Genetic Interactions of Awnness Genes in Barley

Exome-wide variation in a diverse barley panel reveals genetic associations with ten agronomic traits in Eastern landraces

Barley (Hordeum vulgare ssp. vulgare) was one of the first crops to be domesticated and is adapted to a wide range of environments. Worldwide barley germplasm collections possess valuable allelic variations that could further improve barley productivity. Although barley genomics has offered a global picture of allelic variation among varieties and its association with various agronomic traits, polymorphisms from East Asian varieties remain scarce. In this study, we analyzed exome polymorphisms in a panel of 274 barley varieties collected worldwide, including 137 varieties from East Asian countries and Ethiopia. We revealed the underlying population structure and conducted genome-wide association studies for ten agronomic traits. Moreover, we examined genome-wide associations for traits related to grain size such as awn length and glume length. Our results demonstrate the value of diverse barley germplasm panels containing Eastern varieties, highlighting their distinct genomic signatures relative to Western subpopulations.

Studies on mutagenic effect of phosphemide in barley

Background. The method of induced mutagenesis is used to temporarily increase the frequency of mutations, allowing a higher probability of obtaining plants with new alleles and traits valuable for breeding. The search for new agents with high mutagenic activity is of particular interest for the development of mutational breeding. A new mutagen for barley is phosphemide.

Materials and methods. Field and laboratory studies were conducted in 2016–2018. Three barley genotypes were treated with an aqueous solution of phosphemide at two concentrations: 0.002% and 0.01%, exposure: 3 hours. Experimental data were statistically processed by the analysis of variance (ANOVA) using Statistica 7. The error of the mean (Sx) was calculated for the mean values. Significance of differences (P < 0.05) was determined by Student’s t-test. Mutation frequency (Mf), mutagenic effectiveness (ME), and efficiency (Me) were assessed.

Results and conclusion. It was found that the greatest contribution to formation of field seed germination of mutant populations in M1 and M2 generations was made by the mutagenic factor (20,36%) and interaction of the genotype × environment (18,55%) and mutagen × environment factors (14,93%). The concentration of 0.01% was recognized as semi-lethal for two accessions. In the M2 generation, the mutagenic effectiveness of the 0.002% phosphemide concentration exceeded that of 0.01% more than 4 times. The low concentration was more effective for cv. ‘Zernogradsky 813’ (17.43%) and accession Dz02- 129 (12.04%). For C.I. 10995, a higher concentration of phosphemide had greater effect (29.66%) providing a high mutation frequency (9.79%) against a relatively low lethality (33.00%). Nine different types were identified in the mutation spectrum. In M3 generation, distinct inheritance of the changes was confirmed in 46.43% of families. The highest number of families with confirmed changes was recorded for C.I. 10995 in the experiment with a higher concentration. 

Studies on mutagenic effect of phosphemide in barley

Background. The method of induced mutagenesis is used to temporarily increase the frequency of mutations, allowing a higher probability of obtaining plants with new alleles and traits valuable for breeding. The search for new agents with high mutagenic activity is of particular interest for the development of mutational breeding. A new mutagen for barley is phosphemide.

Materials and methods. Field and laboratory studies were conducted in 2016–2018. Three barley genotypes were treated with an aqueous solution of phosphemide at two concentrations: 0.002% and 0.01%, exposure: 3 hours. Experimental data were statistically processed by the analysis of variance (ANOVA) using Statistica 7. The error of the mean (Sx) was calculated for the mean values. Significance of differences (P < 0.05) was determined by Student’s t-test. Mutation frequency (Mf), mutagenic effectiveness (ME), and efficiency (Me) were assessed.

Results and conclusion. It was found that the greatest contribution to formation of field seed germination of mutant populations in M1 and M2 generations was made by the mutagenic factor (20,36%) and interaction of the genotype × environment (18,55%) and mutagen × environment factors (14,93%). The concentration of 0.01% was recognized as semi-lethal for two accessions. In the M2 generation, the mutagenic effectiveness of the 0.002% phosphemide concentration exceeded that of 0.01% more than 4 times. The low concentration was more effective for cv. ‘Zernogradsky 813’ (17.43%) and accession Dz02- 129 (12.04%). For C.I. 10995, a higher concentration of phosphemide had greater effect (29.66%) providing a high mutation frequency (9.79%) against a relatively low lethality (33.00%). Nine different types were identified in the mutation spectrum. In M3 generation, distinct inheritance of the changes was confirmed in 46.43% of families. The highest number of families with confirmed changes was recorded for C.I. 10995 in the experiment with a higher concentration. 

Individual Genetic Heterogeneity

Genetic variation has been widely covered in literature, however, not from the perspective of an individual in any species. Here, a synthesis of genetic concepts and variations relevant for individual genetic constitution is provided. All the different levels of genetic information and variation are covered, ranging from whether an organism is unmixed or hybrid, has variations in genome, chromosomes, and more locally in DNA regions, to epigenetic variants or alterations in selfish genetic elements. Genetic constitution and heterogeneity of microbiota are highly relevant for health and wellbeing of an individual. Mutation rates vary widely for variation types, e.g., due to the sequence context. Genetic information guides numerous aspects in organisms. Types of inheritance, whether Mendelian or non-Mendelian, zygosity, sexual reproduction, and sex determination are covered. Functions of DNA and functional effects of variations are introduced, along with mechanism that reduce and modulate functional effects, including TARAR countermeasures and intraindividual genetic conflict. TARAR countermeasures for tolerance, avoidance, repair, attenuation, and resistance are essential for life, integrity of genetic information, and gene expression. The genetic composition, effects of variations, and their expression are considered also in diseases and personalized medicine. The text synthesizes knowledge and insight on individual genetic heterogeneity and organizes and systematizes the central concepts.

Genetic Loci Underlying Awn Morphology in Barley

Barley awns are highly active in photosynthesis and account for 30–50% of grain weight in barley. They are diverse in length, ranging from long to awnless, and in shape from straight to hooded or crooked. Their diversity and importance have intrigued geneticists for several decades. A large collection of awnness mutants are available—over a dozen of them have been mapped on chromosomes and a few recently cloned. Different awnness genes interact with each other to produce diverse awn phenotypes. With the availability of the sequenced barley genome and application of new mapping and gene cloning strategies, it will now be possible to identify and clone more awnness genes. A better understanding of the genetic basis of awn diversity will greatly facilitate development of new barley cultivars with improved yield, adaptability and sustainability.