Partitioning of 13C-labelled photosynthate varies with growth stage andpanicle size in high-yielding rice

2004 ◽  
Vol 31 (2) ◽  
pp. 131 ◽  
Author(s):  
Pravat K. Mohapatra ◽  
Yasuyuki Masamoto ◽  
Satoshi Morita ◽  
Junichi Takanashi ◽  
Tsuneo Kato ◽  
...  
Keyword(s):  
Oryza Sativa L ◽  
Flag Leaf ◽  
Source Area ◽  
Grain Filling ◽  
Rice Cultivar ◽  
Japonica Rice ◽  
Heavy Carbon ◽  
Heavy Carbon Isotope ◽  
Source Sink ◽  
Developing Grains

A super-high-yielding rice (Oryza sativa L.) cultivar, Takanari, and a traditional japonica rice cultivar, Nakateshinsenbon, were grown under field conditions to compare partitioning of 13C-labelled photosynthate to different plant organs during the period of reproductive development. The flag leaf and the two leaves immediately below it on the main culm were exposed individually to 13CO2 and the movement of the heavy carbon isotope to grains, hull, panicle branches and vegetative parts of plant was assessed. Also, the effect of a reduction of sink size on the partitioning of 13C to different organs was studied by removing some of the primary branches of the panicle. 13C taken up by the three leaves in the post-heading period, moved mostly to the grains and hull of the panicle. At this stage, the uppermost three leaves and the panicle consisted of a single source–sink unit. Partitioning of 13C to the rest of the vegetative structures of the plant was minimal. In the case of Nakateshinsenbon, the flag leaf supplied most of the carbon assimilates for the grains and contributions from the other two leaves were much smaller. However, in Takanari, the contribution of 13C to grains from the second leaf was equivalent to that of the flag leaf. In Takanari, removal of more than one third of the primary branches of the panicle significantly reduced partitioning from the third leaf of the culm, but partitioning from the flag leaf was not significantly changed. In contrast, branch removal treatment significantly depressed transport of carbon assimilates from the flag leaf in Nakateshinsenbon. The obligatory nature of the source–sink relationship in rice is discussed. It is concluded that in lower-yielding traditional rice, photosynthesis in the flag leaf supplies carbon assimilates to the developing grains. But in the super-yielding rice Takanari, the main source area is extended to include the two leaves below the flag leaf so as to sustain an extra large panicle. Even greater grain-filling is possible in super-yielding rice, if the source area is increased further.

Cytokinin concentration gradient in the developing grains and upper leaves of rice (Oryza sativa) during grain filling

1986 ◽  
Vol 64 (9) ◽  
pp. 2068-2072 ◽  
Author(s):  
Shyamali Saha ◽  
P. K. Nagar ◽  
P. K. Sircar
Keyword(s):  
Oryza Sativa ◽  
Concentration Gradient ◽  
Developmental Stages ◽  
Oryza Sativa L ◽  
Flag Leaf ◽  
Grain Filling ◽  
Cytokinin Activity ◽  
Rice Grains ◽  
Nearest Neighbours ◽  
Developing Grains

Changes in cytokinin activity in the flag, first, second, and third leaves and in the developing grain of rice (Oryza sativa L.) were studied using the soybean callus bioassay in relation to the movement of photosynthate during different developmental stages. Cytokininlike activity in leaves was highest at the 85th day after transplantation. The flag leaf maintained higher cytokinin activity than other upper leaves. In grains high cytokininlike activity during the 1st week after anthesis is correlated with the grain setting and cell division period. The concentration gradient of cytokininlike substances in the upper parts of the plant was highest in the panicle after anthesis. The data suggest that the developing rice grains attract most of their photoassimilate from their nearest neighbours, the metabolically active flag, first, and second leaves.

Identification of YAC clones containing the mutable slender glume locus slg in rice (Oryza sativa L.)

Genome ◽  
2001 ◽  
Vol 44 (1) ◽  
pp. 1-6 ◽  
Author(s):  
M Teraishi ◽  
H Hirochika ◽  
Y Okumoto ◽  
A Horibata ◽  
H Yamagata ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Gamma Ray ◽  
Yeast Artificial Chromosome ◽  
Oryza Sativa L ◽  
Artificial Chromosome ◽  
Rice Cultivar ◽  
Inverse Pcr ◽  
Polymorphism Analysis ◽  
Japonica Rice ◽  
Yac Contig

A mutable slender glume gene slg, which often reverts to the wild-type state, was induced by gamma-ray irradiation of seeds of the japonica rice cultivar 'Gimbozu'. The final goal was to understand whether the slender glume mutation was associated with the insertion of a transposable element, utilizing map-based cloning techniques. The RFLP (restriction fragment length polymorphism) analysis revealed that the slg locus was located between two RFLP loci, XNpb33 and R1440, on chromosome 7 with recombination values of 3.1% and 1.0%, respectively. Using these two RFLP loci as probes, five YAC (yeast artificial chromosome) clones containing either of these two loci were selected from a YAC library. Subsequently, both end fragments of these YAC clones, amplified by the inverse PCR (IPCR) method, were used to select new YAC clones more closely located to the slg locus. After repeating such a procedure, we successfully constructed a 6-cM YAC contig, and identified four overlapping YAC clones, Y1774, Y3356, Y5124, and Y5762, covering the slg locus. The chromosomal location of the slg was narrowed down to the region with a physical distance of less than 280 kb between the right-end fragments of Y1774 and Y3356.Key words: Oryza sativa, mutable gene, slender glume mutation, YAC contig.

Biochemical and molecular characterisation of salt-induced poor grain filling in a rice cultivar

2016 ◽  
Vol 43 (3) ◽  
pp. 266 ◽  
Author(s):  
Binay B. Panda ◽  
Alok K. Badoghar ◽  
Sudhanshu Sekhar ◽  
Ekamber Kariali ◽  
Pravat K. Mohapatra ◽  
...  
Keyword(s):  
Gene Expression ◽  
Oryza Sativa L ◽  
Grain Filling ◽  
Rice Cultivar ◽  
Inhibitory Effect ◽  
Protective Role ◽  
Ethylene Receptors ◽  
Transcript Levels ◽  
Spikelets Per Panicle ◽  
Gene Expression Studies

Despite the prevalence of poor grain filling in rice (Oryza sativa L.) under abiotic stress, the reason for this is largely unexplored. Application of 0.75% NaCl to a salt-sensitive rice cultivar at late booting resulted in a >20% yield loss. Spikelets per panicle and the percentage of filled grain decreased significantly in response to NaCl application. The inhibitory effect of NaCl on grain filling was greater in basal than in apical spikelets. Sucrose synthase (SUS) activity was positively correlated with grain weight. The transcript levels of the SUS isoforms differed greatly: the levels of SUS2 increased significantly in response to salt; those of SUS4 decreased drastically. Gene expression studies of starch synthase and ADP-glucose pyrophosphorylase showed that the decreased transcript levels of one isoform was compensated by an increase in those of the other. Salt application also significantly increased the gene expression of the ethylene receptors and the ethylene signalling proteins. The increase in their transcript levels was comparatively greater in basal than in apical spikelets. Significant enhancement in the transcript levels of the ethylene receptors and the increase in the production of ethylene indicated that the salt-induced inhibition of grain filling might be mediated by ethylene. Additionally, the inhibition of chromosomal endoreduplication mediated by decreased transcript levels of B-type cyclin could explain poor grain filling under salt stress. A significant increase in the transcript levels of the ethylene-responsive factors in the spikelets during grain filling in response to salt indicated their possible protective role in grain filling under stress.

scholarly journals Source–Sink Manipulation Affects Accumulation of Zinc and Other Nutrient Elements in Wheat Grains

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1032
Author(s):  
Lan Wang ◽  
Haiyong Xia ◽  
Xiaojing Li ◽  
Yuetong Qiao ◽  
Yanhui Xue ◽  
...  
Keyword(s):  
Nutritional Quality ◽  
Flag Leaf ◽  
Grain Filling ◽  
Kernel Weight ◽  
Nutrient Elements ◽  
Leaf Removal ◽  
Wheat Grains ◽  
Soil Zn ◽  
Positive Correlations ◽  
Source Sink

To better understand the source–sink flow and its relationships with zinc (Zn) and other nutrients in wheat (Triticum aestivum L.) plants for biofortification and improving grain nutritional quality, the effects of reducing the photoassimilate source (through the flag leaf removal and spike shading) or sink (through the removal of all spikelets from one side of the spike, i.e., 50% spikelets removal) in the field of the accumulation of Zn and other nutrients in grains of two wheat cultivars (Jimai 22 and Jimai 44) were investigated at two soil Zn application levels. The kernel number per spike (KNPS), single panicle weight (SPW), thousand kernel weight (TKW), total grain weight (TGW) sampled, concentrations and yields of various nutrient elements including Zn, iron (Fe), manganese (Mn), copper (Cu), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg), phytate phosphorus (phytate-P), phytic acid (PA) and phytohormones (ABA: abscisic acid, and the ethylene precursor ACC: 1-aminocylopropane-1-carboxylic acid), and carbon/N ratios were determined. Soil Zn application significantly increased the concentrations of grain Zn, N and K. Cultivars showing higher grain yields had lower grain protein and micronutrient nutritional quality. SPW, KNPS, TKW (with the exception of TKW in the removal of half of the spikelets), TGW, and nutrient yields in wheat grains were most severely reduced by half spikelet removal, secondly by spike shading, and slightly by flag leaf removal. Grain concentrations of Zn, N and Mg consistently showed negative correlations with SPW, KNPS and TGW, but positive correlations with TKW. There were general positive correlations among grain concentrations of Zn, Fe, Mn, Cu, N and Mg, and the bioavailability of Zn and Fe (estimated by molar ratios of PA/Zn, PA/Fe, PA × Ca/Zn, or PA × Ca/Fe). Although Zn and Fe concentrations were increased and Ca was decreased in treatments of half spikelet removal and spike shading, the treatments simultaneously increased PA and limited the increase in bioavailability of Zn and Fe. In general, different nutrient elements interact with each other and are affected to different degrees by source–sink manipulation. Elevated endogenous ABA levels and ABA/ACC ratios were associated with increased TKW and grain-filling of Zn, Mn, Ca and Mg, and inhibited K in wheat grains. However, the effects of ACC were diametrically opposite. These results provide a basis for wheat grain biofortification to alleviate human malnutrition.

scholarly journals Source-Sink Manipulation Affects Accumulation of Zinc and Other Nutrient Elements in Wheat Grains

2021 ◽  
Author(s):  
Lan Wang ◽  
Haiyong Xia ◽  
Xiaojing Li ◽  
Yuetong Qiao ◽  
Yanhui Xue ◽  
...  
Keyword(s):  
Nutritional Quality ◽  
Flag Leaf ◽  
Grain Filling ◽  
Triticum Aestivum L ◽  
Kernel Weight ◽  
Nutrient Elements ◽  
Leaf Removal ◽  
Wheat Grains ◽  
Soil Zn ◽  
Source Sink

In order to better understand the source-sink flow and relationships of Zinc (Zn) and other nutrients in wheat (Triticum aestivum L.) plants for biofortification and improving grain nutritional quality, effects of reducing photoassimilate source (through the flag leaf removal and spike shading) or sink (through 50% spikelets removal) in the field on accumulation of Zn and other nutrients in wheat grains of two cultivars (Jimai 22 and Jimai 44) were investigated under two soil Zn application levels. The single panicle weight (SPW), kernel number per spike (KNPS), thousand kernel weight (TKW), total grain weight (TGW), concentrations and yields of various nutrient elements (Zn, Fe, Mn, Cu, N, P, K, Ca and Mg), phytate phosphorus (phytate-P), phytic acid (PA) and phytohormones (ABA: abscisic acid, and the ethylene precursor ACC: 1-aminocylopropane-1-carboxylic acid), and C/N ratios were determined. Soil Zn application significantly increased concentrations of grain Zn, N and K. Cultivars showing higher grain yields had lower grain protein and micronutrient nutritional quality. SPW, KNPS, TKW (with an exception of TKW in half spikelets removal), TGW, and nutrient yields in wheat grains were most severely reduced by half spiklets removal, secondly by spike shading, and slightly by flag leaf removal. Grain concentrations of Zn, N and Mg consistently showed negative correlations with SPW, KNPS and TGW, but positively with TKW. There were general positive correlations among grain concentrations of Zn, Fe, Mn, Cu, N and Mg, and bioavailability of Zn and Fe (estimated by molar ratios of PA/Zn, PA × Ca/Zn, PA/Fe, or PA × Ca/Fe). Although concentrations of Zn and Fe were increased and Ca was decreased in treatments of half spikelets removal and spike shading, the simultaneously increased PA limited the increase in bioavailability of Zn and Fe. In general, different nutrient elements interact with each other and are affected to different degrees by source-sink manipulations. Elevated endogenous ABA levels and ABA/ACC ratios were associated with increased TKW and grain-filling of Zn, Mn, Ca and Mg, and inhibited K in wheat grains. However, effects of ACC were diametrically opposite. These results provide basis for wheat grain biofortification to alleviate human malnutrition.

Source–sink relations and effects of post-anthesis canopy defoliation in wheat at low latitudes

1990 ◽  
Vol 114 (1) ◽  
pp. 93-99 ◽  
Author(s):  
P. K. Aggarwal ◽  
R. A. Fischer ◽  
S. P. Liboon
Keyword(s):  
Grain Yield ◽  
Flag Leaf ◽  
Dry Weight ◽  
Grain Filling ◽  
The Philippines ◽  
New Delhi ◽  
Dry Matter Accumulation ◽  
Area Index ◽  
Grain Nitrogen ◽  
Source Sink

SUMMARYSource–sink balance was studied by imposing different canopy defoliation treatments on wheat crops grown in Los Banos (Philippines) in 1985/86 and 1986/87, Sonora (Mexico) in 1972/73 and 1974/75 and New Delhi (India) in 1987/88. The crops were grown in replicated trials with optimum cultural management. Six defoliation treatments were imposed at anthesis on all shoots in the canopy in an area ranging between 1·65 and 3·0 m2. Defoliation reduced dry weight in proportion to the reduction in percentage light interception. The number of grains per unit land area was reduced slightly, and in most cases not significantly, except when all leaves were removed. Despite reduction of leaf lamina area index to as low as 0·5, the decrease in grain yield was small. In particular, flag leaf removal led to a remarkably small reduction in grain yield. Grain nitrogen content in defoliated crops decreased much less than expected from the amount of N removed by defoliation. The slope of the relation between reduction in grain yield with defoliation and reduction in post-anthesis dry matter accumulation was 0·56, indicating moderate source limitation for grain filling. The crops at the hottest site, in the Philippines, were less limited by source than the other crops. It is suggested that selection for smaller flag leaves may be worthwhile for high-input wheat crops.

Metabolite-level carbon-flow analysis reveals that starch synthesis from hexose is a limiting factor in a high-yielding rice cultivar

2021 ◽  
Author(s):  
Masaki Okamura ◽  
Masami Yokota Hirai ◽  
Yuji Sawada ◽  
Mami Okamoto ◽  
Akira Oikawa ◽  
...  
Keyword(s):  
Oryza Sativa L ◽  
Flow Analysis ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Rice Cultivar ◽  
Limiting Factors ◽  
Limiting Factor ◽  
Metabolite Level ◽  
Sink Activity ◽  
Adp Glucose Pyrophosphorylase

Abstract Understanding the limiting factors of grain filling is essential for the further improvement of rice (Oryza sativa L.) grain yields. The slower grain growth of Momiroman, a high-yielding rice cultivar, is not improved by increasing the carbon supply. Thus, a low sink activity, which is the metabolic activity of assimilate consumption/storage in sink organs, may be a limiting factor of grain filling. However, there is no metabolic evidence corroborating this hypothesis, partly because there is no consensus on how to define and quantify sink activity. In this study, we investigated the carbon flows, at a metabolite level, from photosynthesis in leaves to starch synthesis in grains of three high-yielding cultivars using a stable isotope of carbon, 13C. The large amount of newly fixed carbon assimilates in Momiroman was stored as hexose instead of being converted to starch. Additionally, the activity of ADP-glucose pyrophosphorylase and the expression of AGPS2b, encoding an ADP-glucose pyrophosphorylase protein, in the superior grains of Momiroman were lower than in the other two rice cultivars. Thus, the slower starch synthesis from hexose, which is partly explained by the low expression level of AGPS2b, may be the primarily metabolic reason for the lower sink activity in Momiroman. (199/200 words)

scholarly journals Relationship between growth traits and yield formation in Indica-type rice crop

2019 ◽  
pp. 79-100 ◽  
Author(s):  
Lazaro Alberto Maqueira López
Keyword(s):  
Plant Growth ◽  
Dry Matter ◽  
Growth Traits ◽  
Oryza Sativa L ◽  
Meteorological Data ◽  
Flag Leaf ◽  
Growth Dynamics ◽  
Grain Filling ◽  
Dry Season ◽  
Rice Cultivars

Introduction. Climatic variation is one of the causes for the decrease in yield and its variability in Indica-type rice (Oryza sativa L.). This evidences the necessity of the study of the interaction of meteorological variables with the behavior of rice cultivars, to establish the base of management of the harvest and increase of the yield. Objective. The objective of the present study was to relate the yield of rice with variables of plant growth. Materials and methods. Four rice cultivars were planted in the “dry” season of December 2004, February 2005 and January 2006, and in the rainy season of March 2006, April 2008 and 2009, in Los Palacios, Pinar del Río province, Cuba. The yield and its components, the dynamics of plant growth (LAI and dry matter), the variation of the dry matter of the internodes, peduncle, flag leaf, leaf and leaf sheath during the grain filling phase were evaluated the panicle growth in addition to the meteorological data. A multivariate analysis was used to relate the performance to the characteristics of the plants evaluated. Results. The yield was higher in the “dry” season and to obtain higher yields, the growth dynamics of the plant and the variation of the dry matter of the third internode during the grain filling were important. In both seasons, different source-sink relationships were established and these situations depended mainly on the temperature regime at which the plants were subjected. Conclusion. Breeders, in order to increase potencial yields, may fows their atttention in grow traits during vegetative stages.

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