Gene Ppd-D1 Research Articles

Haplotypes of Ppd-D1 gene and alleles of Ppd-A1 and Ppd-B1 in Ukrainian bread wheat varieties

Modern Ukrainian bread wheat varieties are not enough characterized by the alleles of Ppd genes and there is very restricted information about haplotypes of these genes in Ukrainian wheat genetic pool. The dominant alleles ( a ) of Ppd-A1 (2A), Ppd-B1 (2B), Ppd-D1 (2D) genes reduce sensitivity to photoperiod thus shorten the period until earing and genotypes with recessive alleles ( b ) have a strong reaction to the photoperiod. Haplotypes of Ppd-D1 gene could also affect photoperiod sensitivity. According to PCR analysis with allele specific primers most investigated varieties were characterized by Ppd-A1b and Ppd-B1b alleles. 40 varieties (81.2 %) had the deletion upstream the coding region of Ppd-D1 gene, that distinguish Ppd-D1a allele. Also, we analyzed haplotypes of Ppd-D1 gene. There was shown presence of VII haplotype of Ppd-D1 gene for 79.6 % of varieties. The varieties with I (2 %), II (6 %), III (10 %) haplotypes of the Ppd-D1 gene were less frequent. One variety was heterogeneous by Ppd-D1a/b alleles. From the tested ones only varieties of winter bread wheat from The V.M. Remeslo Myronivka Institute of Wheat (MIP) were polymorphic by investigated genes that highlight the importance of Ppd-A1b , Ppd-B1b and Ppd-D1a alleles for environmental conditions in the Ukraine. The haplotype (III) was detected in genotypes of 5 varieties – three of them from MIP and in varieties Etos and Yevdokiia. Also this haplotype was found in the well known old variety created in 1938 year – Odes’ka 3 – by Guo et al. [14], thus transposable element (TE) insertion in the 1 intron of Ppd-D1 gene was historically present in the background of Ukrainian wheats. Simultaneously, spring wheat varieties have higher level of genetic polymorphism at Ppd-D1 loci than winter bread wheat varieties, maybe this locus and sensitivity to photoperiod is not critical for adaptability of spring wheat.

ALLELIC STATUS OF THE Ppd-1 AND VRN-1 GENETIC SYSTEMS IN WINTER WHEAT VARIETIES OF THE INSTITUTE OF IRRIGATED AGRICULTURE OF NAAS UKRAINE

The aim of the current investigation was to determine the alleles of the genes of Ppd-1 and Vrn-1 systems in 13 bread winter wheat varieties created in the Institute of Irrigated Agriculture of the National Academy of Sciences of Ukraine (IIA) and to compare the data of the molecular genetic analysis with the data of field research. To accomplish this goal, the following tasks were set: 1) to determine the allelic state of the genes of the systems Ppd-1 and Vrn-1 in the genotypes of bread wheat varieties created in the IIA; 2) to collect the data of observations at stages of development (heading and flowering) of wheat varieties in the conditions of the Southern steppe of Ukraine and (3) to carry out a statistical analysis of the dependence of the periods of heading and flowering on the allelic composition of genes Ppd-1 and Vrn-1 in the genotypes of wheat varieties. Material. Varieties of winter bread wheat created in IIA. Methods. DNA extraction, allele-specific and nested PCR, electrophoresis of amplification products, one-way dispersion analysis (ANOVA). Results . By the Ppd-1 system in all IIA varieties dominant Ppd-D1a allele was detected, recessive alleles b were identified in Ppd-A1 and Ppd-B1 loci. The combination of mutations in the nucleotide sequence of the Ppd-D1 gene indicates that the studied varieties belong to the haplotype VII. By the Vrn-1 system, the varieties are carriers of a recessive genotype. No increase in the number of Ppd-B1 gene copies was detected in the genotype of the variety. The varieties investigated are early and do not have any significant differences in terms of heading and flowering, which corresponds to the results of the molecular-genetic analysis of Ppd-1 and Vrn-1 genes that control the duration of the vegetative period of wheat plants.

PCR-analysis of photoperiod sensitivity genes in bread wheat varieties from Bilatserkovska experimental breeding station

The aim. Determination of alleles of the photoperiod sensitivity genes Ppd-1 in 16 winter wheat varieties of the Bilatserkovska Experimental Breeding Station and identification of the haplotypes of Ppd-D1 gene according to the accepted classification. Methods. DNA isolation, allele-specific and nested PCR, electrophoresis in agarose and polyacrylamide gels, determination of the significant differences in the time of heading. Results. Plants of the varieties Vodohrai bilotserkivs’kiy; Bilotserkivs’ka napivkarlykova, Olesia, Perlyna lisostepu, Elehiia, Yasochka, Lybid’, Tsarivna, Lisova pisnia, Romantyka, Vidrada, Schedra nyva, Charodiika bilotsekivs’ka, Russa, Driada 1 have the genotype PpdA1b Ppd-B1b Ppd-D1a and belong to the VII haplotype of the Ppd-D1 gene. The genotype of the variety Legenda bilotsekivs’ka is characterized by the presence of the alleles Ppd-A1b Ppd-B1b Ppd-D1b and belongs to the IV haplotype of the Ppd-D1 gene. The significant differences (P = 0.01) in the time of heading was detected only between the varieties Russa and Legenda bilotsekivs’ka and was 12.4 days. Conclusions. Most BEBS varieties are characterized by genotype — PpdA1b Ppd-B1b Ppd-D1a, in which the allele Ppd-D1a determines insensitivity to the photoperiod and leads to early heading. Only variety Legenda bilotsekivs’ka is the carrier of the recessive allele of Ppd-D1 gene, belongs to the IV haplotype, has the latest time of heading. Keywords: Ppd-A1, Ppd-B1, Ppd-D1 genes, winter wheat, PCR analysis, photoperiod sensitivity.

Genome-wide association study of heading and flowering dates and construction of its prediction equation in Chinese common wheat

Heading date is one of the most important traits in wheat breeding as it affects adaptation and yield potential. A genome-wide association study (GWAS) using the 90K iSelect SNP genotyping assay indicated that a total of 306 loci were significantly associated with heading and flowering dates in 13 environments in Chinese common wheat from the Yellow and Huai wheat region. Of these, 105 loci were significantly correlated with both heading and flowering dates and were found in clusters on chromosomes 2, 5, 6, and 7. Based on differences in distribution of the vernalization and photoperiod genes among chromosomes, arms, or block regions, 13 novel, environmentally stable genetic loci were associated with heading and flowering dates, including RAC875_c41145_189 on 1DS, RAC875_c50422_299 on 2BL, and RAC875_c48703_148 on 2DS, that accounted for more than 20% phenotypic variance explained (PVE) of the heading/flowering date in at least four environments. GWAS and t test of a combination of SNPs and vernalization and photoperiod alleles indicated that the Vrn-B1, Vrn-D1, and Ppd-D1 genes significantly affect heading and flowering dates in Chinese common wheat. Based on the association of heading and flowering dates with the vernalization and photoperiod alleles at seven loci and three significant SNPs, optimal linear regression equations were established, which show that of the seven loci, the Ppd-D1 gene plays the most important role in modulating heading and flowering dates in Chinese wheat, followed by Vrn-B1 and Vrn-D1. Additionally, three novel genetic loci (RAC875_c41145_189, Excalibur_c60164_137, and RAC875_c50422_299) also show important effect on heading and flowering dates. Therefore, Ppd-D1, Vrn-B1, Vrn-D1, and the novel genetic loci should be further investigated in terms of improving heading and flowering dates in Chinese wheat. Further quantitative analysis of an F10 recombinant inbred lines population identified a major QTL that controls heading and flowering dates within the Ppd-D1 locus with PVEs of 28.4% and 34.0%, respectively; this QTL was also significantly associated with spike length, peduncle length, fertile spikelets number, cold resistance, and tiller number.

Polymorphism upstream the coding region of the Ppd-D1 gene in Aegilops tauschii Coss.

Aim. Evaluate time of heading and flowering in Aegilops tauschii Coss. accessions, donor of the bread wheat D genome, that are differentiated by polymorphism at upstream the coding region of the Ppd-D1 gene. Methods. NA extraction, allele-specific PCR, electrophoresis in polyacrylamide gel, two-factor analysis of variance. Results. We have found polymorphism upstream the coding region of Ppd-D1 gene with the help of the allele-specific PCR with primers to the Ppd-D1b allele in the accessions from the collection of Ae. tauschii Fragment 414 bp was detected in the samples: k-78, k-396, k-529, k-531, k-1144, k-1162, k-1235, k-1273, k-1283, fragment 429 bp have been revealed in the samples k-187, k-968, k-2178, and 453 bp – in the samples k-80, k-2358, Tetra tauschii. The results of a three-year field experiment showed a significant effect of the detected polymorphisms on the time of heading and flowering. Conclusions. Among the Ae. tauschii accessions by allele-specific PCR with primers to the Ppd-D1b allele have been tested amplification fragments 414 bp, 429 bp and 453 bp. Allele Ppd-D1a was not found in the collection of Ae. tauschii accessions. Samples of aegilops that are carrier of insertions 24 + 15 bp (for which the fragment 453 bp was detected by allele-specific PCR) – were characterized by earlier heading and flowering time in certain years.
 Keywords: time of heading and flowering, Ppd-D1 gene, Aegilops tauschiі Coss.

Photoperiodic sensitivity and Ppd-1 genotypes of bread wheat alternative varieties

Aim. Study the reaction to photoperiod and identify Ppd-1 genotypes of modern alternative bread wheat varieties of various geographical origins. Methods. Plants growing under reduced and prolonged days, hybridological analysis of photoperiodic sensitivity of semi-diallelic F2 hybrids, calculations of average values, their errors and c2, multiplex STS-PCR with specific primers to the Ppd-D1 gene. Results. The phenotypic and genotype differences were detected, Ppd-1 genotypes of 10 alternative bread wheat varieties of different geographical origins were found. Conclusions. Afina, Palada, Solomia, Shestopalivka, Yara, Demir 2000, L897J23 varieties slowly or average react to reduce of day duration because of gene Ppd-D1a presence in their genotypes. Lastivka, Khutorianka, Zumoiarka varieties are highly photoperiodic sensitive genotypes and carriers of Ppd-1 genes recessive alleles only. From this view point, these three varieties correspond to the criteria of "typical alternative varieties".
 Keywords: wheat, alternative varieties, photoperiodic sensitivity, DNA markers, gene, Ppd-1.

Effects of Vrn-B1 and Ppd-D1 on developmental and agronomic traits in Rht5 dwarf plants of bread wheat

Preliminary evidence indicates that Rht5, a gibberellin-responsive (GAR) dwarfing gene, could reduce plant height without affecting coleoptile length and seedling vigour. However, Rht5 delayed ear emergence and anthesis, which would hinder its utilization in wheat improvement. To advance the flowering time of Rht5 dwarf plants, the dominant vernalization gene Vrn-B1 and the photoperiod-insensitive gene Ppd-D1 were introduced through two crosses between Ningchun45 (Vrn-B1) and Jinmai47 (Ppd-D1) with Marfed M (Rht5), respectively. Fifty-nine and 71 F2:3 and F3:4 homozygous lines from the first and the second cross were used to evaluate the effects of Vrn-B1 and Ppd-D1, respectively on the developmental and agronomic traits of Rht5 dwarf plants during two growing seasons in Yangling, Shaanxi, China. The results showed that Rht5 significantly reduced plant height (40.1% and 38.9%) but delayed the flowering time (14.0% and 4.8% in thermal time) in both populations. In general, Rht5 significantly decreased the spike length by 22.6% and 16.7, grain number by 14.5% and 11.5%, 1000-grain weight by 24.1% and 18.4%, and grain yield by 35.1% and 21.5% in the two populations, respectively. Vrn-B1 could not compensate for the negative effect of Rht5 on spike development and the flowering time and had no significant effect on plant height or other agronomic traits. However, Ppd-D1 was able to overcome the delaying effect of Rht5 on spike development by shortening the duration of the reproductive phase (double ridge stage-anthesis) and finally promoting earlier flowering (8.7% in thermal time) in Rht5 dwarf lines. Ppd-D1 also reduced plant height (10.0%), and the combination of Ppd-D1 and Rht5 produced even shorter plants (45.0%), achieving dwarf plants with higher lodging resistance. Additionally, Ppd-D1 increased the grain number (6.3% and 9.6%), 1000-grain weight (13.0% and 21.5%), plant yield (22.6% and 39.5%) and harvest index (31.1% and 49.6%) in both tall and dwarf plants, respectively. Clearly, the combination of Rht5 and Ppd-D1 had no negative effect on plant growth or grain yield, advanced spike development and the flowering time, and improved agronomic traits, which may be conducive to exploiting Rht5 for wheat improvement.

Features of Ppd-B1 expression regulation and their impact on the flowering time of wheat near-isogenic lines

BackgroundPhotoperiod insensitive Ppd-1a alleles determine early flowering of wheat. Increased expression of homoeologous Ppd-D1a and Ppd-A1a result from deletions in the promoter region, and elevated expression of Ppd-B1a is determined by an increased copy number.ResultsIn this study, using bread wheat cultivars Sonora and PSL2, which contrast in flowering time, and near-isogenic lines resulting from their cross, “Ppd-m” and “Ppd-w” with Ppd-B1a introgressed from Sonora, we investigated the putative factors that influence Ppd-B1a expression. By analyzing the Ppd-B1a three distinct copies, we identified an indel and the two SNPs, which distinguished the investigated allele from other alleles with a copy number variation.We studied the expression of the Ppd-A1, Ppd-B1a, and Ppd-D1 genes along with genes that are involved in light perception (PhyA, PhyB, PhyC) and the flowering initiation (Vrn-1, TaFT1) and discussed their interactions. Expression of Ppd-B1a in the “Ppd-m” line, which flowered four days earlier than “Ppd-w”, was significantly higher. We found PhyC to be up-regulated in lines with Ppd-B1a alleles. Expression of PhyC was higher in “Ppd-m”. Microsatellite genotyping demonstrated that in the line “Ppd-m”, there is an introgression in the pericentromeric region of chromosome 5B from the early flowering parental Sonora, while the “Ppd-w” does not have this introgression. FHY3/FAR1 is known to be located in this region. Expression of the transcription factor FHY3/FAR1 was higher in the “Ppd-m” line than in “Ppd-w”, suggesting that FHY3/FAR1 is important for the wheat flowering time and may cause earlier flowering of “Ppd-m” as compared to “Ppd-w”.ConclusionsWe propose that there is a positive bidirectional regulation of Ppd-B1a and PhyC with an FHY3/FAR1 contribution.The bidirectional regulation can be proposed for Ppd-A1a and Ppd-D1a. Using in silico analysis, we demonstrated that the specificity of the Ppd-B1 regulation compared to that of homoeologous genes involves not only a copy number variation but also distinct regulatory elements.

日長反応性遺伝子Ppd-D1が春まき小麦の安定多収性に及ぼす影響(平成27年度年次講演会一般公演)

日長反応性遺伝子Ppd-D1が春まき小麦の安定多収性に及ぼす影響(平成27年度年次講演会一般公演)

Physiological, biochemical and agronomic traits associated with drought tolerance in a synthetic-derived wheat diversity panel

Synthetic hexaploid wheat and their advanced derivatives (SYN-DERs) are promising sources for introducing novel genetic diversity to develop climate-resilient cultivars. In a series of field and laboratory experiments, we measured biochemical, physiological and agronomic traits in a diversity panel of SYN-DERs evaluated under well-watered (WW) and water-limited (WL) conditions. Analysis of variance revealed significant differences among genotypes, treatments and their interaction for all agronomic and physiological traits. Grain yield (GY) was reduced by 62.75% under WL, with a reduction of 38.10% in grains per spike (GS) and 19.42% in 1000-grain weight (TGW). In a Pearson’s coefficient correlation, GY was significantly correlated with GS, number of tillers per plant and TGW in both conditions. Path coefficient analysis showed that TGW and GS made the highest contribution to GY in WW and WL conditions, respectively. The traits examined in this experiment explained 59.6% and 63.01% of the variation in GY under WL and WW conditions, respectively; TGW, canopy temperature at spike and superoxide dismutase were major determinants of GY under WL conditions. The major flowering-time determinant gene Ppd-D1 was fixed in the diversity panel, with presence of the photoperiod-insensitive allele (Ppd-D1a) in 99% accessions. Wild-type alleles at Rht-B1 and Rht-D1, and presence of the rye translocation (1B.1R), favoured GY under WL conditions. Continuous variation for the important traits indicated the potential use of genome-wide association studies to identify favourable alleles for drought adaptation in the SYN-DERs. This study showed sufficient genetic variation in the SYN-DERs diversity panel to improve yields during droughts because of better adaptability than bread wheat.

THE GENOTYPES OF MODERN MYRONIVSKY VARIETIES OF WINTER WHEAT FOR Ppd-A1, Ppd-B1, Ppd-D1 GENES AND THEIR SENSITIVITY TO PHOTOPERIOD

Problem. The system of photoperiodic response genes Ppd-1 affects the speed of winter wheat growth. Dominant alleles (a) of Ppd genes reduce the sensitivity to daylength and shorten the time period before heading, while genotypes with recessive alleles (b) have a strong response to photoperiod. Іnformation about the alleles of the photoperiod genes is important for obtaining new breeding material and reliable characteristics of the genotypes of modern Ukrainian varieties which can be used as parental forms. The aim of the work was to determine alleles of genes Ppd-A1, Ppd-B1, Ppd-D1 for modern Myronivsky varieties of winter wheat using molecular markers and to compare the genotypes of Ppd-1 genes with the sensitivity of varieties to photoperiod. Methods. We used methods of allele-specific PCR with primers to Ppd-A1, Ppd-B1, Ppd-D1 genes. Results. Alleles of genes Ppd-A1, Ppd-B1, Ppd-D1 and sensitivity to photoperiod for modern Myronivsky varieties of winter wheat have been detected. Conclusion. Varieties have been differentiated into three groups, with different genotypes according to the system of genes Ppd-1 – group I – genotype Ppd-A1a/ Ppd-B1b/ Ppd-D1a, group II – genotype Ppd-А1b/ Ppd-B1b/ Ppd-D1a, group III – genotype Ppd-А1b/Ppd-B1b/ Ppd-D1b – and the dependence of the sensitivity to reduction of daylight according to genotype has been shown for these groups. Also, within the group of varieties with alleles Ppd-A1b/Ppd-B1b/Ppd-D1a and Ppd-A1b/Ppd-B1b/Ppd-D1b variation in time of heading was observed.

High resolution mapping of traits related to whole-plant transpiration under increasing evaporative demand in wheat.

Atmospheric vapor pressure deficit (VPD) is a key component of drought and has a strong influence on yields. Whole-plant transpiration rate (TR) response to increasing VPD has been linked to drought tolerance in wheat, but because of its challenging phenotyping, its genetic basis remains unexplored. Further, the genetic control of other key traits linked to daytime TR such as leaf area, stomata densities and - more recently - nocturnal transpiration remains unknown. Considering the presence of wheat phenology genes that can interfere with drought tolerance, the aim of this investigation was to identify at an enhanced resolution the genetic basis of the above traits while investigating the effects of phenology genes Ppd-D1 and Ppd-B1 Virtually all traits were highly heritable (heritabilities from 0.61 to 0.91) and a total of mostly trait-specific 68 QTL were detected. Six QTL were identified for TR response to VPD, with one QTL (QSLP.ucl-5A) individually explaining 25.4% of the genetic variance. This QTL harbored several genes previously reported to be involved in ABA signaling, interaction with DREB2A and root hydraulics. Surprisingly, nocturnal TR and stomata densities on both leaf sides were characterized by highly specific and robust QTL. In addition, negative correlations were found between TR and leaf area suggesting trade-offs between these traits. Further, Ppd-D1 had strong but opposite effects on these traits, suggesting an involvement in this trade-off. Overall, these findings revealed novel genetic resources while suggesting a more direct role of phenology genes in enhancing wheat drought tolerance.

Attributes of wheat cultivars for late autumn sowing in genes expression and field estimates

Due to the growing interest in Central and Eastern Europe on cropping of wheat in optional late autumn terms, called facultative, genetic research and field evaluation were taken on four spring cultivars: Tybalt (NL), Monsun (DE), Ostka Smolicka (PL) and Bombona (PL), currently being recommended by breeders. The PPD gene analyze, expression level of dehydrine genes (WCS120 and WDHN13) in cooling test, and qPCR for RNA isolation and analyses of WCS120 and WDHN13 gene expression at the BBCH12 stage of wheat were estimated. Molecular analysis of PPD-D1 gene confirmed the presence of photoperiod sensitive allele ppd-D1b in all tested genotypes. The highest level of NRE WCS120 gene was detected in cultivars Tybalt and Bombona. Two-year field experimental study assessed the growth, development and productivity of facultative and spring crops of studied cultivars. Based on our results from field experiments and result of molecular analysis of alleles of PPD-D1 gene, the tested genotypes can be considered as potentially facultative genotypes.

Analysis of main effect QTL for thousand grain weight in European winter wheat (Triticum aestivum L.) by genome-wide association mapping.

Grain weight, an essential yield component, is under strong genetic control and at the same time markedly influenced by the environment. Genetic analysis of the thousand grain weight (TGW) by genome-wide association study (GWAS) was performed with a panel of 358 European winter wheat (Triticum aestivum L.) varieties and 14 spring wheat varieties using phenotypic data of field tests in eight environments. Wide phenotypic variations were indicated for the TGW with BLUEs (best linear unbiased estimations) values ranging from 35.9 to 58.2 g with a mean value of 45.4 g and a heritability of H2 = 0.89. A total of 12 candidate genes for plant height, photoperiodism and grain weight were genotyped on all varieties. Only three candidates, the photoperiodism gene Ppd-D1, dwarfing gene Rht-B1and the TaGW-6A gene were significant explaining up to 14.4, 2.3, and 3.4% of phenotypic variation, respectively. For a comprehensive genome-wide analysis of TGW-QTL genotyping data from 732 microsatellite markers and a set of 7769 mapped SNP-markers genotyped with the 90k iSELECT array were analyzed. In total, 342 significant (-log10 (P-value) ≥ 3.0) marker trait associations (MTAs) were detected for SSR-markers and 1195 MTAs (−log10(P-value) ≥ 3.0) for SNP-markers in all single environments plus the BLUEs. After Bonferroni correction, 28 MTAs remained significant for SSR-markers (−log10 (P-value) ≥ 4.82) and 58 MTAs for SNP-markers (−log10 (P-value) ≥ 5.89). Apart from chromosomes 4B and 6B for SSR-markers and chromosomes 4D and 5D for SNP-markers, MTAs were detected on all chromosomes. The highest number of significant SNP-markers was found on chromosomes 3B and 1B, while for the SSRs most markers were significant on chromosomes 6D and 3D. Overall, TGW was determined by many markers with small effects. Only three SNP-markers had R2 values above 6%.

Genetic architecture of main effect QTL for heading date in European winter wheat.

A genome-wide association study (GWAS) for heading date (HD) was performed with a panel of 358 European winter wheat (Triticum aestivum L.) varieties and 14 spring wheat varieties through the phenotypic evaluation of HD in field tests in eight environments. Genotyping data consisted of 770 mapped microsatellite loci and 7934 mapped SNP markers derived from the 90K iSelect wheat chip. Best linear unbiased estimations (BLUEs) were calculated across all trials and ranged from 142.5 to 159.6 days after the 1st of January with an average value of 151.4 days. Considering only associations with a −log10 (P-value) ≥ 3.0, a total of 340 SSR and 2983 SNP marker-trait associations (MTAs) were detected. After Bonferroni correction for multiple testing, a total of 72 SSR and 438 SNP marker-trait associations remained significant. Highly significant MTAs were detected for the photoperiodism gene Ppd-D1, which was genotyped in all varieties. Consistent associations were found on all chromosomes with the highest number of MTAs on chromosome 5B. Linear regression showed a clear dependence of the HD score BLUEs on the number of favorable alleles (decreasing HD) and unfavorable alleles (increasing HD) per variety meaning that genotypes with a higher number of favorable or a low number of unfavorable alleles showed lower HD and therefore flowered earlier. For the vernalization gene Vrn-A2 co-locating MTAs on chromosome 5A, as well as for the photoperiodism genes Ppd-A1 and Ppd-B1 on chromosomes 2A and 2B were detected. After the construction of an integrated map of the SSR and SNP markers and by exploiting the synteny to sequenced species, such as rice and Brachypodium distachyon, we were able to demonstrate that a marker locus on wheat chromosome 5BL with homology to the rice photoperiodism gene Hd6 played a significant role in the determination of the heading date in wheat.

Effect of different sowing times on the plant developmental parameters of wheat (Triticum aestivumL.)

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 (R2 = 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.

Ppd1, Vrn1, ALMT1 and Rht genes and their effects on grain yield in lower rainfall environments in southern Australia

Allele-specific markers for important genes can improve the efficiency of plant breeding. Their value can be enhanced if effects of the alleles for important traits can be estimated in identifiable types of environment. Provided potential bias can be minimised, large, unbalanced, datasets from previous plant-breeding and agronomic research can be used. Reliable, allele-specific markers are now available for the phenology genes Ppd-D1, Vrn-A1, Vrn-B1 and Vrn-D1, the aluminium-tolerance gene TaALMT1, and the plant-stature genes Rht-B1 and Rht-D1. We used a set of 208 experiments with growing-season rainfall of <347 mm from southern Australia to estimate the effects of seven frequent combinations of the phenology genes, an intolerant and a tolerant allele of TaALMT1, and two semi-dwarf combinations Rht-B1b + Rht-D1a (Rht-ba) and Rht-B1a + Rht-D1b (Rht-ab) on grain yield in lower rainfall, Mediterranean-type environments in southern Australia. There were 775 lines in our analyses and a relationship matrix was used to minimise bias. Differences among the phenology genes were small, but the spring allele Vrn-B1a might be desirable. The tolerant allele, TaALMT1-V, was advantageous in locations with alkaline soils, possibly because of toxic levels of aluminium ions in subsoils. The advantage of TaALMT1-V is likely to be highest when mean maximum temperatures in spring are high. Rht-ab (Rht2 semi-dwarf) was also advantageous in environments with high mean maximum temperatures in spring, suggesting that for these stress environments, the combination of Vrn-B1a plus TaALMT1-V plus Rht-ab should be desirable. Many successful cultivars carry this combination.

Molecular characterization of vernalization and photoperiod genes in wheat varieties from different agro-climatic zones of India

Ninety-nine wheat cultivars from six different agro-climatic zones of India were analyzed for the Vrn-1, Vrn-2, Vrn-B3, Vrn-4 and Ppd-D1 composition with DNA sequenced based allele specific or linked markers for the above-mentioned genes. A majority of the germplasm carried the dominant Vrn-A1a allele alone or in combination with Vrn-B1 and Vrn-D1. The three dominant genes were cumulatively present in 30 cultivars among all the zones, whereas double dominant combination, Vrn- A1/Vrn-B1 was identified in 18 cultivars, Vrn-A1/Vrn-D1 in 6 cvs and Vrn-B1/Vrn-D1 in 16 cvs. The combination of the dominant alleles of all three genes was most frequent in cvs of Northern Western Plains Zone. Northern Hill Zone had vrn-B1 and vrn-D1 alleles in higher proportions compared to the dominant alleles Vrn-B1 and Vrn-D1 indicating successful spring/winter wheat cross breeding. All of the cvs had the recessive Vrn-B3 allele. Most of the cvs had photoperiod insensitive allele in all the zones and only 9% cvs possessed the photoperiod sensitive allele (b) of the Ppd-D1 gene. This information will be useful in selecting parental lines for crossing to maximize diversity at these loci and for future molecular marker assisted breeding for cultivar improvement.

The combination of the Ppd and Vrn gene alleles determines the heading date in common wheat varieties

Combinations of the Ppd-D1, Vrn-A1, Vrn-B1, and Vrn-D1 gene alleles were analyzed using allele-specific primers in 56 varieties and lines of common wheat that were selected in the Lukyanenko Agricultural Research Institute. The significant influence of the combination of these alleles on the time of the beginning of the heading of the studied varieties was determined, which is manifested differently under conditions of long and short photoperiods, as well as depending on whether vernalization occurs. Molecular labeling of wheat Vrn and Ppd gene alleles allows breeders to consciously manipulate the original material (by having information in advance about the adaptive potential of the plants that are involved in the breeding process), as well as to select the allele combinations that are optimal for specific conditions of cultivation.

Алелі гена Ppd-d1 у зразках колекції Aegilops tauschii і м’якої пшениці

Алелі гена Ppd-d1 у зразках колекції Aegilops tauschii і м’якої пшениці