Agronomic Traits In Common Wheat Research Articles

Functional Characterization of Accessible Chromatin in Common Wheat.

Eukaryotic gene transcription is fine-tuned by precise spatiotemporal interactions between cis-regulatory elements (CREs) and trans-acting factors. However, how CREs individually or coordinated with epigenetic marks function in regulating homoeolog bias expression is still largely unknown in wheat. In this study, through comprehensively characterizing open chromatin coupled with DNA methylation in the seedling and spikelet of common wheat, we observed that differential chromatin openness occurred between the seedling and spikelet, which plays important roles in tissue development through regulating the expression of related genes or through the transcription factor (TF)-centered regulatory network. Moreover, we found that CHH methylation may act as a key determinant affecting the differential binding of TFs, thereby resulting in differential expression of target genes. In addition, we found that sequence variations in MNase hypersensitive sites (MHSs) result in the differential expression of key genes responsible for important agronomic traits. Thus, our study provides new insights into the roles of CREs in regulating tissue or homoeolog bias expression, and controlling important agronomic traits in common wheat. It also provides potential CREs for genetic and epigenetic manipulation toward improving desirable traits for wheat molecule breeding.

Analysis of the Effects of the Vrn-1 and Ppd-1 Alleles on Adaptive and Agronomic Traits in Common Wheat (Triticum aestivum L.).

Wheat heading time is primarily governed by two loci: VRN-1 (response to vernalization) and PPD-1 (response to photoperiod). Five sets of near-isogenic lines (NILs) were studied with the aim of investigating the effect of the aforementioned genes on wheat vegetative period duration and 14 yield-related traits. Every NIL was sown in the hydroponic greenhouse of the Institute of Cytology and Genetics, SB RAS. To assess their allelic composition at the VRN-1 and PPD-1 loci, molecular markers were used. It was shown that HT in plants with the Vrn-A1vrn-B1vrn-D1 genotype was reduced by 29 and 21 days (p < 0.001) in comparison to HT in plants with the vrn-A1Vrn-B1vrn-D1 and the vrn-A1vrn-B1Vrn-D1 genotypes, respectively. In our study, we noticed a decrease in spike length as well as spikelet number per spike parameter for some NIL carriers of the Vrn-A1a allele in comparison to carriers of the Vrn-B1 allele. PCA revealed three first principal components (PC), together explaining more than 70% of the data variance. Among the studied genetic traits, the Vrn-A1a and Ppd-D1a alleles showed significant correlations with PCs. Regarding genetic components, significant correlations were calculated between PC3 and Ppd-B1a (-0.26, p < 0.05) and Vrn-B1 (0.57, p < 0.05) alleles. Thus, the presence of the Vrn-A1a allele affects heading time, while Ppd-D1a is associated with plant height reduction.

Effect of a novel dwarfing mutant site on chromosome 4B on agronomic traits in common wheat.

The introduction of dwarfing genes triggered a wave of "green revolution". A number of wheats dwarfing genes have been reported in previous studies, and only a small fraction of these have been applied to production practices. Therefore, the development of novel dwarfing genes for wheat is of great value. In this study, a novel dwarfing site, Rht-yz, identified in the Yanzhan mutation, is located on chromosome 4B (30-33MB) and its mechanism of action is different from that of Rht-B1b (C-T mutation), but whether it affects the Rht-B1a (TraesCS4B02G043100) or other genes is unclear. Exogenously applied GA3 experiments showed that Rht-yz is one of the gibberellin-insensitive dwarf genes. The effects of the dwarf gene Rht-yz on agronomic traits in wheat were evaluated in the field using Yanzhan, Yanzhan mutations, F2:3 and F3:4 lines. The results showed that Rht-yz improved lodging resistance by reducing plant height, increasing diameter, wall thickness and mechanical strength of the basal stem. In terms of yield traits, Rht-yz had negative effects on tiller number plant-1, biomass plant-1 and yield plant-1, but had no significant effect on harvest index, 1000-kernel weight and spike traits. In addition, Rht-yz significantly increased crude protein, wet gluten and starch content. Therefore, the rational use of the new dwarfing site Rht-yz has potential and value in dwarf wheat breeding.

An improved in-vitro regeneration protocol using scutellum of mature and immature embryos of wheat

Generally, conventional practices take a long time to improve agronomic traits in common wheat (Triticum aestivum L.). However, biotechnological tools provide the best opportunity to enhance crop potential within a limited time. A simple and repeatable protocol for wheat regeneration is the priority for transforming the genetic makeup of elite wheat cultivars. Among 10 types of callus induction media (CIM), CIM4 with supplemented Murashige and Skoog (MS) media+ dicamba (2 mg/l) has 98.22 and 97.33% callus induction efficiency (CIE) in immature and mature scutellum, respectively. Precocious germination, considered a key barrier during callus induction, was fully controlled by excising the embryonic axis. Among 29 different shoot induction media (SIM) assessed in the study, SIM 29 containing zeatin 5 mg/l, 6-benzylaminopurine (BAP) 5 mg/l, 2,4-dichlorophenoxyacetic acid (2,4-D) 0.25 mg/l,1-naphthaleneacetic acid (NAA) 0.25 mg/l, and copper sulfate (CuSO4) 20 mg/l was found most responsive for shoot induction. The combined effect of cytokinin and CuSO4 resulted in an improved wheat regeneration response in two popular Indian wheat varieties, namely HD2967 and HD3171. Rooting was observed at 100% using IAA and IBA @ 0.2 mg/l concentration in root induction media (RIM). The whole in-vitro regeneration protocol from embryo to transfer in the greenhouse took 8 to 9 weeks. The in-vitro regeneration protocol developed in the present study could further be utilized to improve the genetic makeup of elite wheat cultivars utilizing genetic engineering tools.

Quantitative trait loci for seeding root traits and the relationships between root and agronomic traits in common wheat.

A completely developed and vigorous root system can provide a stable platform for aboveground plant organs. To identify loci controlling root traits that could be used in wheat (Triticum aestivum L.) breeding, 199 recombinant inbred lines were used to measure and analyze eight root traits. A total of 18 quantitative trait loci (QTL) located on chromosomes 1A, 2A, 2B, 2D, 4B, 4D, 6A, 7A, and 7B were identified. The phenotypic variation explained by these 18 QTL ranged from 3.27% to 11.75%, and the logarithm of odds scores ranged from 2.50 to 6.58. A comparison of physical intervals indicated several new QTL for root traits were identified. In addition, significant correlations between root and agronomic traits were detected and discussed. The results presented in this study, along with those of previous reports, suggest that chromosomes 2 and 7 likely play important roles in the growth and development of wheat roots.

Identification of TaPPH-7A haplotypes and development of a molecular marker associated with important agronomic traits in common wheat

BackgroundPremature senescence of flag leaf severely affects wheat yield and quality. Chlorophyll (Chl) degradation is the most obvious symptom during leaf senescence and catalyzed by a series of enzymes. Pheophytin pheophorbide hydrolase (Pheophytinase, PPH) gene encodes a Chl degradation hydrolase.ResultsIn this study, the coding, genomic and promoter sequences of wheat TaPPH-A gene were cloned. The corresponding lengths were 1467 bp, 4479 bp and 3666 bp, respectively. Sequence structure analysis showed that TaPPH-A contained five exons and four introns. After the multiple sequences alignment of TaPPH-A genome from 36 accessions in a wheat diversity panel, four SNPs and one 2-bp InDel were observed, which formed two haplotypes, TaPPH-7A-1 and TaPPH-7A-2. Based on the SNP at 1299 bp (A/G), a molecular marker TaPPH-7A-dCAPS was developed to distinguish allelic variation (A/G). Using the molecular markers, 13 SSR, and 116 SNP markers, a linkage map of chromosome 7A were integrated. TaPPH-A was mapped on the chromosome region flanked by Xwmc9 (0.94 cM) and AX-95634545 (1.04 cM) on 7A in a DH population. Association analysis between TaPPH-7A allelic variation and agronomic traits found that TaPPH-7A was associated with TGW in 11 of 12 environments and Chl content at grain-filling stage under drought stress using Population 1 consisted of 323 accessions. The accessions possessed TaPPH-7A-1 (A) had higher TGW and Chl content than those possessed TaPPH-7A-2 (G), thus TaPPH-7A-1 (A) was a favorable allelic variation. By analyzing the frequency of favorable allelic variation TaPPH-7A-1 (A) in Population 2 with 157 landraces and Population 3 with 348 modern cultivars, we found it increased from pre-1950 (0) to 1960s (54.5%), then maintained a relatively stable level about 56% from 1960s to 1990s.ConclusionThese results suggested the favorable allelic variation TaPPH-7A-1 (A) should be valuable in enhancing grain yield by improving the source (chlorophyll content) and sink (the developing grain) simultaneously. Furthermore, the newly developed molecular marker TaPPH-7A-dCAPS could be integrated into a breeding kit of screening high TGW wheat for marker-assisted selection.

Elite Haplotypes of a Protein Kinase Gene TaSnRK2.3 Associated with Important Agronomic Traits in Common Wheat.

Plant-specific protein kinase SnRK2s play crucial roles in response to various environmental stimuli. TaSnRK2.3, a SnRK2 member, was involved in the response to multiple abiotic stresses in wheat. To facilitate the use of TaSnRK2.3 in wheat breeding, the three genomic sequences of TaSnRK2.3, originating from the A, B, and D genomes of hexaploid wheat, were obtained. Sequence polymorphism assays showing 4 and 10 variations were detected at TaSnRK2.3-1A and at TaSnRK2.3-1B, respectively, yet no variation was identified at TaSnRK2.3-1D. Three haplotypes for A genome, and two main haplotypes for B genome of TaSnRK2.3 were identified in 32 genotypes. Functional markers (2.3AM1, 2.3AM2, 2.3BM1, 2.3BM2) were successfully developed to distinguish different haplotypes. Association analysis was performed with the general linear model in TASSEL 2.1. The results showed that both TaSnRK2.3-1A and TaSnRK2.3-1B were significantly associated with plant height (PH), length of peduncle and penultimate node, as well as 1,000-grain weight (TGW) under different environments. Additionally, TaSnRK2.3-1B was significantly associated with stem water-soluble carbohydrates at flowering and mid-grain filling stages. Hap-1A-1 had higher TGW and lower PH; Hap-1B-1 had higher TGW and stem water-soluble carbohydrates, as well as lower PH, thus the two haplotypes were considered as elite haplotypes. Geographic distribution and allelic frequencies indicated that the two preferred haplotypes Hap-1A-1 and Hap-1B-1 were positively selected in the process of Chinese wheat breeding. These results could be valuable for genetic improvement and germplasm enhancement using molecular marker assisted selection in wheat breeding.

Dwarfing genes Rht4 and Rht-B1b affect plant height and key agronomic traits in common wheat under two water regimes

To explore the potential utilization of Rht4 in wheat improvement, we investigated and compared the effects of Rht4 and Rht-B1b on the plant height and yield components using four groups of recombinant inbred lines derived from the cross between “IDO444” (tall, no known dwarfing alleles) and “Rio Blanco” (semi-dwarf, Rht4+Rht-B1b) grown under two water regimes.Rht4, Rht-B1b and Rht4+Rht-B1b significantly reduced plant height by 11.5%, 19.3% and 18.2%, respectively. There were no additive effects on plant height in Rht4+Rht-B1b lines. Both Rht4 and Rht-B1b significantly reduced internode length and lodging score with stronger effects by Rht-B1b. Water stress affected the plant height related traits of the single Rht-B1b lines more than that of the Rht4 lines, except for distance from spike to flag leaf ligule.Grain number was increased by Rht4 and Rht-B1b, but higher spike numbers was only observed in lines with Rht-B1b. Both Rht4 and Rht-B1b significantly reduced thousand kernels weight. Rht-B1b reduced above-ground biomass but increased grain yield and harvest index, while Rht4 had less effect on these traits, compared with tall lines under both well-watered and water-stressed conditions. The Rht4+Rht-B1b lines produced the highest yield under both water regimes, with more grain number, greater spike number and higher harvest index.In conclusion, Rht4 did not show advantages over Rht-B1b on grain yield, but Rht4+Rht-B1b did, in both water regimes, which suggests that Rht4 should be combined with Rht-B1b in wheat improvement.

Effects of Gibberellic Acid Responsive Dwarfing Gene &amp;lt;i&amp;gt;Rht9&amp;lt;/i&amp;gt; on Plant Height and Agronomic Traits in Common Wheat

To explore the potential use of GA-responsive dwarfing gene <i>Rht9</i> in common wheat breeding program, its effects on plant height, seedling vigor, photosynthesis and yield traits were investigated and compared in field experiments using hexaploid <i>Rht9</i> dwarf lines derived from two crosses of Chinese winter wheat cultivars Xifeng 20 and Jinmai 47 with the <i>Rht9</i> tetraploid donor Granaoto. Xifeng20-<i>Rht9</i> dwarf lines reduced plant height on average by 25.38%, while on average by 9.39% in Jinmai47-<i>Rht9/Rht8</i> dwarf lines. Compared with taller parents, coleoptile length was reduced by 19.80% in Xifeng20-<i>Rht9</i> dwarf lines, while it was increased by 14.22% in Jinmai 47-<i>Rht9/Rht8</i> dwarf lines. There were no adverse effects of <i>Rht9</i> on root characters and flag leaf characters, though slightly increased relative leaf chlorophyll content (SPAD) observed. Grain numbers per spike was increased on average by 19.63%, and biomass per plant was slightly decreased on average by 3.37% in Xifeng 20-<i>Rht9</i> dwarf lines, while, grain number per spike was decreased on average by 11.49%, and biomass per plant was increased on average by 8.57% in Jinmai47-<i>Rht9/Rht8</i> dwarf lines. Compared with taller parents, <i>Rht9</i> increased fertile tillers on average by 11.25% and 11.19%, grain yield on average by 10.11% and 14.10%, harvest index on average by 12.67% and 6.85%, while decreased spike length on average by 4.80% and 16.23%, slightly decreased 1000 kernels weight by 4.43% and 4.61%, in the <i>Rht9</i> dwarf lines of Xifeng 20 and Jinmai 47, respectively. The results of current study could be useful for proper use of dwarfing gene Rht9 to improve lodging resistance, grain yield potential in wheat breeding programs for water limited area.

Effects of the Vrn-D1b allele associated with facultative growth habit on agronomic traits in common wheat

The Vrn-D1b allele associated with facultative growth habit was recently found in the wheat cultivars mostly distributed in the Yellow and Huai River Valley Winter Wheat Zone (YHWZ) in China. The objective of the present study was to understand the effects of Vrn-D1b on agronomic traits. A population of F3:8 derived lines, having the same allelic variation at all known vernalization loci except Vrn-D1 and photoperiod loci, was developed, from which 50 lines with homozygous Vrn-D1b genotype and 50 lines with homozygous vrn-D1 genotype were evaluated in two environments. The results showed that the Vrn-D1b-carrying lines had significantly higher grain yield (0.3 t ha−1, P ≤ 0.01), more kernels per spike (1.2, P ≤ 0.01), greater thousand kernel weight (0.8 g, P ≤ 0.05), higher seedling height (2.5 cm, P ≤ 0.01) and plant height (2.0 cm, P ≤ 0.01), fewer sterile spikelet number per spike (−0.3, P ≤ 0.01), earlier in both heading (1.0 days, P ≤ 0.01) and anthesis (1.0 days, P ≤ 0.01), compared to the vrn-D1-carrying lines. Grain yield was positively correlated with seedling height (r = 0.47, P ≤ 0.01), plant height (r = 0.37, P ≤ 0.01) and kernel number per spike (r = 0.51, P ≤ 0.01), but negatively correlated with the heading date (r = −0.50, P ≤ 0.01) and anthesis date (r = −0.55, P ≤ 0.01). Path analysis and clustering analysis based on the principal component analysis showed that the yield advantage of Vrn-D1b lines over vrn-D1 lines was attributed primarily to the increased kernel number per spike. The findings indicate that the Vrn-D1b allele had a direct or indirect effect on grain yield.

Cytological and molecular analysis of wheat - Agropyron cristatum translocation lines with 6P chromosome fragments conferring superior agronomic traits in common wheat.

Agropyron cristatum (2n = 4x = 28, PPPP) is a wild relative of common wheat and confers several desirable agronomic traits to wheat, such as high grain number per spike and enhanced resistance to certain diseases. Development of wheat - A. cristatum 6P translocation lines facilitates its utilization in wheat improvement. In this study, 26 wheat - A. cristatum 6P translocation lines were characterized by in situ hybridization (ISH) and 6P-specific sequence-tagged-site (STS) markers. These translocation lines carried different 6P chromosomal segments, which covered the whole 6P chromosome. FISH results showed that 15, 5, and 6 lines were translocated onto wheat A, B, and D genomes, respectively. Compared with the previous reports, a fine physical map of 6P chromosome was constructed, consisting of 31 chromosomal bins with 255 STS markers. Twelve translocation lines containing 6PS13∼14 chromosomal bins were highly resistant to leaf rust. Two lines showed high grain number per spike, and three lines displayed both enhanced grain number per spike and thousand-grain weight. Development of wheat - A. cristatum 6P translocation lines will not only provide novel wheat germplasm for wheat breeding but also be helpful to broaden the genetic basis of common wheat.

Comparing the effects of GA-responsive dwarfing genes Rht13 and Rht8 on plant height and some agronomic traits in common wheat

Rht8 is the only GA-responsive dwarfing gene used in wheat grown in rainfed or irrigation-limited areas. To assess an alternative dwarfing gene, the effects of GA-responsive dwarfing gene Rht13 on plant height and some agronomic traits were compared with Rht8 in this study. The four homozygous genotypes of the F2 individuals, F2:3 and F3:4 lines derived from the cross between Jinmai47 (Rht8) and Magnif M1 (Rht13) were used to evaluate and compare the effects of Rht13 and Rht8. The coleoptile length and seedling root characteristics was conducted under laboratory conditions, while plant height and various yield components were evaluated in field environments in northwest China. Rht13 significantly shortened the length of all internodes (except the basal internode) and reduced final plant height by 30.3% (30.1cm) on average, while Rht8 mainly reduced peduncle length alone to obtain a plant stature shortened by only 15.7% (16.0cm). The greater effect of Rht13 on plant height resulted in the distance from spike to flag leaf ligule being decreased by 97.7%. The effect of Rht13 was even greater when combined with Rht8 (104.9%), such that the spikes failed to fully emerge from the flag leaf sheath. Compared with tall genotypes, coleoptile length and seedling root characteristics were not significantly affected by either Rht13 or Rht8, which might favor the utilization of Rht13 or Rht13+Rht8 in rainfed and irrigation-limited areas. Fewer grains spike−1 were observed in lines with Rht13 alone (18.2%) and with both dwarfing genes (Rht13+Rht8, 18.9%), whereas there was no significant difference between the lines with Rht8 alone and tall lines. Rht13 and Rht8 reduced biomass plant−1 by 27.9% and 25.2% and grain yield plant−1 by 29.0% and 17.4%, respectively. Rht13 did not affect 1000-kernel weight and harvest index whereas Rht8 significantly increased 1000-kernel weight and harvest index. In the rainfed winter wheat environment encountered in northwest China, Rht13 reduced grain number spike−1 significantly. This effect may be due to the very short distance from spike to flag leaf ligule. This undesirable effect may be improved through selection. If so, then there is potential for using Rht13 in wheat improvement in rainfed and irrigation-limited areas.

Genetic effect of dwarfing gene Rht13 compared with Rht-D1b on plant height and some agronomic traits in common wheat (Triticum aestivum L.)

GA-insensitive (GAI) dwarfing genes Rht-B1b and Rht-D1b have been widely used to reduce plant height, increase yield and improve harvest index, but they also express shorter coleoptiles and poor seedling vigor. GA-responsive dwarfing genes, such as Rht13 have potential for wheat improvement since they may not be associated with the latter effects. In this study, the effects of dwarfing genes Rht-D1b and Rht13 on plant height, coleoptile length, seedling root characters and yield components were investigated and compared in field environments in northwest China, using F2:3 and F3:4 lines derived from a cross between the Chinese winter wheat Xinong223 (Rht-D1b) and Magnif M1 (Rht13). The results showed that both Rht13 and Rht-D1b significantly reduced internode length and plant height. GA-responsive (GAR) dwarfing gene Rht13 reduced plant height by 16.5%, but did not affect coleoptile length or seedling root characters. Rht13 lines demonstrated better seedling vigor with greater potential for seedling establishment in the field. The GAI dwarfing gene Rht-D1b was associated with shorter plant height (22.0% in general) along with shorter coleoptile length, shorter total root length, smaller root surface area, and less root volume. These phenotypes may contribute to lower seedling vigor and poorer seedling emergence in the field. The GAR dwarfing gene Rht13 could compensate for some of the negative effect of the GAI dwarfing gene Rht-D1b on root surface area and root volume, which could benefit the root system. The combination of these two dwarfing genes produced even shorter plants (40.3% in general) and resulted in the shortest distance from spike to flag-leaf ligule. Rht-D1b did not affect the diameter of stems and flag leaf size adversely, while Rht13 narrowed the diameter of stems (except the peduncle) and narrowed flag leaf width. Grain number spike−1 and number of fertile tillers plant−1 was similar between lines with single dwarfing gene (Rht-D1b or Rht13) and tall lines, but less grain number spike−1 was observed in lines with double dwarfing genes. 1000-kernel weight was significantly reduced by Rht13, while Rht-D1b had no significant effect on 1000-kernel weight. In the rainfed winter wheat environments encountered here, Rht13 and Rht-D1b reduced biomass plant−1 by 24.5% and 19.9% and grain yield plant−1 by 25.8% and 25.7%, respectively, but harvest index remained the same as tall lines in both Rht13 and Rht-D1b dwarf lines.

Genetic effects of dwarfing gene Rht-5 on agronomic traits in common wheat (Triticum aestivum L.) and QTL analysis on its linked traits

In order to evaluate the genetic effects of Rht-5 dwarfing gene on agronomic traits in common wheat, F2 population and 32 F2:3 lines derived from the cross between Jinmai47 (rht-5) and Marfed M (Rht-5) along with the two parents were grown in the winter wheat growing seasons of 2011–2012 and 2012–2013, respectively. The F2 population formed the mapping population and their phenotypic and genotypic data were merged for QTL mapping. The dwarf and tall individuals in the F2 population were selected to compose the F2:3 lines. Analysis of variance in the F2 population and F2:3 lines showed highly significant differences among individuals or lines for all of traits studied, except for biomass and grain yield. In general, in the background of Jinmai47, dwarfing gene Rht-5 was associated with a plant height reduction of 25.84%, delaying heading date by 1 day, increasing the number of fertile tillers plant−1 by 37.39%, while reducing the number of spikelets spike−1 and number of grains spike−1 by 8.07% and 22.31%, respectively. Individuals with earlier heading date, longer spikes, more spikelets spike−1, and more grains spike−1 could be observed in the dwarf lines when compared to the dwarf parent. Plant height showed highly positive and significant correlation with peduncle length (0.88), spike length (0.80), number of spikelets spike−1 (0.63), number of grains spike−1 (0.64), biomass (0.47), grain yield (0.56) and harvest index (0.37), whereas it had negative and highly significant correlation with the number of fertile tillers plant−1 (−0.64). A partial chromosomal linkage map was constructed with three polymorphic markers based on their genotypes in the F2 population. Using composite interval mapping (CIM) analysis, four QTLs were detected for plant height, heading date, peduncle length and number of grains spike−1 and accounted for up to 11.82%, 8.02%, 10.32% and 15.65% of the phenotypic variation, respectively. The results of the current study could be useful for proper use of Rht-5 dwarfing gene in breeding programs to improve lodging tolerance, yield potential in wheat and increase efficiency of marker assisted selection for agronomic traits.

Genetic Mapping of Quantitative Trait Loci Associated with Important Agronomic Traits in the Spring Wheat (Triticum aestivum L.) Cross ‘Louise’ × ‘Penawawa’

Understanding the genetic factors underlying agronomic traits in common wheat (Triticum aestivum L.) is essential to making gains from selection during the breeding process. A set of 188 recombinant inbred lines (RILs) from a ‘Louise’ × ‘Penawawa’ mapping population was grown for two crop years at two locations in the Pacific Northwest region of the United States to identify quantitative trait loci (QTL) associated with seedling growth habit, leaf color, plant height, flowering date, maturity date, grain volume weight, grain protein content, and grain yield. Quantitative trait loci for flowering date and maturity date were associated with the Ppd‐D1 gene for photoperiod insensitivity. Variation in the QTL for plant height was dependent on location and year and localized to chromosome 2D and 3B. A QTL for leaf color was identified on chromosome 2B. Seedling growth habit mapped to chromosome 2D, and a significant QTL for grain volume weight was detected on chromosome 1B. Quantitative trait loci were identified for grain yield; however, some of these QTL were associated with other known QTL for pest resistance, seedling growth habit, or photoperiod insensitivity. Flowering date, maturity date, and plant height were significantly correlated, which resulted from the pleiotropic effects of the Ppd‐D1 gene. The identification of agronomic QTL, and the correlations between and among them, is the first step toward making gains from selection using molecular marker‐assisted selection for these important agronomic traits.

QTL Analysis of Plant Height based on Doubled Haploid (DH) Population derived from PTSMS Wheat

Plant height is one of the important agronomic traits in common wheat. Comprehensive studies of genetic basis on plant heigh will lay the grounds for breeding program, variety improvement and extension. In this study, a population of 234 doubled haploid (DH) lines derived from the cross between BS366, the photopeiod-thermo sensitive male sterile line, and common wheat cultivar Baiyu149 was used to detect the QTLs for plant height in wheat. The DH lines of the population and their parents were planted at Experimental Station in Beijing and Funan of Anhui in 2007 and 2008, respectively. With the aid of the method of composite interval mapping (CIM), 25 QTLs related to the trait of plant height were detected , which were mapped on chromosomes 1A, 1B, 2A, 2B, 2D, 3B (two QTLs), 3D (two QTLs), 4B, 5A (two QTLs), 6A, 6B (three QTLs), 6D, 7A (three QTLs), 7B (four QTLs) and 7D chromosomes. Single QTL can explain 2.11%~9.64% of the phenotypic variations while the additive effect of the detected QTL ranged from 3.35 to 16.19. Seven QTLs were detected at both experimental sites in Beijing and Funan in 2007, which were mapped on 1B, 2A, 3B (2 QTLs), 3D, and 6B (2 QTLs), whereas only five QTLs were both detected in the two locations in 2008, which were mapped on 2B, 6B, 7B (2QTLs ), and 7D. The QTLs mapped on chromosome 7A were only found in the location of Beijing, which might imply that the environmental effects exit in different locations . In this research the significant QTL mapped on Chromosome 6B was detected under the conditions of the four environments, which demonstrated that the detected QTL might be stable in different environmental conditionss and could be as a dominant loci for the applications of marker-assisted breeding program.

Effects of Hordeum chilense cytoplasm on agronomic traits in common wheat

AbstractThe genome of bread wheat, AABBDD, was substituted into the cytoplasm of Hordeum chilense by repeated backcrossing to produce alloplasmic lines. The aim of this work was to investigate the effect of H. chilense cytoplasm on agronomic traits in common wheat. Three cytolines were developed. The alloplasmic nature of these lines was confirmed using chloroplast simple‐sequence repeat markers. Each cytoline was compared with its respective euplasmic control for agronomic performance during 2 years of field trials. The interaction between H. chilense cytoplasm and common wheat genome greatly affected most of the traits evaluated. Among them, alloplasmic lines showed delayed anthesis date, lower yield and lower plant height. These effects are similar to those caused by Aegilops cytoplasm. The main conclusion of this work is that H. chilense cytoplasm is of limited value for wheat breeding.

Mapping quantitative trait loci controlling agronomic traits in the spring wheat cross RL4452 × 'AC Domain'

Relatively little is known about the genetic control of agronomic traits in common wheat (Triticum aestivum L.) compared with traits that follow Mendelian segregation patterns. A doubled-haploid population was generated from the cross RL4452x'AC Domain' to study the inheritance of the agronomic traits: plant height, time to maturity, lodging, grain yield, test weight, and 1000-grain weight. This cross includes the genetics of 2 western Canadian wheat marketing classes. Composite interval mapping was conducted with a microsatellite linkage map, incorporating 369 loci, and phenotypic data from multiple Manitoba environments. The plant height quantitative trait loci (QTLs), QHt.crc-4B and QHt.crc-4D, mapped to the expected locations of Rht-B1 and Rht-D1. These QTLs were responsible for most of the variation in plant height and were associated with other agronomic traits. An additional 25 agronomic QTLs were detected in the RL4452x'AC Domain' population beyond those associated with QHt.crc-4B and QHt.crc-4D. 'AC Domain' contributed 4 alleles for early maturity, including a major time to maturity QTL on 7D. RL4452 contributed 2 major alleles for increased grain yield at QYld.crc-2B and QYld.crc-4A, which are potential targets for marker-assisted selection. A key test weight QTL was detected on 3B and prominent 1000-grain weight QTLs were identified on 3D and 4A.

Diallel analysis of four agronomic traits in common wheat.

The common wheat cultivars Aköz, Florence, Mentana, Jaral, and Siete Cerros were crossed in 1972 in all possible combinations excluding reciprocals. In 1972--1973 the F1 hybrids and the five parents were field grown at Bornova in randomized complete blocks. The characters studied were plant height, spike length, 1000-kernel weight, and plant yield. The analysis of data showed that (a) with respect to plant height and 1000-kernel weight all F1 combinations deviated from the corresponding midparental values, (b) for the same characters the GCA variances were significant and the GCA divided by SCA ratios high, (c) the characters' plant height, spike length, and 1000-kernel weight were probably controlled by two effective factors each, and (d) plant height had the highest and 1000-kernel weight the lowest heritability (h2=0.66 and h2=0.26, respectively). It was concluded that a desired response to selection could be expected for plant height and 1000-kernel weight.