Wheat Heading Date Research Articles

Weather-Based Logistic Regression Models for Predicting Wheat Head Blast Epidemics.

Wheat head blast is a major disease of wheat in the Brazilian Cerrado. Empirical models for predicting epidemics were developed using data from field trials conducted in Patos de Minas (2013 to 2019) and trials conducted across 10 other sites (2012 to 2020) in Brazil, resulting in 143 epidemics, with each being classified as either outbreak (≥20% head blast incidence) or nonoutbreak. Daily weather variables were collected from the National Aeronautics and Space Administration (NASA) Prediction of Worldwide Energy Resources (POWER) website and summarized for each epidemic. Wheat heading date (WHD) served to define four time windows, with each comprising two 7-day intervals (before and after WHD), which combined with weather-based variables resulted in 36 predictors (nine weather variables × four windows). Logistic regression models were fitted to binary data, with variable selection using least absolute shrinkage and selection operator (LASSO) and sequentially best subset analyses. The models were validated using the leave-one-out cross-validation (LOOCV) technique, and their statistical performance was compared. One model was selected, implemented in a 24-year series, and assessed by experts and literature. Models with two to five predictors showed accuracies between 0.80 and 0.85, sensitivities from 0.80 to 0.91, specificities from 0.72 to 0.86, and area under the curve (AUC) from 0.89 to 0.91. The accuracy of LOOCV ranged from 0.76 to 0.81. The model applied to a historical series included temperature and relative humidity in preheading date, as well as postheading precipitation. The model accurately predicted the occurrence of outbreaks, aligning closely with real-world observations, specifically tailored for locations with tropical and subtropical climates.

The Effects of Vernalization and Photoperiod Genes Composition on Heading Date in Wheat

The vernalization characteristics of wheat are mainly controlled by vernalization and photoperiod genes, which determine the winter-spring habit and heading-flowering of wheat, and affect its environmental adaptability. In order to understand the effects of vernalization and photoperiod genes on heading date, 12 common wheat varieties widely cultivated in the Huang-Huai region were used as experimental materials, and the effects of different low-temperature vernalization treatments on wheat heading date were studied. Using molecular markers from previous studies, the allelic variations and genotypes of vernalization genes (VRN-A1, VRN-B1, VRN-D1 and VRN-B3) and photoperiod genes (Ppd-A1, Ppd-B1, Ppd-D1) were detected. By identifying the heading date in a controlled greenhouse, the relationship between the vernalization and photoperiod genes composition and the heading date phenotype was analyzed. The experimental results showed that different wheat varieties had different phenotypes after different vernalization treatments. Tian min 198 carried a dominant vernalization gene, and its vernalization characteristics were expressed as spring wheat varieties, with low requirements for low-temperature vernalization. Wheat without a dominant vernalization gene had winter wheat characteristics, with high requirements for low-temperature vernalization. Wheat varieties carrying a dominant vernalization gene can be used to improve late-maturing wheat varieties, and serve as valuable germ plasma resources for variety improvement and introduction. Exploring the effects of different wheat vernalization and photoperiod genes composition on heading date is beneficial to provide a scientific basis for the rational use of wheat varieties, and studying the vernalization and photoperiod genes composition has guiding significance for wheat introduction and ecological breeding.

Fine mapping and genetic analysis identified a C2H2-type zinc finger as a candidate gene for heading date regulation in wheat.

A minor-effect QTL, Qhd.2AS, that affects heading date in wheat was mapped to a genomic interval of 1.70-Mb on 2AS, and gene analysis indicated that the C2H2-type zinc finger protein gene TraesCS2A02G181200 is the best candidate for Qhd.2AS. Heading date (HD) is a complex quantitative trait that determines the regional adaptability of cereal crops, and identifying the underlying genetic elements with minor effects on HD is important for improving wheat production in diverse environments. In this study, a minor QTL for HD that we named Qhd.2AS was detected on the short arm of chromosome 2A by Bulked Segregant Analysis and validated in a recombinant inbred population. Using a segregating population of 4894 individuals, Qhd.2AS was further delimited to an interval of 0.41cM, corresponding to a genomic region spanning 1.70Mb (from 138.87 to 140.57Mb) that contains 16 high-confidence genes based on IWGSC RefSeq v1.0. Analyses of sequence variations and gene transcription indicated that TraesCS2A02G181200, which encodes a C2H2-type zinc finger protein, is the best candidate gene for Qhd.2AS that influences HD. Screening a TILLING mutant library identified two mutants with premature stop codons in TraesCS2A02G181200, both of which exhibited a delay in HD of 2-4days. Additionally, variations in its putative regulatory sites were widely present in natural accession, and we also identified the allele which was positively selected during wheat breeding. Epistatic analyses indicated that Qhd.2AS-mediated HD variation is independent of VRN-B1 and environmental factors. Phenotypic investigation of homozygous recombinant inbred lines (RILs) and F2:3 families showed that Qhd.2AS has no negative effect on yield-related traits. These results provide important cues for refining HD and therefore improving yield in wheat breeding programs and will deepen our understanding of the genetic regulation of HD in cereal plants.

Gene Mapping and Identification of a Missense Mutation in One Copy of VRN-A1 Affects Heading Date Variation in Wheat

Heading date (HD) is an important trait for wide adaptability and yield stability in wheat. The Vernalization 1 (VRN1) gene is a key regulatory factor controlling HD in wheat. The identification of allelic variations in VRN1 is crucial for wheat improvement as climate change becomes more of a threat to agriculture. In this study, we identified an EMS-induced late-heading wheat mutant je0155 and crossed it with wide-type (WT) Jing411 to construct an F2 population of 344 individuals. Through Bulk Segregant Analysis (BSA) of early and late-heading plants, we identified a Quantitative Trait Locus (QTL) for HD on chromosome 5A. Further genetic linkage analysis limited the QTL to a physical region of 0.8 Mb. Cloning and sequencing revealed three copies of VRN-A1 in the WT and mutant lines; one copy contained a missense mutation of C changed to T in exon 4 and another copy contained a mutation in intron 5. Genotype and phenotype analysis of the segregation population validated that the mutations in VRN-A1 contributed to the late HD phenotype in the mutant. Expression analysis of C- or T-type alleles in exon 4 of the WT and mutant lines indicated that this mutation led to lower expression of VRN-A1, which resulted in the late-heading of je0155. This study provides valuable information for the genetic regulation of HD and many important resources for HD refinement in wheat breeding programs.

TaGW2L, a GW2-like RING finger E3 ligase, positively regulates heading date in common wheat (Triticum aestivum L.)

RING finger E3 ligases play an important role in regulating plant growth and development by mediating substrate degradation. In this study, we identified TaGW2L, encoding a Grain width and weight2 (GW2)-like RING finger E3 ligase, as a novel positive regulator of heading date in wheat (Triticum aestivum L.). TaGW2L exhibited high amino acid sequence similarities with TaGW2 homoeologs, particularly in the conserved RING finger domain. Expression analysis indicated that TaGW2L was constitutively expressed in various wheat tissues. TaGW2L showed transactivation activity in yeast and could interact with the ubiquitin-conjugating enzymes E2s. An in vitro ubiquitination assay verified that TaGW2L possessed a similar E3 ligase activity to TaGW2. Overexpression of the TaGW2L-7A homoeolog in wheat led to a significantly earlier heading date under both natural conditions and long-day conditions. Transcriptome analysis revealed that multiple known genes positively regulating wheat heading were significantly upregulated in the TaGW2L-7A-overexpression plants compared with the wild-type control. Together, our findings shed light on the role of TaGW2L in wheat heading date and provide potential applications of TaGW2L for the adaptation improvement of crops.

Predicting Winter Wheat Heading Date: A Simple Model and Its Validation in Kansas

Abstract Accurate prediction of winter wheat (Triticum aestivum L.) heading date is important for determining the potential incidence of diseases and abiotic stresses such as freeze or heat events. Wheat phenological modeling requires cultivar- and crop-zone-specific vernalization and photoperiod knowledge. Previous models applied in Kansas showed that the uncertainties of predicting heading date were large and could be improved. In this study, a modification to the Scientific Impact Assessment and Modeling Platform for Advanced Crop and Ecosystem Management (SIMPLACE) model was developed and implemented to improve the accuracy of winter wheat heading date estimation. The cultivar- and crop-zone-specific model parameters were calculated using a Markov chain Monte Carlo simulation. The modified models were calibrated by using the longest observation site to cover all cultivars planted in each crop zone. Model performance was then evaluated for seven winter wheat cultivars at eight experiment sites distributed across four crop zones in Kansas. Our modified model (MS) had a root-mean-square error (RMSE) between predicted and observed heading date of 4 days, which reflects an improved accuracy by 5–8 days on average compared to the Agricultural Production Systems Simulator (APSIM) or the original SIMPLACE models. There was a clear correlation between the uncertainty of the modeled heading date and the sowing date in previous models. Our modified model demonstrates that integrating nonlinear temperature response functions, temperature stress factors, and sowing date information improved prediction of the heading date in winter wheat across Kansas.

Transcriptome profiling of developing leaf and shoot apices to reveal the molecular mechanism and co-expression genes responsible for the wheat heading date

BackgroundWheat is one of the most widely planted crops worldwide. The heading date is important for wheat environmental adaptability, as it not only controls flowering time but also determines the yield component in terms of grain number per spike.ResultsIn this research, homozygous genotypes with early and late heading dates derived from backcrossed progeny were selected to conduct RNA-Seq analysis at the double ridge stage (W2.0) and androgynous primordium differentiation stage (W3.5) of the leaf and apical meristem, respectively. In total, 18,352 differentially expressed genes (DEGs) were identified, many of which are strongly associated with wheat heading date genes. Gene Ontology (GO) enrichment analysis revealed that carbohydrate metabolism, trehalose metabolic process, photosynthesis, and light reaction are closely related to the flowering time regulation pathway. Based on MapMan metabolic analysis, the DEGs are mainly involved in the light reaction, hormone signaling, lipid metabolism, secondary metabolism, and nucleotide synthesis. In addition, 1,225 DEGs were annotated to 45 transcription factor gene families, including LFY, SBP, and MADS-box transcription factors closely related to flowering time. Weighted gene co-expression network analysis (WGCNA) showed that 16, 336, 446, and 124 DEGs have biological connections with Vrn1-5 A, Vrn3-7B, Ppd-1D, and WSOC1, respectively. Furthermore, TraesCS2D02G181400 encodes a MADS-MIKC transcription factor and is co-expressed with Vrn1-5 A, which indicates that this gene may be related to flowering time.ConclusionsRNA-Seq analysis provided transcriptome data for the wheat heading date at key flower development stages of double ridge (W2.0) and androgynous primordium differentiation (W3.5). Based on the DEGs identified, co-expression networks of key flowering time genes in Vrn1-5 A, Vrn3-7B, WSOC1, and Ppd-1D were established. Moreover, we discovered a potential candidate flowering time gene, TraesCS2D02G181400. Taken together, these results serve as a foundation for further study on the regulatory mechanism of the wheat heading date.

An automatic method based on daily in situ images and deep learning to date wheat heading stage

Accurate and timely observations of wheat phenology and, particularly, of heading date are instrumental for many scientific and technical domains such as wheat ecophysiology, crop breeding, crop management or precision agriculture. Visual annotation of the heading date in situ is a labour-intensive task that may become prohibitive in scientific and technical activities where high-throughput is needed. This study presents an automatic method to estimate wheat heading date from a series of daily images acquired by a fixed RGB camera in the field. A convolutional neural network (CNN) is trained to identify the presence of spikes in small patches. The heading date is then estimated from the dynamics of the spike presence in the patches over time. The method is applied and validated over a large set of 47 experimental sites located in different regions in France, covering three years with nine wheat cultivars. Results show that our method provides good estimates of the heading dates with a root mean square error close to 2 days when compared to the visual scoring from experts. It outperforms the predictions of a phenological model based on the ARCWHEAT crop model calibrated for our local conditions. The potentials and limits of the proposed methodology towards a possible operational implementation in agronomic applications and decision support systems are finally further discussed.

Pleiotropic QTL influencing spikelet number and heading date in common wheat (Triticum aestivum L.).

Three pleiotropic QTL regions associated with spikelet number and heading date were identified, with FT-A1 considered the candidate gene for QTspn/Hd.cau-7A. Spikelet number traits and heading date (HD) play key roles in yield improvement of wheat and its wide adaptation to different environments. Here, we used a Recombinant Inbred Lines population derived from a cross between Yi5029 (5029) and Nongda4332 (4332) to construct a high-density genetic linkage map and identify quantitative trait loci (QTL) associated with total spikelet number per spike (TSPN), fertile spikelet number per spike (FSPN), sterile spikelet number per spike (SSPN) and HD. A total of 22 environmentally stable QTL for TSPN, FSPN, SSPN and HD were identified. Notably, three pleiotropic QTL regions for TSPN and HD were detected on chromosomes 2A, 7A and 7D. The QTL associated with TSPN and HD on chromosome 7AS was designated QTspn/Hd.cau-7A. Furthermore, the candidate gene FT-A1 located in the region of QTspn/Hd.cau-7A had a single-nucleotide polymorphism (T-G) within the third exon, which might be the cause of diversity in spikelet number and HD between the two parents. Additionally, we developed a semi-thermal asymmetric reverse PCR (STARP) marker to analyze the geographical distribution and evolution of FT-A1 (T or G) alleles. This study contributes to our understanding of the molecular mechanisms of the four traits (TSPN, FSPN, SSPN and HD) and provides further insights into the genetic relationship between spikelet number traits and HD in wheat.

Introgression of chromosomal segments conferring early heading date from wheat diploid progenitor, Aegilops tauschii Coss., into Japanese elite wheat cultivars.

The breeding of agriculturally useful genes from wild crop relatives must take into account recent and future climate change. In Japan, the development of early heading wheat cultivars without the use of any major gene controlling the heading date is desired to avoid overlap of the harvesting time before the rainy season. Here, we backcrossed two early heading lines of a synthetic hexaploid wheat, derived from a crossing between durum wheat and the wild wheat progenitor Aegilops tauschii, with four Japanese elite cultivars to develop early heading lines of bread wheat. In total, nine early heading lines that showed a heading date two to eight days earlier than their parental cultivars in field conditions were selected and established from the selfed progenies of the two- or three-times backcrossed populations. The whole appearance and spike shape of the selected early heading lines looked like their parental wheat cultivars. The mature grains of the selected lines had the parental cultivars' characteristics, although the grains exhibited longer and narrower shapes. RNA sequencing-based genotyping was performed to detect single nucleotide polymorphisms between the selected lines and their parental wheat cultivars, which revealed the chromosomal regions transmitted from the parental synthetic wheat to the selected lines. The introgression regions could shorten wheat heading date, and their chromosomal positions were dependent on the backcrossed wheat cultivars. Therefore, early heading synthetic hexaploid wheat is useful for fine-tuning of the heading date through introgression of Ae. tauschii chromosomal regions.

Winter wheat response to climate change under irrigated and dryland conditions in the US southern High Plains

A rise in global temperature has been observed since the 1980s. The objective of the study was to understand the winter wheat (Triticum aestivum L.) responses and yield performances to the changing climate. The study was performed using growing degree day (GDD) model and regression analysis method. Wheat data (1940 to 2016) were obtained from the Southern Regional Performance Nursery (SRPN) experiments at Bushland, Texas. Wheat genotypes were divided into three groups: Kharkof as a check cultivar, the highest yielding cultivar for each year, and all other cultivars. Climate data were obtained from USDA Agricultural Research Service at Bushland and the National Oceanic and Atmospheric Administration. Temperatures between 1940 and 2016 showed a curvilinear trend with a significant rise since 1980. Mean temperature during wheat growing season (September 15 to June 15) increased at a rate of 0.35°C per decade since 1980. Consequently, seasonal GDD and extreme degree days (EDD) increased at a rate of 69°C d and 19°C d per decade. From 1940 to 2016, wheat heading date has shifted earlier by 16 days for dryland wheat and 11 days for irrigated wheat. Maximum and minimum temperatures in March and April had a negative relationship with heading date, while precipitation had a positive relationship with heading date for both dryland and irrigated wheat. Early heading may have benefits for heat escape but also has the disadvantage of reducing precipitation prior to heading—a loss of 25 mm when heading shifted earlier by 16 days for dryland wheat. The five-year moving average yields increased steadily from about 1960 to 1980, plateaued until the late 1980s, and then declined significantly. However, average genetic yield gains were 505 kg ha−1 under dryland and 1,671.4 kg ha−1 under irrigated conditions for all new cultivars during 1940 to 2016. Yield trends for all three cultivar groups had similar patterns over the years. Increase in maximum temperature, frequencies of maximum temperature greater than or equal to 31°C, and minimum temperature during grain filling period had significant negative effect on grain filling days and yield (except for minimum temperature under dryland conditions). Precipitation during the vegetative growth (November, January, and March) and grain filling (May) had a significant positive effect on dryland wheat yields, but only the January precipitation had significant effect on wheat yield under irrigated conditions. The study indicated that the rising temperature and shifting precipitation timings as a result of early heading are less favorable conditions for winter wheat production in the US southern High Plains.

Fine Mapping of a Novel Heading Date Gene, TaHdm605, in Hexaploid Wheat.

The heading date is critical in determining the adaptability of plants to specific natural environments. Molecular characterization of the wheat genes that regulate heading not only enhances our understanding of the mechanisms underlying wheat heading regulation but also benefits wheat breeding programs by improving heading phenotypes. In this study, we characterized a late heading date mutant, m605, obtained by ethyl methanesulfonate (EMS) mutation. Compared with its wild-type parent, YZ4110, m605 was at least 7 days late in heading when sown in autumn. This late heading trait was controlled by a single recessive gene named TaHdm605. Genetic mapping located the TaHdm605 locus between the molecular markers cfd152 and barc42 on chromosome 3DL using publicly available markers and then further mapped this locus to a 1.86 Mb physical genomic region containing 26 predicted genes. This fine genetic and physical mapping will be helpful for the future map-based cloning of TaHdm605 and for breeders seeking to engineer changes in the wheat heading date trait.

Phenotypic Plasticity of Winter Wheat Heading Date and Grain Yield across the US Great Plains

Phenotypic plasticity describes the range of phenotypes produced by a single genotype in different environments. We quantified the extent of phenotypic plasticity (evaluated as responsiveness to varying environmental conditions) of thermal time to heading and grain yield in 299 hard winter wheat (Triticum aestivum L.) genotypes from the US Great Plains. The genotypes, which included advanced breeding lines and recent and historic cultivars, were evaluated in 11 environments in 2011–2012 and 2012–2013. The average number of days from 1 January to heading across environments ranged from 109 to 150, and the cumulative growing degree days (GDD) from 1 January to heading ranged from 730 to 1112 GDD. Environmental mean grain yield varied from 1.3 to 5.3 Mg ha−1. Plasticity of GDD (GDDP) was strongly correlated with GDD (r = 0.81, P < 0.001), especially maximum GDD (r = 0.90, P < 0.001) across environments, indicating genotypes with greater plasticity developed later, especially within the earliest environments. Plasticity of GDD was negatively associated with yield (r = −0.58, P < 0.001) and therefore detrimental in the germplasm and environments evaluated. Yield plasticity of a genotype was positively correlated with its maximum (r = 0.80, P < 0.001) and minimum (r = 0.33, P < 0.001) grain yield across environments, indicating greater plasticity was favorable under optimal conditions, without a penalty under low‐yielding conditions. More than a century of wheat breeding in this region suggests GDDP has declined and yield plasticity has increased at similar rates. This is encouraging because it indicates the favorable plasticity traits (high yield plasticity, low GDDP) have been selected for indirectly and would respond to further selection.

Allelic Variation in Developmental Genes and Effects on Winter Wheat Heading Date in the U.S. Great Plains.

Heading date in wheat (Triticum aestivum L.) and other small grain cereals is affected by the vernalization and photoperiod pathways. The reduced-height loci also have an effect on growth and development. Heading date, which occurs just prior to anthesis, was evaluated in a population of 299 hard winter wheat entries representative of the U.S. Great Plains region, grown in nine environments during 2011–2012 and 2012–2013. The germplasm was evaluated for candidate genes at vernalization (Vrn-A1, Vrn-B1, and Vrn-D1), photoperiod (Ppd-A1, Ppd-B1 and Ppd-D1), and reduced-height (Rht-B1 and Rht-D1) loci using polymerase chain reaction (PCR) and Kompetitive Allele Specific PCR (KASP) assays. Our objectives were to determine allelic variants known to affect flowering time, assess the effect of allelic variants on heading date, and investigate changes in the geographic and temporal distribution of alleles and haplotypes. Our analyses enhanced understanding of the roles developmental genes have on the timing of heading date in wheat under varying environmental conditions, which could be used by breeding programs to improve breeding strategies under current and future climate scenarios. The significant main effects and two-way interactions between the candidate genes explained an average of 44% of variability in heading date at each environment. Among the loci we evaluated, most of the variation in heading date was explained by Ppd-D1, Ppd-B1, and their interaction. The prevalence of the photoperiod sensitive alleles Ppd-A1b, Ppd-B1b, and Ppd-D1b has gradually decreased in U.S. Great Plains germplasm over the past century. There is also geographic variation for photoperiod sensitive and reduced-height alleles, with germplasm from breeding programs in the northern Great Plains having greater incidences of the photoperiod sensitive alleles and lower incidence of the semi-dwarf alleles than germplasm from breeding programs in the central or southern plains.

Association between Septoria tritici Blotch, Plant Height, and Heading Date in Wheat

The relationship between resistance to Septoria tritici blotch with plant height and heading date has been in most cases attributed to genetic associations. More efficient selection for higher levels of quantitative resistance may result if the nature of the association between susceptibility with earliness and shortness can be determined. Genetic resistance to Septoria tritici blotch and its relationships with plant height and heading date were recorded in 50 Argentinean wheat (Triticum aestivum L.) cultivars in three environments (two in the field and one in the greenhouse) with one virulent isolate of Mycosphaerella graminicola (Fuckel) Schroeter, in Cohn (anamorph Septoria tritici Rob. ex Desm.). Furthermore, a set of 16 cultivars was tested with seven isolates of M. graminicola in the greenhouse at the adult stage. Cultivars varied greatly in resistance to the disease and plant material was identified with moderate to high levels of resistance to several isolates. The field and greenhouse experiments demonstrated no evidence of genetic associations between plant height, heading date, and resistance, indicating that selection of early and short lines with high levels of quantitative resistance is possible. The relationships between those traits were mainly caused by environmental and epidemiological factors, which indicates that management of cultivars should be optimized to minimize these associations.

Selection for Early Heading and Correlated Response in Maturity of Soft Red Winter Wheat

Heading date in wheat (Triticum aestivum L. emend. Thell.) is an easily identifiable trait, and previous research has shown it can be modified. However, several studies have shown that heading date is not always highly correlated with harvest maturity. This study was conducted to gain a more thorough understanding of the relationships between heading date and traits related to maturity such as kernel growth rate (KGR), effective filling period (EFP), and time physiological maturity. We evaluated direct and correlated response to two cycles of phenotypic recurrent selection for early heading date in two wheat populations in 1989. Direct response to selection for early heading date was −5 and −10 d, respectively, in the two populations, In Population 1, correlated response to selection was not significant. We observed a significant reduction in mean KGR from 2.56 to 2.13 mg kernel−1 d−1 from the C0 to the C2 in Population 2, with no significant change in mean EFP. Heritability estimates ranged from 0.10 for yield in population 1 to 0.81 (P<0.01) for heading date in Population 2. Mean estimated date of physiological maturity (EPM) was significantly reduced in both populations after two selection cycles. Early EPM of the C2 apparently reflected an early heading date and not a reduced grain filling period. However, the earliest heading entries were not always the first to reach EPM. Thus we suggest a maturity rating based on EPM in later generations to ensure continued selection pressure for early physiological maturity.