The germplasm collection of 87 wheat-wheatgrass hybrids developed in Tsitisin Main Botanical Garden (Russia, Moscow) was evaluated for resistance to pre-harvest sprouting (PHS) by spike sprouting (SS) and germination index (GI) assays as well as for spike and grain features. The PHS resistance variation and haplotype polymorphism of the wheatgrass ThVp-1 and wheat TaVp-1B genes orthologues of Vp-1 was revealed in the studied collection. Four haplotypes of ThVp-1 were revealed: ThVp-1a (41% of the entries), ThVp-1b (13%), ThVp-1c (29%), and ThVp-1d (15%). The association between the allelic state of ThVp-1 and PHS resistance in the wheat-wheatgrass hybrids was shown: haplotype ThVp-1d of the wheatgrass Vp-1 gene is significantly associated with reduced PHS in the wheat-wheatgrass hybrids (mean SS 0.33, mean GI 0.64). The resistant entries may be perspective as a source of PHS resistance in the development of commercial cultivars of perennial wheat.

Background: Phosphorus nutrition is important for obtaining high yields of crop plants. However, wheat plants are known to be almost incapable of taking up phosphorus from insoluble phosphate sources, and reduced height genes are supposed to decrease this ability further. Methods: We performed a pot experiment using Triticum durum Desf. tall spring variety LD222, its near-isogenic semidwarf line carrying Rht17 (Reduced height 17) gene, and winter rye (Secale cereale L.) variety Chulpan. The individual plants were grown in quartz sand. The phosphorus was provided either as phosphate rock powder mixed with sand, or as monopotassium phosphate solution (normal nutrition control) or was not supplemented at all (no-phosphorus control). Other nutrients were provided in soluble form. During experiment the plants were assessed using the TraitFinder (Phenospex Ltd., Heerlen, Netherlands) digital phenotyping system for a standard set of parameters. Double scan with 90 degrees turns of pots around vertical axis vs. single scan were compared for accuracy of phenotyping. Results: The phenotyping showed that at least 20 days of growth after seedling emergence were necessary to get stable differences between genotypes. After this initial period, phenotyping confirmed poor ability of wheat to grow on substrate with phosphate rock as the only source of phosphorus compared to rye; however, Rht17 did not cause an additional reduction in growth parameters other than plant height under this variant of substrate. The agreement between digital phenotyping and conventionally measured traits was at previously reported level for grasses (R² = 0.85 and 0.88 for digital biomass and 3D leaf area vs. conventionally measured biomass and leaf area, single scan). Among vegetation indices, only the normalized differential vegetation index (NDVI) and the green leaf index (GLI) showed significant correlations with manually measured traits, including the percentage of dead leaves area. The double scan improved phenotyping accuracy, but not substantially.

The Growth-regulating factors (GRF) are a family of plant-specific transcription factors that have roles in plant growth, development and stress response. In this study the diversity of the TaGRF3-2A (TraesCS2A02G435100) gene was investigated in Russian bread wheat germplasm by means of next generation sequencing and molecular markers, and the results compared with those from multiple wheat genome and exome sequencing projects. The results showed that an allele possessing c.495G>T polymorphism found in Bezostaya 1 and designated as TaGRF3-2Ab, is connected with earlier heading and better grain filling under conditions of the Krasnodar Krai. TaGRF3-2Ab is more frequent among Russian winter wheat cultivars than in other germplasms found in the world, implying that it is adaptive for the Chernozem region. A new rare mutation of the TaGRF3-2A was found in the spring wheat cultivar Novosibirskaya 67. The molecular markers developed will facilitate utilization of TaGRF3-2A mutations in future agronomic studies and wheat improvement. Albeit GRF3-2Ab may be good at maintaining high milling quality of the grain, it should be used with caution in breeding of winter wheat cultivars in the perspective of climate change.

The reduction in plant height caused by mutations in Rht-B1 or Rht-D1 (Reduced height-1) genes in combination with day-length-independent early flowering associated with the Ppd-D1 (Photoperiod-D1) gene were the main factors of the drastic yield increase in bread wheat in the 1960s. Increasing nitrogen use efficiency as well as maintaining high yields under conditions of global climate change are the modern goals of wheat breeding. The glutamine synthetase (GS) enzyme plays a key role in ammonium assimilation in plants. In previous studies, the TaGS2-A1 gene, coding the plastid isoform of GS, was shown to be connected with nitrogen use efficiency in wheat. Using the polymerase chain reaction (PCR) markers, the association of yield and agronomical traits with haplotypes of Rht-B1, Rht-D1, Ppd-D1 and TaGS2-A1 genes was studied in a diverse collection of winter bread wheat cultivars grown in Krasnodar (Russia). In the three-year experiment, semidwarfism and photoperiod insensitivity were confirmed to be highly favorable for the grain yield. The TaGS2-A1b haplotype had a tendency for increased grain yield and lodging resistance, but mainly in plants not possessing the ‘green revolution’ alleles. Thus, TaGS2-A1b may have potential in breeding wheat cultivars with alternative dwarfing genes or tall cultivars, which may be optimal for growing under certain environments.

Alleles of the genes, conferring a dwarfing phenotype, play a crucial role in wheat breeding, as they not only reduce plant height, ensuring their resistance to lodging, but also have a number of positive and negative pleiotropic effects on plant productivity. Durum wheat carries only two subgenomes (A and B), which limits the use of the D-subgenome genes and requires the expansion of the arsenal of dwarfing alleles and the study of their effects on height and agronomically important traits. We studied the effect of the gibberellin-insensitive allele Rht-B1p in the B2F2:3 families, developed by crossing Chris Mutant /#517//LD222 in a field experiment in Moscow and Krasnodar. In our experiments, plants homozygous for Rht-B1p were shorter than those homozygous for the wild-type allele Rht-B1a by 36.3 cm (40 %) in Moscow and 49.5 cm (48 %) in Krasnodar. In the field experiment in Krasnodar, each plant with Rht-B1p had one less internode than any plant with Rht-B1a, which additionally contributed to the decrease in plant height. Grain weight per main spike was lower in plants with Rht-B1p than in plants with Rht-B1a by 12 % in Moscow and by 23 % in Krasnodar due to a decrease in 1000 grain weight in both regions of the field experiment. The number of grains per main spike in plants with Rht-B1p was higher in comparison to that with Rht-B1a by 6.5 % in Moscow due to an increase in spikelet number per main spike and by 11 % in Krasnodar due to an increase in grain number per spikelet. The onset of heading in plants with Rht-B1p in comparison with the plants with the wild-type allele Rht-B1a was 7 days later in Krasnodar. The possibility and prospects for the use of Rht-B1p in the breeding of durum wheat are discussed.