Multiple Hormonal Control of the Lectin Content in Roots of Wheat Seedlings

The effects of 0.2 M GA, 4.4 M benzyladenine (BA), and 5.7 M IAA on the contents of wheat germ agglutinin (WGA) and ABA in the roots of four-day-old wheat (Triticum aestivumL.) seedlings were studied. All phytohormones tested almost doubled the level of WGA. BA and IAA evidently stimulated the WGA accumulation by inducing ABA accumulation, whereas GA affected the level of the WGA in an ABA-independent way. The authors conclude that phytohormones control the WGA level via several pathways.     

Coronatine Alleviates Water Deficiency Stress on Winter Wheat Seedlings

With the aim to determine whether coronatine(COR) alleviates drought stress on wheat,two winter wheat(Triticum aestivum L.) cultivars,ChangWu134(drought-tolerant) and Shan253(drought-sensitive) were studied under hydroponic conditions.Seedlings at the three-leaf stage were cultured in a Hoagland solution containing COR at 0.1 μM for 24 h,and then exposed to 20% polyethylene glycol 6000(PEG6000).Under simulated drought(SD),COR increased the dry weight of shoots and roots of the two cultivars significantly;the root/shoot ratio also increased by 30% for Shan253 and 40% for ChangWu134.Both cultivars treated with COR under SD(0.1COR+PEG) maintained significantly higher relative water content,photosynthesis,transpiration,intercellular concentration of CO2 and stomatal conductance in leaves than those not treated with PEG.Under drought,COR significantly decreased the relative conductivity and malondialdehyde production,and the loss of 1,1-diphenyl-2-picrylhydrazyl scavenging activity in leaves was significantly alleviated in COR-treated plants.The activity of peroxidase,catalase,glutathione reductase and ascorbate peroxidase were adversely affected by drought.Leaves of plants treated with COR under drought produced less abscisic acid(ABA) than those not treated.Thus,COR might alleviate drought effects on wheat by reducing active oxygen species production,activating antioxidant enzymes and changing the ABA level.     

抗旱性不同的冬小麦幼苗对渗透胁迫的生理效应

抗旱性不同的冬小麦幼苗在渗进胁迫下叶片相对透性、Pro含量和在总游离氨基酸中的Pro比例均增加,但品种间变化幅度有明显差别。在严重胁迫下,抗旱性弱的品种济南13,烟农15和鲁麦5号的叶片相对透性增加大于抗旱性强的品种昌乐5号,秦麦3号和山农587;而Pro含量和在总游离氨基酸中Pro比例的增加小于抗旱性强的品种、叶片Pro累积与RWC呈显著负相关。     

Protection of Wheat Seedlings from Helminthosporium Infection by Seed Treatment with Chemicals

Twenty of twenty-four chemicals known to induce phytoalexin production in other plants, when used to soak seed, provided effective protection to 3-week-old susceptible wheat seedlings against inoculation with Helminthosporium sativum. The number of lesions was very significantly reduced in most of these treatments and there was evidence for inhibition of lesion expansion in a few. Studies with twelve of the more effective chemicals showed that the protective effect persisted at significant levels even in 5-week-old plants and that at this stage the inhibitory effect on lesion expansion was more pronounced in most of the treatments. Different treatments led to the development of a moderate to high level of fungitoxicity in young wheat seedlings which gradually declined with age of the plant and disappeared in 5-week-old plants. When inoculated at the age of 3 or 5 weeks, plants receiving most of the treatments developed appreciably higher fungitoxicity than the untreated plants.     

Toxicity of Anaerobic Metabolites Accumulating in Winter Wheat Seedlings during Ice Encasement

Ice encasement damages cold-hardened winter wheat without major disruption of cellular organelles. CO₂ accumulates during total ice encasement to higher levels in Kharkov than in less hardy Fredrick wheat. Partial ice encasement and exposure to a nitrogen atmosphere at -1 C allows greater CO₂ accumulation but neither treatment is as damaging as total ice encasement. Lactic acid accumulates to low levels only during the 1st day of encasement and thereafter remains constant. Exposure of plants to a combination of 50% CO₂ and 5% ethanol reduces survival, with a cultivar difference similar to that found in ice-encased plants. Plants in CO₂ and ethanol show a proliferation of membranes and nuclear condensation similar to that in cells of ice-encased plants. Permeability increases markedly in the presence of CO₂ and ethanol, to levels similar to or greater than those of iced plants. Ethanol alone does not increase permeability but in combination with CO₂ raises permeability of the less hardy Fredrick, although not of Kharkov, but reduces survival of both cultivars. A comparison of the endogenous levels of ethanol, CO₂, and lactic acid at the 50% kill point of plants due to ice encasement or due to externally supplied metabolite indicates that only CO₂ accumulates to independently toxic levels. Permeability and ultrastructural evidence suggest that CO₂ and ethanol in combination are the agents reducing plant viability during ice encasement.     

Involvement of Oligosaccharides in Adaptation of Winter Wheat Seedlings to Subzero Temperatures

We studied the dynamics of endogenous content of biologically active oligosaccharides in the roots of winter wheat seedlings. Previously, these oligosaccharides proved to mediate the development of frost resistance during the first days of hardening (Zabotinaet al., 1998). The changes in their endogenous content can be described by a curve with a single peak observed 6 h after the onset of frost hardening. The capacity of these polysaccharides to increase frost resistance (LT₅₀was evaluated by leakage of electrolytes) when added to growth medium did not depend on the pretreatment duration (from 1.5 to 18 h) but decreased if they were introduced in the course of the adaptive response. Inhibition of the adaptive response by inhibitors of RNA and protein synthesis ceased in the presence of the oligosaccharides. We believe that the oligosaccharides that are products of metabolism of the cell wall polysaccharides are involved in adaptation to low temperature.     

Activity of Lectins of Winter Wheat Seedlings Infected with Mycoplasma and Treated with Salicylic Acid

Changes in activity of soluble and cell wall lectins have been revealed in seedlings of winter wheat Triticum aestivum L. cultivar Mironovskaya 808 after infection with mycoplasma Acholeplasma laidlawii 118. The protective effect of salicylic acid was manifested as negating the bursts of lectin activity induced by mycoplasma infection.__________Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 4, 2005, pp. 423–427.Original Russian Text Copyright © 2005 by Trifonova, Maksyutova, Timofeeva, Chernov.     

红花菜豆凝集素的糖结合专一性

经肼解、Ｂｉｏ－Ｇｅｌ Ｐ－２柱层析、ＮａＢ＾３Ｈ４和ＮａＢＨ４还原,制备各种来源的、氚标记在还原末端的、还原末端为Ｎ－乙酰氨基葡萄糖醇的混合寡糖,经Ｂｉｏ－Ｇｅｌ Ｐ－４凝胶柱分离,以及用糖苷酶酶解,制备了各种不同类型的氚标记的寡糖。这些寡糖在固定化的ＰＣＬ－Ｓｅｐｈａｒｏｓｅ柱上亲和层析,根据各种类型寡糖在ＰＣＬ－Ｓｅｐｈａｒｏｓｅ柱上的层析行为,确定红花菜豆（矮生红花变种）凝集素（ＰＣＬ）的     

Low-Temperature Adaptation of Winter Wheat Seedlings under Excessive Zinc Content in the Root Medium

Russian Journal of Plant Physiology - Cold adaptation of winter wheat (Triticum aestivum L.) seedlings was investigated under excessive zinc content (1000 μM) in the root medium. The ability...     

Adaptive Changes in ATPase Activity in the Cells of Winter Wheat Seedlings during Cold Hardening

A cytochemical study of ATPase activity in the cells of cold hardened and nonhardened winter wheat (Triticum aestivum L. cv. Nongke No. 1) seedlings was carried out by electron microscopic observation of lead phosphate precipitation. ATPase activity associated with various cellular organelles was altered during cold hardening. (a) At 22°C, high plasmalemma ATPase activity was observed in both cold hardened and nonhardened tissues; at 5°C, high activity of plasmalemma ATPase was observed in hardened tissues, but not in unhardened tissues. (b) In nonhardened tissues, tonoplast and vacuoles did not exhibit high ATPase activity at either 22 or 5°C, while in hardened tissues high activity was observed at both temperatures. (c) At 5°C, ATPase activity of nucleoli and chromatin was decreased in hardened tissues, but not in nonhardened tissues. It is suggested that adaptive changes in ATPase activity associated with a particular cellular organelle or membrane may be associated with the development of frost resistance of winter wheat seedlings.     

Effects of Self-sown Wheat on Levels of the Take-all Disease on Seedlings of Winter Wheat Grown in a Model System

Abstract The mechanisms of build-up of inoculum of the take-all fungus, Gaeumannomyces graminis var. tritici. and infection of crop plants from self-sown (volunteer) wheat were analysed in a factorial experiment in a glasshouse. Treatments comprised sowing-date, inoculum density, soil aeration and texture, volunteer density and control of volunteers. Timing of treatments was related to field practice by the use of cumulative day-degrees and by consideration of sowing date and the geometry of seed placement. Prior sowing of volunteers, which were exposed to soil inoculum. resulted in significant increases in the incidence and severity of disease on subsequently sown seedlings. Increasing the density of volunteer seedlings increased the levels of subsequent infection. This effect, however, was significantly influenced by sowing date and density of the initial inoculum. The use of glyphosate to kill volunteers did not markedly affect the carry-over of disease.     

冬季小麦叶片光合作用对温度响应方式的变化

冬季田间生长的小麦离体叶片净光合速率（Ｐｎ）对温度的响应有两种方式。在１２月上旬可以观测到第一种方式。在离体叶片周围空气温度从１０℃逐步升到３０℃后的１ｈ内Ｐｎ逐渐升高,在随后气温逐步降低到１０℃的过程中,Ｐｎ都比先前升温过程中同样温度下的数值高。３０℃下叶片胞间ＣＯ２浓度（Ｃｉ）降低和叶片无机磷含量增高表明,这种响应方式可能起因于一些光合碳同化酶活性的增高。在１２月中旬以后可以观测到第二种方式。Ｐｎ在３０℃下的１ｈ内逐步下降,在随后的降温过程中Ｐｎ都比升温过程中同样温度下的数值低。３０℃下叶片Ｃｉ和膜透性增高表明,这种响应方式可能是适应冬季低温的光合机构膜系统在高温下遭受破坏的结果。     

Changes in Hormonal Status and Expression of Lectin Genes in Wheat Seedlings Treated with Stevioside and Exposed to Low Above-Zero Temperatures

Russian Journal of Plant Physiology - Effect of presowing treatment with stevioside (10–8 M) on activity, content, and expression of the wheat-germ agglutinin (WGA) gene, as well as the...     

Electron Microscopic Cytochemical Studies on the Glycoproteins in Cellular Membranes of Winter Wheat Seedlings with Concanavalin A-Horseradish Peroxidase Method

The localization and distribution of the glycoproteins in cellular membranes of strong cold hardy winter wheat (Triticum aestivum L. cv. Yanda 1817) seedlings were studied employing the modified cytochemical method using Concanavalin A-Horseradish peroxidase conjugates. The results obtained showed that the reaction products of Horseradish peroxidase activity which indicated the presence of glycoproteins appeared as individual particles distributed at plasmalemma, endoplasmic reticulmn, nuclear envelope and tonoplast in the leaflet cells of the seedlings grown under optimum temperature 25℃ day/20℃ night. After cold acclimation of the seedlings at low temperature during late autumn and early winter, the quantity of glycoproteins distributed in endoplasmic reticulum and nuclear envelope was significantly increased, and glycoproteins were transported into almost all of the plasmodesmata. At some sites of mitochondria and plastides newly formed glycoproteins were observed. However, no distribution of glycoproteins was for,nd in Golgi bodies during the whole observations. The role of glycoproteins for the development and stability of cold resistance in plant through blocking up the plasmodesma passage in the overwintering period of winter wheat seedlings, and the possible differences of the synthetic site and transportation pathway of glycoproteins between animal and plant systems were discussed.     

Maintenance of Membrane Fluidity during Development of Freezing Tolerance of Winter Wheat Seedlings

Fluidity of membrane lipids of shoot and root tissue and of chloroplasts from young wheat seedlings of contrasting freezing tolerance was investigated by measuring the motion and order parameters after spin labeling. A striking similarity was observed in membrane lipid fluidity of the five cultivars grown at 22 C. After cold hardening by growth at 2 C, a small change in membrane lipid fluidity was observed, but this was not correlated with the development of freezing tolerance, and there was no alteration in the transition temperature of membrane lipids. The results show that neither changes in membrane lipid fluidity nor transition temperature are a necessary feature of cold acclimation in wheat.     

Stability Effects of Cold-acclimation on the Plasmolemma Ca2+ ATPase of Winter Wheat Seedlings

The cold-acclimation effects on the Ca2 + -ATPase activities in plasmolemma of the winter wheat seedlings ( Triticum aestivum L. ) were studied with electromicmscopic-cytochemical assay in which cerium trichloride precipitation method was adopted. The main conclusions are: (1) The plasmolemma Ca2+ -ATPase activities of the wheat seedlings treated at –9 ℃ for 3 h decreased considerably as compared with those of the seedlings grown at the optimal temperature of 20 ℃. A further impediment of the enzyme activities was observed when the cold-stress was prolonged to 12 h at –9 ℃. And complete enzyme inactivation as well as damage of ultrastructure of cells occurred when the seedlings were subjected to cold-stress at –9 ℃ for 24 h. (2) If seedlings were cold-ac- climated at 2 ℃ for 15 d, the plasmolemma Ca2 + -ATPase activities were higher than those of the non-acclimated seedlings. When the cold-acclimated seedlings were then treated at –9 ℃ for 3 h, the enzyme activities decreased less markedly than those of the non-acclimated seedings under the same treatment condition. Similarly, under prolonged cold-stress of both seedlings at – 9 ℃ for 12 h, the enzyme activities of the cold-acclimated seedlings still kept higher than those of the non-ac- climated ones. Finally, when the cold-stress lasted for 24 h at – 9 ℃, the enzyme activities of the cold acclimated seedlings remained active, and the cellular ultrastructure also remained unchanged. The above results indicate that cold-acclimation has enhanced the stability of the plasmolemma Ca2 + -ATPase activities of the winter seedlings under low temperature stress.     

干旱条件下冬小麦幼苗根细胞膜脂组成的变化

干旱条件下小麦幼苗根膜脂总脂肪酸含量、磷脂含量及总脂肪酸双键指数均下降,而游离甾醇含量却明显增加,结果导致游离甾醇／磷脂比率上升。用薄层层析法测得小麦根细胞磷脂主要由磷脂酰胆碱(PC)、磷脂酰乙醇胺(PE)、磷脂酰肌醇(PI)及磷脂酸(PA)组成。干旱降低了各种磷脂的含量,但不改变其相对配比。文中讨论了膜脂代谢变化与植物抗旱性的关系。     

稀土元囊对小麦幼苗氮素吸收及同化的影响

稀土元素浸种能够促进小麦(Triticum aestivum L.)幼苗对No3-的吸收,提高硝酸还原酶活力。这些效应与稀土浓度有关,低浓度有促进作用,高浓度则有抑制作用。稀土元素处理还能促进小麦幼苗体内No3-的同化还原,使硝态氮含量降低,氨基氮含量增加,促进了氮素代谢过程。