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1.
Plants of Helianthemum almeriense were micropropagated on MS medium and inoculated in vitro with Terfezia claveryi mycelium on MH medium and vermiculite. Mycorrhizal (M) and non-mycorrhizal (NM) plants were subjected to a drought stress
period of 3 weeks in greenhouse conditions with the soil matric potential maintained at –0.5 MPa. Drought stress did not affect
the amount of mycorrhizal colonization. The survival rate of M plants at the end of the drought stress period was higher than
that of NM plants. The water potential was higher in M plants than in NM plants by 14% in well-watered and 26% in drought-stressed
plants. Transpiration, stomatal conductance and net photosynthesis were higher in M plants than in NM plants. Transpiration
was 92% higher in M plants than in NM plants under drought-stress conditions and 40% when irrigated. Stomatal conductance
was 45% and 14% higher and net photosynthesis 88% and 54% higher, respectively, in M than in NM plants. Drought-stressed M
plants accumulated more N, P and K than drought-stressed NM plants. Reduced negative effects of drought stress on H. almeriense by the desert truffle T. claveryi could be ascribed to specific physiological and nutritional mechanisms, suggesting that this mycorrhizal symbiosis aids adaptation
to arid climates.
Accepted: 7 July 2000 相似文献
2.
José Eduardo Marqués-Gálvez Alfonso Navarro-Ródenas José Javier Peguero-Pina Francisco Arenas Angel Luigi Guarnizo Eustaquio Gil-Pelegrín Asunción Morte 《Physiologia plantarum》2020,170(4):537-549
Predicted increases in atmospheric concentration of carbon dioxide (CO2) coupled with increased temperatures and drought are expected to strongly influence the development of most of the plant species in the world, especially in areas with high risk of desertification like the Mediterranean basin. Helianthemum almeriense is an ecologically important Mediterranean shrub with an added interest because it serves as the host for the Terfezia claveryi mycorrhizal fungus, which is a desert truffle with increasingly commercial interest. Although both plant and fungi are known to be well adapted to dry conditions, it is still uncertain how the increase in atmospheric CO2 will influence them. In this article we have addressed the physiological responses of H. almeriense × T. claveryi mycorrhizal plants to increases in atmospheric CO2 coupled with drought and high vapor pressure deficit. This work reports one of the few estimations of mesophyll conductance in a drought deciduous Mediterranean shrub and evaluates its role in photosynthesis limitation. High atmospheric CO2 concentrations help desert truffle mycorrhizal plants to cope with the adverse effects of progressive drought during Mediterranean springs by improving carbon net assimilation, intrinsic water use efficiency and dispersal of the species through increased flowering events. 相似文献
3.
Root Respiration,Photosynthesis and Grain Yield of Two Spring Wheat in Response to Soil Drying 总被引:3,自引:0,他引:3
The effects of soil water regime and wheat cultivar, differing in drought tolerance with respect to root respiration and grain
yield, were investigated in a greenhouse experiment. Two spring wheat (Triticum aestivum) cultivars, a drought sensitive (Longchun 8139-2) and drought tolerant (Dingxi 24) were grown in PVC tubes (120 cm in length and 10 cm in diameter) under an automatic rain-shelter. Plants were subjected
to three soil moisture regimes: (1) well-watered control (85% field water capacity, FWC); (2) moderate drought stress (50%
FWC) and (3) severe drought stress (30% FWC). The aim was to study the influence of root respiration on grain yield under
soil drying conditions. In the experiment, severe drought stress significantly (p < 0.05) reduced shoot and root biomass, photosynthesis and root respiration rate for both cultivars, but the extent of the
decreases was greater for Dingxi 24 compared to that for Longchun 8139-2. Compared with Dingxi 24, 0.04 and 0.07 mg glucose m−2 s−1 of additional energy, equivalent to 0.78 and 1.43 J m−2 s−1, was used for water absorption by Longchun 8139-2 under moderate and severe drought stress, respectively. Although the grain yield of both cultivars decreased with declining
soil moisture, loss was greater in Longchun 8139-2 than in Dingxi 24, especially under severe drought stress. The drought tolerance cultivar (Dingxi 24), had a higher biomass and metabolic activity under severe drought stress compared to the sensitive cultivar (Longchun 8139-2), which resulted in further limitation of grain yield. Results show that root respiration, carbohydrates allocation (root:shoot
ratio) and grain yield were closely related to soil water status and wheat cultivar. Reductions in root respiration and root
biomass under severe soil drying can improve drought tolerant wheat growth and physiological activity during soil drying and
improve grain yield, and hence should be advantageous over a drought sensitive cultivar in arid regions. 相似文献
4.
V. Sandhya Sk. Z. Ali Minakshi Grover Gopal Reddy B. Venkateswarlu 《Plant Growth Regulation》2010,62(1):21-30
Drought is one of the major abiotic stresses affecting yield of dryland crops. Rhizobacterial populations of stressed soils
are adapted and tolerant to stress and can be screened for isolation of efficient stress adaptive/tolerant, plant growth promoting
rhizobacterial (PGPR) strains that can be used as inoculants for crops grown in stressed ecosystems. The effect of inoculation
of five drought tolerant plant growth promoting Pseudomonas spp. strains namely P.
entomophila strain BV-P13, P. stutzeri strain GRFHAP-P14, P. putida strain GAP-P45, P. syringae strain GRFHYTP52, and P. monteilli strain WAPP53 on growth, osmoregulation and antioxidant status of maize seedlings under drought stress conditions was investigated.
Drought stress induced by withholding irrigation had drastic effects on growth of maize seedlings. However seed bacterization
of maize with Pseudomonas spp. strains improved plant biomass, relative water content, leaf water potential, root adhering soil/root tissue ratio, aggregate
stability and mean weight diameter and decreased leaf water loss. The inoculated plants showed higher levels of proline, sugars,
free amino acids under drought stress. However protein and starch content was reduced under drought stress conditions. Inoculation
decreased electrolyte leakage compared to uninoculated seedlings under drought stress. As compared to uninoculated seedlings,
inoculated seedlings showed significantly lower activities of antioxidant enzymes, ascorbate peroxidase (APX), catalase (CAT),
glutathione peroxidase (GPX) under drought stress, indicating that inoculated seedlings felt less stress as compared to uninoculated
seedlings. The strain GAP-P45 was found to be the best in terms of influencing growth and biochemical and physiological status
of the seedlings under drought stress. The study reports the potential of rhizobacteria in alleviating drought stress effects
in maize. 相似文献
5.
Sorghum (Sorghum bicolor L. Moench) plants were grown in solution culture and stressed at three rates of decreasing leaf water potential (−0.123,
−0.068 and −0.029 MPa day−1) achieved by the incremental addition of an osmoticum, polyethylene glycol (PEG) 6000 to the solutions. Plants were also
grown in soil and given different amounts of water which resulted in rates of decreasing leaf water potentials of −0.130 and
−0.073 MPa day−1.
The rate of stress and the culture system influenced the accumulation of solutes in the cell, but not cell volume. A rapid
stress (−0.123 and −0.130 MPa day−1) to approximately −1.6 MPa leaf water potential resulted in 0.75 and 0.16 MPa of osmotic adjustment in the PEG and soil culture
respectively. At moderate stress (−0.068 and −0.073 MPa day−1) respective values were 1.68 and 0.58 MPa. There were some visual symptoms in the solution grown plants characteristic of
uptake of high molecular weight PEG. However the relative growth rates of these plants were equal to or greater than those
of the soil grown plants.
In view of the differences in plant water status of soil and PEG solution cultured plants it was concluded that the use of
the latter system would not be entirely suitable for some studies of drought resistance in sorghum, as related to crop performance
in the field. 相似文献
6.
José Manuel López‐Nicolás Manuela Pérez‐Gilabert Francisco García‐Carmona María Cecilia Lozano‐Carrillo Asunción Morte 《Biotechnology progress》2013,29(6):1558-1564
The commercial value of Terfezia claveryi, an edible desert truffle with important gastronomic, nutritional, and antioxidant properties, has led to growing interest in its cultivation. The erratic and slow growth of T. claveryi mycelium in vitro represents an impairment to obtain mycorrhizal plants, and it makes necessary to find a new culture medium able to overcome these drawbacks. In this work, we analyze the effect of cyclodextrins (CDs) on the growth of T. claveryi mycelium. Different parameters, including colony diameter, growth rate, and colony fresh weight, were evaluated, both in the presence and absence of these encapsulant agents. The results obtained confirm the ability of CDs to stimulate the growth of T. claveryi mycelium when present in the culture medium. A similar effect was observed when CDs were added to the culture medium of Tuber melanosporum. Three natural (α‐, β‐, and γ) and two modified (hydroxypropil‐β and methyl‐β) CDs were assayed. The best results were obtained with β‐cyclodextrin, but no improvement was observed with its chemically modified derivatives. CDs complex the different compounds present in the culture medium which impair mycelial growth. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1558–1564, 2013 相似文献
7.
U. Celikkol Akcay O. Ercan M. Kavas L. Yildiz C. Yilmaz H. A. Oktem M. Yucel 《Plant Growth Regulation》2010,61(1):21-28
Two cultivars of peanut (Arachis
hypogaea L.) which were designated as resistant (Florispan) and sensitive (Gazipasa) according to their growth retardation under drought
stress conditions were compared for their oxidative damage and antioxidant responses. Sixteen days-old peanut seedlings were
subjected to PEG-6000 solutions of two different osmotic potentials; −0.4 and −0.8 MPa, and various growth parameters, photosystem
II activity, changes in malondialdehyde (MDA), hydrogen peroxide (H2O2) and proline levels, activities of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POX) and gluthatione reductase
(GR) enzymes were determined. Both cultivars exhibited water deficit at −0.8 MPa osmotic potential of PEG-6000 and H2O2 levels significantly increased during exposure to −0.4 MPa osmotic potential. However, H2O2 levels were under control in both cultivars at exposure to −0.8 MPa osmotic potential. Significant proline accumulation was
observed in the tissues of cv. Florispan at −0.8 MPa osmotic potential, whereas proline accumulation did not appear to be
an essential part of the protection mechanism against drought in cv. Gazipasa. No significant variation in chlorophyll fluorescence
values were detected in neither of the cultivars. Enzyme activity measurements revealed that Gazipasa copes well with lesser
magnitudes of drought stress by increasing the activity of mainly APX, and during harsh stress conditions, only APX maintains
its activity in the tissues. In cultivar Florispan, GR activity appears to take role in lesser magnitudes of drought stress,
whereas CAT and APX activities appear to be very crucial antioxidative defenses during intense stress conditions. The results
indicate that, the level of proline and activities of the enzymes CAT and APX are important mechanisms for the maintenance
of drought tolerance in peanut plants. 相似文献
8.
Francisco Arenas Alfonso Navarro-Ródenas José Eduardo Marqués-Gálvez Stefano Ghignone Antonietta Mello Asunción Morte 《Environmental microbiology》2021,23(10):5917-5933
The desert truffle Terfezia claveryi is one of the few mycorrhizal fungi currently in cultivation in semiarid and arid areas. Agroclimatic parameters seem to affect its annual yield, but there is no information on the influence of biotic factors. In this study, fungal diversity was analysed by high-throughput sequencing of the ITS2 rDNA region from soil and root samples to compare productive and non-productive mycorrhizal plants in a 4-years old plantation (Murcia, Spain). The fungal metaprofile was dominated by Ascomycota phylum. Desert truffle productivity was driven by different patterns of fungal species composition in soil (species replacement) and root (species richness differences). Moreover, positive associations for ectomycorrhizal and negative for arbuscular mycorrhizal guilds were found in productive roots, and positive associations for fungal parasite-plant pathogen guild in non-productive ones. Soil samples were dominated by pathotroph and saprotroph trophic modes, showing positive associations for Aureobasidium pullulans and Alternaria sp. in productive areas, and positive associations for Fusarium sp. and Mortierella sp. were found in non-productive soils. Finally, some significant OTUs were identified and associated to ascocarp producing patches, which could serve as predictive and location markers of desert truffle production. 相似文献
9.
Catarino Ávila José Luis Guardiola Sergio G. Nebauer 《Trees - Structure and Function》2012,26(3):833-840
The photosynthetic responses to a flowering-inductive water-stress period and recovery were studied and compared in two Citrus species. Under greenhouse conditions, Fino lemon and Owari satsuma trees were subjected to moderate (−2 MPa at predawn) and
severe (−3 MPa) water stress levels and were re-watered after 60 days. Vegetative growth was inhibited during the stress assays,
and strong defoliation levels were reported, especially in Fino lemon. In both species, bud sprouting was induced after re-watering.
Flowers and vegetative shoots developed in Owari satsuma after a drought period, and the development was independent of the
stress level. In Fino lemon, vegetative shoots and flowers were primarily formed after moderate and severe stress, respectively.
The photosynthetic rate and stomatal conductance were reduced by water stress, and a marked increase in water-use efficiency
at the moderate water deficit level was observed. Nevertheless, the photosynthetic apparatus was not damaged, since the maximum
quantum yield, photosynthetic pigment concentrations and Rubisco level and activity did not change. Furthermore, the measured
malonyldialdehyde (MDA) and peroxidase activity indicated that oxidative stress was not specifically triggered by water stress
in our study. Therefore, the gas exchange, fluorescence and biochemical parameters suggested that diffusional limitations
to photosynthesis predominated in both of the studied Citrus species, and explained the rapid recovery of the photosynthetic parameters after rehydration. The net CO2 fixation rate and stomatal conductance were recovered within 24 h in Fino lemon, whereas 3 days were required in Owari satsuma.
This suggests the presence of some metabolic limitations in the latter species. Furthermore, the sensibility of the defoliation
rates, the accumulation of proline and the stomatal behaviour in response to water stress indicated a higher drought tolerance
of Fino lemon, according to its better acclimation to hot climates. 相似文献
10.
Fengyan Yi Zhaoren Wang Carol C. Baskin Jerry M. Baskin Ruhan Ye Hailian Sun Yuanyuan Zhang Xuehua Ye Guofang Liu Xuejun Yang Zhenying Huang 《Ecology and evolution》2019,9(4):2149-2159
Investigating how seed germination of multiple species in an ecosystem responds to environmental conditions is crucial for understanding the mechanisms for community structure and biodiversity maintenance. However, knowledge of seed germination response of species to environmental conditions is still scarce at the community level. We hypothesized that responses of seed germination to environmental conditions differ among species at the community level, and that germination response is not correlated with seed size. To test this hypothesis, we determined the response of seed germination of 20 common species in the Siziwang Desert Steppe, China, to seasonal temperature regimes (representing April, May, June, and July) and drought stress (0, ?0.003, ?0.027, ?0.155, and ?0.87 MPa). Seed germination percentage increased with increasing temperature regime, but Allium ramosum, Allium tenuissimum, Artemisia annua, Artemisia mongolica, Artemisia scoparia, Artemisia sieversiana, Bassia dasyphylla, Kochia prastrata, and Neopallasia pectinata germinated to >60% in the lowest temperature regime (April). Germination decreased with increasing water stress, but Allium ramosum, Artemisia annua, Artemisia scoparia, Bassia dasyphylla, Heteropappus altaicus, Kochia prastrata, Neopallasia pectinata, and Potentilla tanacetifolia germinated to near 60% at ?0.87 MPa. Among these eight species, germination of six was tolerant to both temperature and water stress. Mean germination percentage in the four temperature regimes and the five water potentials was not significantly correlated with seed mass or seed area, which were highly correlated. Our results suggest that the species‐specific germination responses to environmental conditions are important in structuring the desert steppe community and have implications for predicting community structure under climate change. Thus, the predicted warmer and dryer climate will favor germination of drought‐tolerant species, resulting in altered proportions of germinants of different species and subsequently change in community composition of the desert steppe. 相似文献
11.
Three species of fast growing fuel wood yielding plants locally available (Acacia holosericea, Bauhinia variegata and Cassia siamea) were characterized in respect of their responses to water stress. Seedlings (25 days) of these species, exposed to two levels
of water stress (−0.5 and −1.0 MPa) induced by PEG-6000 for 24 h, were analysed for relative water content (RWC) and the contents
of chlorophyll, protein, soluble sugars and proline in leaves along with activities of catalase, peroxidase and superoxide
dismutase (SOD). RWC was lower in stressed compared to the unstressed seedlings. However, stress-induced decline in RWC was
lowest in B. variegata. Chlorophyll and protein contents declined with increasing levels of water stress, decline being least in B. variegata. Soluble sugar and proline contents increased under water stress particularly in B. variegata. The enzyme activity of catalase (EC-1.11.1.6), peroxidase (EC-1.11.1.7) and SOD (EC-1.15.1.1) decreased with increased levels
of water stress. Such decline in the activity of these enzymes was least in B. variegata. Apparently, B. variegata is potentially the species most tolerant to water stress among these three fuel wood-yielding plants. 相似文献
12.
B. R. Lee L. S. Li W. J. Jung Y. L. Jin J. C. Avice A. Ourry T. H. Kim 《Biologia Plantarum》2009,53(3):505-510
The objective of this study was to determine the development of the antioxidant enzymes induced by drought stress in white
clover (Trifolium repens L.) leaves. Water stress was imposed during 28 d by decreasing the daily irrigation. Leaf water potential (Φw) gradually decreased from −0.46 to −2.33 MPa. For the first 7 d, dry mass (DM), H2O2 and lipid peroxidation were not significantly affected by water deficit. From 14 d of treatment, water stress decreased dry
mass and increased content of reactive oxygen species (O2
·− and H2O2) and oxidative stress (malondialdehyde content). The ascorbate peroxidase (APOD) was activated most rapidly, already during
the first week of water stress, but then its activity slowly decreased. Activation of superoxide dismutase (SOD) and catalase
(CAT) by water deficit continued during the 14 d (Φw ≥ −1.65 MPa) and then their activities remain on the similar level. The activity of guaiacol-peroxidase (GPOD) increased
mostly under progressive water stress and was correlated with increase in lipid peroxidation and growth restriction. 相似文献
13.
Imed Sbissi Mohamed Neffati Abdellatif Boudabous Claude Murat Maher Gtari 《Antonie van Leeuwenhoek》2010,98(4):429-436
The molecular phylogeny and comparative morphological studies reported here provide evidence for the recognition of the genus
Picoa, an hypogeous desert truffle, in the family Pyronemataceae (Ascomycota, Pezizales). Picoa juniperi and Picoa lefebvrei were reassigned to the genus Picoa based on large subunit (LSU) sequence (28S) rDNA and internal transcribed spacer (ITS) rDNA (including the partial 18S, ITS1,
ITS2, 5.8S gene, and partial 28S of the nuclear rDNA) data. Morphological studies of spores, asci, perida, and gleba revealed
high similarities between P. lefebvrei and P. juniperi, thereby confirming the membership of both species in the genus Picoa. These two species were primarily distinguishable based on ascospore ornamentation. 相似文献
14.
S. Silim R. Nash D. Reynard B. White W. Schroeder 《Trees - Structure and Function》2009,23(5):959-969
The dynamic responses of stomatal conductance (g
s) net photosynthesis (A) and leaf water potential (Ψleaf) to a progressive drought were examined in nine poplar clones (Populus spp.) with contrasting drought tolerance from the Canadian Prairies, a region prone to frequent droughts. Plants were grown
in a greenhouse and either well-watered or drought preconditioned (5–6 cycles of drought) for 8 weeks. At the end of the last
cycle, plants were watered to saturation then progressively dried-down (−1.25 MPa Ψsoil) during which A, g
s and Ψleaf were measured. Drought tolerant Okanese reached the lowest combined Ψleaf while sensitive clones (Assiniboine and Imperial) had the highest (−1.6 vs. −1.1 MPa). Steady state g
s (measured under well watered conditions) was lower in tolerant (Okanese and Tristis SBC#1) than in sensitive clones. Preconditioning
reduced steady state g
s in all clones, lowered the threshold Ψleaf for stomatal closure and the minimum Ψleaf in most clones but did not affect the steady state A. Tolerant and some moderately tolerant clones maintained higher A at lower Ψleaf than the other clones. Stomatal closure was gradual in tolerant clones and in moderately tolerant Northwest but rapid in
the other clones. Stomata in the sensitive clones closed at the highest Ψleaf, Okanese closed at the lowest. The substantial range in gas exchange and Ψleaf responses observed here represented both drought tolerance and taxonomic (Aegiros or Tacamahaca sections) traits which could play a role in the survival and productivity in environments with limited water or during periods
of drought. 相似文献
15.
Photosynthetic parameters and leaf water potential of five common bean genotypes under mild water deficit 总被引:2,自引:0,他引:2
The leaf water potential, gas exchange and chlorophyll fluorescence were evaluated in five common bean (Phaseolus vulgaris) genotypes A222, A320, BAT477, Carioca and Ouro Negro subjected to moderate water deficit. At the maximum water deficit (10
d of water withholding), the leaf water potential of genotypes A320 and A222 was higher (−0.35 and −0.50 MPa) when compared
to the other genotypes (−0.67 to −0.77 MPa). The stomatal conductance and net photosynthetic rate were significantly reduced
in all genotypes due to the water deficit. The greater reduction in stomatal conductance of A320 under drought resulted in
high intrinsic water use efficiency. Mild water deficit affected the photochemical apparatus in bean genotypes probably by
down-regulation since plants did not show photoinhibition. The photochemical apparatus of A222 and A320 genotypes was more
sensitive to drought stress, showing reduced apparent electron transport even after the recovery of plant water status. On
the other hand, even after 10 d of water withholding, the maximum efficiency of photosystem 2 was not affected, what suggest
efficiency of the photoprotection mechanisms. 相似文献
16.
J. Huzulák 《Biologia Plantarum》1979,21(1):9-14
Diurnal and seasonal changes of the xylem pressure potential (Ψxylem) were investigated in five species during three years. Intraspecific comparison was made on the basis of the mathematically
expressed relationship Ψxylem of the individual species to Ψxylem inCrataegus oxyacantha, which exhibited the highest drought resistance. With increasing water stress the value for Ψxylem of the individual species decreases linearly in comparison with that ofC. oxyacantha, namely to −1.02 MPa inLigustrum vulgare, to −1.33 MPa inCornus mas, and to −2.09 MPa inEuonymus verrucosa. At a higher water deficit the value for Ψxylem of these species decreases more rapidly than inC. oxyacantha. On the basis of these findings, the relative drought resistance of the species may by evaluated, and from the value of Ψxylem forC. oxyacantha Ψxylem of the individual species may be derived. By measuring the difference between Ψxylem of free- and polyethylene-covered individuals the existence of water redistribution within the shrub individual was confirmed. 相似文献
17.
We tested the hypotheses that a reduction of incident light of 50 % over sun-acclimated leaves of water stressed kiwifruit
(Actinidia deliciosa var. deliciosa) would (1) reduce stomatal limitations to carbon supply and (2) mitigate the inactivation of the primary photochemistry associated with photosystem (PS) II, thereby this increases carbon
gain and water-use efficiency (WUE). Groups of field-grown vines were either shaded or left naturally exposed and subjected
to progressive water stress in order to study moderately and severely droughted vines, while other groups were well irrigated.
Daily variations in leaf gas exchange and midday chlorophyll (Chl) a fluorescence were determined once plants had −0.6 MPa (moderate stress) and −1.0 MPa pre-down leaf water potential (severe
stress). Variations in Chl pigment content and specific leaf area (SLA) are also discussed. Results reveal that 50 % shade
application maintained efficiency of PSII close to 0.8 even under severe drought so that to prevent its large decline (0.65)
recorded in sunlit leaves. Under moderate stress level stomata behaviour dominated upon metabolic impairments of PSII. Reduction
of irradiance increased WUE (15–20 %) in droughted vines, representing a valuable intervention to save photosynthetic apparatus
and improve WUE in vines experiencing typical Mediterranean summer stresses. 相似文献
18.
Asish Kumar Parida Vipin S. Dagaonkar Manoj S. Phalak Laxman P. Aurangabadkar 《Acta Physiologiae Plantarum》2008,30(5):619-627
The relative water content (RWC), free proline levels and the activities of enzymes involved in proline metabolism were studied
in drought tolerant (Ca/H 680) and drought sensitive (Ca/H 148) genotypes of cotton (Gossypium hirsutum L.) during induction of water stress and posterior recovery. Water stress caused a significant increase in proline levels
and P5CS activity in leaves of both tolerant and sensitive genotypes, whereas the activity of P5CR increased minimally and
the activity of OAT remains unchanged. The activity of PDH decreased under drought stress in both the genotypes. The leaf
of tolerant genotype maintained higher RWC, photosynthetic activity and proline levels, as well as higher P5CS and P5CR activities
under water stress than that of drought sensitive genotype. The drought induced proline levels and activities of P5CS and
P5CR declined and tend to be equal to their respective controls, during recovery, whereas the PDH activity tends to increase.
These results indicate that induction of proline levels by up regulation of P5CS and down regulation of PDH may be involved
in the development of drought tolerance in cotton. 相似文献
19.
Soil fungi of areas in the North-Eastern region of Saudi Arabia where truffles are native were surveyed. Forty-three species of fungi belonging to twenty genera were isolated. Most were recovered from soils underneath or around truffle ascocarps: thirty species from soil under the surface of Tirmania nivea ascocarps, twenty-four from Terfezia boudieri soil and twenty species each from Tirmania pinoyi and Terfezia claveryi soils. Rhizosphere soil of Helianthemum lippi, on the other hand, yielded twenty-four fungal species while only fourteen fungal species were found in soil without vegetation. The total counts of fungi/g soil were highest in soils from the under surface of truffles, followed by rhizosphere soil, with the lowest in soils without vegetation. 相似文献
20.
Summary
Bromus inermis Leyss. was grown in a 2×2×2 factorial design using different levels of mycorrhizal inoculation (inoculated and noninoculated),
soil water stress (Ψ1 or −0.8 MPa) and potassium (K) fertilization (0 or 150 ppm) as factors. Soil water stress and mycorrhizal inoculation significantly
reduced plant top dry weight during the 18 week study. Chlamydospore production by the mycorrhizal symbiontGlomus fasciculatum (Thaxter sensu. Gerd.) Gerd. and Trappe was significantly reduced by soil water stress of −0.8 MPa. Potassium (K) fertilization
did not significantly influence plant top growth or mycorrhizal colonization. However, foliar Ca and Mg were significantly
lower in plants fertilized with K. Foliar Ca and Mg concentrations of P, K, N, Mn, Zn and Cu were significantly greater in
drought stressed plants whereas Ca and Mg concentrations were significantly greater in well-watered plants. 相似文献