Natural variations in the promoter of Awn Length Inhibitor 1 (ALI-1) are associated with awn elongation and grain length in common wheat.

Wheat awn plays a vital role in photosynthesis, grain production, and drought tolerance. However, the systematic identification or cloning of genes controlling wheat awn development is seldom reported. Here, we conducted a genome-wide association study (GWAS) with 364 wheat accessions and identified 26 loci involved in awn length development, including previously characterized B1, B2, Hd, and several rice homologs. The dominant awn suppressor B1 was fine mapped to a 125-kb physical interval, and a C2 H2 zinc finger protein Awn Length Inhibitor 1 (ALI-1) was confirmed to be the underlying gene of the B1 locus through the functional complimentary test with native awnless allele. ALI-1 expresses predominantly in the developing spike of awnless individuals, transcriptionally suppressing downstream genes. ALI-1 reduces cytokinin content and simultaneously restrains cytokinin signal transduction, leading to a stagnation of cell proliferation and reduction of cell numbers during awn development. Polymorphisms of four single nucleotide polymorphisms (SNPs) located in ALI-1 promoter region are diagnostic for the B1/b1 genotypes, and these SNPs are associated with awn length (AL), grain length (GL) and thousand-grain weight (TGW). More importantly, ali-1 was observed to increase grain length in wheat, which is a valuable attribute of awn on grain weight, aside from photosynthesis. Therefore, ALI-1 pleiotropically regulates awn and grain development, providing an alternative for grain yield improvement and addressing future climate changes.

A novel NAC family transcription factor SPR suppresses seed storage protein synthesis in wheat.

The synthesis of seed storage protein (SSP) is mainly regulated at the transcriptional level. However, few transcriptional regulators of SSP synthesis have been characterized in common wheat (Triticum aestivum) owing to the complex genome. As the A genome donor of common wheat, Triticum urartu could be an elite model in wheat research considering its simple genome. Here, a novel NAC family transcription factor TuSPR from T. urartu was found preferentially expressed in developing endosperm during grain-filling stages. In common wheat transgenically overexpressing TuSPR, the content of total SSPs was reduced by c. 15.97% attributed to the transcription declines of SSP genes. Both in vitro and in vivo assays showed that TuSPR bound to the cis-element 5'-CANNTG-3' distributed in SSP gene promoters and suppressed the transcription. The homolog in common wheat TaSPR shared a conserved function with TuSPR on SSP synthesis suppression. The knock-down of TaSPR in common wheat resulted in 7.07%-20.34% increases in the total SSPs. Both TuSPR and TaSPR could be superior targets in genetic engineering to manipulate SSP content in wheat, and this work undoubtedly expands our knowledge of SSP gene regulation.

Molecular Characterization of Novel x-Type HMW Glutenin Subunit 1B × 6.5 in Wheat.

A novel high molecular weight glutenin subunit encoded by the Glu-1B locus was identified in the French genotype Bagou, which we named 1B × 6.5. This subunit differed in SDS-PAGE from well-known 1B × 6 and 1B × 7 subunits, which are also encoded at this locus. Subunit 1B × 6.5 has a theoretical molecular weight of 88,322.83 Da, which is more mobile than 1B × 6 subunit, and isoelectric point (pI) of about 8.7, which is lower than that for 1B × 6 subunit. The specific primers were designed to amplify and sequence 2476 bp of the Glu-1B locus from genotype Bagou. A high level of similarity was found between the sequence encoding 1B × 6.5 and other x-type encoding alleles of this locus.

Occurrence of deoxynivalenol in wheat in Slovakia during 2010 and 2011.

In this study, a total of 299 grain samples of wheat were collected from four production regions: the maize, sugar beet, potato and feed sectors of Slovakia. The samples were analyzed for deoxynivalenol (DON) content by using an enzyme-linked immunosorbent assay Ridascreen® Fast DON. Analysis of variance revealed a significant difference between years in DON contents (p < 0.027). The occurrence of samples with DON was 82.2% in 2010, with maximum DON content of 7.88 mg kg⁻¹, and 70.7% in 2011, with maximum DON content of 2.12 mg·kg⁻¹. The total mean DON content was 0.62 mg·kg⁻¹; in the feed region 0.22 mg·kg⁻¹; 0.63 mg·kg⁻¹ in the maize region; 0.78 mg·kg⁻¹ in the sugar beet region; 0.45 mg·kg⁻¹ the potato region. The limit of 1.25 mg·kg⁻¹ imposed by the European Union (EU) for DON content was exceeded in 13.7% of the studied samples. The average monthly rainfall for May to June played a critical role in DON content of wheat grains for maize and sugar beet producing regions. The present results indicate that DON content was at a high level in grains from wheat grown during 2010.

Microsatellite markers discriminating accessions within collections of plant genetic resources.

The reliability of microsatellite analyses for discriminating between plant accessions maintained in collections of genetic resources was tested for 53 accessions of barley, 65 of soybean, 49 of chickpea, and 19 of alfalfa. The specific primer pairs used in this study were based on microsatellite DNA sequences surrounded by perfect dinucleotide and imperfect trinucleotide tandem repeat units. The evaluated polymorphic information content, diversity index, and probabilities of identity indicate that there is value in the application of SSR analyses in barley, soybean, and chickpea genetic resource management. Variation between alfalfa genotypes was not revealed at the five analyzed microsatellite loci.