Gibberellin production and plant growth promotion by a newly isolated strain of <Emphasis Type="Italic">Gliomastix murorum</Emphasis>

Endophytic fungi are known to play a vital role in the growth and development of their host plants. We isolated eleven endophytic fungi from the roots of sand-dune plant Elymus mollis and their growth-promoting ability was studied on waito-c rice and Atriplex gemelinii. We found that eight fungal isolates promoted growth of both plants. Fungal isolate EM-7-1 induced maximum growth promotion in waito-c rice (9.25 cm) and Atriplex gemelinii (3.1 cm), which was higher than wild-type Gibberella fujikuroi. Gibberellin analysis of EM-7-1 culture filtrate showed the presence of bioactive gibberellins GA₁ (0.32 ng/ml), GA₃ (5.76 ng/ml), GA₄ (0.82 ng/ml) and GA₇: (0.1 ng/ml) along with physiologically inactive GA₅ (0.59 ng/ml), GA₉ (5.38 ng/ml), GA₂₀ (0.25 ng/ml) and GA₂₄ (2.03 ng/ml). The fungal isolate EM-7-1 was identified as new strain of Gliomastix murorum (G. murorum KACC43902) with 99% sequence homology. This study reports the plant growth-promoting ability of genus Gliomastix and the presence of GA₅ in the culture filtrate of fungi for the first time. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Study of the Morphological and Functional State of Higher Plant Tissues by Optical Coherence Microscopy and Optical Coherence Tomography

Comparative analysis of two optical methods—optical coherence tomography (OCT) and optical coherence microscopy (OCM)—was made for vital visualization of plant tissues in tomato (Lycopersicon esculentum Mill), spiderwort (Tradescantia pallida (Rose) D. Hunt), orach (Atriplex sp.), and leaves and seeds of medium starwort (Stellaria media L.). The obtained OCT- and OCM-images allowed the morphological and functional state of plant tissues to be assessed in vivo. A higher spatial resolution of the OCM method, as compared to OCT method, allowed plant morphological structures to be identified with greater confidence. The morphological and functional state of tissues can be monitored with a time resolution of 1–4 s in intact plants, without removing them from the habitat.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 4, 2005, pp. 628–634.Original Russian Text Copyright © 2005 by Kutis, Sapozhnikova, Kuranov, Kamenskii.     

Gas exchange in the salt marsh species <Emphasis Type="Italic">Atriplex portulacoides</Emphasis> L. and <Emphasis Type="Italic">Limoniastrum monopetalum</Emphasis> L. in Southern Portugal

Salt marshes are ecosystems subjected to a variety of environmental stresses like high salinity, water deficit, intense radiation or high temperatures. Field measurements were conduced in two halophyte species, Atriplex portulacoides L. and Limoniastrum monopetalum L., in the Reserva Natural do Sapal de Castro Marim, to compare their physiological response, i.e., water potential (ψ), net photosynthetic rate (A), stomatal conductance (gs) under natural conditions. Both species demonstrated marked variations in ψ throughout the year, with very low values in the summer, the period of higher salinity, drought and temperature. Deficit water potential (Δψ = ψ_midday − ψ_predawn) was lower in the summer than in other seasons in A. portulacoides but not in L. monopetalum. The highest values for A and gs in L. monopetalum were observed in autumn and for A. portulacoides in winter, presenting both lowest values in spring and summer. A_max was particularly high for L. monopetalum than for A. portulacoides in summer and autumn, despite gs_max was similar in both species. Diurnal pattern of A and gs were similar in both species, with higher values in the morning, decreasing throughout the day.     

不同光照强度下三角叶滨藜光合作用对盐激胁迫的响应

以溶液培养的三角叶滨藜植株为材料研究了不同光照条件下其叶片光合作用对盐(NaCl)激胁迫的即刻反应及变化规律.结果表明,三角叶滨藜光合作用对盐激胁迫的响应有8 min左右的滞后期.在光照强度为100umol·m-2·-1和100 mmol·L-1浓度NaCl共同作用下,三角叶滨藜叶片净光合速率略有上升;但随NaCl浓度和光照强度进一步增加,其净光合速率呈下降趋势,且光照越强,盐胁迫导致的净光合速率下降幅度越大.同时,弱光下或强光低浓度NaCl胁迫下,盐激胁迫导致的净光合速率下降主要是气孔限制引起的;而强光下,高浓度的NaCl胁迫导致的净光合速率下降在盐激胁迫处理的前30-40 min主要由气孔限制引起.40 min后则主要由非气孔限制引起.可见,不同光照强度和NaCl浓度胁迫下三角叶滨藜叶片光合作用响应规律不同,引起净光合速率下降机制各异.     

Comparison of salt tolerance and osmotic adjustment of low-sodium and high-sodium subspecies of the C4 halophyte, Atriplex canescens

The relationship between Na⁺ accumulation and salt tolerance was tested by comparing subspecies of the halophyte, Atriplex canescens (fourwing saltbush), that differed markedly in Na⁺ content and Na:K ratios. Above ground tissues of one low-sodium and two high-sodium subspecies were compared with respect to cation accumulation, osmotic adjustment and growth along a salinity gradient in greenhouse trials. Plants of each subspecies were grown for 80 d on 2.2, 180, 540 and 720 mol m^?3 NaCl. At harvest, A. canescens ssp. canescens had significantly lower Na⁺ levels, higher K⁺ levels and lower Na:K ratios in leaf and stem tissues than A. canescens ssp. macropoda and linearis over the salinity range (P < 0.05 or 0.01). Na:K ratios in leaves of the latter two, high-sodium, subspecies were approximately 2 on the lowest salinity treatment and ranged from 5 to 10 on the more saline solutions. By contrast, Na:K ratios in leaves of the low-sodium subspecies canescens, were only 0.4 on the lowest salinity and ranged narrowly from 1.7 to 2.3 at higher salinities. However, despite different patterns of Na⁺ and K⁺ accumulation, all three subspecies exhibited equally high salt tolerance and had similar osmotic pressures in their leaves or stems over the salinity range. Contrary to expectations, high salt tolerance was not necessarily dependent on high levels of Na⁺ accumulation in this species.     

Restoring Salt Marshes Using Small Cordgrass, Spartina maritima

The use of exotic cordgrasses in salt marsh restoration projects has caused important negative environmental impacts and little is known about the possibilities of applying the endangered cordgrass Spartina maritima as a biotool at many European estuaries where it is the only native cordgrass. This paper discusses the planning and the development of an innovative restoration project based on S. maritima plantations in Odiel marshes (S.W. Iberian Peninsula). Our ecological restoration project had four specific goals: (1) to recover native vegetation, restoring the degraded landscape; (2) to phytostabilize oil-polluted sediments; (3) to prevent erosion and stabilize banks; and (4) to promote the conservation of S. maritima . Spartina maritima was planted at two physiographical locations: slightly sloping channel banks and flat interior marshes. Nonsuccessional stands of S. maritima develop at the channel banks where the marsh surface was stabilized. In contrast, successional stands of S. maritima grown in flat interior marshes are being replaced naturally by Sarcocornia perennis .     

Effects of NaCl on ion relations and carbohydrate status of roots and on osmotic regulation of roots and shoots of Atriplex amnicola

Abstract Atriplex amnicola was grown at 25, 200 or 400 mol m³ NaCl. Root tissues at different stages of development were investigated for concentrations of K⁺, Na⁺ and Mg²⁺, and in some cases for Cl^?. Sugar and starch concentrations were measured for plants grown at 25 or 400 mol m³ NaCl. In the ‘slightly vaeuolated’ root tips, Na⁺ was only 40 mol m^?3 at an external concentration of 400 mol m^?3 NaCl. The concentrations of K⁺ were not affected substantially by external NaCl between 25 mol m^?3 and 400 mol m^?3. The ‘highly vacuolated’ root tissues had substantially higher concentrations of K⁺, Na⁺ and Cl^? in plants grown at 200 and 400 mol m ³ NaCl than in plants grown at 25 mol m^?3 NaCl. Concentrations of Cr and of the sum of the cations in recently expanded tissue were similar to those in the bulk of the roots, consisting mainly of old cells. However, the K⁺: Na⁺ decreased with age; at 400 mol m^?3 external NaCl with a K⁺: Na⁺ of 0.012, the K⁺: Na⁺ in recently expanded 12 mm root tips was as high as 1.6, compared with 0.7 for the bulk of the roots. These ion data were used to estimate cytoplasmic and vacuolar concentrations of K⁺ and Na ⁺. Such calculations indicated that between 25 mol m³ and 400 mol m^?3 external NaCl the concentration of the sum of (Na⁺+K⁺) in the cytoplasm was maintained at about 180–200 mol m^?3 (cell water basis). In contrast, the (Na⁺+ K⁺) concentration in the vacuole was 170 mol m^?3 for plants grown at 25 mol m^?3 NaCl and 420 mol 400 mol m^?3 NaCl. The expanding root (issues exhibited greatly decreased soluble sugars and starch between dusk and dawn. Ai both times, sugar and starch concentrations in these tissues were 2.5–4.0 times greater in plants grown at 400 mol m^?3 NaCl compared with plants grown at 25 mol m^?3 NaCl. In contrast, carbohydrate concentrations in expanded root tissues were very similar at 25 and 400 mol m^?3 and showed little diurnal fluctuation. This paper considers the causes for the slower growth of A. amnicola at 400 than at 25 mol m”³ NaCl, using the data for the roots described here, and those for the shoots presented in the preceding paper (Aslam et al., 1986). There is no support for possible adverse effects by high internal ion concentrations. Instead, there may be deficiencies in supply of organic solutes for osmotic regulation; during part of the night a limited supply of such solutes may well restrict the rate of expansion of cells in plants growing at 400 mol m^?3 NaCl. There is insufficient evidence to decide whether this limitation in the expanding tissues is particularly prominent for the roots or for the shoots.