Preservation of moist grain anaerobically by so-called crimping has many advantages. Generally, preservation has been successfully performed when grain is harvested at 30–40% moisture content (MC). However, there is a trend towards using drier than the optimal MC of the raw material. This leads to an increasing need to control aerobic spoilage of the material and also to experimental challenges in assessing the quality and stability of low-MC crimped grain. The objective of the current work was to evaluate fermentation quality, microbial composition and aerobic stability (AS) of drier than the optimal crimped grain ensiled with different additives and to use these materials to compare three different AS evaluation methods. Crimped wheat grain with 28% MC was ensiled using eight additive treatments based mainly on formic and propionic acids including a control without any additive. The low MC resulted in no lactic acid fermentation, but significant ethanol formation occurred in the control. The treatments used resulted in clear differences in microbial quality and AS of the feeds, and use of formic and propionic acid-based additives provided a clear benefit in improving the AS of crimped wheat grain. The correlation between increasing temperature and carbon dioxide (CO2) production under aerobic conditions was very close, indicating that CO2 produced by aerobic bacteria can be used as a method of evaluating AS. Visual inspection of mould growth resulted in somewhat different ranking of the treatments.

We developed a multiplex PCR DNA marker for quick and easy identification of the AAGG-genome timopheevii lineage, including Triticum timopheevii, Triticum araraticum and hexaploid Triticum zhukovskyi (AAAmAmGG), and the AABB-genome emmer wheat lineage, including Triticum durum, Triticum dicoccum and Triticum dicoccoides. Distinguishing between tetraploid AAGG- and AABB-genome wheat species based on morphology is known to be difficult. This multiplex PCR system is based on the simultaneous PCR amplification of two chloroplast regions, matK and rbcL. The matK region molecularly distinguishes the two lineages, whereas the rbcL region is a positive control amplicon. We also examined whether the simple sequence repeat is a fixed mutation within species, using genetic resources in the collection of KOMUGI, Kyoto University, which comprises accessioned species collected across diverse geographical areas. The multiplex PCR marker distinguished AAGG from AABB species with complete accuracy.

It is known that genetic diversity is the most important factor in classical and modern plant breeding. The considerable increase in the number of transgenic crops reveals the value of new plant genetic resources. In this study, a set of 12 wheat progenitors were screened for tissue culture parameters such as callus induction, callus weight, regeneration capacity of callus and callus efficiency using mature embryos. Embryos were excised from imbibed seeds of the progenitors. The excised embryos were placed scutellum upwards in dishes containing 2 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) for callus induction. The developed calli and regenerated plants were maintained on 2,4-D free MS medium. When mature embryos of 12 wheat progenitors (Aegilops sp. and Triticum sp.) were compared, significant differences were detected in callus induction frequency, weight of callus, regeneration capacity and culture efficiency. A significant genotypic effect was observed on the culture responses. Of the 12 wheat progenitors tested, Aegilops umbellulata had the highest regeneration capacity of callus. Aegilops biuncialis created the most regenerable calli because of the highest callus induction and culture efficiency. In the experiment, callus induction was significantly correlated with callus weight (r= 0.820) and regeneration capacity (r= 0.955). Weight of callus was significantly correlated with regeneration capacity (r= 0.740), while there was no significant correlation between callus induction frequency and culture efficiency (r= 0.350). Our results showed that, generally, mature embryos of some Aegilops and Triticum species have a high regeneration capacity, and therefore, can be used as an effective explant source for the successful application of biotechnology in crop improvement.

To preliminarily evaluate the genetic diversity of the Iranian diploid Triticum L. gene pool, in this study, a total of 176 individuals belonging to T. monococcum L. ssp. aegilopoides (Link) Thell. and T. urartu Thum. ex Gandil. were pre-screened using single-strand conformation polymorphism (SSCP) analysis of the Acc-1 and Pgk-1 loci. A selected set of 76 DNA samples corresponding to the observed SSCP variants were sequenced for both loci and evaluated for nucleotide diversity associated with the taxonomic groups and geographical regions. We found three haplotypes, including one that was new for Iran, at each locus. Population structure and analysis of molecular variation results proved that the collection evaluated could be genetically divided into two distinct groups, which to a great extent was in accordance with the taxonomic classification. A genetic leakage from T. monococcum ssp. aegilopoides into T. urartu was observed during structure analysis, which was inferred on the basis of occasional outcrossing, despite their inbreeding nature. The results revealed that there was no variation within the populations belonging to T. urartu, while a meaningful variation was found between the geographical regions for T. monococcum ssp. aegilopoides. The median-joining networks revealed a conflict between morphology and haplotype variation, which was interpreted on the basis of introgressive hybridization, recombination signature and rapid speciation. In conclusion, we suggest that SSCP analysis is a useful tool in regions where thorough sequencing of an enormous number of DNA samples is time consuming and not affordable.

Artificial aging of wheat grains (Triticum aestivum cv. Mercia) for 3 d resulted in the gradual loss of seed vigour without loss of viability, but the latter decreased rapidly over the next 24 h. Loss of vigour was expressed as a delay in germination i.e. an increasing ‘lag’ period with aging before the onset of radicle emergence, but the subsequent rate of seedling growth was not affected. There was an overall decrease in the incorporation of 35S-methionine into protein in aged embryos, and associated with the aging-induced delay in the completion of germination (i.e. start of radicle emergence) there was a delay in the production of certain polypeptides. In embryos of both non-aged and aged seeds these polypeptides appeared just prior to radicle emergence but several of these were never synthesized in embryos from non-viable seeds. The synthesis of mRNA coding for in vitro translated polypeptides, or groups of polypeptides, was similarly delayed in lowvigour embryos. Furthermore, some polypeptides were identified which were induced by the accelerated aging treatment. It is concluded that a reduced level of protein and mRNA synthesis in the embryos of low-vigour seeds may result in the delay in the accumulation of specific of mRNAs and polypeptides which are needed for the normal completion of germination, i.e. radicle emergence.

Seed dormancy is an important physiological stage in the life cycle of many seed-bearing plants. In an ever-changing environment, dormancy increases survival by distributing germination over time. In general, seed dormancy is a quantitative trait that is influenced by environmental factors. Depending on the species and accession, dormancy is controlled by nuclear factors, maternal factors or both, and dormancy can be genetically the dominant or recessive form of the trait. Wild oat (Avena fatua) is a well developed system for dormancy investigations. Dormancy in wild oat is regulated by three major genes as well as environmental factors, and dormancy is conditionally the recessive form of the trait. This paper summarizes current knowledge on genetic and environmental factors, and the interaction of these factors, on seed dormancy in several cereal grain and dicotyledonous species. Some applications of this knowledge to improve crops and manage weeds are outlined.