Background Gossypium hirsutum L., or upland cotton, is an important renewable resource for textile fiber. To enhance understanding of the genetic basis of cotton earliness, we constructed an intra-specific recombinant inbred line population (RIL) containing 137 lines, and performed linkage map construction and quantitative trait locus (QTL) mapping.ResultsUsing restriction-site associated DNA sequencing, a genetic map composed of 6,434 loci, including 6,295 single nucleotide polymorphisms and 139 simple sequence repeat loci, was developed from RIL population. This map spanned 4,071.98 cM, with an average distance of 0.63 cM between adjacent markers. A total of 247 QTLs for six earliness-related traits were detected in 6 consecutive years. In addition, 55 QTL coincidence regions representing more than 60 % of total QTLs were found on 22 chromosomes, which indicated that several earliness-related traits might be simultaneously improved. Fine-mapping of a 2-Mb region on chromosome D3 associated with five stable QTLs between Marker25958 and Marker25963 revealed that lines containing alleles derived from CCRI36 in this region exhibited smaller phenotypes and earlier maturity. One candidate gene (EMF2) was predicted and validated by quantitative real-time PCR in early-, medium- and late-maturing cultivars from 3- to 6-leaf stages, with highest expression level in early-maturing cultivar, CCRI74, lowest expression level in late-maturing cultivar, Bomian1.ConclusionsWe developed an SNP-based genetic map, and this map is the first high-density genetic map for short-season cotton and has the potential to provide deeper insights into earliness. Cotton earliness-related QTLs and QTL coincidence regions will provide useful materials for QTL fine mapping, gene positional cloning and MAS. And the gene, EMF2, is promising for further study.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3269-y) contains supplementary material, which is available to authorized users.
Family 1 GT, designated as UGT, is the largest and most functionally important multigene family in the plant kingdom. In this study, we carried out a genome-wide identification, analysis, and comparison of 142, 146, and 196 putative UGTs from Gossypium raimondii, Gossypium arboreum, and Gossypium hirsutum, respectively. All members present the 44 amino-acid conserved consensus sequence termed the plant secondary product glycosyltransferase motif. According to the phylogenetic relationship among the cotton UGT proteins and those from other species, GrUGTs and GaUGTs could be classified into 16 major phylogenetic groups (A-P), whereas GhUGTs are classified into 15 major phylogenetic groups with a lack of group C. All cotton UGTs are dispersed throughout the chromosomes and are displayed in clusters with the same open reading frame orientation. The expansion of them appears to result from genome duplication and rearrangement. Two conserved introns, A and B, are detected in most of the intron-containing-UGTs in G. raimondii and G. arboreum, whereas only intron A is detected in the intron-containing-UGTs in G. hirsutum. Furthermore, expression patterns of the UGT genes in G. hirsutum wild type and its near isogenic fuzzless-lintless mutant at the stage of fiber initiation were analyzed using the RNA-seq data. Overall, this study not only deepens our understanding of the structure, phylogeny, evolution, and expression of cotton UGT genes, but also provides a solid foundation for further cloning and functional studies of the UGT family genes.
In deformation twinning, twin boundaries (TBs) should coincide with the twinning plane. Here we show that the TBs of the most common twinning mode in hexagonal close-packed metals, f1 0 1 2gh1 0 1 1i, may not lie on the f1 0 1 2g twinning plane. Examinations using transmission electron microscopy (TEM) reveal that the TBs in Co and Mg deviate significantly from the f1 0 1 2g plane. High-resolution TEM confirms that the incoherent TBs entirely depart from the twinning plane with a magnitude greater than 45°. Ó 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.Keywords: Twin; Twin boundary; Deformation twinning; Cobalt; Magnesium When crystalline solids are subjected to plastic deformation, in addition to dislocation slip, deformation twinning can be activated to accommodate the microscopic strain. A deformation twin, which predated the concept of dislocation (1934), was defined as "a region of a crystalline body which has undergone a homogeneous shape deformation in such a way that the crystal structure of the resulting product is identical with that of the parent, but oriented differently" [1]. Because the two structures are identical, the boundary plane, also known as the twinning plane, must remain invariant during twinning. The parent and the twin lattices are reflected about the twinning plane.The homogeneous shear involved in twinning carries parent atoms to the twin lattice [2]. To accomplish a homogeneous shear on a twinning plane, passage of twinning dislocations at the interface is required to complete such displacements. A twinning system comprising a twinning plane and a twinning direction along which the shear takes place can be rigorously defined in this scenario. The twin boundary (TB), i.e. the interface between parent and twin, has to coincide with the twinning plane, although microscopically local disregistry is permissible in the presence of twinning dislocation loops. In face-centered cubic (fcc) metals such as aluminum, copper, nickel, etc., the twinning plane is identical to the slip plane of dislocations, i.e. the close-packed {1 1 1} planes, and the twinning dislocations are Shockley partials 1 6 h1 2 1i. In low-symmetry, hexagonal close-packed (hcp) materials such as Mg, which have attracted tremendous attention in the quest for lightweight vehicle design, twinning plays a crucial role in plastic deformation and strain-path anisotropy [3]. On one hand, the easy slip directions contained in the basal plane are incapable of accommodating strain when the unit cell is loaded normal to the basal plane. On the other hand, non-basal slip systems are harder to activate than twinning by at least a factor of 3. The most frequently observed twinning mode in all hcp metals, which is always believed to be on the f1 0 1 2g plane and parallel to the h1 0 1 1 i direction, predominates in plastic deformation among multiple twinning modes. Within the framework of classical deformation theories, numerous crystallographic models have attempted to resolve twinning dislocations on the tw...
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