Ion-mediated compensation for drought-induced loss of xylem hydraulic conductivity in field-growing plants of Laurus nobilis

2011 ◽  
Vol 38 (7) ◽  
pp. 606 ◽  
Author(s):  
Patrizia Trifilò ◽  
Andrea Nardini ◽  
Fabio Raimondo ◽  
Maria A. Lo Gullo ◽  
Sebastiano Salleo
Keyword(s):  
Drought Stress ◽  
Hydraulic Conductivity ◽  
Potassium Concentration ◽  
Stomatal Closure ◽  
Xylem Sap ◽  
Hydraulic Conductance ◽  
Residual Water ◽  
Xylem Cavitation ◽  
Laurus Nobilis ◽  
Mild Drought

Xylem cavitation is a common occurrence in drought-stressed plants. Cavitation-induced embolism reduces xylem hydraulic conductivity (kxylem) and may lead to stomatal closure and reduction of photosynthetic rates. Recent studies have suggested that plants may compensate for kxylem loss through ion-mediated enhancement of the residual water transport capacity of functioning conduits. To test this hypothesis, field-grown laurel (Laurus nobilis L.) plants were subjected to mild drought stress by suspending irrigation. Drought treatment induced a significant increase in xylem embolism compared with control (well watered) plants. Xylem sap potassium concentration ([K+]) increased during the day both in control and water stressed plants. Midday values of sap [K+] were significantly higher in water stressed plants. The recorded increase in sap potassium concentration induced significant enhancement of residual kxylem when solutions with different [K+] were perfused through excised stems sampled in the field and measured in the laboratory. In planta measurements of stem hydraulic conductance revealed no change between water stressed plants and controls. Our data suggest that ion-mediated enhancement of residual kxylem buffered the actual loss of hydraulic conductance suffered by plants during the warmest hours of the day as well as under mild drought stress conditions.

Water transfer in a mature oak stand (Quercuspetraea): seasonal evolution and effects of a severe drought

1993 ◽  
Vol 23 (6) ◽  
pp. 1136-1143 ◽  
Author(s):  
N. Bréda ◽  
H. Cochard ◽  
E. Dreyer ◽  
A. Granier
Keyword(s):  
Stomatal Conductance ◽  
Potential Evapotranspiration ◽  
Stomatal Closure ◽  
Time Lag ◽  
Xylem Sap ◽  
Water Shortage ◽  
Hydraulic Conductance ◽  
Canopy Conductance ◽  
Severe Drought ◽  
Order Of Magnitude

The reactions of sessile oak (Quercuspetraea (Mattuschka) Liebl.) to drought were studied under natural conditions in a 32-year-old stand near Nancy (northeastern France) during the summers of 1989 (strongly rain deficient) and 1990. A plot of five trees was subjected to imposed water shortage, while a group of irrigated trees was used as a control. Measurements of xylem sap flows and water potential enabled the computation of plot transpiration, canopy conductance, and specific hydraulic conductance in the soil–tree continuum. Stomatal conductance was measured directly with a porometer. Specific hydraulic conductance of our oaks was of the same order of magnitude as that reported for other species. It decreased significantly during spring because of a time lag between cambial growth and leaf area expansion. Measured transpiration was close to potential evapotranspiration, except during days with high vapor pressure deficits, which promoted stomatal closure in the absence of soil water deficits. Imposed drought caused predawn leaf water potentials to reach values as low as −2.0 MPa and a progressive decline in hydraulic conductance, which was probably attributable to modifications in hydraulic properties at the soil–root interface. This gradual decline in conductance was attributed to their deep rooting (1.40 m). This study revealed that Q. petraea may be considered as drought tolerant because of adaptations like deep rooting, efficient and safe xylem sap transport, maintenance of significant stomatal conductance, and significant transpiration, even during strong drought stress.

A review of drought adaptation in crop plants: changes in vegetative and reproductive physiology induced by ABA-based chemical signals

2005 ◽  
Vol 56 (11) ◽  
pp. 1245 ◽  
Author(s):  
Fulai Liu ◽  
Christian R. Jensen ◽  
Mathias N. Andersen
Keyword(s):  
Drought Stress ◽  
Stomatal Closure ◽  
Xylem Sap ◽  
Reproductive Development ◽  
Leaf Expansion ◽  
Rhizobium Japonicum ◽  
Soil Drying ◽  
Drought Adaptation ◽  
Chemical Signalling

This review discusses the role of abscisic acid (ABA)-based drought stress chemical signalling in regulating crop vegetative and reproductive development and its contributions to crop drought adaptation. Increased concentrations of ABA in the root induced by soil drying may maintain root growth and increase root hydraulic conductivity; both lead to an increase in water uptake and thereby postpone the development of water deficit in the shoot. Root ABA is also transported in the xylem to the shoot and is perceived at the acting sites, where it causes stomatal closure and reduced leaf expansion, thereby preventing dehydration of leaf tissues and enhancing the chance for survival under prolonged drought. ABA-based chemical signalling can be amplified by several factors, particularly increased pH in the xylem/apoplast, which retains anionic ABA. Such an increase in xylem pH detected in field-grown maize might have been brought about by reduced nitrate uptake by plants during soil drying. In contrast, xylem sap alkalinisation was not found in soybeans, which depend on fixing nitrogen through their association with Rhizobium japonicum. Evidence has also shown that the xylem-borne ABA can be transported to plant reproductive structures and influence their development, presumably by regulating gene expression that controls cell division and carbohydrate metabolic enzyme activity under drought conditions. The possible involvement of ABA in the up- and down-regulation of acid invertase in crop source (adult leaves) v. sink (young ovaries) organs indicates a crucial role of the hormone in balancing source and sink relationship in plants according to the availability of water in the soil. A novel irrigation technique named partial root-zone drying (PRD), has been developed to allow exploitation of ABA-based drought stress signalling to improve water-use efficiency (WUE) based on its roles in regulating stomatal aperture and leaf expansion. However, little is known about how crop reproductive development is regulated when irrigated under PRD. We suggest that more attention should be paid to the latter aspect as it directly relates to crop yield and quality.

scholarly journals Distinct Cellular Strategies Determine Sensitivity to Mild Drought of Arabidopsis Natural Accessions

2020 ◽  
Author(s):  
Ying Chen ◽  
Marieke Dubois ◽  
Mattias Vermeersch ◽  
Dirk Inzé ◽  
Hannes Vanhaeren
Keyword(s):  
Drought Stress ◽  
Stress Responses ◽  
Cell Expansion ◽  
Leaf Growth ◽  
Stomatal Closure ◽  
Wide Distribution ◽  
Abiotic Stress Response ◽  
Transcriptional Responses ◽  
Drought Tolerant ◽  
Mild Drought

AbstractThe world-wide distribution of Arabidopsis thaliana (Arabidopsis) accessions imposes different types of evolutionary pressures, which contributes to various responses of these accessions to environmental stresses. Drought stress responses have been well studied, particularly in Columbia, a common Arabidopsis accession. However, the reactions to drought stress are complex and our understanding of which of these responses contribute to the plant’s tolerance to mild drought is very limited. Here, we studied the mechanisms by which natural accessions react to mild drought at a physiological and molecular level during early leaf development. We documented variations in mild drought tolerance among natural accessions and used transcriptome sequencing of a drought-sensitive accession, ICE163, and a drought-tolerant accession, Yeg-1, to get insights into the mechanisms underlying this tolerance. This revealed that ICE163 preferentially induces jasmonates and anthocyanin-related pathways, which are beneficial in biotic stress defense, while Yeg-1 has a more pronounced activation of abscisic acid signaling, the classical abiotic stress response. Related physiological traits, including content of proline, anthocyanins and ROS, stomatal closure and cellular leaf parameters, were investigated and linked to the transcriptional responses. We conclude that most of these processes constitute general drought response mechanisms that are regulated similarly in drought-tolerant and -sensitive accessions. However, the capacity to close stomata and maintain cell expansion under mild drought appeared to be major factors that contribute to a better leaf growth under mild drought.One-sentence summaryThis paper demonstrates that an efficient closure of stomata and maintenance of cell expansion during drought conditions are crucial to maximally preserve plant growth during water deficit.

Plant hydraulic conductivity determines photosynthesis in rice under PEG-induced drought stress

2020 ◽  
Vol 53 (2) ◽  
Author(s):  
Guanglong Zhu ◽  
Lifeng Gu ◽  
Yu Shi ◽  
Huize Chen ◽  
Yuqian Liu ◽  
...  
Keyword(s):  
Drought Stress ◽  
Hydraulic Conductivity ◽  
Plant Hydraulic Conductivity

scholarly journals Arabidopsis MADS-box factor AGL16 negatively regulates drought resistance via stomatal density and stomatal movement

2020 ◽  
Vol 71 (19) ◽  
pp. 6092-6106 ◽  
Author(s):  
Ping-Xia Zhao ◽  
Zi-Qing Miao ◽  
Jing Zhang ◽  
Si-Yan Chen ◽  
Qian-Qian Liu ◽  
...  
Keyword(s):  
Drought Stress ◽  
Drought Resistance ◽  
Molecular Mechanisms ◽  
Stomatal Density ◽  
Stomatal Closure ◽  
Negative Regulator ◽  
Stomatal Development ◽  
Mads Box ◽  
Mobility Shift ◽  
Aba Metabolism

Abstract Drought is one of the most important environmental factors limiting plant growth and productivity. The molecular mechanisms underlying plant drought resistance are complex and not yet fully understood. Here, we show that the Arabidopsis MADS-box transcription factor AGL16 acts as a negative regulator in drought resistance by regulating stomatal density and movement. Loss-of-AGL16 mutants were more resistant to drought stress and had higher relative water content, which was attributed to lower leaf stomatal density and more sensitive stomatal closure due to higher leaf ABA levels compared with the wild type. AGL16-overexpressing lines displayed the opposite phenotypes. AGL16 is preferentially expressed in guard cells and down-regulated in response to drought stress. The expression of CYP707A3 and AAO3 in ABA metabolism and SDD1 in stomatal development was altered in agl16 and overexpression lines, making them potential targets of AGL16. Using chromatin immunoprecipitation, transient transactivation, yeast one-hybrid, and electrophoretic mobility shift assays, we demonstrated that AGL16 was able to bind the CArG motifs in the promoters of the CYP707A3, AAO3, and SDD1 and regulate their transcription, leading to altered leaf stomatal density and ABA levels. Taking our findings together, AGL16 acts as a negative regulator of drought resistance by modulating leaf stomatal density and ABA accumulation.

scholarly journals Leaf Responses to Mild Drought Stress in Natural Variants of Arabidopsis

2015 ◽  
Vol 167 (3) ◽  
pp. 800-816 ◽  
Author(s):  
Pieter Clauw ◽  
Frederik Coppens ◽  
Kristof De Beuf ◽  
Stijn Dhondt ◽  
Twiggy Van Daele ◽  
...  
Keyword(s):  
Drought Stress ◽  
Natural Variants ◽  
Mild Drought

Monitoring of transcriptional responses in roots of six wheat cultivars during mild drought stress

2013 ◽  
Vol 41 (4) ◽  
pp. 527-538 ◽  
Author(s):  
M. Szécsényi ◽  
M. Cserháti ◽  
Á. Zvara ◽  
D. Dudits ◽  
J. Györgyey
Keyword(s):  
Drought Stress ◽  
Wheat Cultivars ◽  
Transcriptional Responses ◽  
Mild Drought

scholarly journals Testing for ion-mediated enhancement of the hydraulic conductance of the leaf xylem in diverse angiosperms

2017 ◽  
Vol 4 ◽  
pp. e004 ◽  
Author(s):  
Christine Scoffoni ◽  
Grace John ◽  
Herve Cochard ◽  
Lawren Sack
Keyword(s):  
Water Solution ◽  
Pure Water ◽  
Xylem Sap ◽  
Hydraulic Conductance ◽  
Membrane Pores ◽  
Whole Plant ◽  
Pit Membrane ◽  
Major Bottleneck ◽  
The Difference ◽  
Xylem Conduits

Replacing ultra-pure water solution with ion solution closer to the composition of natural xylem sap increases stem hydraulic conductance by up to 58%, likely due to changes in electroviscosity in the pit membrane pores. This effect has been proposed to contribute to the control of plant hydraulic and stomatal conductance and potentially to influence on carbon balance during dehydration. However, this effect has never been directly tested for leaf xylem, which constitutes a major bottleneck in the whole plant. We tested for an ion-mediated increase in the hydraulic conductance of the leaf xylem (Kx) for seven species diverse in phylogeny and drought tolerance. Across species, no significant changes in Kx were observed between 0 and 15 mM KCl. We further tested for an effect of ion solution during measurements of Kx vulnerability to dehydration in Quercus agrifolia and found no significant impact. These results for leaf xylem contrast with the often strong ion effect reported for stems, and we suggest several hypotheses to account for the difference, relating to the structure of xylem conduits across vein orders, and the ultrastructure of leaf xylem pores. A negligible ion response in leaves would weaken xylem sap ion-mediated control of plant hydraulic conductance, facilitating modeling of whole plant hydraulic behavior and its influence on productivity.

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