Responses to water stress of enzyme activities and metabolite levels in relation to sucrose and starch synthesis, the Calvin cycle and the C4 pathway in sugarcane (Saccharum sp.) leaves

1998 ◽  
Vol 25 (2) ◽  
pp. 253 ◽  
Author(s):  
Y.-C. Du ◽  
A. Nose ◽  
K. Wasano ◽  
Y. Uchida
Keyword(s):  
Water Stress ◽  
Enzyme Activities ◽  
Stomatal Closure ◽  
Starch Synthesis ◽  
Calvin Cycle ◽  
Severe Water Stress ◽  
C4 Pathway ◽  
Saccharum Sp ◽  
Almost All ◽  
Mild Water Stress

During a slowly induced water stress, almost all measured activities of enzymes, including the important enzymes associated with the Calvin cycle, the C4 pathway, and sucrose and starch synthesis, and the pool sizes of metabolites, including hexose phosphates, 3-phosphoglycerate, triose phosphates, malate, pyruvate and PEP, in leaves of sugarcane (Saccharum sp. cv. NiF4) were not or only moderately reduced by mild water stress (above –0.9 MPa leaf water potential (Ψw)), and the magnitudes of reductions in those parameters were less than the reductions in photosynthetic rates. We conclude that the biochemical processes of sucrose and starch synthesis, the Calvin cycle and the C4 pathway in sugarcane leaves were not seriously affected by mild water stress, and the changes in those processes were not the cause for the decline in photosynthesis; mild water stress induced decline in photosynthesis is caused by stomatal closure. Under severe water stress (–1.2 MPa leaf Ψw), most metabolite levels and enzyme activities decreased significantly compared with those under mild water stress. But the enzyme activities and metabolite levels relating to sucrose and starch synthesis, and the Calvin cycle still remained at high levels compared with the corresponding photosynthetic rate. PPDK activity and pyruvate content decreased to very low levels. It is suggested that PPDK is a possible limiting enzyme for photosynthesis in leaves of sugarcane under severe water stress.

ROOT CHARACTERISTICS IN COWPEA RELATED TO DROUGHT TOLERANCE AT THE SEEDLING STAGE

2003 ◽  
Vol 39 (1) ◽  
pp. 29-38 ◽  
Author(s):  
T. MATSUI ◽  
B. B. SINGH
Keyword(s):  
Water Stress ◽  
Drought Tolerance ◽  
Leaf Area ◽  
Dry Matter ◽  
Stress Conditions ◽  
Root Characteristics ◽  
Severe Water Stress ◽  
Cowpea Varieties ◽  
Root Box ◽  
Mild Water Stress

Cowpea (Vigna unguiculata) has relatively higher drought tolerance than other legume crops. It is widely grown in semi-arid regions, particularly in West Africa. One objective of the present study was to determine the effects of soil moisture stress on the length, dry matter and distribution of the roots of two cowpea varieties with different drought tolerances. Another objective was to evaluate the pin-board root-box as a method for identifying the role of root characteristics in drought tolerance. Two cowpea varieties, IT96D-604 (drought tolerant) and TVu7778 (drought susceptible), were used in this study. There were three watering treatments, T1 (well-watered), T2 (mild water stress) and T3 (severe water stress). Between varieties, there were no significant differences in shoot and root characteristics except for leaf area in T1. Under T2, the shoot:root ratio (S:R ratio) of IT96D-604 was significantly decreased compared with that under T1 as a result of the increase in root dry matter and decrease in leaf area without significant differences in total dry matter. In addition, the root dry matter per leaf area, which indicates the capacity to absorb water, of IT96D-604 was significantly higher than that of TVu7778. Under T3, the total dry matter of TVu7778 was about one third of those of the other treatments for the same variety, whereas that of IT96D-604 was more than half. Regarding root distribution, the centres of root dry matter and root length density of both varieties moved downwards significantly under water-stress conditions compared with those of the well-watered condition. This tendency was more pronounced in IT96D-604 than in TVu7778. Drought tolerance in IT96D-604 was associated with the increase in root dry matter per leaf area under mild water-stress conditions, and downward movement of roots (increasing access and use of soil moisture in deep soil layers) under mild and severe water stress conditions. In addition, the root-box method was versatile and can be used for studying root responses to edaphic factors relevant to root growth.

Effects of Water Stress on Carbon Exchange Rate and Activities of Photosynthetic Enzymes in Leaves of Sugarcane (Saccharum Sp.)

1996 ◽  
Vol 23 (6) ◽  
pp. 719 ◽  
Author(s):  
YC Du ◽  
Y Kawamitsu ◽  
A Nose ◽  
S Hiyane ◽  
S Murayama ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Water Stress ◽  
Stomatal Closure ◽  
Total Soluble Protein ◽  
Carbon Exchange ◽  
Bisphosphate Carboxylase ◽  
Pyruvate Orthophosphate Dikinase ◽  
Photosynthetic Enzymes ◽  
Orthophosphate Dikinase ◽  
Saccharum Sp

The responses of carbon exchange rate (CER), stomatal conductance (gs), activities of phosphoenolpyruvate carboxylase (PEPcase), NADP malic enzyme (NADP-ME), ribulose-1,5- bisphosphate carboxylase (Rubisco), fructose-1,6-bisphosphatase (FBPase) and pyruvate, orthophosphate dikinase (PPDK), and contents of chlorophyll (Chl) and total soluble protein (Tsp) in leaves of sugar cane (Saccharum sp. cv. NiF4) to gradually developed water stress were investigated. The initial inhibitions of CER, gs, activities of the photosynthetic enzymes and contents of Chl and Tsp were observed from leaf water potentials (Ψw) of -0.37 MPa. During water stress, CER and gs, decreased in a non-linear way, activities of the five enzymes and contents of Chl and Tsp decreased linearly with decreasing leaf Ψw. The changes of gs the photosynthetic enzymes, Chl and Tsp were highly related to the changes of CER. The decline in CER during water stress was caused by both stomatal and non- stomatal limitations. Above leaf �w of -0.85 MPa, the decline in CER was caused by stomatal closure, below -0.85 MPa, the decline in CER was caused by non-stornatal limitation. Among non-stomatal components, PPDK activities decreased 9.1 times during water stress, much more than other enzymes which decreased from 2 to 4 times. Measured PPDK activities were only a little higher than the corresponding CER values at various leaf Ψw suggesting that PPDK is very likely to be the limiting enzyme to photosynthesis under water stress.

scholarly journals Unravelling the Role of Piriformospora indica in Combating Water Deficiency by Modulating Physiological Performance and Chlorophyll Metabolism-Related Genes in Cucumis sativus

Horticulturae ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 399
Author(s):  
Mohamed E. Abdelaziz ◽  
Mohamed A. M. Atia ◽  
Mohamed Abdelsattar ◽  
Suzy M. Abdelaziz ◽  
Taha A. A. Ibrahim ◽  
...  
Keyword(s):  
Water Stress ◽  
Chlorophyll A ◽  
Irrigation Water ◽  
Chlorophyll Biosynthesis ◽  
Stomatal Closure ◽  
Stress Conditions ◽  
Piriformospora Indica ◽  
Activity Levels ◽  
Chlorophyll Metabolism ◽  
Severe Water Stress

Water stress is the most critical aspect restricting the development of agriculture in regions with scarce water resources, which requires enhancing irrigation water-saving strategies. The current work discusses the potential application of the plant-strengthening root endophyte Piriformospora indica against moderate (25% less irrigation water) and severe (50% less irrigation water) water stress in comparison to the optimum irrigation conditions of greenhouse cucumbers. P. indica improved growth, nutrient content, and photosynthesis apparatus under normal or water-stress conditions. On the other hand, moderate and severe water stress reduced yield up to 47% and 83%, respectively, in non-colonized cucumber plants, while up to 28 and 78%, respectively, in P. indica-colonized plants. In terms of water-use efficiency (WUE), P. indica improved the WUE of colonized cucumber plants grown under moderate (26 L/kg) or severe stress (73 L/kg) by supporting colonized plants in producing higher yield per unit volume of water consumed by the crop in comparison to non-colonized plants under the same level of moderate (43 L/kg) or severe (81 L/kg) water stress. Furthermore, P. indica increased the indole-3-acetic acid (IAA) content, activity levels of catalase (CAT) and peroxidase (POD) with an apparent clear reduction in the abscisic acid (ABA), ethylene, malondialdehyde (MDA), proline contents and stomatal closure compared to non-stressed plants under both water-stress levels. In addition, chlorophyll a, b, a + b contents were increased in the leaves of the colonized plants under water-stress conditions. This improvement in chlorophyll content could be correlated with a significant increment in the transcripts of chlorophyll biosynthesis genes (protochlorophyllide oxidoreductase [POR], chlorophyll a oxygenase [CAO]) and a reduction in the chlorophyll degradation genes (PPH, pheophorbide a oxygenase [PAO], and red chlorophyll catabolite reductase [RCCR]). In conclusion, P. indica has the potential to enhance the cucumber yield grown under moderate water stress rather than severe water stress by improving WUE and altering the activity levels of antioxidant enzymes and chlorophyll metabolism-related genes.

scholarly journals Taxane and ABA Production in Yew under Different Soil Water Regimes

HortScience ◽  
1999 ◽  
Vol 34 (5) ◽  
pp. 882-885 ◽  
Author(s):  
Angela Hoffman ◽  
Clinton Shock ◽  
Erik Feibert
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Soil Water ◽  
Anticancer Agent ◽  
Stomatal Closure ◽  
Plant Water ◽  
Registered Trademark ◽  
Baccatin Iii ◽  
Severe Water Stress ◽  
Aba Content

Taxol® (paclitaxel), an important anticancer agent, is found in many species of yew. As the need for Taxol increases, sustainable sources must be found for this drug. Plants often respond to stress with increased production of terpenoid compounds such as Taxol and related taxanes or hormones such as abscisic acid (ABA). To determine whether water stress would enhance the production and recovery of Taxol from stem clippings, 100 young Taxu×media `Hicksii' shrubs were grown for sustainable production of Taxol from stem clippings for two seasons in the dry climate of the Malheur Experiment Station in Ontario, Ore. Shrubs were grown under minimal, moderate, or severe water stress, and the relationships between taxane content and 1) soil and plant water potentials, 2) percentage of stomatal closure, and 3) ABA content were examined. Severely water-stressed shrubs produced significantly more taxanes and ABA than did the less stressed shrubs. Chemical names used: Taxol; 10-deacetyl baccatin III; baccatin III; 10-deacetyl taxol, cephalomannine; 7-epi; 10-deacetyl taxol; abscisic acid. Taxol is a registered trademark of Bristol-Myers Squibb.

scholarly journals Effect of Early Water Deficits on Nodulation and Nitrogen Content of Inoculated Soybean

2018 ◽  
Vol 20 (2) ◽  
pp. 11-16
Author(s):  
JA Adjetey ◽  
BNG Nxumalo
Keyword(s):  
Water Stress ◽  
Dry Mass ◽  
Growth Stages ◽  
Mild Stress ◽  
Severe Stress ◽  
Production Potential ◽  
Severe Water Stress ◽  
Kwazulu Natal ◽  
The University ◽  
Mild Water Stress

The study was conducted at the University of KwaZulu-Natal (29o37’ S, 30o23’ E) from May to November 2012 under controlled environment conditions with three water regimes namely: well watered controls, mild water stress to -1.4 MPa and severe water stress to -2.0 MPa, at the V4 (28 DAS) and V5 stages (35 DAS). Severe stress significantly reduced no. of nodule and root mass, leaf area, shoot dry mass and uptake, regardless of the stage. Mild stress on the other hand had little effect on this parameter as plants recovered on re-watering, to attain values similar to the control treatments. The V4 and V5 stages can recover from mild stress, but severe stress at both growth stages reduces nodulation and nitrogen uptake and this can lead to reduction in production potential of soybean.Bangladesh Agron. J. 2017, 20(2): 11-16

scholarly journals Detecting Mild Water Stress in Olive with Multiple Plant-Based Continuous Sensors

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 131
Author(s):  
Giulia Marino ◽  
Alessio Scalisi ◽  
Paula Guzmán-Delgado ◽  
Tiziano Caruso ◽  
Francesco Paolo Marra ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Deficit ◽  
Stomatal Closure ◽  
Irrigation Management ◽  
Great Influence ◽  
Solid Base ◽  
Mild Stress ◽  
Tissue Elasticity ◽  
Stress Studies ◽  
Mild Water Stress

A comprehensive characterization of water stress is needed for the development of automated irrigation protocols aiming to increase olive orchard environmental and economical sustainability. The main aim of this study is to determine whether a combination of continuous leaf turgor, fruit growth, and sap flow responses improves the detection of mild water stress in two olive cultivars characterized by different responses to water stress. The sensitivity of the tested indicators to mild stress depended on the main mechanisms that each cultivar uses to cope with water deficit. One cultivar showed pronounced day to day changes in leaf turgor and fruit relative growth rate in response to water withholding. The other cultivar reduced daily sap flows and showed a pronounced tendency to reach very low values of leaf turgor. Based on these responses, the sensitivity of the selected indicators is discussed in relation to drought response mechanisms, such as stomatal closure, osmotic adjustment, and tissue elasticity. The analysis of the daily dynamics of the monitored parameters highlights the limitation of using non-continuous measurements in drought stress studies, suggesting that the time of the day when data is collected has a great influence on the results and consequent interpretations, particularly when different genotypes are compared. Overall, the results highlight the need to tailor plant-based water management protocols on genotype-specific physiological responses to water deficit and encourage the use of combinations of plant-based continuously monitoring sensors to establish a solid base for irrigation management.

scholarly journals Physiological and Yield Responses of Green-Shelled Beans (Phaseolus vulgaris L.) Grown under Restricted Irrigation

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 562
Author(s):  
Karen Campos ◽  
Andrés R. Schwember ◽  
Daniel Machado ◽  
Mónica Ozores-Hampton ◽  
Pilar M. Gil
Keyword(s):  
Water Stress ◽  
Deficit Irrigation ◽  
Pot Experiment ◽  
Water Restriction ◽  
One Pot ◽  
Dry Land ◽  
Severe Water Stress ◽  
The Face ◽  
Use Efficiency ◽  
Yield Responses

Common bean is an important crop, consumed as green-shelled bean in several countries. In Chile, green-shelled beans are cultivated often as a dry land crop, vulnerable to drought. The objective of this study was to characterize the hydric and productive responses of four green-shelled bean genotypes subjected to deficit irrigation in order to outline production strategies in the face of increasing water scarcity. Two experiments were evaluated: one pot experiment with three irrigation treatments, supplying 100% of the crop evapotranspiration (ETc) (T100), 50% (T50), and 30% (T30); and an open field experiment with two treatments: 100% (I100) and 40% of ETc (I40). Treatments were applied during reproductive stage in determinate cultivars and vegetative stage in indeterminate plants. Severe water restriction (T30 and I40) in both experiments showed a significant decrease in stomatal conductances, as well as biomass and number of grains per pod; I40 treatment also showed a reduction in chlorophyll fluorescence. Water use efficiency (WUE) was higher under water stress in field (I40), but lower on the T30 treatment from the pot experiment. Determinate cultivars showed 22.7% higher of 100-seed weight compared to indeterminate type, and, thus, higher tolerance to drought. Our results indicate that severe water stress is highly harmful in terms of yield, and a moderate controlled deficit irrigation plus the use of determinate genotypes may be a strategy for producing green-shelled bean successfully under a drought scenario.

scholarly journals Change of Ascorbic Acid Level after Grafting of Tomato Seedlings

1999 ◽  
Vol 54 (9-10) ◽  
pp. 830-833 ◽  
Author(s):  
Akira Wadano ◽  
Mitsuharu Azeta ◽  
Shin-ichi Itotani ◽  
Ai Kanda ◽  
Toshio Iwaki ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Water Stress ◽  
Ascorbate Peroxidase ◽  
Phosphate Buffer ◽  
Acid Level ◽  
Active Oxygen ◽  
Ascorbic Acid Level ◽  
Electrochemical Detector ◽  
Tomato Seedlings ◽  
Severe Water Stress

Grafting is an easy way to produce a new seedling, which can tolerate against various stresses. During the acclimation after grafting, however, the seedlings still suffer a severe water stress. It is well known that water stress produces active oxygen to oxidize ascorbic acid. The concentration of ascorbic acid in the leaves was analyzed by HPLC equipped with an electrochemical detector. The column used was SP-120-5-ODS-BP (DAISO, JAPAN) and elution was performed with 0.1 ᴍ phosphate buffer, pH 3.0. After grafting the seedlings were acclimated under a 6-hr light/dark regimen. The content of ascorbic acid increased gradually during 2 days compared with control. The ascorbate peroxidase showed about constant activity, so the increase of ascorbic acid may be due to its requirement to cure the grafting

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