Characterization of a new wheat-Aegilops biuncialis addition line conferring quality-associated HMW glutenin subunits.

In this study, a new disomic addition line, 12-5-2, with 44 chromosomes that was derived from BC3F2 descendants of the hybridization between Triticum aestivum cv. CN19 and Aegilops biuncialis was created and reported. 12-5-2 was immune to both powdery mildew and stripe rust and has stable fertility. Fluorescence in situ hybridization and C-banding revealed that 12-5-2 was a 1U(b) disomic addition line (ADL1U(b)). The seed storage protein electrophoresis showed that 12-5-2 presented all high molecular weight glutenin subunits (7 + 8 and 2 + 12) of CN19 and 2 new subunits that were designated Ux and Uy. Additionally, the flour quality parameters showed that the protein content, Zeleny sedimentation value, wet gluten content, and grain hardness of 12-5-2 were significantly higher than those of its parent CN19. Moreover, 5 pairs of the chromosome 1U(b)-specific polymerase chain reaction-based landmark unique gene markers, TNAC1021, TNAC1041, TNAC1071, TNAC1-01, and TNAC1-04, were also obtained. The new ADL1U(b) 12-5-2 could be a valuable source for wheat improvement, especially for wheat end-product quality and resistance to disease.

QTL analysis of the spring wheat "Chapio" identifies stable stripe rust resistance despite inter-continental genotype × environment interactions.

Chapio is a spring wheat developed by CIMMYT in Mexico by a breeding program that focused on multigenic resistances to leaf rust and stripe rust. A population consisting of 277 recombinant inbred lines (RILs) was developed by crossing Chapio with Avocet. The RILs were genotyped with DArT markers (137 randomly selected RILs) and bulked segregant analysis conducted to supplement the map with informative SSR markers. The final map consisted of 264 markers. Phenotyping against stripe rust was conducted for three seasons in Toluca, Mexico and at three sites over two seasons (total of four environments) in Sichuan Province, China. Significant loci across the two inter-continental regions included Lr34/Yr18 on 7DS, Sr2/Yr30 on 3BS, and a QTL on 3D. There were significant genotype × environment interactions with resistance gene Yr31 on 2BS being effective in most of the Toluca environments; however, a late incursion of a virulent pathotype in 2009 rendered this gene ineffective. This locus also had no effect in China. Conversely, a 5BL locus was only effective in the Chinese environments. There were also complex additive interactions. In the Mexican environments, Yr31 suppressed the additive effect of Yr30 and the 3D locus, but not of Lr34/Yr18, while in China, the 3D and 5BL loci were generally not additive with each other, but were additive when combined with other loci. These results indicate the importance of maintaining diverse, multi-genic resistances as Chapio had stable inter-continental resistance despite the fact that there were QTLs that were not effective in either one or the other region.

Isolation and phylogenetic analysis of novel γ-gliadin genes in genus Dasypyrum.

As the most ancient member of the wheat gluten family, the γ-gliadin genes are suitable for phylogenetic analysis among wheat and related species. Species in the grass genus Dasypyrum have been widely used for wheat cross breeding. However, the genomic relationships among Dasypyrum species have been little studied. We isolated 22 novel γ-gliadin gene sequences, among which 10 are putatively functional. The open reading frame lengths of these sequences range from 642 to 933 bp, and these putative proteins consist of five domains. Phylogenetic analyses showed that all Dasypyrum γ-gliadin gene sequences clustered in a large group; D. villosum and tetraploid D. breviaristatum γ-gliadin gene sequences clustered in a subgroup, while diploid D. breviaristatum γ-gliadin gene sequences clustered at the edge of the subgroup. All of the Dasypyrum γ-gliadin gene sequences were absent in three major T cell-stimulatory epitopes binding to HLA-DQ2/8 in celiac disease patients. Based on the phylogenetic analyses, we suggest that D. villosum and tetraploid D. breviaristatum evolved in parallel from a diploid ancestor D. breviaristatum.

Molecular cytogenetic characterization of a new leaf rolling triticale.

Leaf rolling occurs in some cereal genotypes in response to drought. We identified and made a phenotypic, cytological and physiological analysis of a leaf-rolling genotype (CMH83) of hexaploid triticale (X Triticosecale Wittmack) that exhibited reduced plant height, rolled and narrow leaves. Gliadin electrophoresis of seed protein showed that CMH83 was genetically stable. Sequential Giemsa-C-banding and genomic in situ hybridization showed that CMH83 contains 12 rye chromosomes; two pairs of these chromosomes have reduced telomeric heterochromatin bands. Tests of relative water content and water loss rate of leaves of CMH83 compared with those of wheat cultivars indicated that rapid water loss after drought stress in CMH83 is associated with the leaf rolling phenotypes. Leaf rolling in CMH83 was a dominant trait in our inheritance studies. Triticale line CMH83 could be used to study drought resistance mechanisms in triticale.

A review: the location, molecular characterisation and multipotency of hair follicle epidermal stem cells.

INTRODUCTION: Recent work has focused on the hair follicle as the main repository of multipotent stem cells in skin, which is a neat model to study the mechanisms regulating the proliferation, migration and final fate of adult stem cells. This review examines the available literature for its location, molecular markers and multipotency. METHODS: Peer-reviewed journals and monographs on the subject were covered. RESULTS: With the application of stem cell-labelling techniques and clonogenicity assay, it is clear that most of the hair follicle stem cells are located at the bulge region, but the base of the hair follicle does contain some clonogenic cells; whether they are stem cells is still unknown. Extensive works have been done in identifying hair follicle stem cells. The potential markers for hair follicle stem cells include: b1-integrin, keratin 19, a6- integrin, CD71, p63, and CD34. Most of these markers are expressed in high levels in hair follicle stem cells, but there is still difficulty in distinguishing hair follicle stem cells from their transitamplifying progeny, and the sorted hair follicle stem cells with these markers are far from pure. As hair follicle stem cells might have been activated after leaving the stem cell niche, the markers for cells in vitro might not be identical to those in vivo. Using double-labelling techniques with BrdU and 3H-Thymidine, and the creation of novel chimera transgenic mice, it was proved that hair follicle stem cells can repopulate wound epidermis, forming epidermis, hair follicles and sebaceous glands, but it contributes little to the epidermis in physiological condition, except the hair follicle. CONCLUSIONS: Slow cycling, label-retaining cells exist at the bulge of the hair follicle, with high proliferative potential and clonogenicity. The putative bulge stem cells can contribute to the epidermis, outer root sheath, inner root sheath, hair shaft and sebaceous gland. However, they still lack certain markers to distinguish bulge stem cells from their progeny, and much work needs to focus on the interrelations between bulge cells and interfollicular keratinocyte stem cells, the relations between bulge cells and dermal papilla mesenchyme cells, and the mechanism of hair growth.