Molecular Cytogenetic Identification of Wheat-Aegilops Biuncialis 5Mb Disomic Addition Line with Tenacious and Black Glumes

Production of wheat-alien disomic addition lines is of great value to the exploitation and utilization of elite genes originated from related species to wheat. In this study, a novel wheat-Aegilops biuncialis 5Mb disomic addition line WA317 was characterized by in situ hybridization (ISH) and specific-locus amplified fragment sequencing (SLAF-seq) markers. Compared to its parent Chinese Spring (CS), the glumes of WA317 had black color and were difficult to remove after harvesting, suggesting chromosome 5Mb carried gene(s) related to glume development and Triticeae domestication process. A total of 242 Ae. biuncialis SLAF-based markers (298 amplified patterns) were developed and further divided into four categories by Ae. biuncialis Y17, Ae. umbellulata Y139 and Ae. comosa Y258, including 172 markers amplifying the same bands of U and M genome, six and 102 markers amplifying U-specific and M-specific bands, respectively and eighteen markers amplifying specific bands in Y17. Among them, 45 markers had the specific amplifications in WA317 and were 5Mb specific markers. Taken together, line WA317 with tenacious and black glumes should serve as the foundation for understanding of the Triticeae domestication process and further exploitation of primitive alleles for wheat improvement. Ae. biuncialis SLAF-based markers can be used for studying syntenic relationships between U and M genomes as well as rapid tracking of U and M chromosomal segments in wheat background.

Evaluation of root porosity and radial oxygen loss of disomic addition lines of Hordeum marinum in wheat

Hordeum marinum Huds. is a waterlogging-tolerant wild relative of wheat (Triticum aestivum L.). Greater root porosity (gas volume per root volume) and formation of a barrier to reduce root radial O2 loss (ROL) contribute to the waterlogging tolerance of H. marinum and these traits are evident in some H. marinum–wheat amphiploids. We evaluated root porosity, ROL patterns and tolerance to hypoxic stagnant conditions for 10 various H. marinum (two accessions) disomic chromosome addition (DA) lines in wheat (two varieties), produced from two H. marinum–wheat amphiploids and their recurrent wheat parents. None of the DA lines had a barrier to ROL or higher root porosity than the wheat parents. Lack of a root ROL barrier in the six DA lines for H. marinum accession H21 in Chinese Spring (CS) wheat indicates that the gene(s) for this trait do not reside on one of these six chromosomes; unfortunately, chromosome 3 of H. marinum has not been isolated in CS. Unlike the H21–CS amphiploid, which formed a partial ROL barrier in roots, the H90–Westonia amphiploid and the four derived DA lines available did not. The unaltered root aeration traits in the available DA lines challenge the strategy of using H. marinum as a donor of these traits to wheat.

Development of new PCR-based markers specific for chromosome arms of rye (Secale cereale L.)

PCR-based rye (Secale cereale L.) chromosome-specific markers can contribute to the effective utilization of elite genes of rye in wheat (Triticum aestivum L.) breeding programs. In the present study, 578 new PCR-based rye-specific markers have been developed by using specific length amplified fragment sequencing (SLAF-seq) technology, and 76 markers displayed different polymorphism among rye Kustro, Imperial, and King II. A total of 427 and 387 markers were, respectively, located on individual chromosomes and chromosome arms of Kustro by using a set of wheat–rye monosomic addition lines and 13 monotelosomic addition lines, which were derived from T. aestivum L. ‘Mianyang11’ × S. cereale L. ‘Kustro’. In addition, two sets of wheat–rye disomic addition lines, which were derived from T. aestivum L. var. Chinese Spring × S. cereale L. var. Imperial and T. aestivum L. ‘Holdfast’ × S. cereale L. var. King II, were used to test the chromosomal specificity of the 427 markers. The chromosomal locations of 281 markers were consistent among the three sets of wheat–rye addition lines. The markers developed in this study can be used to identify a given segment of rye chromosomes in wheat background and accelerate the utilization of elite genes on rye chromosomes in wheat breeding programs.

Development of a specific SCAR marker for the Ns genome of Psathyrostachys huashanica Keng

Wang, J., Du, W., Wu, J., Chen, X., Liu, C., Zhao, J., Yang, Q. and Li, F. 2014. Development of a specific SCAR marker for the Ns genome of Psathyrostachys huashanica Keng. Can. J. Plant Sci. 94: 1441–1447. Psathyrostachys huashanica Keng (2n=2x=14, NsNs) possesses many agronomically desirable traits that could be used in wheat improvement. We have previously produced a complete set of wheat–P. huashanica disomic addition lines (1Ns–7Ns, 2n=44=22 II). To track the addition of P. huashanica chromatin in wheat rapidly and effectively, a repetitive sequence of 1665 base pairs, designated pHs8, was isolated based on 21 different Triticeae species, including the parents’ common wheat cv. 7182 and P. huashanica, by RAPD analysis. The diagnostic fragments of the RAPD marker OPF151665 were cloned, sequenced, and converted into a sequence-characterized amplified region (SCAR) marker, known as RHS12. Southern hybridization using labeled pHs8 as probe showed intense hybridization signals on P. huashanica, but not on the other 20 species at all. RHS12 was validated using 21 different plant species and a complete set of wheat–P. huashanica disomic addition lines. Our results indicated that the SCAR marker targeted the Ns genome of P. huashanica and it was present in all seven P. huashanica chromosomes. The newly developed SCAR marker should help wheat breeders to screen for genotypes containing P. huashanica chromatin with low costs and high throughput.

Path analysis of genotype × environment interaction in wheat-barley disomic addition lines

In order to locate QTLs controlling the phenotypic stability and drought tolerance of yield and yield components in barley, seven disomic addition lines were sown together with their parents (donor and recipient) in a randomized complete block design with three replications under four rainfed and irrigated conditions. The descriptive diagram of yield and yield components exhibited a genotype (G) × environment (E) interaction and moderate variability over different environments, indicating the possibility of selection for stable and drought-tolerant entries. The AMMI stability value (ASV) and yield stability index (YSI) discriminated addition lines 2H and 4H as the most stable and droughttolerant.Path analysis revealed that the relative contribution of the number of seeds per plant (NSPP) (0.71) to grain yield (GY) was higher than that of the number of seeds per spike (SPS) (−0.44) and of thousand-seed weight (TSW) (−0.14). Therefore, the contribution of NSPP to the stability of GY over different environments was higher than that of other yield components. In other words, the instability of GY was caused by TSW and SPS in different environments. Path analysis on the drought susceptibility index revealed that most of the QTLs controlling drought tolerance and drought susceptibility in barley are located on chromosomes 3H and 6H, respectively.