Potential of Wide Crosses to Improve the Resistance to Vomitoxin Accumulation in Wheat Following Infection by Fusarium Head Blight

Deoxynivalenol (DON) levels were determined in landraces of rye from Brazil, in a collection of triticales and a series of triticale amphiploids. Two of three rye landraces showed a resistant reaction to DON. Seven triticale accessions of the 371 score showed lower levels of incidence, severity and DON content. A total of eight Tritordeum (Triticum durum × Hordeum chilense amphiploids) were scored and showed lower DON levels. Stable lines with lower Fusarium head blight (FHB) and DON levels were selected in progenies from crosses of wheat to preselected accessions of Triticum monococcum and Aegilops speltoides. Both selections compared favourably to the check cultivars in term of agronomic traits indicating minimal linkage drag. One stable resistant line with lower DON levels was isolated in the F7 generation of progenies from crosses to Tritium timopheevii. Lower DON levels were observed in field trials of advanced generation progeny from crosses of wheat to Aegilops cylindrica and Triticum miguschovae. The findings indicate that the alien species accessions or segregating populations from the inter‐specific or inter‐generic hybridization can provide material with variability for DON content

Procedures for Transfer of Agronomic Traits from Alien Species to Crop Plants

The steps involved in the transfer of alien genetic variation will be outlined and the impact of recent technologies on improving the efficiency of the process will be discussed. The selection of parents is the first step; it is critically important that each selection be carefully screened for maximum expression of the desired trait. The crossing process is becoming increasingly more efficient with improved efficiency of growth regulators and embryo rescue media. Doubled haploid methods are being used to facilitate the production of chromosome addition lines. Molecular methods such as RFLPs, RAPDs, chromosome banding, and in situ hybridization add an increased level of resolution to the identification of chromosome additions and the monitoring of introgressed chromosome segments. Emerging technologies such as monocot transformation, chromosome-specific libraries, and transposon tagging may soon replace some of the traditional methods of gene transfer

Introgression of Chromosome 3Ns from Psathyrostachys huashanica into Wheat Specifying Resistance to Stripe Rust

Wheat stripe rust is a destructive disease in the cool and humid wheat-growing areas of the world. Finding diverse sources of stripe rust resistance is critical for increasing genetic diversity of resistance for wheat breeding programs. Stripe rust resistance was identified in the alien species Psathyrostachys huashanica, and a wheat- P. huashanica amphiploid line (PHW-SA) with stripe rust resistance was reported previously. In this study, a P. huashanica 3Ns monosomic addition line (PW11) with superior resistance to stripe rust was developed, which was derived from the cross between PHW-SA and wheat J-11. We evaluated the alien introgressions PW11-2, PW11-5 and PW11-8 which were derived from line PW11 for reaction to new Pst race CYR32, and used molecular and cytogenetic tools to characterize these lines. The introgressions were remarkably resistant to CYR32, suggesting that the resistance to stripe rust of the introgressions thus was controlled by gene(s) located on P. huashanica chromosome 3Ns. All derived lines were cytologically stable in term of meiotic chromosome behavior. Two 3Ns chromosomes of P. huashanica were detected in the disomic addition line PW11-2. Chromosomes 1B of substitution line PW11-5 had been replaced by a pair of P. huashanica 3Ns chromosomes. In PW11-8, a small terminal segment from P. huashanica chromosome arm 3NsS was translocated to the terminal region of wheat chromosomes 3BL. Thus, this translocated chromosome is designated T3BL-3NsS. These conclusions were further confirmed by SSR analyses. Two 3Ns-specific markers Xgwm181 and Xgwm161 will be useful to rapidly identify and trace the translocated fragments. These introgressions, which had significant characteristics of resistance to stripe rust, could be utilized as novel germplasms for wheat breeding

Heart Valve Tissue Engineering: Concepts, Approaches, Progress, and Challenges

Potential applications of tissue engineering in regenerative medicine range from structural tissues to organs with complex function. This review focuses on the engineering of heart valve tissue, a goal which involves a unique combination of biological, engineering, and technological hurdles. We emphasize basic concepts, approaches and methods, progress made, and remaining challenges. To provide a framework for understanding the enabling scientific principles, we first examine the elements and features of normal heart valve functional structure, biomechanics, development, maturation, remodeling, and response to injury. Following a discussion of the fundamental principles of tissue engineering applicable to heart valves, we examine three approaches to achieving the goal of an engineered tissue heart valve: (1) cell seeding of biodegradable synthetic scaffolds, (2) cell seeding of processed tissue scaffolds, and (3) in-vivo repopulation by circulating endogenous cells of implanted substrates without prior in-vitro cell seeding. Lastly, we analyze challenges to the field and suggest future directions for both preclinical and translational (clinical) studies that will be needed to address key regulatory issues for safety and efficacy of the application of tissue engineering and regenerative approaches to heart valves. Although modest progress has been made toward the goal of a clinically useful tissue engineered heart valve, further success and ultimate human benefit will be dependent upon advances in biodegradable polymers and other scaffolds, cellular manipulation, strategies for rebuilding the extracellular matrix, and techniques to characterize and potentially non-invasively assess the speed and quality of tissue healing and remodeling

A study of plant color in crested wheatgrass, Agrophron cristatum (L.) Gaertn

Chlorophyll mutants have been noted in many agricultural crops and have proved useful in inheritance studies. There have been few inheritance studies in the wheatgrasses, partly because of a lack of distinctive characters. The presence of grey-green and bright-green spike colors in diploid crested wheatgrass Agropyron cristatum (L.) The frequencies of grey-green and bright-green plants in Fairway-type strains were noted and the inheritance determined from test crosses. An assessment was made to determine if spike color types were related to agronomic worth. This included an appraisal of heterozygous plants for heterosis effects. Preliminary observations were made of differences in chlorophyll pigments of the various color types

Meiotic pairing in new hybrids of Hordeum procerum (6x) with H. parodii (6x) and Elymus virginicus (4x)

Hybrids of Hordeum procerum were readily produced with H. parodii (7.9%) and Elymus virginicus (14.3%). The average meiotic pairing per cell in the interspecific hybrid between H. procerum and H. parodii was 14.56 I + 12.19 II + 1.04 III, which indicated that the species have two genomes in common. In the hybrid between H. procerum and E. virginicus the average metaphase I configuration was 20.35 I + 6.86 II + 0.31 III indicating one common genome

Variation in induction of homoeologous pairing among chromosomes of 6x Hordeum parodii as a result of three triticale (xTriticosecale Wittmack) cultivars

Intergeneric hybrids were obtained between Hordeum parodii Covas s.1. (6x) and three cultivars of triticale (xTriticosecale) at frequencies of 0.47 to 1.21% of pollinated florets. The triticale cultivars varied in their chromosome constitutions of the rye genome as well as the telomeric heterochromatin content of some of the rye chromosomes. The average chiasmata frequency per cell varied from 0.58 to 13.14 in different hybrid combinations. The differences in the chiasmata frequencies in the different hybrid combinations were attributed to a meiotic pairing control mechanism in H. parodii whose function was affected primarily by the rye chromosome constitutions of the triticale cultivars and to a lesser extent by the heterochromatin content of the rye chromosomes