Effects of ectomycorrhizal fungi (Suillus variegatus) on the growth, hydraulic function, and non-structural carbohydrates of Pinus tabulaeformis under drought stress

Abstract Background A better understanding of non-structural carbohydrate (NSC) dynamics in trees under drought stress is critical to elucidate the mechanisms underlying forest decline and tree mortality from extended periods of drought. This study aimed to assess the contribution of ectomycorrhizal (ECM) fungus (Suillus variegatus) to hydraulic function and NSC in roots, stems, and leaves of Pinus tabulaeformis subjected to different water deficit intensity. We performed a continuous controlled drought pot experiment from July 10 to September 10, 2019 using P. tabulaeformis seedlings under 80, 40, and 20% of the field moisture capacity that represented the absence of non-drought, moderate drought, and severe drought stress, respectively. Results Results indicated that S. variegatus decreased the mortality rate and increased height, root biomass, and leaf biomass of P. tabulaeformis seedlings under moderate and severe drought stress. Meanwhile, the photosynthetic rates, stomatal conductance, and transpiration rates of P. tabulaeformis were significantly increased after S. variegatus inoculation. Moreover, the inoculation of S. variegatus also significantly increased the NSC concentrations of all seedling tissues, enhanced the soluble sugars content, and increased the ratios of soluble sugars to starch on all tissues under severe drought. Overall, the inoculation of S. variegatus has great potential for improving the hydraulic function, increasing the NSC storage, and improving the growth of P. tabulaeformis under severe drought. Conclusions Therefore, the S. variegatus can be used as a potential application strain for ecological restoration on arid regions of the Loess Plateau, especially in the P. tabulaeformis woodlands.

Download Full-text

Effects of mild and severe drought stress on the biomass, phenolic compounds production and photochemical activity of Aloe vera (L.) Burm.f.

Acta agriculturae Slovenica ◽

10.14720/aas.2018.111.2.19 ◽

2018 ◽

Vol 111 (2) ◽

pp. 463 ◽

Cited By ~ 2

Author(s):

Ghader HABIBI

Keyword(s):

Drought Stress ◽

Secondary Metabolite ◽

Soluble Sugars ◽

Compatible Solutes ◽

Aloe Vera ◽

Photochemical Activity ◽

Leaf Biomass ◽

Total Phenolic ◽

Severe Drought ◽

Mild Drought

In this study, the biomass, compatible solutes, PSII functioning and phenolic profiles of Aloe vera (<a title="Carl Linnaeus" href="https://en.wikipedia.org/wiki/Carl_Linnaeus">L.</a>) <a title="" href="https://en.wikipedia.org/wiki/Nicolaas_Laurens_Burman">Burm.f.</a> leaves were investigated at different time intervals after drought stress (20, 40 and 80 % of the field capacity). While the impaired ability of leaves for synthesis of assimilates caused growth inhibition in A. vera under severe drought stress, we observed that the content of proline, soluble sugars, total phenolic and flavonoids tended to increase in plants treated with mild drought stress. Under mild drought stress, the increased leaf thickness correlated with the higher productivity in terms of leaf biomass and gel production. Also, mild drought stress enhanced photochemical activity in Aloe leaves, and changed the entire quantity of secondary metabolite of vanillic acid produced, which may be considered to obtain better growth and considerable secondary metabolite of the medicinal Aloe plants treated with mild drought stress.

Download Full-text

Drought resistance mechanisms of Phedimus aizoon L.

Scientific Reports ◽

10.1038/s41598-021-93118-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yuhang Liu ◽

Zhongqun He ◽

Yongdong Xie ◽

Lihong Su ◽

Ruijie Zhang ◽

...

Keyword(s):

Drought Stress ◽

Soluble Sugars ◽

Resistance Mechanisms ◽

Severe Drought ◽

Available Water Content ◽

Drought Tolerant ◽

Moderate Drought ◽

Leaf Anatomical Structure ◽

Physiological Indexes ◽

Mild Drought

AbstractPhedimus aizoon L. is a drought-resistant Chinese herbal medicine and vegetable. However, its drought tolerant limit and the mechanism of drought tolerance are unknown, which restricts the promotion of water-saving cultivation of Phedimus aizoon L. in arid areas. To solve the above problem, we carried out a 30-day-long drought stress experiment in pots that presented different soil water contents and were divided into four groups: control check, 75–80% of the maximum water-holding capacity (MWHC); mild drought, 55–60%; moderate drought, 40–45%; and severe drought, 20–25%. The dynamic changes in both plant physiological indexes from 10 to 30 days and leaf anatomical structure on the 30th day of stress were recorded. The results show that Phedimus aizoon L. grew normally under mild drought stress for 30 days, but the growth of the plants became inhibited after 20 days of severe drought and after 30 days of moderate drought. At the same time, Phedimus aizoon L. physiologically responded to cope with drought stress: the growth of the root system accelerated, the waxy layer of the leaves thickened, and the dark reactions of the plants transformed from those of the C3 cycle to CAM. The activity of antioxidant enzymes (SOD, POD and CAT) continuously increased to alleviate the damage caused by drought stress. To ensure the relative stability of the osmotic potential, the contents of osmoregulatory substances such as proline, soluble sugars, soluble protein and trehalose increased correspondingly. Although Phedimus aizoon L. has strong drought stress resistance, our experimental results show that the soil available water content should not be less than 27% during cultivation.

Download Full-text

Enhancement of drought tolerance in diverse Vicia faba cultivars by inoculation with plant growth-promoting rhizobacteria under newly reclaimed soil conditions

Scientific Reports ◽

10.1038/s41598-021-02847-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Elsayed Mansour ◽

Hany A. M. Mahgoub ◽

Samir A. Mahgoub ◽

El-Sayed E. A. El-Sobky ◽

Mohamed I. Abdul-Hamid ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Plant Growth ◽

Plant Growth Promoting Rhizobacteria ◽

Severe Drought ◽

Drought Conditions ◽

Moderate Drought ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Effects Of Drought

AbstractWater deficit has devastating impacts on legume production, particularly with the current abrupt climate changes in arid environments. The application of plant growth-promoting rhizobacteria (PGPR) is an effective approach for producing natural nitrogen and attenuating the detrimental effects of drought stress. This study investigated the influence of inoculation with the PGPR Rhizobium leguminosarum biovar viciae (USDA 2435) and Pseudomonas putida (RA MTCC5279) solely or in combination on the physio-biochemical and agronomic traits of five diverse Vicia faba cultivars under well-watered (100% crop evapotranspiration [ETc]), moderate drought (75% ETc), and severe drought (50% ETc) conditions in newly reclaimed poor-fertility sandy soil. Drought stress substantially reduced the expression of photosynthetic pigments and water relation parameters. In contrast, antioxidant enzyme activities and osmoprotectants were considerably increased in plants under drought stress compared with those in well-watered plants. These adverse effects of drought stress reduced crop water productivity (CWP) and seed yield‐related traits. However, the application of PGPR, particularly a consortium of both strains, improved these parameters and increased seed yield and CWP. The evaluated cultivars displayed varied tolerance to drought stress: Giza-843 and Giza-716 had the highest tolerance under well-watered and moderate drought conditions, whereas Giza-843 and Sakha-4 were more tolerant under severe drought conditions. Thus, co-inoculation of drought-tolerant cultivars with R. leguminosarum and P. putida enhanced their tolerance and increased their yield and CWP under water-deficit stress conditions. This study showed for the first time that the combined use of R. leguminosarum and P. putida is a promising and ecofriendly strategy for increasing drought tolerance in legume crops.

Download Full-text

Phedimus Aizoon L. Responds to Drought Stress: Growth, Physiological Changes and Mechanism of Drought Resistance

10.21203/rs.3.rs-132688/v1 ◽

2020 ◽

Author(s):

Yuhang Liu ◽

Zhongqun He ◽

Yongdong Xie ◽

Lihong Su ◽

Ruijie Zhang ◽

...

Keyword(s):

Drought Stress ◽

Drought Resistance ◽

Soluble Sugar ◽

Severe Drought ◽

Physiological Changes ◽

Moderate Drought ◽

Negative Effect ◽

Mda Content ◽

Maximum Water ◽

Mild Drought

Abstract A pot experiment was conducted to investigate the growth, physiological changes and mechanism of drought resistance of Phedimus aizoon L. under different levels of water content .CK: 75% ~ 80% of the MWHC (maximum water holding capacity), Mild drought: 55% ~ 60%, Moderate drought: 40% ~ 45%, Severe drought: 20% ~ 25%.We observed that the plants grew normally in the first two treatments, even the mild drought promoted the growth of the roots. In the last two treatments, drought stress had a significant negative effect on plant growth, at the same time, Phedimus aizoon L. also made positive physiological response to cope with the drought: The aboveground part of the plant (leaf, plant height, stem diameter) was smaller, the waxy layer of the leaves was thickened, the stomata of the leaves were closed during the day, and only a few stomata were opened at night, which proved that the dark reaction cycle metabolism mode of the plant was transformed from C3 cycle to CAM pathway. The activity of antioxidant enzymes (SOD, POD and CAT) was continuously increased to alleviate the damage caused by drought. To ensure the relative stability of osmotic potential, the contents of osmoregulation substances such as proline, soluble sugar, soluble protein and trehalose increased correspondingly. But plants have limited regulatory power, with aggravation of drought stress degree and extension of stress time, the MDA content and electrolyte leakage of leaves increased continuously. Observed under electron microscope,the morphology of chloroplast and mitochondria changed and the membrane structure was destroyed. The plant's photosynthetic and respiratory mechanisms are destroyed and the plant gradually die.

Download Full-text

Foliar Supplementation of Clove Fruit Extract and Salicylic Acid Maintains the Performance and Antioxidant Defense System of Solanum tuberosum L. Under Deficient Irrigation Regimes

Horticulturae ◽

10.3390/horticulturae7110435 ◽

2021 ◽

Vol 7 (11) ◽

pp. 435

Author(s):

El-Sayed M. Desoky ◽

Eman Selem ◽

Mohamed F. Abo El-Maati ◽

Asem A. S. A. Hassn ◽

Hussein E. E. Belal ◽

...

Keyword(s):

Salicylic Acid ◽

Solanum Tuberosum ◽

Drought Stress ◽

Solanum Tuberosum L ◽

Combined Treatment ◽

Soluble Sugars ◽

Growth And Yield ◽

Severe Drought ◽

Fruit Extract ◽

Irrigation Regimes

A field trial was conducted twice (in 2020 and 2021) to evaluate the effect of clove fruit extract (CFE) and/or salicylic acid (SA), which were used as a foliar nourishment, on growth and yield traits, as well as physiological and biochemical indices utilizing potato (Solanum tuberosum L.) plants irrigated with deficient regimes in an arid environment. Three drip irrigation regimes [e.g., well watering (7400 m3 ha−1), moderate drought (6200 m3 ha−1), and severe drought (5000 m3 ha−1)] were designed for this study. The tested growth, yield, and photosynthetic traits, along with the relative water content, were negatively affected, whereas markers of oxidative stress (hydrogen peroxide and superoxide), electrolyte leakage, and peroxidation of membrane lipids (assessed as malondialdehyde level) were augmented along with increased antioxidative defense activities under drought stress. These effects were gradually increased with the gradual reduction in the irrigation regime. However, under drought stress, CFE and/or SA significantly enhanced growth characteristics (fresh and dry weight of plant shoot and plant leaf area) and yield components (average tuber weight, number of plant tubers, and total tuber yield). In addition, photosynthetic attributes (chlorophylls and carotenoids contents, net photosynthetic and transpiration rates, and stomatal conductance) were also improved, and defensive antioxidant components (glutathione, free proline, ascorbate, soluble sugars, and α-tocopherol levels, and activities of glutathione reductase, peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase) were further enhanced. The study findings advocate the idea of using a CFE + SA combined treatment, which was largely efficient in ameliorating potato plant growth and productivity by attenuating the limiting influences of drought stress in dry environments.

Download Full-text

Leaf morphology, photochemistry and water status changes in resprouting Quercus ilex during drought

Functional Plant Biology ◽

10.1071/fp04137 ◽

2005 ◽

Vol 32 (2) ◽

pp. 117 ◽

Cited By ~ 41

Author(s):

Karen Peña-Rojas ◽

Xavier Aranda ◽

Richard Joffre ◽

Isabel Fleck

Keyword(s):

Drought Stress ◽

Quercus Ilex ◽

Structural Characteristics ◽

Water Status ◽

Stomatal Closure ◽

Severe Drought ◽

Clear Cut ◽

Leaf Mass Area ◽

Relative Water ◽

Moderate Drought

Functional and morphological (structural) characteristics of Quercus ilex L. leaves under drought stress were studied in the forest and in a nursery. We compared undisturbed individuals (controls) with resprouts emerging after clear-cut or excision. When soil water availability was high, gas-exchange was similar in resprouts and controls, despite higher midday leaf water potential, midday leaf hydration and relative water content (RWC). In moderate drought, stomatal closure was found to limit photosynthesis in controls, and in severe drought non-stomatal limitations of photosynthesis were also greater than in resprouts. Leaf structure and chemical composition changed under drought stress. Leaves tended to be smaller in controls with increasing drought, and resprouts had larger leaves and lower leaf mass area (LMA). The relationship between nitrogen (N) content and LMA implied lower N investment in photosynthetic components in controls, which could be responsible for their increased non-stomatal limitation of photosynthesis. Changes were more apparent in leaf density (D) and thickness (T), components of LMA. Decreases in D were related to reductions in cell wall components: hemicellulose, cellulose and lignin. In resprouts, reduced D and leaf T accounted for the higher mesophyll conductance (gmes) to CO2 measured.

Download Full-text

The resistance and resilience of European beech seedlings to drought stress during the period of leaf development

Tree Physiology ◽

10.1093/treephys/tpaa066 ◽

2020 ◽

Vol 40 (9) ◽

pp. 1147-1164

Author(s):

Roman Gebauer ◽

Roman Plichta ◽

Josef Urban ◽

Daniel Volařík ◽

Martina Hájíčková

Keyword(s):

Drought Stress ◽

Hydraulic Conductivity ◽

Gas Exchange ◽

Tree Ring ◽

Leaf Development ◽

Leaf Gas Exchange ◽

Recovery Period ◽

European Beech ◽

Leaf Biomass ◽

Severe Drought

Abstract Spring drought is becoming a frequently occurring stress factor in temperate forests. However, the understanding of tree resistance and resilience to the spring drought remains insufficient. In this study, European beech (Fagus sylvatica L.) seedlings at the early stage of leaf development were moderately and severely drought stressed for 1 month and then subjected to a 2-week recovery period after rewatering. The study aimed to disentangle the complex relationships between leaf gas exchange, vascular anatomy, tree morphology and patterns of biomass allocation. Stomatal conductance decreased by 80 and 85% upon moderate and severe drought stress, respectively, which brought about a decline in net photosynthesis. However, drought did not affect the indices of slow chlorophyll fluorescence, indicating no permanent damage to the light part of the photosynthetic apparatus. Stem hydraulic conductivity decreased by more than 92% at both drought levels. Consequently, the cambial activity of stressed seedlings declined, which led to lower stem biomass, reduced tree ring width and a lower number of vessels in the current tree ring, these latter also with smaller dimensions. In contrast, the petiole structure was not affected, but at the cost of reduced leaf biomass. Root biomass was reduced only by severe drought. After rewatering, the recovery of gas exchange and regrowth of the current tree ring were observed, all delayed by several days and by lower magnitudes in severely stressed seedlings. The reduced stem hydraulic conductivity inhibited the recovery of gas exchange, but xylem function started to recover by regrowth and refilling of embolized vessels. Despite the damage to conductive xylem, no mortality occurred. These results suggest the low resistance but high resilience of European beech to spring drought. Nevertheless, beech resilience could be weakened if the period between drought events is short, as the recovery of severely stressed seedlings took longer than 14 days.

Download Full-text

Drought Tolerance Responses in Vegetable-Type Soybean Involve a Network of Biochemical Mechanisms at Flowering and Pod-Filling Stages

Plants ◽

10.3390/plants10081502 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1502

Author(s):

Makoena Joyce Moloi ◽

Rouxlene van der Merwe

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Soluble Sugars ◽

Seed Mass ◽

H2o2 Production ◽

Guaiacol Peroxidase ◽

Severe Drought ◽

Flowering Stage ◽

Tolerance Response ◽

Total Seed

Severe drought stress affects the production of vegetable-type soybean (Glycine max L. Merrill), which is in infancy for Africa despite its huge nutritional benefits. This study was conducted under controlled environmental conditions to establish the effects of severe drought stress on ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and glutathione reductase (GR) activities as well as proline, total soluble sugars (TSS), and hydrogen peroxide (H2O2) contents of five vegetable-type soybean cultivars (UVE8, UVE14, UVE17, AGS354, AGS429) at flowering and pod-filling stages. Drought induced significant increases in the contents of proline (selectively at pod filling for AGS429), TSS (at both stages for AGS429, and only at pod filling for UVE14), and malondialdehyde (AGS354 at flowering; UVE17 at pod filling). UVE8 and AGS354 had the highest H2O2 levels at flowering under drought stress, while AGS429 had the lowest. However, AGS429 was the only cultivar with significantly increased H2O2 under drought stress. Furthermore, drought stress induced significant increases in APX, GPX, and GR activities at flowering for AGS429. AGS354 recorded the highest decline for all antioxidative enzymes, while UVE17 decreased for GPX only. All biochemical parameters, except H2O2, were significantly higher at pod filling than at the flowering stage. The relationship between H2O2 and total seed mass (TSMP) or total seed per plant (TSP) was significantly positive for both stages, while that of TSS (at flowering) and proline (at pod filling) were significantly related to total pods per plant (TPP). The study suggests that during drought, the tolerance responses of vegetable-type soybean, APX, GPX, and GR (especially at the flowering stage), function in concert to minimize H2O2 production and lipid peroxidation, thereby allowing H2O2 to function in the signaling events leading to the induction of drought tolerance. The induction of TSS at flowering and proline at pod filling is important in the drought tolerance response of this crop.

Download Full-text

Mycorrhiza Fungus Rhizophagus intraradices Mediates Drought Tolerance in Eleusine coracana Seedlings

10.20944/preprints201805.0064.v1 ◽

2018 ◽

Cited By ~ 2

Author(s):

Jaagriti Tyagi ◽

Neeraj Shrivastava ◽

A. K. Sharma ◽

Ajit Varma ◽

Ramesh Namdeo Pudake

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Finger Millet ◽

Soluble Sugars ◽

Leaf Tissue ◽

Am Fungi ◽

Mycorrhizal Symbiosis ◽

Severe Drought ◽

Rhizophagus Intraradices

Under abiotic stress conditions, arbuscular mycorrhizal (AM) fungi help plants by improving nutrient and water uptake. Finger millet is an arid crop having soils with poor water holding capacity. Therefore, it is difficult for the plants to obtain water and mineral nutrients from the soil to sustain life. To understand the role of mycorrhizal symbiosis in water and mineral up-take from the soil, we studied the role of Rhizophagus intraradices colonization and its beneficial role for drought stress tolerance in finger millet seedling. Under severe drought stress condition, AM inoculation led to the significant increase in plant growth (7%), phosphorus, and chlorophyll content (29%). Also, the level of osmolytes including proline and soluble sugars were found in higher quantities in AM inoculated seedlings under drought stress. Under water stress, the lipid peroxidation in leaves of mycorrhized seedlings was reduced by 29%. The flavonoid content of roots in AM colonized seedlings was found 16% higher compared to the control, whereas the leaves were accumulated more phenol. Compared to the control, ascorbate level was found to be 25% higher in leaf tissue of AM inoculated seedlings. Moreover, glutathione (GSH) level was increased in mycorrhiza inoculated seedlings with a maximum increment of 182% under severe stress. The results demonstrated that AM provided drought tolerance to the finger millet seedlings through a stronger root system, greater photosynthetic efficiency, a more efficient antioxidant system and improved osmoregulation.

Download Full-text

Effects of root phenotypic changes on the deep rooting of Populus euphratica seedlings under drought stresses

PeerJ ◽

10.7717/peerj.6513 ◽

2019 ◽

Vol 7 ◽

pp. e6513 ◽

Cited By ~ 2

Author(s):

Zi-qi Ye ◽

Jian-ming Wang ◽

Wen-juan Wang ◽

Tian-han Zhang ◽

Jing-wen Li

Keyword(s):

Drought Stress ◽

Root Architecture ◽

Mass Fraction ◽

Populus Euphratica ◽

Severe Drought ◽

Root Depth ◽

Phenotypic Changes ◽

Positive Effects ◽

Drought Conditions ◽

Moderate Drought

Background Deep roots are critical for the survival of Populus euphratica seedlings on the floodplains of arid regions where they easily suffer drought stress. Drought typically suppresses root growth, but P. euphratica seedlings can adjust phenotypically in terms of root-shoot allocation and root architecture and morphology, thus promoting deep rooting. However, the root phenotypic changes undertaken by P. euphratica seedlings as a deep rooting strategy under drought conditions remain unknown. Methods We quantified deep rooting capacity by the relative root depth (RRD), which represents the ratio of taproot length to plant biomass and is controlled by root mass fraction (RMF), taproot mass fraction (TRMF), and specific taproot length (STRL). We recorded phenotypic changes in one-year-old P. euphratica seedlings under control, moderate and severe drought stress treatments and assessed the effects of RMF, TRMF, and STRL on RRD. Results Drought significantly decreased absolute root depth but substantially increased RRD via exerting positive effects on TRMF, RMF, and STRL. Under moderate drought, TRMF contributed 55%, RMF 27%, and STRL 18% to RRD variation. Under severe drought, the contribution of RMF to RRD variation increased to 37%, which was similar to the 41% for TRMF. The contribution of STRL slightly increased to 22%. Conclusion These results suggest that the adjustments in root architecture and root-shoot allocation were predominantly responsible for deep rooting in P. euphratica seedlings under drought conditions, while morphological changes played a minor role. Moreover, P. euphratica seedlings rely mostly on adjusting their root architecture to maintain root depth under moderate drought conditions, whereas root-shoot allocation responds more strongly under severe drought conditions, to the point where it plays a role as important as root architecture does on deep rooting.

Download Full-text