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.

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.

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 Kaolin Application Modulates Grapevine Photochemistry and Defence Responses in Distinct Mediterranean-Type Climate Vineyards

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 477
Author(s):  
Sara Bernardo ◽  
Ana Luzio ◽  
Nelson Machado ◽  
Helena Ferreira ◽  
Vicente Vives-Peris ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Stress Responses ◽  
Transient Analysis ◽  
Adaptation Strategy ◽  
Inhibitory Effect ◽  
Protective Role ◽  
Fluorescence Transient ◽  
Summer Stress ◽  
Defence Responses

At a local scale, kaolin particle-film technology is considered a short-term adaptation strategy to mitigate the adverse effects of global warming on viticulture. This study aims to evaluate kaolin application effects on photochemistry and related defence responses of Touriga Franca (TF) and Touriga Nacional (TN) grapevines planted at two Portuguese winegrowing regions (Douro and Alentejo) over two summer seasons (2017 and 2018). For this purpose, chlorophyll a fluorescence transient analysis, leaf temperature, foliar metabolites, and the expression of genes related to heat stress (VvHSP70) and stress tolerance (VvWRKY18) were analysed. Kaolin application had an inhibitory effect on VvHSP70 expression, reinforcing its protective role against heat stress. However, VvWRKY18 gene expression and foliar metabolites accumulation revealed lower gene expression in TN-treated leaves and higher in TF at Alentejo, while lipid peroxidation levels decreased in both treated varieties and regions. The positive kaolin effect on the performance index parameter (PIABS) increased at ripening, mainly in TN, suggesting that stress responses can differ among varieties, depending on the initial acclimation to kaolin treatment. Moreover, changes on chlorophyll fluorescence transient analysis were more pronounced at the Douro site in 2017, indicating higher stress severity and impacts at this site, which boosted kaolin efficiency in alleviating summer stress. Under applied contexts, kaolin application can be considered a promising practice to minimise summer stress impacts in grapevines grown in Mediterranean-like climate regions.

The Inhibition of Platelet Aggregation by an Aorta Intima Extract

1974 ◽  
Vol 32 (02/03) ◽  
pp. 417-431 ◽  
Author(s):  
A. du P Heyns ◽  
D. J van den Berg ◽  
G. M Potgieter ◽  
F. P Retief
Keyword(s):  
Platelet Aggregation ◽  
Degradation Products ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Protective Role ◽  
Vascular Trauma ◽  
Wear And Tear ◽  
Sequential Addition ◽  
Aggregation Activity

SummaryThe platelet aggregating activity of extracts of different layers of the arterial wall was compared to that of Achilles tendon. Arterial media and tendon extracts, adjusted to equivalent protein content as an index of concentration, aggregated platelets to the same extent but an arterial intima extract did not aggregate platelets. Platelet aggregation induced by collagen could be inhibited by mixing with intima extract, but only to a maximum of about 80%. Pre-mixing adenosine diphosphate (ADP) with intima extracts diminished the platelet aggregation activity of the ADP. Depending on the relationship between ADP and intima extract concentrations aggregating activity could either be completely inhibited or inhibition abolished. Incubation of ADP with intima extract and subsequent separation of degradation products by paper chromatography, demonstrated a time-dependent breakdown of ADP with AMP, adenosine, inosine and hypoxanthine as metabolic products; ADP removal was complete. Collagen, thrombin and adrenaline aggregate platelets mainly by endogenous ADP of the release reaction. Results of experiments comparing inhibition of aggregation caused by premixing aggregating agent with intima extract, before exposure to platelets, and the sequential addition of first the intima extract and then aggregating agent to platelets, suggest that the inhibitory effect of intima extract results from ADP breakdown. It is suggested that this ADP degradation by intima extract may play a protective role in vivo by limiting the size of platelet aggregates forming at the site of minimal “wear and tear” vascular trauma.

scholarly journals Assessment of common housekeeping genes as reference for gene expression studies using RT-qPCR in mouse choroid plexus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kim Hoa Ho ◽  
Annarita Patrizi
Keyword(s):  
Gene Expression ◽  
Choroid Plexus ◽  
Sensory Deprivation ◽  
Housekeeping Genes ◽  
Housekeeping Gene ◽  
Experimental Conditions ◽  
Brain Repair ◽  
Expression Studies ◽  
Testing Algorithms ◽  
Gene Expression Studies

AbstractChoroid plexus (ChP), a vascularized secretory epithelium located in all brain ventricles, plays critical roles in development, homeostasis and brain repair. Reverse transcription quantitative real-time PCR (RT-qPCR) is a popular and useful technique for measuring gene expression changes and also widely used in ChP studies. However, the reliability of RT-qPCR data is strongly dependent on the choice of reference genes, which are supposed to be stable across all samples. In this study, we validated the expression of 12 well established housekeeping genes in ChP in 2 independent experimental paradigms by using popular stability testing algorithms: BestKeeper, DeltaCq, geNorm and NormFinder. Rer1 and Rpl13a were identified as the most stable genes throughout mouse ChP development, while Hprt1 and Rpl27 were the most stable genes across conditions in a mouse sensory deprivation experiment. In addition, Rpl13a, Rpl27 and Tbp were mutually among the top five most stable genes in both experiments. Normalisation of Ttr and Otx2 expression levels using different housekeeping gene combinations demonstrated the profound effect of reference gene choice on target gene expression. Our study emphasized the importance of validating and selecting stable housekeeping genes under specific experimental conditions.

Sign in / Sign up

Export Citation Format

Share Document