Molecular characterization of the genome-wide BOR transporter family and their responses to boron conditions in common wheat (Triticum aestivum L.).

Boron (B) deficiency is an agricultural problem that causes significant yield losses in many countries. B transporters (BORs) are responsible for B uptake and distribution and play important roles in yield formation. A comprehensive analysis of the BOR family members in common wheat is still lacking. In the present study, to clarify the molecular characterization and response to B status, genome-wide TaBOR genes and expression patterns were investigated. Fourteen TaBOR genes were identified in common wheat by a homology search. The corresponding phylogenetic tree indicated that 14 TaBOR genes were separately classified into subfamilies of TaBOR1, TaBOR3, and TaBOR4. All TaBOR genes had 12-14 extrons and 11-13 introns. Most TaBOR proteins contained 10 conserved motifs, and motifs 1, 2, 3, 4, and 6 constituted the conserved bicarbonate (HCO3 -) domain. Fourteen TaBOR genes were mapped on 13 chromosomes mainly distributed in the first, third, fifth, and seventh homologous groups. The promoters of TaBOR genes consisted of phytohormones, light responses, and stress-related cis-elements. GO analysis indicated that TaBOR genes were enriched in terms of transmembrane transport and ion homeostasis. TaBOR genes showed diverse expression profiles in different tissues. The members of the TaBOR1 subfamily showed high expression in grains, leaves, roots, stems, and spikes, but members of the TaBOR4 subfamily were highly expressed only in spikes and grains. RT-qPCR indicated that TaBOR1-5A, TaBOR1-5B, and TaBOR1-5D were induced by low B concentrations and had much higher expression in roots than in shoots. TaBOR3-3A, TaBOR3-3B, TaBOR3-3D, TaBOR4-1A, TaBOR4-1B, TaBOR4-1D, and TaBOR3-4B were induced by low and high B concentrations and had high expression in roots and shoots. TaBOR3-4D and TaBOR3-7B were upregulated by low and high B concentrations, respectively, but had expression only in roots. Our results provide basic information on the TaBOR family, which is beneficial for elucidating the functions of TaBOR genes to overcome the problem of B deficiency.

Sequencing and characterization of the complete mitochondrial genome of Thinopyrum obtusiflorum (DC.) Banfi, 2018 (Poaceae).

In this study, the mitochondrial genome of Thinopyrum obtusiflorum was sequenced, assembled, and annotated. The complete circular mitogenome of Th. obtusiflorum is 390,725 bp in length and the overall A + T content of mitogenome is 55.61%. It harbors 33 protein-coding genes (PCGs), 21 transfer RNA genes (tRNAs), six ribosomal RNA genes (rRNAs), and 20 simple sequence repeats (SSRs). Phylogenetic analysis indicates that Th. obtusiflorum is a sister to the clade including Aegilops speltoides, Triticum aestivum, and Triticum aestivum cultivar Chinese Yumai in the Triticeae.

Genetic Diversity and Population Structure of Asian and European Common Wheat Accessions Based on Genotyping-By-Sequencing.

Obtaining information on the genetic diversity and population structure of germplasm facilitates its use in wheat breeding programs. Recently, with the development of next-generation sequencing technology, genotyping-by-sequencing (GBS) has been used as a high-throughput and cost-effective molecular tool for examination of the genetic diversity of wheat breeding lines. In this study, GBS was used to characterize a population of 180 accessions of common wheat originating from Asia and Europe between the latitudes 30° and 45°N. In total, 24,767 high-quality single-nucleotide polymorphism (SNP) markers were used for analysis of genetic diversity and population structure. The B genome contained the highest number of SNPs, followed by the A and D genomes. The polymorphism information content was in the range of 0.1 to 0.4, with a mean of 0.26. The distribution of SNPs markers on the 21 chromosomes ranged from 243 on chromosome 4D to 2,337 on chromosome 3B. Structure and cluster analyses divided the panel of accessions into two subgroups (G1 and G2). G1 principally consisted of European and partial Asian accessions, and G2 comprised mainly accessions from the Middle East and partial Asia. Molecular analysis of variance showed that the genetic variation was greater within groups (99%) than between groups (1%). Comparison of the two subgroups indicated that G1 and G2 contained a high level of genetic diversity. The genetic diversity of G2 was slightly higher as indicated by the observed heterozygosity (H o) = 0.23, and unbiased diversity index (uh) = 0.34. The present results will not only help breeders to understand the genetic diversity of wheat germplasm on the Eurasian continent between the latitudes of 30° and 45°N, but also provide valuable information for wheat genetic improvement through introgression of novel genetic variation in this region.

Molecular characterization of two y-type high molecular weight glutenin subunit alleles 1Ay12 and 1Ay8 from cultivated einkorn wheat (Triticum monococcum ssp. monococcum).

Two y-type high molecular weight glutenin subunits (HMW-GSs) 1Ay12 and 1Ay8 from the two accessions PI560720 and PI345186 of cultivated einkorn wheat (Triticum monococcum ssp. monococcum, AA, 2n=2x=14), were identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The mobility of 1Ay12 and 1Ay8 was similar to that of 1Dy12 and 1By8 from common wheat Chinese Spring, respectively. Their ORFs respectively consisted of 1812bp and 1935bp, encoding 602 and 643 amino acid residues with the four typical structural domains of HMW-GS including signal peptide, conserved N-, and C-terminal and central repetitive domains. Compared with the most similar active 1Ay alleles previous published, there were a total of 15 SNPs and 2 InDels in them. Their encoding functions were confirmed by successful heterogeneous expression. The two novel 1Ay alleles were named as 1Ay12 and 1Ay8 with the accession No. JQ318694 and JQ318695 in GenBank, respectively. The two alleles were classed into the two distinct groups, Phe-type and Cys-type, which might be relevant to the differentiation of Glu-A1-2 alleles. Of which, 1Ay8 belonged to Cys-type group, and its protein possessed an additional conserved cysteine residue in central repetitive region besides the six common ones in N- and C-terminal regions of Phe-type group, and was the second longest in all the known active 1Ay alleles. These results suggested that the subunit 1Ay8 of cultivated einkorn wheat accession PI345186 might have a potential ability to strengthen the gluten polymer interactions and be a valuable genetic resource for wheat quality improvement.

Variation and their relationship of NAM-G1 gene and grain protein content in Triticum timopheevii Zhuk.

NAM is an important domestication gene and valuable to enhance grain protein contents (GPCs) of modern wheat cultivars. In the present study, 12 NAM-G1 genes in Triticum timopheevii Zhuk. (AAGG, 2n=4x=28) were cloned. These genes had the same length of 1546 bp including two introns and three exons, and encoded a polypeptide of 407 amino acid residues which contained a N-terminal NAC domain with five sub-domains, and a C-terminal transcriptional activation region (TAR). They were highly similar to the previously published functional NAM-B1 gene DQ871219 from T. turgidum ssp. dicoccoides Körn. (AABB, 2n=4x=28) in both the nucleotide and protein sequences, with a very high identity of 99.5%. The differences among the 12 NAM-G1 genes resulted from 17 SNPs including 14 transitions and 3 transversions. They had outstandingly different expression levels in qRT-PCR. And, their relative expression quantities were significantly positively correlated with GPC of the accessions. In addition, the difference in amino acid sequences of the NAM-G1 genes may also affect the GPC variation.