondly, the QTL showed up in all the six environments and also with the pooled data, which is rather rare in QTL analysis. The positive additive effects in the present study suggest that a superior allele of the QTL is available in the superior parent (SPR8198), which can be used for marker-aided selection for the transfer of this QTL allele to obtain PHS-tolerant progeny. It has also been shown that the red-coloured grain of PHS tolerant parent is not associated with the QTL for PHST identified during the present study, suggesting that PHS tolerant white-grained cultivars can be developed.Electronic Supplementary Material Supplementary material is available for this article at     

Genetic mapping of 66 new microsatellite (SSR) loci in bread wheat

In hexaploid bread wheat ( Triticum aestivum L. em. Thell), ten members of the IWMMN ( International Wheat Microsatellites Mapping Network) collaborated in extending the microsatellite (SSR = simple sequence repeat) genetic map. Among a much larger number of microsatellite primer pairs developed as a part of the WMC ( Wheat Microsatellite Consortium), 58 out of 176 primer pairs tested were found to be polymorphic between the parents of the ITMI ( International Triticeae Mapping Initiative) mapping population W7984 x Opata 85 (ITMI pop). This population was used earlier for the construction of RFLP ( Restriction Fragment Length Polymorphism) maps in bread wheat (ITMI map). Using the ITMI pop and a framework map (having 266 anchor markers) prepared for this purpose, a total of 66 microsatellite loci were mapped, which were distributed on 20 of the 21 chromosomes (no marker on chromosome 6D). These 66 mapped microsatellite (SSR) loci add to the existing 384 microsatellite loci earlier mapped in bread wheat.     

Bestimmung von Fumonisinen in komplexen Lebensmittelmatrices mittels Accelerated Solvent Extraktion (ASE)

Accelerated solvent extraction (ASE) is an alternative sample extraction procedure for fumonisins in corn and corn products. ASE gave results comparable to that of a draft CEN method, but required less extraction time. Furthermore, ASE gave significantly higher quantitative values than another method reported for extraction of fumonisins (Trucksess et al., 1995).     

Single-trait,multi-locus and multi-trait GWAS using four different models for yield traits in bread wheat

Molecular Breeding - Rice (Oryza sativa L.) is a saline-alkali-sensitive crop. Saline-alkali environments can seriously affect the growth, development, and yield of rice. The mechanisms of salt...     

Marker-assisted pyramiding of eight QTLs/genes for seven different traits in common wheat (Triticum aestivum L.)

Common wheat (Triticum aestivum L.) contributes substantially to global food and nutritional security. Thus, an important goal of wheat breeding is to develop high-yielding varieties with better nutritional quality and resistance to all major diseases. During the present study, in the background of a popular elite wheat cultivar PBW343, we pyramided eight quantitative trait loci (QTLs)/genes for four grain quality traits (high grain weight, high grain protein content, pre-harvest sprouting tolerance, and desirable high-molecular-weight glutenin subunits) and resistance against the three rusts. For pyramiding eight QTLs/genes, four improved PBW343 lines, each carrying different combinations of the desired QTLs/genes (developed by us earlier), were crossed in pairs to produce two single-cross F₁ hybrids. The single-cross F₁ hybrids were intercrossed to produce a double-cross hybrid (DCH). Using marker-assisted selection in five consecutive generations (DCHF₁–DCHF₅), four pyramided lines (PYLs) were selected, each with all the eight desired QTLs/genes in homozygous state. The phenotypic characterization of the progenies of these PYLs suggested that the genetic background of PBW343 was retained in all these four PYLs. Therefore, these PYLs should prove useful in future wheat breeding programs for improving not only the grain quality, but also the durability of resistance against all three rusts. Multi-year/multi-location trials are planned for these pyramided lines to evaluate their potential for release as a next-generation improved version of wheat cv. PBW343 for commercial cultivation.     

Evaluation of SSR Markers for the Assessment of Genetic Diversity and Fingerprinting of Gossypium hirsutum Accessions

A total 177 simple sequence repeat (SSR) markers were screened using a set of 47 Upland cotton genotypes comprising 14 commercial varieties, 14 germplasm accessions and 19 advanced breeding lines to identify informative markers for genetic diversity assessment and fingerprinting in G. hirsutum. Only 21% (381177) of SSR markers tested showed polymorphism with a mean of 2.18 alleles per locus and with average polymorphism information content (PIC) of 0.32. The SSR markers revealed a Jaccard’ similarity coefficient ranging between 0.43 and 0.89, with an average of 0.67 among accessions. Cluster analysis using unweighted pair group method with arithmetic averages (UPGMA) and principal component analysis (PCA) indicated that majority of the genotypes were very closely related. All the 47 genotypes showed heterorygosity for at least one of the SSR loci. We discovered 19 rare and 6 unique alleles among the tested genotypes of cotton. Fingerprint based on all the 38 loci revealed a probability of identical match by chance of 3.98x10. A set of ten SSR markers was identified which could distinguish all the 47 genotypes with a moderate probability of identical match by chance (X?_D ⁿ = 0.01).