Conversion of mature leaves into sinks on the dicotyledonous C4 plants Amaranthus caudatus and Gomphrena globosa

1984 ◽  
Vol 62 (5) ◽  
pp. 1081-1089 ◽  
Author(s):  
Sabine Blechschmidt-Schneider
Keyword(s):  
Mature Leaf ◽  
Anatomical Studies ◽  
Amaranthus Caudatus ◽  
Mature Leaves ◽  
Free Air ◽  
Gomphrena Globosa ◽  
Sink Demand ◽  
Source Sink ◽  
Source And Sink ◽  
Storage Processes

The effect of an artificially created sink leaf on translocation of 14C-labeled assimilates from a source leaf of the C4 plants Amaranthus caudatus L. and Gomphrena globosa L. was studied with autoradiography. Anatomical studies showed that the vasculature of two successive leaves within a given orthostichy is directly connected by stem bundles. Therefore, in an intact plant, much of the acropetally translocated 14C-labeled assimilates from a mature source leaf moved into the next younger leaf directly above. When such a young leaf on an otherwise illuminated plant was kept under sink conditions (dark, CO2-free air), its increased sink demand resulted in a clearly higher 14C-import, compared with a control. Even a mature leaf of Gomphrena subjected to the similar sink conditions developed sufficient sink demand to import a certain amount of basipetally transported 14C-labeled assimilates from a younger source leaf. In Amaranthus, there was no basipetal translocation from a younger source leaf and, consequently, no 14C-import into a mature leaf under sink conditions occurred. A complete conversion of a mature leaf into a sink was attained only with a pruned source–sink transport system of both plants under source and sink limitation. This conversion from the source to the sink status caused a change in the direction of assimilate flow within the petiolar and stem bundles. The data indicate that a mature leaf under sink conditions can be characterized as a sink with regard to assimilate translocation, although no growth or storage processes are involved in controlling this sink activity.

scholarly journals Biochemical Profiling of Source and Sink Tissues at Different Growth Stages of Early and Late Maturing Varieties of Sugarcane (Saccharum spp. hybrids)

2018 ◽  
Vol 15 (3) ◽  
pp. 611-618 ◽  
Author(s):  
Indu Verma ◽  
Kriti Roopendra ◽  
Amaresh Chandra ◽  
Aisha Kamal
Keyword(s):  
Sugar Content ◽  
Reducing Sugar ◽  
Growth Stages ◽  
Sucrose Content ◽  
Sugarcane Varieties ◽  
Distinct Source ◽  
Sucrose Storage ◽  
Sink Demand ◽  
Source Sink ◽  
Source And Sink

Sugarcane being C4 crop exhibits distinct source-sink signaling pathway that helps in storing remarkably high amount of sucrose in its sink tissues that makes it a highly remunerable crop worldwide. In the present study sugar content was profiled in both source and sink tissues of early (CoJ64) and late (BO91) maturing sugarcane varieties. At early growth stage (i.e. at 210 DAP) sink tissues of both varieties exhibited higher reducing sugar and low sucrose content while in source tissues both sucrose and reducing sugar content was observed high, depicted lower sink demand for sucrose. With maturity, when sink demand for sucrose storage increased, rise in sucrose content was seen in sink tissues, whereas in source tissues gradual decrease in sucrose and reducing sugar content was observed. Accumulation of sucrose was found much higher in CoJ64 than those in BO91. In CoJ64 maximum sucrose content (64.2%) was seen at 330 DAP while in BO91 it was 41.8% at 390 DAP. At this stage, source tissues too exhibited higher sucrose and reducing sugar content. Thus sucrose synthesis in source tissues and its transportation to the sink tissues is primarily governed by the sink demand.

scholarly journals Effects of Elevated Atmospheric CO2 on Respiratory Rates in Mature Leaves of Two Rice Cultivars Grown at a Free-Air CO2 Enrichment Site and Analyses of the Underlying Mechanisms

2018 ◽  
Vol 59 (3) ◽  
pp. 637-649 ◽  
Author(s):  
Ko Noguchi ◽  
Tomonori Tsunoda ◽  
Atsuko Miyagi ◽  
Maki Kawai-Yamada ◽  
Daisuke Sugiura ◽  
...  
Keyword(s):  
Co2 Enrichment ◽  
Atmospheric Co2 ◽  
Rice Cultivars ◽  
Elevated Atmospheric Co2 ◽  
Mature Leaves ◽  
Free Air Co2 Enrichment ◽  
Free Air ◽  
Underlying Mechanisms

Increase in Sink Demand in Response to Perturbed Source–Sink Communication by Partial Shading in Sugarcane

Sugar Tech ◽  
2018 ◽  
Vol 21 (4) ◽  
pp. 672-677 ◽  
Author(s):  
K. Roopendra ◽  
A. Chandra ◽  
S. Saxena
Keyword(s):  
Partial Shading ◽  
Sink Demand ◽  
Source Sink

scholarly journals Phloem mobility of Boron in two eucalypt clones

2009 ◽  
Vol 33 (6) ◽  
pp. 1695-1704 ◽  
Author(s):  
Edson Marcio Mattiello ◽  
Hugo Alberto Ruiz ◽  
Ivo Ribeiro da Silva ◽  
Jorge Eduardo Souza Sarkis ◽  
Júlio César Lima Neves ◽  
...  
Keyword(s):  
Foliar Application ◽  
Soluble Sugars ◽  
Xylem Sap ◽  
Mature Leaf ◽  
Boron Deficiency ◽  
Isotope Tracer ◽  
Mature Leaves ◽  
Productivity Losses ◽  
Leaves And Roots ◽  
B Mobility

Boron deficiency causes large productivity losses in eucalypt stands in extensive areas of the Brazilian Cerrado region, thus understanding B mobility is a key step in selecting genetic materials that will better withstand B limitation. Thus, in this study B mobility was evaluated in two eucalypt clones (68 and 129), under B sufficiency or B deficiency, after foliar application of the 10B isotope tracer to a single mature leaf. Samples of young tissue, mature leaves and roots were collected 0, 1, 5, 12 and 17 days after 10B application. The 10B:11B isotope ratio was determined by HR-ICP-MS. Samples of leaves and xylem sap were collected for the determination of soluble sugars and polyalcohols by ion chromatography. Boron was translocated within eucalypt. Translocation of foliar-applied 10B to the young tissues, mature leaves and roots was higher in clone 129 than in 68. Seventeen days after 10B application to a single mature leaf, between 14 and 18 % of B in the young tissue was originated from foliar B application. In plants with adequate B supply the element was not translocated out of the labeled leaf.

scholarly journals Estimating Organ Contribution to Grain Filling and Potential for Source Upregulation in Wheat Cultivars with a Contrasting Source–Sink Balance

Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1527
Author(s):  
Carolina Rivera-Amado ◽  
Gemma Molero ◽  
Eliseo Trujillo-Negrellos ◽  
Matthew Reynolds ◽  
John Foulkes
Keyword(s):  
Grain Growth ◽  
Photosynthetic Rate ◽  
Grain Filling ◽  
Leaf Sheath ◽  
Grain Weight ◽  
Yield Potential ◽  
Wheat Cultivars ◽  
Sink Limitation ◽  
Source Sink ◽  
Source And Sink

Grain filling may be limited by the joint source and sink capacity in modern wheat cultivars, indicating a need to research the co-limitation of yield by both photosynthesis and the number and potential size of grains. The extent to which the post-anthesis source may be limiting final grain size can be estimated by partial degraining of spikes, while defoliation and shading treatments can be useful to estimate if any excess photosynthetic capacity exists. In the current study, degraining was applied to a set of 26 elite spring wheat cultivars from the International Maize and Wheat Improvement Center (CIMMYT)’s core germplasm (CIMCOG) panel, while lamina defoliation and shading through stem-and-leaf-sheath covering treatments were applied to a subset of the same cultivars. Responses to source treatments in grain weight, pre-anthesis reserve contribution to grain weight, dry-matter translocation efficiency, and flag-leaf and spike photosynthetic rate were measured and compared to an unmanipulated control treatment. Grain weight responses to degraining among cultivars ranged from no response to increases of 28%, suggesting a range of responses from sink limitation, to probable source and sink co-limitation of grain growth. Grain weight’s response to degraining increased linearly with the years of cultivar release from 1966 to 2009, indicating that the current highest yield potential CIMMYT spring wheats have a co-limitation of grain growth by source and sink. This may have been due to an increase in grain sink strength with years of cultivar release with no commensurate increase in post-anthesis source capacity. The relatively low decreases in grain weight with defoliation compared to decreases in light interception by defoliation indicated that sink limitation was still likely predominating in the cultivars with co-limitation. The stem-and-leaf-sheath covering treatment decreased grain weight by nearly 10%, indicating that stem-and-leafsheath photosynthesis plays a key role in grain growth during grain filling. In addition, pre-anthesis reserve contribution to grain weight was increased by ca. 50% in response to lamina defoliation. Our results showed that increasing the post-anthesis source capacity, through increases in stem-and-leaf-sheath photosynthetic rate during grain filling and pre-anthesis reserve contribution to grain weight, is an important objective in enhancing yield potential in wheat through maintaining a source–sink balance.

Changes in source–sink relations during development influence photosynthetic acclimation of rice to free air CO2 enrichment (FACE)

2002 ◽  
Vol 29 (8) ◽  
pp. 947 ◽  
Author(s):  
Saman P. Seneweera ◽  
Oula Ghannoum ◽  
Jann P. Conroy ◽  
Ken Ishimaru ◽  
Masumi Okada ◽  
...  
Keyword(s):  
Flag Leaf ◽  
Supply And Demand ◽  
Co2 Enrichment ◽  
Photosynthetic Acclimation ◽  
Flag Leaves ◽  
N Supply ◽  
Free Air Co2 Enrichment ◽  
Free Air ◽  
Source Sink ◽  
Leaf N

Relationships between photosynthetic acclimation and changes in the balance between source-sink supply and demand of carbon (C) and nitrogen (N) were tested using rice (Oryza sativa L. cv. Akitakomachi). Plants were field-grown in northern Japan at ambient CO2 partial pressure [p(CO2)] or free air CO2 enrichment (FACE; p(CO2) ~ 26-32 Pa above ambient) with low, medium or high N supplies. Leaf CO2 assimilation rates (A) and biochemical parameters were measured at 32-36 (eighth leaf) and 76-80 (flag leaf) d after transplanting, representing stages with a contrasting balance between C and N supply and demand in sources and sinks. Acclimation due to FACE was pronounced in flag leaves at each N supply. This was not fully accounted for by reductions in leaf N concentrations, because A/N and Vcmax/N were lower in FACE-grown flag leaves. Acclimation did not occur in the eighth leaf, and A/N and Vcmax/N was not significantly increased in FACE-grown leaves. Soluble protein / sucrose and amino acid / sucrose concentrations decreased under FACE, whereas sucrose phosphate synthase protein levels increased. At flag leaf stage, there was a discrepancy between the demand and supply of N, which was resolved by enhanced leaf N remobilization, associated with the lower Rubisco concentrations under FACE. In contrast to the early growth stage, enhanced growth of rice plants was accompanied by increased plant N uptake in FACE. We conclude that photosynthetic acclimation in flag leaves occurs under FACE because there is a large demand for N for reproductive development, relative to supply of N from root uptake and remobilization from leaves.

scholarly journals Influence of Heat Source/Sink on Free Convection in Annular Porous Region

2021 ◽  
Vol 39 (3) ◽  
pp. 841-850
Author(s):  
Anurag ◽  
Shyam Lal Yadav ◽  
Ashok Kumar Singh
Keyword(s):  
Heat Source ◽  
Darcy Number ◽  
Constant Heat Flux ◽  
Petroleum Engineering ◽  
Temperature Dependent ◽  
Porous Region ◽  
Annular Gap ◽  
Source Sink ◽  
Thermal Technique ◽  
Source And Sink

The significant interpretation of this model is to explore the influence of temperature-dependent heat source/sink on laminar free-convective flow in an annular porous region such as petroleum engineering, thermal technique and groundwater hydrology. For a unified solution of the Brinkman-Darcy model, the regulatory equations solved analytically by applying the variation of parameter technique in terms of Bessel's functions for the heat source and sink. Moreover, we have investigated the Variations of Darcy number, Heat source/sink and viscosity ratio in the presence of isothermal and constant heat flux sequentially. As a result, we received the critical value of the velocity for the radii ratio (R = 2.05 and 2.92) in both the cases of source and sink (S = 1.0 and Si = 0.1) respectively which is exhibited through the graphs. Further, the numerical outcomes present of the skin friction including volume flow with annular gap by the graphs as well as tables.

scholarly journals Impact of Elevated CO2 and Reducing the Source-Sink Ratio by Partial Defoliation on Rice Grain Quality – A 3-Year Free-Air CO2 Enrichment Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Bo Gao ◽  
Shaowu Hu ◽  
Liquan Jing ◽  
Yunxia Wang ◽  
Jianguo Zhu ◽  
...  
Keyword(s):  
Nutritional Quality ◽  
Grain Quality ◽  
Eating Quality ◽  
Rice Grain ◽  
Milled Rice ◽  
Rice Quality ◽  
Free Air ◽  
Source Sink ◽  
The Impact ◽  
Rice Processing

Evaluating the impact of increasing CO2 on rice quality is becoming a global concern. However, whether adjusting the source-sink ratio will affect the response of rice grain quality to elevated CO2 concentrations remains unknown. In 2016–2018, we conducted a free-air CO2 enrichment experiment using a popular japonica cultivar grown at ambient and elevated CO2 levels (eCO2, increased by 200 ppm), reducing the source-sink ratio via cutting leaves (LC) at the heading stage, to investigate the effects of eCO2 and LC and their interactions on rice processing, appearance, nutrition, and eating quality. Averaged across 3 years, eCO2 significantly decreased brown rice percentage (−0.5%), milled rice percentage (−2.1%), and head rice percentage (−4.2%) but increased chalky grain percentage (+ 22.3%) and chalkiness degree (+ 26.3%). Markedly, eCO2 increased peak viscosity (+ 2.9%) and minimum viscosity (+ 3.8%) but decreased setback (−96.1%) of powder rice and increased the appearance (+ 4.5%), stickiness (+ 3.5%) and balance degree (+ 4.8%) of cooked rice, while decreasing the hardness (−6.7%), resulting in better palatability (+ 4.0%). Further, eCO2 significantly decreased the concentrations of protein, Ca, S, and Cu by 5.3, 4.7, 2.2, and 9.6%, respectively, but increased K concentration by 3.9%. Responses of nutritional quality in different grain positions (brown and milled rice) to eCO2 showed the same trend. Compared with control treatment, LC significantly increased chalky grain percentage, chalkiness degree, protein concentration, mineral element levels (except for B and Mn), and phytic acid concentration. Our results indicate that eCO2 reduced rice processing suitability, appearance, and nutritional quality but improved the eating quality. Rice quality varied significantly among years; however, few CO2 by year, CO2 by LC, or CO2 by grain position interactions were detected, indicating that the effects of eCO2 on rice quality varied little with the growing seasons, the decrease in the source-sink ratios or the different grain positions.

scholarly journals Genotypic variation in morphological source and sink traits affects the response of rice photosynthesis and growth to elevated atmospheric CO2

2019 ◽  
Author(s):  
Denis Fabre ◽  
Michael Dingkuhn ◽  
Xinyou Yin ◽  
Anne Clément-Vidal ◽  
Sandrine Roques ◽  
...  
Keyword(s):  
Photosynthetic Capacity ◽  
Flag Leaf ◽  
Genotypic Variation ◽  
Growth Cycle ◽  
Plant Production ◽  
Leaf Photosynthesis ◽  
Elevated Atmospheric Co2 ◽  
Rice Genotypes ◽  
Source Sink ◽  
Source And Sink

AbstractThis study aimed to understand the response of photosynthesis and growth to e-CO2conditions (800 vs. 400 μmol mol-1) of rice genotypes differing in source-sink relationships. A proxy trait called local C source-sink ratio was defined as the ratio of flag leaf area over the number of spikelets on the corresponding panicle, and five genotypes differing in this ratio were grown in a controlled greenhouse. Differential CO2resources were applied either during the two weeks following heading (EXP1) or during the whole growth cycle (EXP2). Under e-CO2, low source-sink ratio cultivars (LSS) had greater gains in photosynthesis, and they accumulated less nonstructural carbohydrate in the flag leaf than high source-sink ratio cultivars (HSS). In EXP2, grain yield and biomass gain was also greater in LSS probably caused by their strong sink. Photosynthetic capacity response to e-CO2was negatively correlated across genotypes with local C source-sink ratio, a trait highly conserved across environments. HSS were sink-limited under e-CO2, probably associated with low triose phosphate utilization (TPU) capacity. We suggest that the local C source-sink ratio is a potential target for selecting more CO2-responsive cultivars, pending validation for a broader genotypic spectrum and for field conditions.HighlightRice local carbon source-sink ratio and sink plasticity can drive genotypic responses of leaf photosynthesis and plant production in a CO2elevation context.

scholarly journals Night Temperature and Source-sink Effects on Growth, Leaf Carbon Exchange Rate, and Carbohydrate Accumulation in Bell Pepper Ovaries

2013 ◽  
Vol 138 (5) ◽  
pp. 331-337 ◽  
Author(s):  
Rebecca L. Darnell ◽  
Nicacio Cruz-Huerta ◽  
Jeffrey G. Williamson
Keyword(s):  
Exchange Rate ◽  
Leaf Gas Exchange ◽  
Soluble Sugar ◽  
Bell Pepper ◽  
Ovary Wall ◽  
Carbon Exchange ◽  
Night Temperature ◽  
Carbohydrate Accumulation ◽  
Sink Demand ◽  
Source Sink

Low night temperatures and/or high source-sink ratios increase ovary swelling and subsequent fruit malformation in many sweet peppers (Capsicum annuum), including bell pepper. Although this response has been correlated with increased ovary carbohydrate accumulation, evidence for this is limited. Furthermore, it is unknown how the combined effects of night temperature and source-sink ratio affect ovary carbohydrate accumulation and ovary swelling. The objectives of the present work were to determine night temperature and source-sink effects on ovary swelling, net carbon exchange rate (CER), and soluble sugar and starch concentrations in bell pepper ovaries at anthesis. Source-sink and temperature effects were tested by comparing fruiting (low source-sink ratio or high sink demand) with non-fruiting (high source-sink ratio or low sink demand) ‘Legionnaire’ bell pepper plants grown at 22/20 °C [high night temperature (HNT)] or 22/12 °C [low night temperature (LNT)] day:night temperatures. Flowers that opened after imposition of the temperature and fruiting treatments were harvested at anthesis. Ovaries from harvested flowers were weighed and analyzed for non-structural carbohydrates. Leaf gas exchange measurements were performed every 3 days. Ovary fresh weight of flowers harvested at anthesis was highest in non-fruiting plants under LNT and lowest in plants grown under HNT regardless of fruiting status. Mean CER averaged over the experimental period was significantly higher in fruiting plants under HNT compared with all other treatments. There were no significant interactions between night temperature and fruiting status on ovary soluble sugar or starch concentrations. Low night temperature increased glucose, fructose, and starch concentration and decreased sucrose concentration in the ovary wall compared with HNT. There were no differences in soluble sugar or starch concentrations in the ovary wall between fruiting and non-fruiting plants. Thus, although both low temperature and high source-sink ratio (i.e., non-fruiting plants) resulted in ovary swelling, the mechanisms appear to differ. Whereas LNT effects on ovary swelling were associated with increased ovary carbohydrate accumulation, this association was not apparent when ovary swelling occurred in response to high source-sink ratios.

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