Number Of Wheat Research Articles

The trade-off between grain weight and grain number in wheat is explained by the overlapping of the key phases determining these major yield components.

Enhancing grain yield is a primary goal in the cultivation of major staple crops, including wheat. Recent research has focused on identifying the physiological and molecular factors that influence grain weight, a critical determinant of crop yield. However, a bottleneck has arisen due to the trade-off between grain weight and grain number, whose underlying causes remain elusive. In a novel approach, a wheat expansin gene, TaExpA6, known for its expression in root tissues, was engineered to express in the grains of the spring wheat cultivar Fielder. This modification led to increases in both grain weight and yield without adversely affecting grain number. Conversely, a triple mutant line targeting the gene TaGW2, a known negative regulator of grain weight, resulted in increased grain weight but decreased grain number, potentially offsetting yield gains. This study aimed to evaluate the two aforementioned modified wheat genotypes (TaExpA6 and TaGW2) alongside their respective wild-type counterparts. Conducted in southern Chile, the study employed a Complete Randomized Block Design with four replications, under well-managed field conditions. The primary metrics assessed were grain yield, grain number, and average grain weight per spike, along with detailed measurements of grain weight and dimensions across the spike, ovary weight at pollination (Waddington's scale 10), and post-anthesis expression levels of TaExpA6 and TaGW2. Results indicated that both the TaExpA6 and the triple mutant lines achieved significantly higher average grain weights compared to their respective wild types. Notably, the TaExpA6 line did not exhibit a reduction in grain number, thereby enhancing grain yield per spike. By contrast, the triple mutant line showed a reduced grain number per spike, with no significant change in overall yield. TaExpA6 expression peaked at 10 days after anthesis (DAA), and its effect on grain weight over the WT became apparent after 15 DAA. In contrast, TaGW2 gene disruption in the triple mutant line increased ovary size at anthesis, leading to improved grain weight above the WT from the onset of grain filling. These findings suggest that the trade-off between grain weight and number could be attributed to the overlapping of the critical periods for the determination of these traits.

Positional cloning and characterization reveal the role of TaSRN-3D and TaBSR1 in the regulation of seminal root number in wheat.

Seminal roots play a critical role in water and nutrient absorption, particularly in the early developmental stages of wheat. However, the genes responsible for controlling SRN in wheat remain largely unknown. Genetic mapping and functional analyses identified a candidate gene (TraesCS3D01G137200, TaSRN-3D) encoding a Ser/Thr kinase glycogen synthase kinase 3 (STKc_GSK3) that regulated SRN in wheat. Additionally, experiments involving hormone treatment, nitrate absorption and protein interaction were conducted to explore the regulatory mechanism of TaSRN-3D. Results showed that the TaSRN-3D4332 allele inhibited seminal roots initiation and development, while loss-of-function mutants showed significantly higher seminal root number (SRN). Exogenous application of epi-brassinolide could increase the SRN in a HS2-allelic background. Furthermore, chlorate sensitivity and 15N uptake assays revealed that a higher number of seminal roots promoted nitrate accumulation. TaBSR1 (BIN2-related SRN Regulator 1, orthologous to OsGRF4/GL2 in rice) acts as an interactor of TaSRN-3D and promotes TaBSR1 degradation to reduce SRN. This study provides valuable insights into understanding the genetic basis and regulatory network of SRN in wheat, highlighting their roles as potential targets for root-based improvement in wheat breeding.

Chromosomal mapping of a major genetic locus from Agropyron cristatum chromosome 6P that influences grain number and spikelet number in wheat.

A novel locus on Agropyron cristatum chromosome 6P that increases grain number and spikelet number was identified in wheat-A. cristatum derivatives and across 3 years. Agropyron cristatum (2n = 4x = 28, PPPP), which has the characteristics of high yield with multiple flowers and spikelets, is a promising gene donor for wheat high-yield improvement. Identifying the genetic loci and genes that regulate yield could elucidate the genetic variations in yield-related traits and provide novel gene sources and insights for high-yield wheat breeding. In this study, cytological analysis and molecular marker analysis revealed that del10a and del31a were wheat-A. cristatum chromosome 6P deletion lines. Notably, del10a carried a segment of the full 6PS and 6PL bin (1-13), while del31a carried a segment of the full 6PS and 6PL bin (1-8). The agronomic characterization and genetic population analysis confirmed that the 6PL bin (9-13) brought about an increase in grain number per spike (average increase of 10.43 grains) and spikelet number per spike (average increase of 3.67) over the three growing seasons. Furthermore, through resequencing, a multiple grain number locus was mapped to the physical interval of 593.03-713.89Mb on chromosome 6P of A. cristatum Z559. The RNA-seq analysis revealed the expression of 537 genes in the del10a young spike tissue, with the annotation indicating that 16 of these genes were associated with grain number and spikelet number. Finally, a total of ten A. cristatum-specific molecular markers were developed for this interval. In summary, this study presents novel genetic material that is useful for high-yield wheat breeding initiatives to meet the challenge of global food security through enhanced agricultural production.

Phenotypic and transcriptome profiling of spikes reveals the regulation of light regimens on spike growth and fertile floret number in wheat.

The spike growth phase is critical for the establishment of fertile floret (grain) numbers in wheat (Triticum aestivum L.). Then, how to shorten the spike growth phase and increase grain number synergistically? Here, we showed high-resolution analyses of floret primordia(FP) number, morphology and spike transcriptomes during the spike growth phase under three light regimens. The development of all FP in a spike could be divided into four distinct stages: differentiation (Stage I), differentiation and morphology development concurrently (Stage II), morphology development (Stage III), and polarization (Stage IV). Compared to the short photoperiod, the long photoperiod shortened spike growth and stimulated early flowering by shortening Stage III; however, this reduced assimilate accumulation, resulting in fertile floret loss. Interestingly, long photoperiod supplemented with red light shortened the time required to complete Stages I-II, then raised assimilates supply in the spike and promoted anther development before polarization initiation, thereby increasing fertile FP number during Stage III, and finally maintained fertile FP development during Stage IV until they became fertile florets via a predicted dynamic gene network. Our findings proposed a light regimen, critical stagesand candidate regulators that achieved a shorter spike growth phase and a higher fertile floret number in wheat.

Transcriptomic and metabolomic analysis of changes in grain weight potential induced by water stress in wheat

The sink strength of developing ovaries in wheat determines the grain weight potential. The period from booting to the grain setting stage is critical for ovary growth and development and potential sink capacity determination. However, the underlying regulatory mechanism during this period by which the wheat plant balances and coordinates the floret number and ovary/grain weight under water stress has not been clarified. Therefore, we designed two irrigation treatments of W0 (no seasonal irrigation) and W1 (additional 75 mm of irrigation at the jointing stage) and analyzed the responses of the ovary/grain weight to water stress at the phenotypic, metabolomic, and transcriptomic levels. The results showed that the W0 irrigation treatment reduced the soil water content, plant height, and green area of the flag leaf, thus reducing grain number, especially for the inferior grains. However, it improved the grain weight of the superior and inferior grains as well as average grain weight at maturity, while the average ovary/grain weight and volume during –3 to 10 days after anthesis (DAA) also increased. Transcriptomic analysis indicated that the genes involved in both sucrose metabolism and phytohormone signal transduction were prominently accelerated by the W0 treatment, accompanied by greater enzymatic activities of soluble acid invertase (SAI) and sucrose synthase (Sus) and elevated abscisic acid (ABA) and indole-3-acetic acid (IAA) levels. Thus, the sucrose content decreased, while the glucose and fructose contents increased. In addition, several TaTPP genes (especially TaTPP-6) were down-regulated and the IAA biosynthesis genes TaTAR1 and TaTAR2 were up-regulated under the W0 treatment before anthesis, which further increased the IAA level. Collectively, water stress reduced the growth of vegetative organs and eliminated most of the inferior grains, but increased the ABA and IAA levels of the surviving ovaries/grains, promoting the enzymatic activity of Sus and degrading sucrose into glucose and fructose. As a result, the strong sucrose utilization ability, the enhanced enzymatic activity of SAI and the ABA- and IAA-mediated signaling jointly increased the weight and volume of the surviving ovaries/grains, and ultimately achieved the trade-off between ovary/grain weight and number in wheat under water stress.

Genome-wide identification and characterization of circRNAs in wheat tiller

This study found that the intergenic circRNAs of wheat were more abundant than those of other plants. More importantly, a circRNA-mediated network associated with tillering was constructed for the first time. Circular RNAs (circRNAs) are a class of endogenous non-coding RNAs with covalently closed circular structures, which play an important role in transcriptional and post-transcriptional regulation. Tiller is an important agronomic trait that determines plant morphological architecture and affects spike number in wheat. However, no studies on the characteristics and functions of circRNAs involved in the regulation of wheat tiller. Here, we performed a genome-wide identification of circRNAs using ribosomal-depleted RNA-seq from wheat tiller of two pairs near-isogenic lines. A total of 686 circRNAs were identified and distributed on 21 chromosomes of wheat, of which 537 were novel circRNAs. Unlike other plants, the majority of these circRNAs (61.8%) were derived from intergenic regions. One circRNA-mediated network associated with tillering was constructed through weighted gene co-expression network analysis, including 323 circRNAs, 117 miRNAs, and 968 mRNAs. GO and pathway enrichment analysis of mRNAs suggested that these circRNAs are involved in cell cycle, ncRNA export from nucleus, developmental process, plant hormone signal transduction, MAPK signaling pathway, RNA degradation. Of these circRNAs, ten circRNAs are associated with known tillering/branching genes in rice or Arabidopsis thaliana, including OsCesA7, EBR1, DTE1, CRD1, LPA1, PAY1, LRK1, OsNR2, OsCCA1, OsBZR1. In summary, we present the first study of the identification and characterization of circRNAs in wheat tiller, and the results suggest these circRNAs associated with tillering could play an important role in wheat tiller formation and development.

Effects of a novel Cd passivation approach on soil Cd availability, plant uptake, and microbial activity in weakly alkaline soils

Heavy metal pollution, including that caused by cadmium (Cd), is a matter of increasing concern. Although in situ passivation remediation has been widely used to treat heavy metal-polluted soils, most studies have focused on acidic soils, while studies on alkaline soil conditions are scarce. In this study, the effects of biochar (BC), phosphate rock powder (PRP), and humic acid (HA) on Cd2+ adsorption were examined alone and in combination to choose an appropriate Cd passivation approach for weakly alkaline soils. Additionally, the combined impact of passivation on Cd availability, plant Cd absorption, plant physiology indexes, and soil microbial community was elucidated. BC had a higher Cd adsorption capacity and removal rate than those of PRP and HA. Moreover, HA and PRP enhanced the adsorption capacity of BC. A combination of biochar and humic acid (BHA), and biochar and phosphate rock powder (BPRP) significantly affected soil Cd passivation. BHA and BPRP decreased the plant Cd content and soil Cd-DTPA (diethylenetriaminepentaacetic acid) by 31.36 %, 20.80 %, 38.19 %, and 41.26 %, respectively; however, they increased the fresh weight by 65.64–71.48 % respectively, and dry weight by 62.41–71.35 %, respectively. Notably, only BPRP increased the node and root tip number in wheat. Total protein (TP) content increased in BHA and BPRP, with BHA showing lower TP than BPRP. BHA and BPRP showed a reduction in glutathione (GSH), malondialdehyde (MDA), H2O2, and peroxidase (POD); BHA showed a significantly lower GSH than BPRP. Additionally, BHA and BPRP increased soil sucrase, alkaline phosphatase, and urease activities, with BPRP showing considerably higher enzyme activity than BHA. Both BHA and BPRP increased the number of soil bacteria, altered the community composition, and critical metabolic pathways. The results demonstrated that BPRP could be used as a highly effective, novel passivation technique for the remediation of Cd-contaminated soil.

Quantitative trait loci mapping for heading date and spikelet number in wheat (Triticum aestivum L.)based on two recombinant inbred line populations

Quantitative trait loci mapping for heading date and spikelet number in wheat (Triticum aestivum L.)based on two recombinant inbred line populations

Overexpression of TaLBD16-4D alters plant architecture and heading date in transgenic wheat.

Lateral organ boundaries domain (LBD) proteins, a class of plant-specific transcription factors with a special domain of lateral organ boundaries (LOB), play essential roles in plant growth and development. However, there is little known about the functions of these genes in wheat to date. Our previous study demonstrated that TaLBD16-4D is conducive to increasing lateral root number in wheat. In the present work, we further examined important agronomical traits of the aerial part of transgenic wheat overexpressing TaLBD16-4D. Interestingly, it was revealed that overexpressing TaLBD16-4D could lead to early heading and multiple alterations of plant architecture, including decreased plant height, increased flag leaf size and stem diameter, reduced spike length and tillering number, improved spike density and grain width, and decreased grain length. Moreover, auxin-responsive experiments demonstrated that the expression of TaLBD16-4D in wild-type (WT) wheat plants showed a significant upregulation through 2,4-D treatment. TaLBD16-4D-overexpression lines displayed a hyposensitivity to 2,4-D treatment and reduced shoot gravitropic response. The expressions of a set of auxin-responsive genes were markedly different between WT and transgenic plants. In addition, overexpressing TaLBD16-4D affected the transcript levels of flowering-related genes (TaGI, TaCO1, TaHd1, TaVRN1, TaVRN2, and TaFT1). Notably, the expression of TaGI, TaCO1, TaHd1, TaVRN1, and TaFT1 displayed significant upregulation under IAA treatment. Collectively, our observations indicated that overexpressing TaLBD16-4D could affect aerial architecture and heading time possibly though participating in the auxin pathway.

Identification of a major stable QTL for spikelet number in wheat (Triticum aestivum L.) and its genetic effects analysis on yield-related traits

Identification of a major stable QTL for spikelet number in wheat (Triticum aestivum L.) and its genetic effects analysis on yield-related traits

Genome-Wide Association Study of Grain Number in Common Wheat From Shanxi Under Different Water Regimes.

Water availability is a crucial environmental factor on grain number in wheat, which is one of the important yield-related traits. In this study, a diverse panel of 282 wheat accessions were phenotyped for grain number per spike (GNS), spikelet number (SN), basal sterile spikelet number (BSSN), and apical sterile spikelet number (ASSN) under different water regimes across two growing seasons. Correlation analysis showed that GNS is significantly correlated with both SN and BSSN under two water regimes. A total of 9,793 single nucleotide polymorphism (SNP) markers from the 15 K wheat array were employed for genome-wide association study (GWAS). A total of 77 significant marker-trait associations (MTAs) for investigated traits as well as 8 MTAs for drought tolerance coefficient (DTC) were identified using the mixed linear model. Favored alleles for breeding were inferred according to their estimated effects on GNS, based on the mean difference of varieties. Frequency changes in favored alleles associated with GNS in modern varieties indicate there is still considerable genetic potential for their use as markers for genome selection of GNS in wheat breeding.

PIL transcription factors directly interact with SPLs and repress tillering/branching in plants.

Tillering is an important parameter of plant architecture in cereal crops. In this study, we identified the PHYTOCHROME-INTERACTING FACTOR-LIKE (PIL) family transcription factors as new repressors of tillering in cereal crops. Using biochemical and genetic approaches, we explore the roles of TaPIL1 in regulating wheat plant architecture. We found that the PIL protein TaPIL1 controls tiller number in wheat. Overexpression of TaPIL1 reduces wheat tiller number; additionally, overexpression of TaPIL1-SUPERMAN repression domain increases wheat tiller number. Furthermore, we show that TaPIL1 activates the transcriptional expression of wheat TEOSINTE BRANCHED1 (TaTB1); moreover, TaPIL1 physically interacts with wheat SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (TaSPL)3/17, which are activators of TaTB1 transcription. In rice, overexpression and loss-of-function mutations of OsPIL11 reduce or increase tiller number by regulating the expression of OsTB1. In Arabidopsis, we demonstrate that PHYTOCHROME-INTERACTING FACTOR 4 interacts with SPL9 to inhibit shoot branching. This study reveals that PIL family transcription factors directly interact with SPLs and play an important role in repressing tillering/branching in plants.

Reducing expression of TaOTUB1s decreases tiller number in wheat

ABSTRACT Tiller number is an important agronomic trait that affects crop yield. The roles of OTUB1 in regulating tiller numbers in rice have been reported. However, the roles of OTUB1 in wheat remain elusive. In this study, TaOTUB1s were identified in wheat. TaOTUB1 proteins were localized in the nucleus and cytoplasm. Compared with wild-type Fielder, TaOTUB1-RNAi transgenic wheat plants had fewer tillers. Similar to OTUB1 in rice, the yeast double hybrid indicated that the TaOTUB1-A protein could interact with TaSPL17 and TaUBC13 proteins. The results of quantitative real-time polymerase chain reaction revealed that the expression levels of TaOTUB1s decreased while those of TaSPL17 significantly improved in TaOTUB1-RNAi lines. These findings suggested that TaOTUB1s influenced tiller number in wheat.

Fine mapping of the tiller inhibition gene TIN4 contributing to ideal plant architecture in common wheat.

A tiller inhibition gene, TIN4, was mapped to an approximately 311kb genomic interval on chromosome arm 2DL of wheat. The tiller is one of the key components of plant morphological architecture and a central agronomic trait affecting spike number in wheat. Low tiller number has been proposed as a major component of crop ideotypes for high yield potential. In this study, we characterized the development of tillering in near-isogenic lines (NIL7A and NIL7B), indicating that the TIN4 gene inhibited the growth of tillering buds and negatively regulated tiller number. Low-tillering was controlled by a single gene (TIN4) located on chromosome 2DL by genetic analysis and bulked segregant RNA-seq analysis. A total of 17 new polymorphic markers were developed in this study, and 61 recombinants were identified in the secondary F2 population containing 4,266 individuals. TIN4 was finally mapped on a 0.35cM interval, co-segregated with molecular marker M380, within a 311kb genomic interval of the wheat cultivar Chinese Spring reference genome sequence that contained twelve predicted genes. Yield experiments showed that the yield of low-tillering lines was higher than that of high-tillering lines at a higher density. Overall, this study provides a foundation for the construction of a low-tillering ideotype for improving wheat yield and further cloning TIN4 by map-based cloning approach.

Carl Ng.

Carl Ng.

FIELD EVALUATION OF FIVE WHEAT VARIETES AGAINST INSECT PEST INFESTATION

The experiment was conducted to evaluate the infestation status of insect pest on different wheat variety. Five wheat variety (BARI GOM -24, BARI GOM-25, BARI GOM-27, BARI GOM-28and BARI GOM-29) were used as a test crop to conduct the study. The experiment was laid out in Randomized Complete Block Design with three replications. Total 5 insect pests were found from this experiment among wheat aphid and wireworm as major and leaf hopper, grass hopper and cereal leaf beetle as minor insect of wheat. The highest insect pest was found in grain filling stage and lowest was found in panicle initiation stage. In grain filling stage, the lowest number of aphid (6.26) was recorded from BARI GOM-29 and the highest number of wheat aphid (9.11) was found in BARI GOM-24. Effect of different varieties of plant height, filled grain, unfilled grain, weight of 1000 grain and yield showed significant. The highest yield (3.56 tha-1 ) was recorded in BARI GOM-29 and the lowest yield 2.29 tha-1 was recorded in BARI GOM-25. The highest percentage of infested spike hill-1 was recorded in BARI GOM-27 and lowest was found in BARI GOM-29. The lowest yield loss (31.53%) was recorded in BARI GOM-29. This is might be due to physical resistance of the varieties. BARI GOM-29 recommended to wheat growers as it is found the most resistant/tolerant wheat cultivar against wheat insect pest with maximum grain yield as compared to other cultivars.

Overcoming the trade-off between grain weight and number in wheat by the ectopic expression of expansin in developing seeds leads to increased yield potential.

Summary Wheat is the most widely grown crop globally, providing 20% of all human calories and protein. Achieving step changes in genetic yield potential is crucial to ensure food security, but efforts are thwarted by an apparent trade‐off between grain size and number. Expansins are proteins that play important roles in plant growth by enhancing stress relaxation in the cell wall, which constrains cell expansion.Here, we describe how targeted overexpression of an α‐expansin in early developing wheat seeds leads to a significant increase in grain size without a negative effect on grain number, resulting in a yield boost under field conditions.The best‐performing transgenic line yielded 12.3% higher average grain weight than the control, and this translated to an increase in grain yield of 11.3% in field experiments using an agronomically appropriate plant density.This targeted transgenic approach provides an opportunity to overcome a common bottleneck to yield improvement across many crops.

Effects of low temperature in spring on fertility of pollen and formation of grain number in wheat

<p indent=0mm>Grain yield and the number of grains per ear of wheat decreased under the low temperature after jointing stage. In order to explore the physiological reasons of the decrease of grains number per ear by low temperature in spring, the spring wheat variety Yangmai 16 and the semi-winter wheat variety Xumai 30 were used as tested varieties to analyze the effects of low temperature in spring on the fertility of pollen and the formation of grain numbers at the appearance of the penultimate leaf stage (5℃/–3℃, day/night), booting stage (8℃/–1℃, day/night), and anthesis stage (12℃/4℃, day/night). The results showed that low temperature at the appearance of the penultimate leaf stage and booting stage resulted in abnormal metabolism of starch and protein in the anther both at the binuclear and tri-nuclear pollen stages and delayed degradation of the tapetum. The low temperature at the booting stage caused abnormal meiosis of pollen mother cells, abnormalities in chromosome pairing, which affected the formation of male gametophyte. The abortion rate of pollen was more significantly increased under low temperature at the appearance of the penultimate leaf stage than that at the booting stage, and it was the minimum at anthesis stage. The abortion rate of pollen in Xumai 30 was higher than that in Yangmai 16. The low temperature at three stages had significant effects on the number of spikelets, the number of fertile spikelets and the number of grains per spikelet. The effect of low temperature at the appearance of the penultimate leaf stage on grains number per spikelet was the most significant. There was a significant positive correlation between the number of grains per spike and pollen fertility, which was affected by abnormal meiosis, delayed degradation of the tapetum, and undersupply of nutriment for anther development. Therefore, the decline of pollen fertility caused by low temperature in spring is the main reason for the decrease of grains number per spike.

Suppressed ABA signal transduction in the spike promotes sucrose use in the stem and reduces grain number in wheat under water stress

Water stress is a primary trigger for reducing grain number per spike in wheat during the reproductive period. However, under stress conditions, the responses of plant organs and the interactions between them at the molecular and physiological levels remain unclear. In this study, when water stress occurred at the young microspore stage, RNA-seq data indicated that the spike had 970 differentially expressed genes, while the stem, comprising the two internodes below the spike (TIS), had 382. Abscisic acid (ABA) signal transduction genes were down-regulated by water stress in both these tissues, although to a greater extent in the TIS than in the spike. A reduction in sucrose was observed, and was accompanied by increases in cell wall invertase (CWIN) and sucrose:sucrose 1-fructosyl-transferase (1-SST) activities. Hexose and fructan were increased in the TIS but decreased in the spike. ABA was increased in the spike and TIS, and showed significant positive correlation with CWIN and 1-SST activities in the TIS. Overall, our results suggest that water stress induces the conversion of sucrose to hexose by CWIN, and to fructan by 1-SST, due to increased down-regulation of ABA signal transduction related-genes in the TIS; this leads to deficient sucrose supply to the spike and a decrease in grain number.

Development and Molecular Cytogenetic Characterization of Cold-Hardy Perennial Wheatgrass Adapted to Northeastern China.

Cold-hardy perennial wheatgrass plays an important role in the use of barren land for farming, soil and water conservation, variety improvement, and also for increasing grass yield. By crossing octoploid tritelytrigia (2n = 8x = 56, AABBDDEE) with Thinopyrum intermedium (2n = 6x = 42, StStJJJSJS), we developed 34 lines of perennial wheatgrass from F1 to F6 generations, which had vigorous regrowth and cold hardiness. The cold-hardy, perennial wheatgrass lines were well-adapted to the cold environment and developed root and rhizomes, with a longevity between 5 and 11 years and a better seed set. Some of them maintained wheat chromosomes beneficial for breeding perennial wheat. Molecular cytogenetic analysis demonstrated that the Th. intermedium chromosomes contributed the most to the synthetic genome of the wheatgrass hybrids and were associated with the perennial growth habit and winter hardiness. They were also preferentially maintained and transmitted to the progenies. Some wheat chromosomes were also transmitted from the F1 to F6 generations, although they were eliminated in each life cycle of the wheatgrass hybrids. The numbers of wheat and Th. intermedium chromosomes affected seed set and perennial growth habit. Seed set increased with the establishment of a more balanced genomic constitution in later generations. The cold-hardy and perennial wheatgrass lines were produced, which can be the starting point of domestication effort aimed at producing well-adapted ground cover plants under extreme environments.