Comparative Genomics, Evolution, and Drought-Induced Expression of Dehydrin Genes in Model Brachypodium Grasses

Dehydration proteins (dehydrins, DHNs) confer tolerance to water-stress deficit in plants. We performed a comparative genomics and evolutionary study of DHN genes in four model Brachypodium grass species. Due to limited knowledge on dehydrin expression under water deprivation stress in Brachypodium, we also performed a drought-induced gene expression analysis in 32 ecotypes of the genus’ flagship species B. distachyon showing different hydric requirements. Genomic sequence analysis detected 10 types of dehydrin genes (Bdhn) across the Brachypodium species. Domain and conserved motif contents of peptides encoded by Bdhn genes revealed eight protein architectures. Bdhn genes were spread across several chromosomes. Selection analysis indicated that all the Bdhn genes were constrained by purifying selection. Three upstream cis-regulatory motifs (BES1, MYB124, ZAT) were detected in several Bdhn genes. Gene expression analysis demonstrated that only four Bdhn1-Bdhn2, Bdhn3, and Bdhn7 genes, orthologs of wheat, barley, rice, sorghum, and maize genes, were expressed in mature leaves of B. distachyon and that all of them were more highly expressed in plants under drought conditions. Brachypodium dehydrin expression was significantly correlated with drought-response phenotypic traits (plant biomass, leaf carbon and proline contents and water use efficiency increases, and leaf water and nitrogen content decreases) being more pronounced in drought-tolerant ecotypes. Our results indicate that dehydrin type and regulation could be a key factor determining the acquisition of water-stress tolerance in grasses.

Identification of dehydrin genes Dhn1 and Zmdhn13 alleles in maize varieties and lines

Aim. Determination of molecular genetic polymorphism of maize varieties and lines (Zea mays L.) of Ukrainian and world selection by Dhn1 and ZmDHN13 dehydrin genes. Methods. Polymerase chain reaction (PCR), PAAgel-electrophoresis. Results. Maize varieties and lines of different geographical origin and different years of creation were analyzed by Dhn1 and ZmDhn13 dehydrin genes. Conclusions. The use of directional primers revealed five different alleles of the Dhn1 locus, which differed in the size of the amplification product: 186, 190, 194, 196 and 200 bp. The most common allele was 196 bp (46.2%). Two alleles of the ZmDhn13 locus were detected: 86 bp and 82 bp. Allele frequency 86 bp was 61.5% and the allele frequency 82 bp was 38.5%. The sequences of the dehydrin genes Dhn1 and ZmDhn13 are not conservative, deletions and / or insertions within these genes are observed. Accordingly, the structure and functional activity of the dehydrin proteins that encode these genes in different genotypes can vary greatly. Keywords: Zea mays L., dehydrins, genes, drought resistance.

Heterologous Expression of Three Ammopiptanthus mongolicus Dehydrin Genes Confers Abiotic Stress Tolerance in Arabidopsis thaliana

Ammopiptanthus mongolicus, a xerophyte plant that belongs to the family Leguminosae, adapts to extremely arid, hot, and cold environments, making it an excellent woody plant to study the molecular mechanisms underlying abiotic stress tolerance. Three dehydrin genes, AmDHN132, AmDHN154, and AmDHN200 were cloned from abiotic stress treated A. mongolicus seedlings. Cytomembrane-located AmDHN200, nucleus-located AmDHN154, and cytoplasm and nucleus-located AmDHN132 were characterized by constitutive overexpression of their genes in Arabidopsis thaliana. Overexpression of AmDHN132, AmDHN154, and AmDHN200 in transgenic Arabidopsis improved salt, osmotic, and cold tolerances, with AmDHN132 having the largest effect, whereas the growth of transformed plants is not negatively affected. These results indicate that AmDHNs contribute to the abiotic stress tolerance of A. mongolicus and that AmDHN genes function differently in response to abiotic stresses. Furthermore, they have the potential to be used in the genetic engineering of stress tolerance in higher plants.

Identification and expression analyses of two lotus (Nelumbo nucifera) dehydrin genes in response to adverse temperatures, ABA and IAA treatments

Dehydrins (DHNs) play imperative role in the stress tolerance of high plants. In this study, the YSK