The Effect of Plant Size on Wheat Response to Agents of Drought Stress. II. Water Deficit, Heat and ABA

1997 ◽  
Vol 24 (1) ◽  
pp. 43 ◽  
Author(s):  
A. Blum ◽  
C. Y. Sullivan ◽  
H. T. Nguyen
Keyword(s):  
Growth Rate ◽  
Heat Stress ◽  
Drought Stress ◽  
Osmotic Stress ◽  
Osmotic Adjustment ◽  
Plant Size ◽  
Shoot Biomass ◽  
Growth Reduction ◽  
Potential Growth ◽  
Juvenile Plants

Plant size has long been implicated in plant response to drought stress. This study is the second in a series of two intended to examine the effect of plant size on plant performance under the effect of various agents of drought stress. Variable plant size (in terms of plant height and shoot biomass) independent of genetic background effects was experimentally achieved using rht (tallest), Rht1 and Rht2 (medium) and Rht3 (shortest) homozygous height isogenic lines of spring wheat (Triticum aestivum) cultivars Bersee and April-Bearded. Plants were grown in hydroponic culture in the growth chamber. In the first experiment, juvenile plants were challenged by osmotic stress using polyethylene glycol (PEG) in the nutrient solution giving a water potential of –0.55 MPa. The control nutrient solution was at –0.05 MPa. Plant growth, shoot biomass, leaf area, relative water content (RWC) and osmotic adjustment (OA) were measured. In the second experiment, effects on growth rate of chronic heat stress and abscisic acid (ABA) in the root medium of juvenile plants were evaluated. Potential plant size as determined by shoot biomass in the controls at 25 days after emergence was greatest in rht, medium in Rht1 and Rht2, and smallest in Rht3 genotypes. Potential growth rate and leaf area were greater in plants of larger potential biomass (rht) than in plants of smaller potential biomass (Rht3). Growth reduction by osmotic stress was inversely related to plant size, while the extent of osmotic adjustment during osmotic stress was directly related to plant size. RWC did not vary with plant size. Relative growth reduction by heat stress and by ABA also decreased in smaller plants. ABA did not alleviate the depressing effect of heat on growth. Despite the greater stress tolerance of smaller (Rht3) plants, the absolute growth and biomass of large (rht) plants under stress conditions was always better than that of smaller plants. The results of these series of experiments suggest that greater stress tolerance of small plants is derived from their relatively smaller size and slower growth rate. Consequently, we conclude that growth under stress is sustained by potential growth rate and plant size of the genotype when stress is mild and by plant tolerance (even at the expense of potential growth rate and size) when stress is more severe.

The Effect of Plant Size on Wheat Response to Agents of Drought Stress. I. Root Drying

1997 ◽  
Vol 24 (1) ◽  
pp. 35 ◽  
Author(s):  
A. Blum ◽  
C. Y. Sullivan
Keyword(s):  
Drought Stress ◽  
Water Potential ◽  
Plant Height ◽  
Stress Condition ◽  
Stomatal Closure ◽  
Plant Size ◽  
Primary Response ◽  
Plant Performance ◽  
Shoot Biomass ◽  
Diffusive Resistance

Plant size has long been implicated in plant response to drought stress. This study is a first in a series of two intended to examine the effect of plant size on plant performance under the effect of various agents of drought stress. Variable plant size (in terms of plant height and shoot biomass) independent of genetic background effects was experimentally achieved using rht (tallest), Rht1 and Rht2 (medium) and Rht3 (shortest) homozygous height isogenic lines of spring wheat (Triticum aestivum cv. Bersee). Top-root drying is a common stress condition when the top soil dries in the field. In this experiment wheat was grown in hydroponics system in long PVC tubes. Stress was applied by allowing the top (40 cm) roots to dry throughout most of the growing season while the remaining roots were immersed in the nutrient solution. Average seasonal top-root water potential was reduced from –0.097 MPa in the controls to –1.93 MPa under stress. This stress condition caused a reduction in shoot biomass while it increased total root length. There was a general progressive increase in leaf diffusive resistance under the treatment as plants became larger. This stomatal closure could not be accounted for by reduction in leaf water potential. In fact, leaf turgor increased as stomatal diffusive resistance increased with increasing plant size, leading us to conclude that stomatal closure was the primary response to top-root drying, followed by turgor maintenance possibly as a result of a non-hydraulic signal produced by the drying top-roots. Smaller plants were affected relatively less than were larger plants by this stress condition in terms of stomatal closure, plant height, tillering and shoot biomass reduction. Grain yield per plant was actually increased by stress in the smallest plants while it was unaffected by stress in the larger plants. It is concluded that the smallest plants were the most resistant to top-root drying but absolute biomass and yield under this stress condition was the greatest in the largest plants because of their relatively greater potential.

Comparison of Nodular Efficiencies Between Partridge Pea and Soybean Using Acetylene Reduction

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 449f-450
Author(s):  
Lisa M. Barry ◽  
Michael N. Dana
Keyword(s):  
Growth Rate ◽  
Plant Size ◽  
Silica Sand ◽  
Soybean Plant ◽  
Fibrous Root ◽  
Constant Growth Rate ◽  
Soil Microbial ◽  
Soybean Plants ◽  
Nurse Crops ◽  
Partridge Pea

Legumes are grown as nurse crops in agriculture because they increase soil microbial life and productivity. Native legumes have potential in ecological restoration to mimic the benefits found in agriculture plus they enhance the restored ecosystem. This study was initiated to compare the growth rates, nodulation characteristics, and nitrogen fixation rates of a native versus a non-native legume. The two legumes were partridge pea (Cassia fasciculata); a native, wild, annual legume and soybean (Glycine max `Century Yellow); a domesticated, agricultural, annual legume native to Asia. Plants were grown for 11 weeks in pots containing silica sand and received a nitrogen-free Hoagland's nutrient solution. Beginning at week 12, plants were harvested weekly for four consecutive weeks. Nodulated root systems were exposed to acetylene gas and the resulting ethylene amounts were measured. The two legumes exhibited significant differences in nodule size and shape and plant growth rate. In soybean, nodules were large, spherical, and clustered around the taproot while in partridge pea, nodules were small, irregularly shaped, and spread throughout the fibrous root system. Soybean plants had a significantly faster growth rate at the onset of the experiment but partridge pea maintained a constant growth rate and eventually exceeded soybean plant size. In spite of these observed differences, partridge pea and soybean plants were equally efficient at reducing acetylene to ethylene. These results indicate partridge pea has the potential to produce as much nitrogen in the field as soybean. Native legumes such as partridge pea deserve further research to explore their use as nurse crops in agricultural or restoration regimes.

scholarly journals Antagonism of chloride and nitrate inhibits nitrate reductase activity in chloride-stressed maize

2021 ◽  
Author(s):  
Xudong Zhang ◽  
Bastian L. Franzisky ◽  
Lars Eigner ◽  
Christoph‐Martin Geilfus ◽  
Christian Zörb
Keyword(s):  
Zea Mays ◽  
Polyethylene Glycol ◽  
Nitrate Reductase ◽  
Osmotic Stress ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Shoot Biomass ◽  
Lower Intensity ◽  
Maize Variety ◽  
Osmotic Balance

AbstractChloride (Cl−) is required for photosynthesis and regulates osmotic balance. However, excess Cl− application negatively interacts with nitrate ($${\mathrm{NO}}_{3}^{-}$$ NO 3 - ) uptake, although its effect on $${\mathrm{NO}}_{3}^{-}$$ NO 3 - metabolism remains unclear. The aim was to test whether Cl− stress disturbs nitrate reductase activity (NRA). A maize variety (Zea mays L. cv. LG 30215) was hydroponically cultured in a greenhouse under the following conditions: control (2 mM CaCl2), moderate Cl− (10 mM CaCl2), high Cl− (60 mM CaCl2). To substantiate the effect of Cl− stress further, an osmotic stress with lower intensity was induced by 60 g polyethylene glycol (PEG) 6000 L−1 + 2 mM CaCl2), which was 57% of the osmotic pressure being produced by 60 mM CaCl2. Results show that high Cl− and PEG-induced osmotic stress significantly reduced shoot biomass, stomatal conductance and transpiration rate, but NRA was only decreased by high Cl− stress. The interference of NRA in chloride-stressed maize is supposed to be primarily caused by the antagonistic uptake of Cl− and $${\mathrm{NO}}_{3}^{-}$$ NO 3 - .

Precursor processing by SBT3.8 and phytosulfokine signaling contribute to drought stress tolerance in Arabidopsis

2021 ◽  
Author(s):  
Nils Stührwohldt ◽  
Eric Bühler ◽  
Margret Sauter ◽  
Andreas Schaller
Keyword(s):  
Drought Stress ◽  
Osmotic Stress ◽  
Stress Tolerance ◽  
Serine Proteases ◽  
Loss Of Function ◽  
Lateral Root Development ◽  
Osmotic Stress Tolerance ◽  
Stress Symptoms ◽  
C Terminus ◽  
Peptide Precursor

Abstract Increasing drought stress poses a severe threat to agricultural productivity. Plants, however, evolved numerous mechanisms to cope with such environmental stress. Here we report that the stress-induced production of a peptide signal contributes to stress tolerance. The expression of phytosulfokine (PSK) peptide precursor genes, and transcripts of three subtilisin-like serine proteases, SBT1.4, SBT3.7 and SBT3.8 were found to be up-regulated in response to osmotic stress. Stress symptoms were enhanced in sbt3.8 loss-of-function mutants and could be alleviated by PSK treatment. Osmotic stress tolerance was improved in plants overexpressing the precursor of PSK1 (proPSK1) or SBT3.8 resulting in higher fresh weight and improved lateral root development in the transgenic compared to wild-type plants. We further showed that SBT3.8 is involved in the biogenesis of the bioactive PSK peptide. ProPSK1 was cleaved by SBT3.8 at the C-terminus of the PSK pentapeptide. Processing by SBT3.8 depended on the aspartic acid residue directly following the cleavage site. ProPSK1 processing was impaired in the sbt3.8 mutant. The data suggest that increased expression in response to osmotic stress followed by the post-translational processing of proPSK1 by SBT3.8 leads to the production of PSK as a peptide signal for stress mitigation.

scholarly journals Molecular and Physiological Responses of Rice and Weedy Rice to Heat and Drought Stress

Agriculture ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 9
Author(s):  
Leonard Bonilha Piveta ◽  
Nilda Roma-Burgos ◽  
José Alberto Noldin ◽  
Vívian Ebeling Viana ◽  
Claudia de Oliveira ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Heat Stress ◽  
Drought Stress ◽  
Intercellular Co2 Concentration ◽  
Tiller Number ◽  
Weedy Rice ◽  
Photosynthetic Parameters ◽  
World Population ◽  
Rice Grain ◽  
Rice Cultivars

Rice is the staple food for about half of the world population. Rice grain yield and quality are affected by climatic changes. Arguably, rice cultivars’ genetic diversity is diminished from decades of breeding using narrow germplasm, requiring introgressions from other Oryza species, weedy or wild. Weedy rice has high genetic diversity, which is an essential resource for rice crop improvement. Here, we analyzed the phenotypic, physiological, and molecular profiles of two rice cultivars (IRGA 424 and SCS119 Rubi) and five weedy rice (WR), from five different Brazilian regions, in response to heat and drought stress. Drought and heat stress affected the phenotype and photosynthetic parameters in different ways in rice and WR genotypes. A WR from Northern Brazil yielded better under heat stress than the non-stressed check. Drought stress upregulated HSF7A while heat stress upregulated HSF2a. HSP74.8, HSP80.2, and HSP24.1 were upregulated in both conditions. Based on all evaluated traits, we hypothesized that in drought conditions increasing HSFA7 expression is related to tiller number and that increase WUE (water use efficiency) and HSFA2a expression are associated with yield. In heat conditions, Gs (stomatal conductance) and E’s increases may be related to plant height; tiller number is inversely associated with HSPs expression, and chlorophyll content and Ci (intercellular CO2 concentration) may be related to yield. Based on morphology, physiology, and gene regulation in heat and drought stress, we can discriminate genotypes that perform well under these stress conditions and utilize such genotypes as a source of genetic diversity for rice breeding.

A Model of Wheat Grain Growth and Its Applications to Different Temperature and Carbon Dioxide Levels

1995 ◽  
Vol 22 (5) ◽  
pp. 843 ◽  
Author(s):  
YP Wang ◽  
RM Gifford
Keyword(s):  
Growth Rate ◽  
Grain Growth ◽  
Temperature Response ◽  
Rate Sensitivity ◽  
Temperature Sensitive ◽  
Potential Growth ◽  
Carbon Supply ◽  
The Difference ◽  
Carbon Dioxide Levels ◽  
Kernel Growth

Kernel growth after anthesis is simulated as a function of the potential kernel growth rate, current photosynthate production and mobilisation of stored reserves. The potential growth rate of the kernel is simulated as two temperature-sensitive processes, cell production and cell growth. The difference between the potential and actual growth rates of the kernel depends on the carbon supply to the free space of the kernel endosperm, while the carbon supply is itself affected by the actual kernel growth rate. Sensitivity analysis showed that the growth rate of the grain per plant is most sensitive to the potential growth rate of the kernel and number of kernels per plant. This model is able to simulate the observed rates of grain growth and leaf senescence from anthesis to physiological maturity for wheat plants grown in two CO2 concentrations. The simulated temperature response of grain growth agrees well with the experimenal observations.

Ectopic expression a maize ADP-ribosylation factor gene in Arabidopsis, increase plant size and growth rate

2013 ◽  
Vol 24 (2) ◽  
pp. 161-166 ◽  
Author(s):  
Jincheng-Yuan ◽  
Jinhui-Song ◽  
Hailian-Ma ◽  
Xiaoqing-Song ◽  
Huiping-Wei ◽  
...  
Keyword(s):  
Growth Rate ◽  
Ectopic Expression ◽  
Plant Size ◽  
Factor Gene ◽  
Adp Ribosylation ◽  
Adp Ribosylation Factor
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