Anatomical studies on selected species of Viola (Violaceae)

Cross‐sections of roots, stems, petioles and peduncles were investigated in 12 species of Viola distributed mainly in northern Iran: V. kitaibeliana, V. arvensis, V. occulta, V. tricolor (sect. Melanium), V. somchetica (sect. Plagiostigma), V. spathulata (sect. Spathulidium ined.), V. alba, V. odorata, V. sintenisii (sect. Viola subsect. Viola), V. caspia, V. reichenbachiana and V. rupestris (sect. Viola subsect. Rostratae). General anatomical features of Viola species are discussed. The following characters were found to be taxonomically informative: cross‐section shapes of the aerial stem, petiole and peduncle as well as the number of vascular bundles in the aerial stem. In taxa of sect. Melanium, stem cross‐sections are elliptic with two wings, but they are semi‐circular with two wings in taxa of sect. Viola subsect. Rostratae. Within the latter subsection, the number of vascular bundles in the stem can be used to delimit the species V. caspia, V. reichenbachiana and V. rupestris. Calcium oxalate crystals were observed in all vegetative organs of taxa belonging to sect. Viola. All examined taxa had a secondary structure with the exception of V. somchetica. Our results show that anatomical characters are useful for delimiting species, subsections, and sections within Viola.     

Identification and validation of a major cadmium accumulation locus and closely associated SNP markers in North Dakota durum wheat cultivars

Durum wheat has the tendency of accumulating more cadmium (Cd), a biotoxic heavy metal, in seeds than other commonly grown cereals, thus posing a serious food safety/public health concern. This could have serious negative impact on the national pasta industry and the international export market of durum wheat. The phenotyping for selecting low Cd lines is expensive and time consuming. The use of markers could be a more sustainable approach for selecting lines with low Cd levels. Here, a RIL population developed from a cross between Grenora (high Cd) × Haurani (low Cd) and two association mapping panels consisting of advanced breeding lines from the North Dakota durum wheat breeding program were used to identify QTL and associated markers for Cd. A major QTL, with Haurani contributing low Cd uptake allele and explaining 54.3 % phenotypic variation, was detected on chromosome 5BL. Association mapping using 2010 collection validated the results of linkage mapping and identified major QTL on 5BL. The 2009 collection, showed the presence of a major QTL on chromosome 2B. The SNP marker associated with major QTL on 5BL was converted to user friendly KASPar assay. The major QTL and associated KASPar marker were further validated using another RIL population developed from a cross of Strongfield (low Cd) and Alkabo (high Cd). The development of suitable marker assay, associated with major Cd uptake QTL, would help the selection for low Cd accumulating lines, minimizing the costly phenotypic evaluation for this important trait.     

Molecular cytogenetic characterization of an alloplasmic durum wheat line with a portion of chromosome 1D of Triticum aestivum carrying the scs(ae) gene.

Triticum aestivum (2n = 6x = 42, AABBDD) with Triticum longissimum (2n = 2x = 14; S1S1) cytoplasm ((lo) cytoplasm) has normal fertility and plant vigor. However, the nucleus of durum wheat (Triticum turgidum (2n = 4x = 28, AABB)) is incompatible with the T. longissimum cytoplasm, producing non-viable progeny. This incompatibility is alleviated by scs(ae), a species cytoplasm-specific (scs) gene, on the long arm of chromosome 1D (1DL) of common wheat. The hemizygous (lo) durum scs(ae) line is male sterile and is maintained by crossing to normal durum wheat. After pollination, the seeds produced are either plump and viable (with scs(ae)) or shriveled and inviable (without scsae). Thus, the chromosome with scs(ae) is inherited as a whole without recombination. The objectives of this study were to characterize the chromosome carrying scs(ae) and to determine the process through which this gene was introgressed into the (lo) durum background. Molecular marker analysis with 27 probes and primers mapped to homoeologous group 1 and genomic in situ hybridization using differentially labeled total genomic DNA of durum wheat and Aegilops tauschii suggest the presence of a 1AL segment in place of the distal region of 1DL. Owing to the absence of any detectable duplications or deletions, homoeologous recombination is the most likely mechanism by which this introgression occurred.     

Genetic analysis of adaptive syndromes interrelated with seed dormancy in weedy rice (Oryza sativa)

Seed dormancy in rice interrelates to the weedy characteristics shattering, awn, black hull color, and red pericarp color. A cross between the weedy strain SS18-2 and the breeding line EM93-1 was developed to investigate the genetic basis and adaptive significance of these interrelationships. These characteristics or their components differed in average degree of dominance from –0.8 to 1.5, in heritability from 0.5 to 0.96, and in their contribution to phenotypic or genotypic variation in dormancy by up to 25%. Five dormancy, four shattering, and three awn-length quantitative trait loci (QTLs) were detected in the BC₁ population replicated in 2 years. Two QTLs for hull color were identified, and the SS18-2-derived and EM93-1-derived alleles increased the intensity of black, and red or yellow pigmentations, respectively. The only QTL for pericarp color co-located with the red pericarp gene Rc, with the SS18-2-derived allele increasing the intensity of black and red pigmentations. Four of the five dormancy QTLs were flanked or bracketed by one to four QTLs for the interrelated characteristics. The QTL organization pattern indicates the central role of seed dormancy in adaptive syndromes for non-domesticated plants, implies that the elimination of dormancy from cultivars could arise from the selections against multiple interrelated characteristics, and challenges the use of dormancy genes at these loci in breeding varieties for resistance to pre-harvest sprouting (PHS). However, another QTL (qSD12) provides candidate gene(s) for PHS resistance because it has a large effect in the population and it is independent of the loci for interrelated characteristics.     

Genetic characterization of Drosophila Mi-2 ATPase

Zinc-fingers and homeoboxes 1 (ZHX1) is a protein which interacts with the activation domain of the A subunit of nuclear factor-Y. To analyze the physiological role(s) of ZHX1, we searched ZHX1-interacting protein(s) using a yeast two-hybrid system. The rat counterpart of ZHX1 cDNAs was cloned from an ovarian granulosa cell complementary DNA (cDNA) library, indicating that ZHX1 is able to form a homodimer. An analysis of the nucleotide sequence and its deduced amino acid sequence show that rat ZHX1 consists of 873 amino acid residues. Northern blot analysis shows that ZHX1 messenger RNA is expressed ubiquitously and that the level in the ovary are not regulated by gonadotropins. Furthermore, transfection experiments with green fluorescence protein (GFP) expression vectors into human embryonic kidney HEK293 cells reveal that full-length ZHX1 fused to the GFP is localized in the nuclei. Thus, we report on the molecular cloning, expression and characterization of full-length rat ZHX1 cDNA.     

Identification,introgression, and molecular marker genetic analysis and selection of a highly effective novel oat crown rust resistance from diploid oat, <Emphasis Type="Italic">Avena strigosa</Emphasis>

Key message

Oat crown rust is one of the most damaging diseases of oat. We identified a new source of resistance and developed KASP and TaqMan markers for selection in breeding programs.

Abstract

A new highly effective resistance to oat crown rust (Puccinia coronata f. sp. avenae) was identified in the diploid oat Avena strigosa PI 258731 and introgressed into hexaploid cultivated oat. Young plants with this resistance show moderate susceptibility, whereas older plant tissues and adult plants are resistant with no virulent isolates encountered in over 8 years of testing. Resistance was incorporated into hexaploid oat by embryo rescue, colchicine chromosome doubling followed by backcrosses with a hexaploid parent, and selection for stable transmission of resistance. To mitigate flag leaf and panicle chlorosis/necrosis associated with the resistance, crosses were made with derived resistant lines to breeding lines of divergent parentage followed by selection. Subsequently, two F₂ sister lines, termed MNBT1020-1 and MNBT1021-1, were identified in which the chlorosis/necrosis was reduced. These two lines performed well in replicated multi-location state trials in 2015 and 2016 out-yielding all cultivar entries. Segregating F_2:3 plants resulting from crosses of MNBT lines to susceptible parents were genotyped with the oat 6K SNP array, and SNP loci with close linkage to the resistance were identified. KASP assays generated from linked SNPs showed accurate discrimination of the resistance in derivatives of the resistant MNBT lines crossed to susceptible breeding lines. A TaqMan marker was developed and correctly identified homozygous resistance in over 95% of 379 F₄ plants when rust was scored in F_4:5 plants in the field. Thus, a novel highly effective resistance and associated molecular markers are available for use in breeding, genetic analysis, and functional studies.

     

A radiation hybrid map of chromosome 1D reveals synteny conservation at a wheat speciation locus

The species cytoplasm specific (scs) genes affect nuclear-cytoplasmic interactions in interspecific hybrids. A radiation hybrid (RH) mapping population of 188 individuals was employed to refine the location of the scs ^ae locus on Triticum aestivum chromosome 1D. “Wheat Zapper,” a comparative genomics tool, was used to predict synteny between wheat chromosome 1D, Oryza sativa, Brachypodium distachyon, and Sorghum bicolor. A total of 57 markers were developed based on synteny or literature and genotyped to produce a RH map spanning 205.2 cR. A test-cross methodology was devised for phenotyping of RH progenies, and through forward genetic, the scs ^ae locus was pinpointed to a 1.1 Mb-segment containing eight genes. Further, the high resolution provided by RH mapping, combined with chromosome-wise synteny analysis, located the ancestral point of fusion between the telomeric and centromeric repeats of two paleochromosomes that originated chromosome 1D. Also, it indicated that the centromere of this chromosome is likely the result of a neocentromerization event, rather than the conservation of an ancestral centromere as previously believed. Interestingly, location of scs locus in the vicinity of paleofusion is not associated with the expected disruption of synteny, but rather with a good degree of conservation across grass species. Indeed, these observations advocate the evolutionary importance of this locus as suggested by “Maan’s scs hypothesis.”     

Aflatoxin contamination of wheat flour and the risk of esophageal cancer in a high risk area in Iran

Background: Golestan province in northeastern Iran has been known as a high-risk area for esophageal cancer (EC). This study was conducted to assess aflatoxin (AF) contamination of wheat flour (WF) samples in high and low EC-risk areas of Golestan province. Methods: Four WF samples were collected randomly from each of 25 active silos throughout the province in 2009. The levels of AFs were measured using the High-performance liquid chromatography method. Using the data of EC rates obtained from Golestan population-based cancer registry, the province was divided into high and low risk areas for EC. Student t-test and multivariate regression analysis were used to compare the levels of aflatoxins as well as the condition of silos between the two areas. Results: One hundred WF samples were collected. The mean levels of total aflatoxin and aflatoxin B1 was 1.99 and 0.53 ng g^?1, respectively. The levels of total AF (p = 0.03), AFG2 (p = 0.02) and AFB1 (p = 0.003) were significantly higher in samples obtained from high risk area. Multivariate regression analysis showed that humidity of silo was the most important source of difference between silos of the two areas (p = 0.04). Conclusion: We found a positive relationship between AF level of WF samples and the risk of EC. So, AF contamination may be a possible risk factor for EC in our region. We also found that humidity of silos was the most important determinant of AF contamination of WF. Intensive control of silos conditions including humidity and temperature are needed especially in high EC-risk areas.     

Left Ventricular Hypertrophy Is Associated With Obesity,Male Gender,and Symptoms in Healthy Adolescents

Obesity has been found to be associated with left ventricular (LV) hypertrophy (LVH). However, the occurrence of LVH in obese teenagers who are involved in sport programs has not been studied. The objective of this study was to evaluate the prevalence of LVH and its correlation with obesity, gender, and symptoms in teenage athletes. We used echocardiographic database of 1,500 adolescences between the ages of 12 and 20 years who were actively involved in school sport programs. We evaluated associations between obesity and LVH (defined as LV wall thickness (LVWT)) >12 mm, or LV mass (LVM) >215 g or relative wall thickness (RWT) >0.43) and physical symptoms. Using univariate and multivariate analysis, male gender was associated with increased LVWT (multivariate odds ratio (OR) 4.87, confidence interval (CI) 2.41–9.82). Obesity was associated with parameters of LVH using univariate and multivariate analysis. (LVM > 215 g) occurred in 10.32% of obese athletes vs. 0.2% (1/445) of controls, (OR 51.33, CI 6.05–433.8), P < 0.001, LVWT >12 mm occurred in 16.5% of obese students vs. 3.6% of controls (OR 5.2, CI 2.7–10.1, P < 0.001), RWT >0.43 occurred in 41.4% of obese students vs. 15.7% of controls (OR 3.78, CI 2.11–6.76, P < 0.001). After adjusting for age and gender, reported history of shortness of breath (SOB), fatigue and leg edema were also significantly more prevalent in obese students and in students with LVH. In conclusion obesity is associated with LVH in a population of healthy teenagers actively involved in sport programs. Furthermore, the presence of LVH was independently associated with many physical symptoms suggesting negative effect of LVH on myocardial function.