Genetic diversity in wild species and cultivars of strawberry for the FanAAMT gene controlling fruit flavor volatiles

Background. An important consumer trait of strawberry fruits is their aroma. Methyl anthranilate makes a considerable contribution to the fruit flavor. The methyl anthranilate content in strawberry fruits is controlled by the FanAAMT (аnthranilic acid methyltransferase) gene. Identification of genetic determinants for this trait facilitates targeted selection of promising forms based on diagnostic DNA markers. The purpose of this study was to study the allelic diversity of the FanAAMT fruit flavor gene in wild strawberry species and strawberry cultivars for identification of promising genotypes.Materials and methods. The objects of this study were wild species of Fragaria L. as well as F. × anaschata Kantor. and F. × ananassa Duch. cultivars of different ecogeographic origin. The FanAAMT gene was identified with the dominant marker FanAAMT.Results and conclusion. In the analyzed collection of strawberry genotypes, the FanAAMT gene was identified in 36.4% of the forms, including the wild species F. vesca L., F. moschata Duch. and F. virginiana subsp. platypetala (Rydb.) Staudt, and cv. ‘Kupchikha’ (F. × anaschata). Among the analyzed F. × ananassa cultivars, the FanAAMT gene was found in 31.6% of the tested forms, specifically in 27.3% of the 22 Russian cultivars, and 37.5% of the analyzed foreign ones. Promising sources of high methyl anthranilate content in fruits were identified: wild spp. F. moschata, F. vesca, and F. virginiana subsp. platypetala; cv. ‘Kupchikha’ (F. × anaschata); Russian garden strawberry cvs. ‘Bylinnaya’, ‘Zenit’, ‘Lastochka’, ‘Neznakomka’, ‘Feyerverk’ and ‘Tsarskoselskaya’; and foreign garden strawberry cvs. ‘Karmen’, ‘Ostara’, ‘Samson’, ‘Symphony’, ‘Troubadour’ and ‘Vima Tarda’, in which the functional allele of the FanAAMT gene was found. In the remaining studied strawberry genotypes the marker FanAAMT was not detected, which presumably indicates that the FanAAMT gene is absent. cells (R9.4.1).

Development of Markers for Identification and Maker-Assisted Breeding of Xa7 Gene in Rice (Oryza sativa L.)

Utilization of resistance (R) genes to breed resistant cultivars is one of the most effective and economical approach to control rice bacterial blight (BB). Xa7, a dominant, broad-spectrum and durable BB-resistant gene, is an ideal gene resource to improve the resistance of rice varieties to bacterial blight, and this well-known gene with important breeding value has been cloned in our recent study. The isolation of Xa7 will facilitate its application in rice breeding by molecular maker-assisted selection (MAS). In this study, based on the specific sequences in the promoter of Xa7, a functional marker, named as MX7, was developed, which can effectively distinguish the dominant BB-resistant Xa7, the recessive BB-susceptible xa7 and the null allele from different rice varieties. Since MX7 is a dominant marker, it can't tell homozygous from heterozygous, a co-dominant marker closely linked to Xa7, named as M6, was developed simultaneously. After verified by amplification in numerous rice varieties and sequence alignment in RICE 3K database, it is proved that marker M6 is co-segregated with the Xa7 locus. In addition, the effectiveness and accuracy of the two markers were further validated by two F2 populations. Finally, the designed makers were effectively applied in MAS breeding to improve the BB-resistance of a susceptible variety. This study not only provides reliable functional markers for the identification of Xa7 gene in different rice materials, but also will contribute to the application of Xa7 gene in marker-assisted selection to breed rice varieties with durable disease resistance.

Molecular Typing and Virulence Analysis of Pseudomonas Aerugınosa Isolated From Burn Infections Recovered From Duhok and Erbil Hospitals/Iraq.

In this study, 225 isolates of Pseudomonas aeruginosa were recovered from burn wounds in major hospitals in Duhok and Erbil, Iraq, between April 2015 and September 2015. A total of 136 of these isolates were from men, comprising 60.4% of the total, whereas 89 (39.6%) were recovered from women. One hundred of these isolates were selected (50 from each province of Erbil and Duhok) and subjected to 16 different antibiotics using the disc diffusion method. The isolates showed a high level of resistance to most of the tested antibiotics, with 90% of the isolates being multidrug resistant. Imipenem was considered as the most effective antibiotic against these isolates with a resistant rate of 47%. The genome of all of these isolates were successfully amplified and produced a single band for the 16S rDNA locus with a molecular weight of about 956 base pairs, which was used to confirm, at the molecular level, that all these isolates were indeed P. aeruginosa. The results of the detection of five virulence-related genes including opr1, toxA, exoS, lasB, and nan1 revealed that 10 of these isolates, accounting for 10%, lacked any of the tested virulence markers. The opr1 gene, as a marker for the presence of a pathogenicity island, was the most dominant marker among all the virulence markers and was detected in 90 isolates (90%), followed by the toxA and exoS genes, which were both observed in 86 (86%) isolates, whereas the lasB gene was found in 82 (82%) isolates and the nan1 gene in 35 (35%) of the isolates, respectively.

A Convenient Co-Dominant Marker for Height-Reducing Ddw1 Allele Useful for Marker-Assisted Selection

Reducing plant height improves lodging resistance and helps to obtain high grain yield under various environmental conditions. So far, the introduction and maintenance of the dwarfing allele of the Ddw1 gene is the most effective height-reducing genetic approach in rye and triticale breeding programs. However, the dominance of the dwarfing Ddw1 allele makes it difficult to select against heterozygous lines for further breeding based on plant phenotype. To assist breeders in the identification of the allele status of the Ddw1 gene, we developed a cleaved amplified polymorphic sequence (CAPS) marker that requires basic equipment and can be easily applied. The CAPS marker was tested on two F2 segregating populations of triticale, and the test showed the association of the Ddw1 genotype with plant height. The application of the marker for marker-assisted selection (MAS) for rye and triticale is discussed in detail.

Discovery of a naturally-occurring allele of eIF4E1.S in Nicotiana tabacum and development of a co-dominant marker

Background: The Potato Virus Y (PVY) resistance tobacco mutant VAM, which was produced by X-ray irradiation, and its derived mutant va were previously shown to contain large chromosomal deletions. Among the genes deleted in lines containing these loci is a specific eukaryotic translation initiation factor 4E (eIF4E) gene, designated eIF4E1.S, whose protein product has been shown to facilitate infection by certain potyviruses, the most important of which from an agronomic perspective is PVY. Because the extent of the deletions and the exact nature of their specific breakpoints have not been precisely established for VAM or va, it has not been possible to develop co-dominant markers for these loci. Results: Here, we identified a PVY-resistant tobacco landrace Fuquanliuye with a deletion in the 3' region of the eIF4E1.S gene. The approximate position of the 5' deletion breakpoint was defined by segmented amplification, cloning and sequencing. Using information from this analysis, a chromosome walk was initiated and the nucleotide sequence of the deletion junction was obtained. Through comparison with the tobacco reference genome, it was found that an approximately 27 kb sequence including the 3' region of the eIF4E1.S gene was deleted from the Fuquanliuye genome and nine extra nucleotides of unknown origin were inserted at the breakpoint. Based on the information above, a PCR-based co-dominant molecular marker for the identification of the eIF4E1.S mutant allele was developed. Using this co-dominant marker, we genotyped F2 plants segregating for the eIF4E1.S mutant allele and confirmed good consistency between the genotype and the phenotype to PVY virus. Conclusions: We report a novel naturally-occurring mutant allele of eIF4E1.S from the PVY-resistant tobacco landrace Fuquanliuye, designated eIF4E1.Fu, and a PCR-based co-dominant marker specific for eIF4E1.Fu. This may provide a valuable genetic resource and a basis for marker-assisted selection to improve the PVY resistance of breeding cultivars/lines.

Usage of microsatellite markers for characterization of polyploids: a case study in reference to hexaploid bamboo species

Microsatellite markers are most valuable tools for characterization of plant genetic resources or population genetic analysis. Since they are codominant and allelic markers, utilizing them in polyploid species remained doubtful. In such cases, microsatellite markers are usually analyzed by treating them as dominant marker. In the current study, it has been showed that despite of losing the advantage of co-dominance, microsatellite markers are still powerful tool for genotyping of polyploid species because of availability of large number of reproducible alleles per locus. It has been studied by genotyping of nineteen sub populations of Dendrocalamus hamiltonii (hexaploid bamboo species) with seventeen polymorphic SSR primer pairs. Among these, ten primers gave typical banding pattern of microsatellite marker as expected in diploid species but rest seven gave unusual pattern i.e. more than two bands per locus per genotype. In such case genotyping data are generally analyzed by considering as dominant markers. Given these facts, data were analyzed in both ways as dominant and codominant. All the seventeen primer were first scored as non-allelic data and analyzed; later ten primer pairs giving standard banding pattern were analyzed as allelic data and the results were compared. The UPGMA clustering and genetic structure showed that results obtained with both the data sets were very similar, and therefore the SSR marker could be utilized to characterize polyploid species by considering them as dominant marker. The study is highly useful to widen the scope of SSR markers applications and beneficial to the researchers dealing with polyploid species.