Morphological and Physiological Plant Responses to Drought Stress inThymus citriodorus

Water availability is considered as a determinant factor that affects plant growth. The commercial medicinal values of an aromatic plant rely on the presence of secondary metabolites that are affected under water shortage. Two-year-oldThymus citriodorusplants were subjected to different polyethylene glycol (PEG-6000) levels (0, 2%, and 4%) under greenhouse condition. PEG treatment lasted for 15 days. Thyme plant showed a morphological drought avoidance mechanism by maintaining the root system development through shoot fresh weight reduction resulting in promoted root absorption capacity and sustained plant growth. Moreover, stressed plants were able to maintain water use efficiency and root : shoot ratio suggesting a strong relation between root water uptake and water use saving strategies. Furthermore, thyme plants reduced tissue dehydration through stomatal closure and improved root water uptake. Content of volatile oil constituents of geraniol and diisobutyl phthalate increased upon drought stress while pseudophytol was reduced. Unexpectedly, thymol was not reported as a main oil element under either control or mild stress condition, while it was increased upon high drought stress in measure of 4.4%. Finally, carvacrol significantly accumulated under high drought stress (+31.7%) as compared to control plants.

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Overexpression of MdATG8i Enhances Drought Tolerance by Alleviating Oxidative Damage and Promoting Water Uptake in Transgenic Apple

International Journal of Molecular Sciences ◽

10.3390/ijms22115517 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5517

Author(s):

Xin Jia ◽

Xiaoqing Gong ◽

Xumei Jia ◽

Xianpeng Li ◽

Yu Wang ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Oxidative Damage ◽

Water Uptake ◽

Transcript Level ◽

Root Water Uptake ◽

Plant Responses ◽

Severe Drought ◽

Root Hydraulic Conductivity ◽

Drought Conditions

Water deficit adversely affects apple (Malus domestica) productivity on the Loess Plateau. Autophagy plays a key role in plant responses to unfavorable environmental conditions. Previously, we demonstrated that a core apple autophagy-related protein, MdATG8i, was responsive to various stresses at the transcript level. Here, we investigated the function of this gene in the response of apple to severe drought and found that its overexpression (OE) significantly enhanced drought tolerance. Under drought conditions, MdATG8iOE apple plants exhibited less drought-related damage and maintained higher photosynthetic capacities compared with the wild type (WT). The accumulation of ROS (reactive oxygen species) was lower in OE plants under drought stress and was accompanied by higher activities of antioxidant enzymes. Besides, OE plants accumulated lower amounts of insoluble or oxidized proteins but greater amounts of amino acids and flavonoid under severe drought stress, probably due to their enhanced autophagic activities. Particularly, MdATG8iOE plants showed higher root hydraulic conductivity than WT plants did under drought conditions, indicating the enhanced ability of water uptake. In summary, the overexpression of MdATG8i alleviated oxidative damage, modulated amino acid metabolism and flavonoid synthesis, and improved root water uptake, ultimately contributing to enhanced drought tolerance in apple.

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Differences between two grain sorghum genotypes in adaptation to drought stress. II. Root water uptake and water use

Australian Journal of Agricultural Research ◽

10.1071/ar9830627 ◽

1983 ◽

Vol 34 (6) ◽

pp. 627 ◽

Cited By ~ 39

Author(s):

GC Wright ◽

RCG Smith

Keyword(s):

Drought Stress ◽

Grain Yield ◽

Water Content ◽

Soil Water ◽

Water Use ◽

Water Uptake ◽

Root Water Uptake ◽

Grain Sorghum ◽

Sorghum Genotypes ◽

Adaptation To Drought

A study of two sorghum hybrids, E-57 and TX-671, indicated that differences in grain yield under conditions of low rainfall were associated with increased extraction of soil water at depth. E-57 used less water before anthesis than did TX-671, which was more than compensated for by increased water use after anthesis. As soil water declined in a drying cycle, TX-671 tended to restrict its water use at a higher water content than E-57. The implication of these results is discussed.

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Water uptake dynamics under progressive drought stress in diverse accessions of the OryzaSNP panel of rice (Oryza sativa)

Functional Plant Biology ◽

10.1071/fp12015 ◽

2012 ◽

Vol 39 (5) ◽

pp. 402 ◽

Cited By ~ 28

Author(s):

Veeresh R. P. Gowda ◽

Amelia Henry ◽

Vincent Vadez ◽

H. E. Shashidhar ◽

Rachid Serraj

Keyword(s):

Oryza Sativa ◽

Drought Stress ◽

Root Growth ◽

Water Uptake ◽

Root Length Density ◽

Oryza Sativa L ◽

Root Water Uptake ◽

Snp Markers ◽

Drought Response ◽

Genotypic Differences

In addition to characterising root architecture, evaluating root water uptake ability is important for understanding drought response. A series of three lysimeter studies were conducted using the OryzaSNP panel, which consists of 20 diverse rice (Oryza sativa L.) genotypes. Large genotypic differences in drought response were observed in this genotype panel in terms of plant growth and water uptake. Total water uptake and daily water uptake rates in the drought-stress treatment were correlated with root length density, especially at depths below 30 cm. Patterns of water uptake among genotypes remained consistent throughout the stress treatments: genotypes that initially extracted more water were the same genotypes that extracted more water at the end of the study. These results suggest that response to drought by deep root growth, rather than a conservative soil water pattern, seems to be important for lowland rice. Genotypes in the O. sativa type aus group showed some of the greatest water uptake and root growth values. Since the OryzaSNP panel has been genotyped in detail with SNP markers, we expect that these results will be useful for understanding the genetics of rice root growth and function for water uptake in response to drought.

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The Vascular Pathogen Verticillium longisporum Does Not Affect Water Relations and Plant Responses to Drought Stress of Its Host, Brassica napus

Phytopathology ◽

10.1094/phyto-07-16-0280-r ◽

2017 ◽

Vol 107 (4) ◽

pp. 444-454 ◽

Cited By ~ 9

Author(s):

Daniel Teshome Lopisso ◽

Jessica Knüfer ◽

Birger Koopmann ◽

Andreas von Tiedemann

Keyword(s):

Drought Stress ◽

Brassica Napus ◽

Plant Growth ◽

Water Relations ◽

Growth Parameters ◽

Molecular Genetic ◽

Leaf Water Content ◽

Plant Responses ◽

Brassica Napus L ◽

Verticillium Longisporum

Verticillium longisporum is a host-specific vascular pathogen of oilseed rape (Brassica napus L.) that causes economic crop losses by impairing plant growth and inducing premature senescence. This study investigates whether plant damage through Verticillium stem striping is due to impaired plant water relations, whether V. longisporum affects responses of a susceptible B. napus variety to drought stress, and whether drought stress, in turn, affects plant responses to V. longisporum. Two-factorial experiments on a susceptible cultivar of B. napus infected or noninfected with V. longisporum and exposed to three watering levels (30, 60, and 100% field capacity) revealed that drought stress and V. longisporum impaired plant growth by entirely different mechanisms. Although both stresses similarly affected plant growth parameters (plant height, hypocotyl diameter, and shoot and root dry matter), infection of B. napus with V. longisporum did not affect any drought-related physiological or molecular genetic plant parameters, including transpiration rate, stomatal conductance, photosynthesis rate, water use efficiency, relative leaf water content, leaf proline content, or the expression of drought-responsive genes. Thus, this study provides comprehensive physiological and molecular genetic evidence explaining the lack of wilt symptoms in B. napus infected with V. longisporum. Likewise, drought tolerance of B. napus was unaffected by V. longisporum, as was the level of disease by drought conditions, thus excluding a concerted action of both stresses in the field. Although it is evident that drought and vascular infection with V. longisporum impair plant growth by different mechanisms, it remains to be determined by which other factors V. longisporum causes crop loss.

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Leaf Gas Exchange and Water Relations of Lupins and Wheat. II. Root and Shoot Water Relations of Lupin During Drought-Induced Stomatal Closure

Functional Plant Biology ◽

10.1071/pp9890415 ◽

1989 ◽

Vol 16 (5) ◽

pp. 415 ◽

Cited By ~ 13

Author(s):

CR Jensen ◽

IE Henson ◽

NC Turner

Keyword(s):

Water Potential ◽

Soil Water ◽

Water Transport ◽

Water Uptake ◽

Water Relations ◽

Leaf Gas Exchange ◽

Stomatal Closure ◽

Soil Water Potential ◽

Root Water Uptake ◽

Leaf Conductance

Plants of Lupinus cosentinii Guss. cv. Eregulla were grown in a sandy soil in large containers in a glasshouse and exposed to drought by withholding water. Under these conditions stomatal closure had previously been shown to be initiated before a significant reduction in leaf water potential was detected. In the experiments reported here, no significant changes were found in water potential or turgor pressure of roots or leaves when a small reduction in soil water potential was induced which led to a 60% reduction in leaf conductance. The decrease in leaf conductance and root water uptake closely paralleled the fraction of roots in wet soil. By applying observed data of soil water and root characteristics, and root water uptake for whole pots in a single-root model, the average water potential at the root surface was calculated. Potential differences for water transport in the soil-plant system, and the resistances to water flow were estimated using the 'Ohm's Law' analogy for water transport. Soil resistance was negligible or minor, whereas the root resistance accounted for 61-72% and the shoot resistance accounted for about 30% of the total resistance. The validity of the measurements and calculations is discussed and the possible role of root- to-shoot communication raised.

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Estimating the Root Water Uptake of Surface-Irrigated Apples Using Water Stable Isotopes and the Hydrus-1D Model

Water ◽

10.3390/w10111624 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1624 ◽

Cited By ~ 5

Author(s):

Lijian Zheng ◽

Juanjuan Ma ◽

Xihuan Sun ◽

Xianghong Guo ◽

Qiyun Cheng ◽

...

Keyword(s):

Stable Isotopes ◽

Water Use Efficiency ◽

Water Use ◽

Water Uptake ◽

Root Water Uptake ◽

Surface Irrigation ◽

Apple Trees ◽

1D Model ◽

Use Efficiency ◽

Hydrus 1D

The future production of irrigated fruit orchards in the Loess Plateau of China is threatened by a shortage of freshwater. To improve water use efficiency under conditions where irrigation is limited, it is necessary to quantify the root water uptake (RWU) of apple trees. The RWU of apple trees was estimated under surface irrigation using water stable isotope technology and the Hydrus-1D model. Using the Romero-Saltos and IsoSource models, the stable isotopes of water in stems, different soil depths, and different precipitation were analyzed in a 5-year-old dwarfing apple orchard during two seasons 2016 and 2017. Hydrus-1D model was able to simulate the RWU of apple using the maximum coefficient of determination (0.9), providing a root mean square error of 0.019 cm3 cm−3 and a relative error of 2.25%. The results showed that the main depth of RWU ranged from 0–60 cm during the growth season, with the main contribution occurring in the 0–40 cm depth. These findings indicated that reducing the traditional surface irrigation depth will be important for improving the irrigation water use efficiency.

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