QTL analysis and marker assisted selection for improvement in grain protein content and pre-harvest sprouting tolerance in bread wheat

With the ever expanding possibilities to build supramotecutar structures, chemists are challenged to mimic nature including the construction of artificial cells or function thereof. Within the field of immunology, effective immunotherapy critically depends on efficient production of antigen-specific cytotoxic T-cells. Herein lies an opportunity for chemists to design and synthesize so-called artificial antigen presenting cells (aAPCs) that can promote T-cell activation and their subsequent expansion. In this review we discuss the current status of aAPC development, also focusing on developments in nanoscience which might improve future designs. As synthetic mimics of natural antigen-presenting cells, aAPCs encompass three basic signals required for T-cell activation: MHC-antigen complexes, costimulatory molecules and soluble immune modulating compounds. Both spatial and temporal organization of these signals during aAPC/T-cell contact is important for efficient T-cell activation. We discuss how signals have been incorporated in several aAPC designs, but also how physical properties such as size and shape are essential for targeting the aAPCs to T-cell rich areas in vivo

Identification of several small main-effect QTLs and a large number of epistatic QTLs for drought tolerance related traits in groundnut (Arachishypogaea L.)

Cultivated groundnut or peanut (Arachis hypogaea L.), an allotetraploid (2n = 4x = 40), is a self pollinated and widely grown crop in the semi-arid regions of the world. Improvement of drought tolerance is an important area of research for groundnut breeding programmes. Therefore, for the identification of candidate QTLs for drought tolerance, a comprehensive and refined genetic map containing 191 SSR loci based on a single mapping population (TAG 24 × ICGV 86031), segregating for drought and surrogate traits was developed. Genotyping data and phenotyping data collected for more than ten drought related traits in 2–3 seasons were analyzed in detail for identification of main effect QTLs (M-QTLs) and epistatic QTLs (E-QTLs) using QTL Cartographer, QTLNetwork and Genotype Matrix Mapping (GMM) programmes. A total of 105 M-QTLs with 3.48–33.36% phenotypic variation explained (PVE) were identified using QTL Cartographer, while only 65 M-QTLs with 1.3–15.01% PVE were identified using QTLNetwork. A total of 53 M-QTLs were such which were identified using both programmes. On the other hand, GMM identified 186 (8.54–44.72% PVE) and 63 (7.11–21.13% PVE), three and two loci interactions, whereas only 8 E-QTL interactions with 1.7–8.34% PVE were identified through QTLNetwork. Interestingly a number of co-localized QTLs controlling 2–9 traits were also identified. The identification of few major, many minor M-QTLs and QTL × QTL interactions during the present study confirmed the complex and quantitative nature of drought tolerance in groundnut. This study suggests deployment of modern approaches like marker-assisted recurrent selection or genomic selection instead of marker-assisted backcrossing approach for breeding for drought tolerance in groundnut

A FRUITFULL-like gene is associated with genetic variation for fruit flesh firmness in apple (Malus domestica Borkh.)

The FRUITFULL (FUL) and SHATTERPROOF (SHP) genes are involved in regulating fruit development and dehiscence in Arabidopsis. We tested the hypothesis that this class of genes are also involved in regulating the development of fleshy fruits, by exploring genetic and phenotypic variation within the apple (Malus domestica) gene pool. We isolated and characterised the genomic sequences of two candidate orthologous FUL-like genes, MdMADS2.1 and MdMADS2.2. These were mapped using the reference population ‘Prima x Fiesta’ to loci on Malus linkage groups LG14 and LG06, respectively. An additional MADS-box gene, MdMADS14, shares high amino acid identity with the Arabidopsis SHATTERPROOF1/2 genes and was mapped to Malus linkage group LG09. Association analysis between quantitative fruit flesh firmness estimates of ‘Prima x Fiesta’ progeny and the MdMADS2.1, MdMADS2.2 and MdMADS14 loci was carried out using a mixed model analysis of variance. This revealed a significant association (P < 0.01) between MdMADS2.1 and fruit flesh firmness. Further evidence for the association between MdMADS2.1 and fruit flesh firmness was obtained using a case–control population-based genetic association approach. For this, a polymorphic repeat, (AT)n, in the 3′ UTR of MdMADS2.1 was used as a locus-specific marker to screen 168 apple accessions for which historical assessments of fruit texture attributes were available. This analysis revealed a significant association between the MdMADS2.1 and fruit flesh firmness at both allelic (χ 2 = 34, df = 9, P < 0.001) and genotypic (χ 2 = 57, df = 32, P < 0.01) levels

Marker-assisted wheat breeding: present status and future possibilities

First published online in 2009Wheat production and productivity in the past witnessed a remarkable growth. However, this growth rate could not be sustained during the last decade, causing concern among world wheat community. Marker-assisted selection (MAS), which is being practiced for improvement of a variety of traits in wheat around the world, may at least partly help in providing the desired solution. Marker-trait associations are now known for a number of simple, but difficult-to-score traits, so that MAS has been found useful for improvement of several of these important economic traits. Breeding strategies including marker-assisted backcrossing, forward breeding, MAS involving doubled haploid technology and F2 enrichment have been successfully utilized for this purpose. However, for improvement of complex polygenic traits, newer technologies based on high throughput genotyping associated with new marker systems (e.g., DArT and SNP), and new selection strategies such as AB-QTL, mapping-as-you-go, marker-assisted recurrent selection and genome-wide selection will have to be tried in future. The progress made in all these aspects of marker-assisted wheat breeding, and the limitations and future prospects of this emerging technology have been reviewed in this article.P. K. Gupta, Peter Langridge and R. R. Mi