13C Labeling kinetics of sucrose in glumes indicates significant refixation of respiratory CO2 in the wheat ear

Photosynthesis by the vegetative structures of the ear (i.e. glumes) of wheat (Triticum aestivum L.) may draw on two sources of CO2: atmospheric CO2 and CO2 originating from respiration within the ear. We exposed wheat plants to a changed C isotope composition (δ) of one of the two sources, atmospheric CO2, to assess the contributions of atmospheric and respiratory CO2 to ear photosynthesis by following the labeling kinetics of water-soluble carbohydrates (WSC; fructose, glucose, sucrose, fructan) in glumes. Experiments included sampling during diurnal cycles and after extended exposures (7 and 14 d). The labeling kinetics of sucrose in the flag leaf and grains was also determined. Significant diurnal changes in sucrose content (depletion during dark and accumulation during light periods) were observed in flag leaves and in glumes. In flag leaves (but not in glumes) the sucrose accumulating during the light period had a d that was close to the value expected if atmospheric CO2 (with changed δ) was the sole source of CO2 for photosynthesis. The δ of sucrose in glumes did not saturate after extended exposure to the labeling CO2 indicating the utilization of unlabeled (respiratory) CO2 for photosynthesis (i.e. refixation). Short-term labeling indicated that 73% of the sucrose accumulating in glumes after the start of labeling came from fixation of respiratory CO2. Stable C isotope discrimination during glume photosynthesis is discussed.

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Carbohydrate Storage and Mobilisation by the Culm of Wheat Between Heading and Grain Maturity: the Relation to Sucrose Synthase and Sucrose-Phosphate Synthase

Functional Plant Biology ◽

10.1071/pp9940255 ◽

1994 ◽

Vol 21 (3) ◽

pp. 255 ◽

Cited By ~ 66

Author(s):

IF Wardlaw ◽

J Willenbrink

Keyword(s):

Sucrose Synthase ◽

Flag Leaf ◽

Sucrose Phosphate Synthase ◽

Leaf Sheath ◽

Water Soluble ◽

Soluble Carbohydrates ◽

Carbohydrate Storage ◽

Stem Reserves ◽

Sucrose Phosphate ◽

Phosphate Synthase

Wheat plants grown under non-stress conditions at a dayhight temperature of 18/13�C under glasshouse conditions from head emergence to maturity showed a maximum accumulation of water-soluble, non-structural carbohydrates 20-25 days after anthesis. This storage was largely as fructans with the timing and amount of storage and mobilisation varying between cultivars, although the maximum concentration (fructose equivalents per unit stem fresh weight) was similar in all cultivars. The main storage in the culm was located in the lower part of the peduncle enclosed by the flag leaf sheath, in the penultimate internode and for one cultivar also in the flag leaf sheath. 14CO2 pulse-chase studies showed that there was a considerable delay in the incorporation of flag leaf assimilates into stem fructans, a delay probably associated with transfer and metabolic processes in the stem itself. At anthesis, when soluble carbohydrates were rapidly accumulating in the culm, the level of activity of sucrose synthase (SS) in the penultimate internode was much greater than that of sucrose phosphate synthase (SPS). The activity of SS declined rapidly as active storage ceased. This pattern was the reverse of that found in the leaf where SPS, rather than SS, was initially high and declined towards maturity. These changes are discussed in relation to the possible role of sucrose synthesising enzymes, particularly SS, in the accumulation and mobilisation of stem reserves in wheat.

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Measurements of leaf sucrose to explain variability in hydrogen isotope composition of leaf cellulose

10.5194/egusphere-egu21-8918 ◽

2021 ◽

Author(s):

Meisha Holloway-Philips ◽

Jochem Baan ◽

Daniel Nelson ◽

Guillaume Tcherkez ◽

Ansgar Kahmen

Keyword(s):

Hydrogen Isotope ◽

Metabolic Flux ◽

Species Differences ◽

Dark Respiration ◽

Isotope Composition ◽

Turnover Time ◽

Water Soluble ◽

Soluble Carbohydrates ◽

Model Parameters ◽

Hydrogen Isotope Composition

The hydrogen isotope composition (&#948;2H) of cellulose has been used to assess ecohydrological processes and carries metabolic information, adding new understanding to how plants respond to environmental change. However, experimental approaches to isolate drivers of &#948;2H variation is limited to the Yakir & DeNiro model (1990), which is difficult to implement and largely unvalidated. Notably, the two biosynthetic fractionation factors in the model, associated with photosynthetic (&#949;A) and post-photosynthetic (&#949;H) processes are currently accepted as constants, and the third parameter &#8211; the extent to which organic molecules exchange hydrogen (fH) with local water &#8211; is usually tuned in order to resolve the difference between modelled and observed cellulose &#948;2H values. Thus, by virtue, the metabolically interpretable parameter is only fH, whilst from theory, metabolic flux rates will also impact on the apparent fractionations. To overcome part of this limitation, we measured the &#948;2H of extracted leaf sucrose from fully-expanded leaves of seven species and a phosphoglucomutase &#8216;starchless&#8217; mutant of tobacco to estimate the isotopic offset between sucrose and leaf water (&#949;sucrose). Sucrose &#948;2H explained ~60% of the &#948;2H variation observed in cellulose. In general, &#949;sucrose&#160;was higher (range: -203&#8240; to -114&#8240;; mean: -151 &#177; 21&#8240;) than the currently accepted value of -171&#8240; (&#949;A) reflecting 2H-enrichment downstream of triose-phosphate export from the chloroplast, with statistical differences in &#949;sucrose&#160;observed between species estimates. The remaining &#948;2H variation in cellulose was explained by species differences in fH&#160;(estimated by assuming &#949;H = +158&#8240;). We also tested possible links between model parameters and plant metabolism. &#949;sucrose&#160;was positively related to dark respiration (R2=0.27) suggesting an important branch point influencing sugar &#948;2H. In addition, fH was positively related to the turnover time (&#964;) of water-soluble carbohydrates (R2=0.38), but only when estimated using fixed &#949;A = -171&#8240;. To decipher and isolate the &#8220;metabolic&#8221; information contained within &#948;2H values of cellulose it will be important to assess &#948;2H values of non-structural carbohydrates so that hydrogen isotope fractionation during sugar metabolism can be better understood. This study provides the first attempt at such measurements showing species differences in both source and sink processes are important in understanding &#948;2H variation of cellulose.

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Diurnal Changes in Water Soluble Carbohydrate Components in Leaves and Sucrose Associated TaSUT1 Gene Expression during Grain Development in Wheat

International Journal of Molecular Sciences ◽

10.3390/ijms21218276 ◽

2020 ◽

Vol 21 (21) ◽

pp. 8276

Author(s):

Sarah Al-Sheikh Ahmed ◽

Jingjuan Zhang ◽

Hussein Farhan ◽

Yingquan Zhang ◽

Zitong Yu ◽

...

Keyword(s):

Gene Expression ◽

Developmental Stages ◽

Grain Filling ◽

Water Soluble ◽

Soluble Carbohydrate ◽

Diurnal Changes ◽

Flag Leaves ◽

Diurnal Patterns ◽

Carbohydrate Components ◽

Water Soluble Carbohydrate

In plant tissues, sugar levels are determined by the balance between sugar import, export, and sugar synthesis. So far, water soluble carbohydrate (WSC) dynamics have not been investigated in a diurnal context in wheat stems as compared to the dynamics in flag leaves during the terminal phases of grain filling. Here, we filled this research gap and tested the hypothesis that WSC dynamics interlink with gene expression of TaSUT1. The main stems and flag leaves of two genotypes, Westonia and Kauz, were sampled at four hourly intervals over a 24 h period at six developmental stages from heading to 28 DAA (days after anthesis). The total levels of WSC and WSC components were measured, and TaSUT1 gene expression was quantified at 21 DAA. On average, the total WSC and fructan levels in the stems were double those in the flag leaves. In both cultivars, diurnal patterns in the total WSC and sucrose were detected in leaves across all developmental stages, but not for the fructans 6-kestose and bifurcose. However, in stems, diurnal patterns of the total WSC and fructan were only found at anthesis in Kauz. The different levels of WSC and WSC components between Westonia and Kauz are likely associated with leaf chlorophyll levels and fructan degradation, especially 6-kestose degradation. High correlation between levels of TaSUT1 expression and sucrose in leaves indicated that TaSUT1 expression is likely to be influenced by the level of sucrose in leaves, and the combination of high levels of TaSUT1 expression and sucrose in Kauz may contribute to its high grain yield under well-watered conditions.

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Truncation of grain filling in wheat (Triticum aestivum) triggered by brief heat stress during early grain filling: association with senescence responses and reductions in stem reserves

Functional Plant Biology ◽

10.1071/fp15384 ◽

2016 ◽

Vol 43 (10) ◽

pp. 919 ◽

Cited By ~ 13

Author(s):

Hamid Shirdelmoghanloo ◽

Daniel Cozzolino ◽

Iman Lohraseb ◽

Nicholas C. Collins

Keyword(s):

Triticum Aestivum ◽

Grain Size ◽

Heat Stress ◽

Heat Waves ◽

Flag Leaf ◽

Grain Filling ◽

Water Soluble ◽

Grain Weight ◽

Soluble Carbohydrates ◽

Stem Reserves

Short heat waves during grain filling can reduce grain size and consequently yield in wheat (Triticum aestivum L.). Grain weight responses to heat represent the net outcome of reduced photosynthesis, increased mobilisation of stem reserves (water-soluble carbohydrates, WSC) and accelerated senescence in the grain. To compare their relative roles in grain weight responses under heat, these characteristics were monitored in nine wheat genotypes subjected to a brief heat stress at early grain filling (37°C maximum for 3 days at 10 days after anthesis). Compared with the five tolerant varieties, the four susceptible varieties showed greater heat-triggered reductions in final grain weight, grain filling duration, flag leaf chla and chlb content, stem WSC and PSII functionality (Fv/Fm). Despite the potential for reductions in sugar supply to the developing grains, there was little effect of heat on grain filling rate, suggesting that grain size effects of heat may have instead been driven by premature senescence in the grain. Extreme senescence responses potentially masked stem WSC contributions to grain weight stability. Based on these findings, limiting heat-triggered senescence in the grain may provide an appropriate focus for improving heat tolerance in wheat.

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Storing carbon in leaf lipid sinks enhances perennial ryegrass carbon capture especially under high N and elevated CO2

Journal of Experimental Botany ◽

10.1093/jxb/erz494 ◽

2019 ◽

Vol 71 (7) ◽

pp. 2351-2361 ◽

Cited By ~ 6

Author(s):

Zac Beechey-Gradwell ◽

Luke Cooney ◽

Somrutai Winichayakul ◽

Mitchell Andrews ◽

Shen Y Hea ◽

...

Keyword(s):

Leaf Area ◽

Perennial Ryegrass ◽

Lipid Droplets ◽

Feedback Inhibition ◽

Leaf Growth ◽

Water Soluble ◽

Atmospheric Co2 ◽

Soluble Carbohydrates ◽

Elevated Atmospheric Co2 ◽

N Supply

Abstract By modifying two genes involved in lipid biosynthesis and storage [cysteine oleosin (cys-OLE)/diacylglycerol O-acyltransferase (DGAT)], the accumulation of stable lipid droplets in perennial ryegrass (Lolium perenne) leaves was achieved. Growth, biomass allocation, leaf structure, gas exchange parameters, fatty acids, and water-soluble carbohydrates were quantified for a high-expressing cys-OLE/DGAT ryegrass transformant (HL) and a wild-type (WT) control grown under controlled conditions with 1–10 mM nitrogen (N) supply at ambient and elevated atmospheric CO2. A dramatic shift in leaf carbon (C) storage occurred in HL leaves, away from readily mobilizable carbohydrates and towards stable lipid droplets. HL exhibited an increased growth rate, mainly in non-photosynthetic organs, leading to a decreased leaf mass fraction. HL leaves, however, displayed an increased specific leaf area and photosynthetic rate per unit leaf area, delivering greater overall C capture and leaf growth at high N supply. HL also exhibited a greater photosynthesis response to elevated atmospheric CO2. We speculate that by behaving as uniquely stable microsinks for C, cys-OLE-encapsulated lipid droplets can reduce feedback inhibition of photosynthesis and drive greater C capture. Manipulation of many genes and gene combinations has been used to increase non-seed lipid content. However, the cys-OLE/DGAT technology remains the only reported case that increases plant biomass. We contrast cys-OLE/DGAT with other lipid accumulation strategies and discuss the implications of introducing lipid sinks into non-seed organs for plant energy homeostasis and growth.

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Simultaneous recording of diurnal changes in leaf turgor pressure and stem water status of bread wheat reveal variation in hydraulic mechanisms in response to drought

Functional Plant Biology ◽

10.1071/fp15087 ◽

2015 ◽

Vol 42 (10) ◽

pp. 1001 ◽

Cited By ~ 5

Author(s):

Helen Bramley ◽

Rebecca Bitter ◽

Gertraud Zimmermann ◽

Ulrich Zimmermann

Keyword(s):

Water Status ◽

Flag Leaf ◽

Turgor Pressure ◽

Crop Productivity ◽

Simultaneous Recording ◽

Diurnal Changes ◽

Use Efficiency ◽

Stem Water ◽

The Impact ◽

Kinetics Of

Information about water relations within crop canopies is needed to improve our understanding of canopy resource distribution and crop productivity. In this study, we examined the dehydration/rehydration kinetics of different organs of wheat plants using ZIM-probes that continuously monitor water status non-destructively. ZIM-probes were clamped to the flag leaf and penultimate leaf of the same stem to monitor changes in turgor pressure, and a novel stem probe was clamped to the peduncle (just below the spike of the same stem) to monitor changes in stem water status. All organs behaved similarly under well-watered conditions, dehydrating and recovering at the same times of day. When water was withheld, the behaviour diverged, with the leaves showing gradual dehydration and incomplete recovery in leaf turgor pressure during the night, but the stem was affected to a lesser extent. Penultimate leaves were the most severely affected, reaching turgor loss point before the flag leaf. Upon rewatering, turgor pressure recovered but the output patch-pressure of the probes (Pp) oscillated at ~30 min periods in all organs of most plants (n = 4). Oscillations in Pp were attributed to oscillations in stomatal opening and appear to only occur above a threshold light intensity. The mechanisms identified in this study will be beneficial for crop productivity because the flag leaf is the source of most photoassimilates in developing grains, so the plant’s ability to maintain flag leaf hydration at the expense of older leaves should moderate the impact of drought on yield. Stomatal oscillations could increase water use efficiency as the plant attempts to rehydrate after drought.

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Synthesis and accumulation of amylase-trypsin inhibitors and changes in carbohydrate profile during grain development of bread wheat (Triticum aestivum L.)

BMC Plant Biology ◽

10.1186/s12870-021-02886-x ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Lisa Call ◽

Elisabeth Haider ◽

Stefano D’Amico ◽

Elisabeth Reiter ◽

Heinrich Grausgruber

Keyword(s):

Biological Activity ◽

Developmental Stages ◽

Time Lag ◽

Grain Filling ◽

Triticum Aestivum L ◽

Trypsin Inhibitors ◽

Water Soluble ◽

Soluble Carbohydrates ◽

Grain Development ◽

Inhibitory Potential

Abstract Background Recent studies indicate that amylase-trypsin inhibitors (ATIs) and certain carbohydrates referred to as FODMAPs (fermentable oligo-, di-, monosaccharides and polyols) play an important role in promoting wheat sensitivity. Hitherto, no study has investigated the accumulation of ATIs during the development of the wheat caryopsis. We collected caryopses of common wheat cv. ‘Arnold’ at eight different grain developmental stages to study compositional changes in ATI and FODMAP content. Results The harvested caryopses were analysed for their size, protein and carbohydrate concentrations. ATIs were further characterized by MALDI-TOF MS, and their trypsin inhibition was evaluated by an enzymatic assay. The results showed that ATI accumulation started about 1 week after anthesis and subsequently increased steadily until physiological maturity. However, the biological activity of ATIs in terms of enzyme inhibition was not detectable before about 4 weeks after anthesis. Carbohydrate analysis revealed the abundance of short-chain fructans in early stages of grain development, whereas non-water-soluble carbohydrates increased during later developmental stages. Conclusions The results provide new insights into the complex metabolisms during grain filling and maturation, with particular emphasis on the ATI content as well as the inhibitory potential towards trypsin. The time lag between ATI accumulation and development of their biological activity is possibly attributed to the assembling of ATIs to dimers and tetramers, which seems to be crucial for their inhibitory potential.

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Drought Stress Induces Changes in the Non-Structural Carbohydrate Composition of Wheat Stems

Functional Plant Biology ◽

10.1071/pp9910239 ◽

1991 ◽

Vol 18 (3) ◽

pp. 239 ◽

Cited By ~ 19

Author(s):

JM Virgona ◽

EWR Barlow

Keyword(s):

Molecular Weight ◽

Drought Stress ◽

Flag Leaf ◽

Grain Filling ◽

Triticum Aestivum L ◽

Water Soluble ◽

Soluble Carbohydrate ◽

Structural Carbohydrate ◽

Water Soluble Carbohydrate ◽

Hydrolysis Of

The effect of drought stress on the non-structural carbohydrate (NSC) composition and water relations of the wheat (Triticum aestivum L.) stem has been investigated. Five separate parts of the stem were sampled: the unsheathed portion of the peduncle (Stem 1a), the sheathed portion of the peduncle (Stem 1b), the penultimate internode (Stem 2), the lower internodes (Stem 3+4) and the flag-leaf-pulvinus (pulvinus). The NSC was analysed as two fractions, an ethanol-soluble carbohydrate (ESC) fraction containing mono- and di-saccharides and some low molecular weight oligosaccharides, and a water-soluble carbohydrate (WSC) fraction containing mostly fructans and some high molecular weight oligosaccharides. In Stems 1b, 2 and 3 +4, the imposition of drought midway through grain filling resulted in a shift in soluble carbohydrate from the WSC to the ESC fraction indicating hydrolysis of fructans. In Stem 2 on day 29 of grain filling, the WSC/ESC ratio was 7.6 � 1.5 in well watered plants in contrast to 0.5 � 0.1 in droughted plants on day 30, even though NSC concentration did not differ. The NSC content of Stem la and the pulvinus increased threefold under drought, although levels were significantly lower than in the rest of the stem. The WSC/ESC ratio in these tissues was low com- pared to the rest of the stem but still declined noticeably under drought stress. Turgor (P) was fully maintained in Stem 2 and the pulvinus of droughted plants. Under drought, P in the pulvinus was maintained at higher levels (1.9-2.4 MPa) than in Stem 2 (0.8-1.2 MPa).

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Genotypic variation of wheat (Triticum aestivum L.) in grain filling and contribution of culm reserves to yield

Bangladesh Journal of Botany ◽

10.3329/bjb.v50i1.52671 ◽

2021 ◽

Vol 50 (1) ◽

pp. 51-59

Author(s):

Md Amirul Islam ◽

Md Soaliman Ali Fakir ◽

Md Alamgir Hossain ◽

Maria Akter Sathi

Keyword(s):

Grain Yield ◽

Genotypic Variation ◽

Grain Filling ◽

Triticum Aestivum L ◽

Dry Mass ◽

Water Soluble ◽

Soluble Carbohydrates ◽

The Mean ◽

Ripe Stage ◽

Different Parts

To study the genotypic variation in the rate of grain filling and contribution of culm reserves to yield in wheat, an experiment was conducted consisting 12 popular cultivars of Bangladesh, viz., BARI Gom21 (Shatabdi), BARI Gom22 (Shufi), BARI Gom23 (Bijoy), BARI Gom24 (Prodip), BARI Gom25, BARI Gom26, Akbar (BAW 43), BARI Gom18 (Protiva), BARI Gom19 (Sourav), BARI Gom20 (Gourab), Agrani (BAW38), and Kanchan (BAW28). Tillers were sampled from anthesis to maturity to determine the changes in dry weights of different parts to examine the contribution of culm reserves to grain yield. The results in the experiment revealed that the grain yield varied from 2.61 to 5.35 ton/ha with the mean of 4.18 ton/ha. Among the cultivars BARI Gom24, BARI Gom26, BARI Gom19, and BARI Gom23 appeared as high yielders while Kanchan, Agrani, BARI Gom20, BARI Gom22 as the low yielders. Generally, high yielding cultivars showed higher total dry mass accumulation compared to low yielding ones. Moreover, high yielding cultivars also showed higher water soluble carbohydrates (WSCs) contents in culm at milk ripe stage than the low yielders. In general, contribution of culm WSCs to grain yield was more in high yielders than low yielders and it ranged from 2 to 29% of total grain weight. So, higher contribution of culm reserves resulted in higher grain yield of wheat.

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Diurnal changes in the concentration of water-soluble carbohydrates in Phalaris aquatica L. pasture in spring, and the effect of short-term shading

Australian Journal of Agricultural Research ◽

10.1071/ar99150 ◽

2000 ◽

Vol 51 (6) ◽

pp. 749 ◽

Cited By ~ 26

Author(s):

T. A. Ciavarella ◽

R. J. Simpson ◽

H. Dove ◽

B. J. Leury ◽

I. M. Sims

Keyword(s):

Dry Matter ◽

Nitrogen Concentration ◽

Matter Content ◽

Water Soluble ◽

Soluble Carbohydrates ◽

Soluble Carbohydrate ◽

Dry Matter Content ◽

Diurnal Changes ◽

Phalaris Aquatica ◽

Early Afternoon

The concentrations of water-soluble carbohydrate (WSC) and its components, starch, total nitrogen, and dry matter of phalaris (Phalaris aquatica L. cv. Australian) pasture were varied by shading for periods ranging from 38.5 to 46.5 h. In unshaded pasture, WSC concentrations were lowest at sunrise [103 mg/g dry matter (DM)] and increased until early afternoon (to 160 mg/g DM). Sucrose and starch increased in concentration during daylight, whilst the concentrations of glucose, fructose, fructan, and a component of WSC considered to be mainly the carbohydrate moiety of glycoside(s) were relatively constant. The concentrations of starch, and all components of WSC except sucrose, were reduced by shading, but increased to the concentrations observed in the unshaded pasture within 2–4 h after removal of the cover. The fructans present in phalaris were determined to be oligosaccharides of degree of polymerisation (DP) 3 and DP 4 and high molecular mass fructans with DP >10. Nitrogen concentration of shaded pasture was initially higher (4.7% DM) than in unshaded pasture (3.9% DM), but decreased after removal of the shade cover. Dry matter content was reduced in shaded pasture, partly due to increased retention of water on the exterior of plants. The experiment was a precursor for a grazing trial in which the WSC content of pasture was to be altered by shading. It indicated that shading would potentially alter WSC and N concentrations, and DM content, but would have only a relatively small impact on the digestibility of the pasture.

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