In addition to its role in vernalization, temperature is an important environmental stimulus in determining plant growth and development. We used factorial combinations of two photoperiods (16H, 12H) and three temperature levels (11, 18 and 25 °C) to study the temperature responses of 19 wheat cultivars with established genetic relationships. Temperature produced more significant effects on plant development than photoperiod, with strong genotypic components. Wheat genotypes with PPD-D1 photoperiod sensitive allele were sensitive to temperature; their development was delayed by higher temperature, which intensified under non-inductive conditions. The effect of temperature on plant development was not proportional; it influenced the stem elongation to the largest extent, and warmer temperature lengthened the lag phase between the detection of first node and the beginning of intensive stem elongation. The gene expression patterns of VRN1, VRN2 and PPD1 were also significantly modified by temperature, while VRN3 was more chronologically regulated. The associations between VRN1 and VRN3 gene expression with early apex development were significant in all treatments but were only significant for later plant developmental phases under optimal conditions (16H and 18 °C). Under 16H, the magnitude of the transient peak expression of VRN2 observed at 18 and 25 °C associated with the later developmental phases.

Studies on plant development phases and yield component patterns of wheat are essential for a better understanding of adaptation in wheat. Our main aim was to carry out detailed phenological analyses of 18 wheat genotypes in three sowing times for determining the effect of sowing date on individual phenophases, and yield components. Sowing date had the single greatest effect on the start of intensive stem elongation. The longer vegetation period had a favourable effect on main spike length and on the spikelet number per spike, but had no influence on thousand-kernel weight and grain number per spike. The time between the first node appearance and start of intensive stem elongation had a significant effect on the number of reproductive tillers. A close association (R 2 = 0.191) was observed during the second phase of intensive stem elongation between the boot stage-to-heading interval and the number of spikelets per spike. Two-way analysis of variance on the yield components showed that the sowing date, as a main factor, had a weaker effect on the phenophases than on morphological and developmental parameters. The insensitive allele of the Ppd-D1 gene shortened the time required for first node appearance and heading both in autumn and spring sowing.

An important objective of wheat improvement programmes is to breed varieties for high yield in optimum conditions and for minimum yield reduction under stress-prone conditions such as heat and drought. Analyses of yield and its components in multiple years allow a comprehensive and comparative understanding of genetic yield potential and stress-tolerance mechanisms in the study germplasm. The present study was carried out to evaluate performance of elite varieties and landraces of spring durum wheat under different water regimes, determine the repeatability of the examined traits, and identify superior genotypes for their potential use in breeding for drought tolerance. A total of 97 accessions of spring durum wheat (T. durum Desf.) were evaluated under rain-fed and well-watered conditions in the nursery of the Centre for Agricultural Research at Martonvásár, Hungary (2011. The experiments were laid out in an unbalanced, incomplete alpha lattice block design. The trait with the lowest broad-sense repeatability was seed length (0.075), while high h 2 values were observed for heading date (0.89), thousand-grain weight (0.85) and the protein content (0.85). Grain yield showed moderate level of repeatability (0.53) across the three years. The principal component analysis revealed that grain yield (t/ha) is positively associated with the fertile tiller number, chlorophyll content values at early waxy ripeness stages and plant height. Based on biplot analysis, 'DP-133′, 'DP-017′ and 'DP-061′ proved to be the best durum cultivars in terms of yield whereas genotypes 'DP-011′, 'DP-185′, 'DP-126′ and 'DP-136′ preceded them with their good yield stability.

Abstract:Abstract The precise elimination of selectable marker genes is highly desirable, when their function is no longer needed, because their presence raised worldwide public concerns against the release of genetically modified plants. This is the first report of simultaneous application of the minimal gene cassette and cold-inducible Cre/lox recombination system in wheat. The bar selection and cre-recombinase genes were eliminated from T0 and T1 transgenic lines with 44% and 51% efficiency. This approach provides a new, reasonably effective technique to produce selection genefree transgenic wheat lines either immediately after tissue culture, or from the subsequent transgenic generation. The advantage of this method is that it does not require any additional cold treatment during the plant regeneration/growing because the transgene elimination is ensured by the vernalisation. Application of this method prevents gene flow by pollen and seed, because the selection and recombinase genes are eliminated before pollen development, therefore reducing the risk of GM plants. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems CorporationGenerating marker-free transgenic wheat using minimal gene cassette and cold inducible Cre/lox system AbstractThe precise elimination of selectable marker genes is highly desirable, when their function is no longer needed, because their presence raised worldwide public concerns against the release of genetically modified plants. This is the first report of simultaneous application of the minimal gene cassette and cold-inducible Cre/lox recombination system in wheat. The bar selection and cre-recombinase genes were eliminated from T 0 and T 1 transgenic lines with 44% and 51% efficiency. This approach provides a new, reasonably effective technique to produce selection gene-free transgenic wheat lines either immediately after tissue culture, or from the subsequent transgenic generation. The advantage of this method is that it does not require any additional cold treatment during the plant regeneration/growing because the transgene elimination is ensured by the vernalisation. Application of this method prevents gene flow by pollen and seed, because the selection and recombinase genes are eliminated before pollen development, therefore reducing the risk of GM plants.

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In the present study, heat treatment was carried out in five different phenological phases, from the first node detectable (DEV31) growth stage to 20 days after flowering, on four wheat genotypes with very different adaptation strategies. They were grown in a controlled environment in a phytotron chamber and exposed to a night temperature of 20ºC and a day temperature of either 30ºC, at DEV31, or 35ºC at all the later developmental phases, for an interval of 14 days. Plant height, leaf number, number of tillers, grain number and grain weight per main and side spikes, TKW per main and side spikes, length of the main and side spikes, and spikelet number per main and side spikes were recorded. High temperature enhanced the stem growth intensity, plant height and tiller number. In contrast, the length of side spikes, spikelet no./side spike, grain no./main and side spike, grain weight/main and side spike and TKW/main and side spike were significantly decreased. The stress response depended strongly on the developmental phase in which the heat stress was applied. Fleischmann 481 and Soissons showed definitely contrasting tendencies both in grain number and grain weight. In the case of the Plainsman V and Mv Magma pair, the higher heat stress tolerance of Magma compared to Plainsman V was evident also from the grain number and weight of the main spike at each developmental phase.

Heat stress negatively affects barley production and under elevated temperatures defense responses to powdery mildew (Blumeria graminis f. sp. hordei, Bgh) are altered. Previous research has analyzed the effects of short-term (30 s to 2 h) heat stress, however, few data are available on the influence of long-term exposure to heat on powdery mildew infections. We simultaneously assessed the effects of short and long term heat pre-exposure on resistance/susceptibility of barley to Bgh, evaluating powdery mildew infection by analyzing symptoms and Bgh biomass with RT-qPCR in barley plants pre-exposed to high temperatures (28 and 35 °C from 30 s to 5 days). Plant defense gene expression after heat stress pre-exposure and inoculation was also monitored. Our results show that prolonged heat stress (24, 48 and 120 h) further enhanced Bgh susceptibility in a susceptible barley line (MvHV118-17), while a resistant line (MvHV07-17) retained its pathogen resistance. Furthermore, prolonged heat stress significantly repressed the expression of several defense-related genes (BAX inhibitor-1, Pathogenesis related-1b and Respiratory burst oxidase homologue F2) in both resistant and susceptible barley lines. Remarkably, heat-suppressed defense gene expression returned to normal levels only in MvHV07-17, a possible reason why this barley line retains Bgh resistance even at high temperatures.

The main aim of the experiments was to demonstrate the possible correlation between developmental and morphological traits and yield components under variable climatic conditions. For this purpose, a collection of 188 wheat (Triticum aestivum L.) genotypes with a heterogeneous gene pool was included in a 3‐yr field experiment applying normal and late sowing dates each year. Under these conditions, almost all the traits were significantly influenced by the genotype, which had the greatest effect on the morphological traits and yield components (explaining 20–58 and 50–60% of the phenotypic variance for the two trait groups, respectively). In the case of plant development, however, the year effect, particularly in the late sowing treatment, was more significant than that of the genotype. Sowing date had the strongest effect on the early developmental phases, explaining 50% of the phenotypic variance, whereas the year had a significant influence on the late developmental phases, being responsible for 37 to 53% of the phenotypic variance. The turning point between the two factors was during the first phase of rapid stem elongation. The environmental driven variation in developmental patterns led to significant variation in yield‐related traits, which ranged from 4.6 (average thousand‐kernel weight) to 16.3% (average seed number) with normal sowing, and from 2.9 (average seed weight) to 29.4% (average thousand‐kernel weight) under late sowing conditions. The significance of the two intervals, from sowing to the start of rapid (intensive) stem elongation and from the start of stem elongation to the boot stage (Z49), was most apparent in the case of yield‐related traits.