Differences in the metabolic responses of root tips of wheat and rye to aluminium stress

The effects of aluminium (Al) ions on the metabolism of root apical meristems were examined in 4-day-old seedlings of two cereals which differed in their tolerance to Al: wheat cv. Grana (Al-sensitive) and rye cv. Dakowskie Nowe (Al tolerant). During a 24 h incubation period in nutrient solutions containing 0.15 mM and 1.0 mM of Al for wheat and rye, respectively, the activity of first two enzymes in the pentose phosphate pathway (G-6-PDH and 6-PGDH) decreased in the sensitive cultivar. In the tolerant cultivar activities of these enzymes increased initially, then decreased slightly, and were at control levels after 24 h. In the Al-sensitive wheat cultivar a 50% reduction in the activity of 6-phosphogluconate dehydrogenase was observed in the presence of Al. Changes in enzyme activity were accompanied by changes in levels of G-6-P- the initial substrate in the pentose phosphate pathway. When wheat was exposed for 16 h to a nutrient solution containing aluminium, a 90% reduction in G-6-P concentration was observed. In the Al-tolerant rye cultivar, an increase and subsequently a slight decrease in G-6-P concentration was detected, and after 16 h of Al-stress the concentration of this substrate was still higher than in control plants. This dramatic Al-induced decrease in G-6-P concentration in the Al-sensitive wheat cultivar was associated with a decrease in both the concentration of glucose in the root tips as well as the activity of hexokinase, an enzyme which is responsible for phosphorylation of glucose to G-6-P. However, in the Al-tolerant rye cultivar, the activity of this enzyme remained at the level of control plants during Al-treatment, and the decrease in the concentration of glucose occurred at a much slower rate than in wheat. These results suggest that aluminium ions change cellular metabolism of both wheat and rye root tips. In the Al-sensitive wheat cultivar, irreversible disturbances induced by low doses of Al in the nutrient solution appear very quickly, whereas in the Al-tolerant rye cultivar, cellular metabolism, even under severe stress conditions, is maintained for a long time at a level which allows for root elongation to continue.Abbreviations G-6-PDH glucose-6-phosphate dehydrogenase - 6-PGDH 6-phosphogluconate dehydrogenase - G-6-P glucose-6-phosphate - TEA triethanolamine     

一氧化氮在微波预处理提高小麦幼苗抗镉胁迫中的作用

为了探讨一氧化氮在微波预处理提高小麦抗镉胁迫中的作用,利用微波(126mW·cm-2)辐照小麦种子10 s,待其长至一叶一心时,用150 μmol·L-l CdCl2胁迫其幼苗,并通过添加一氧化氮专一清除剂cPTIO(0.5％,w/v),研究一氧化氮对微波预处理小麦幼苗脂质过氧化、抗氧化酶活性、光合色素含量及幼苗生长的影响.结果表明:微波预处理可使镉胁迫的小麦幼苗丙二醛含量显著降低(P＜0.05),超氧化物歧化酶、过氧化物酶、过氧化氢酶活性、一氧化氮、叶绿素a、叶绿素b、类胡萝卜素含量和株高、根长、地上部干重、根干重显著增加(P＜0.05);经过适当剂量微波辐照镉胁迫小麦幼苗再加外源cPTIO处理能有效逆转微波对镉胁迫小麦幼苗的防护作用.说明微波对镉胁迫损伤小麦幼苗起到一定的防护作用主要是通过NO起作用.     

Subcellular localization of beta-glucosidase in rye, maize and wheat seedlings

The subcellular compartmentation of β -glucosidase was studied in rye, maize and wheat seedlings by immunocytochemical methods. For detection, we used a 10 nm gold-labeled secondary antibody, and results were observed using transmission electron microscopy. In all three species, β -glucosidase was found in plastids, cytoplasm and cell walls. In rye, gold particles were seen on cell walls and cytoplasm in epidermal cells of the root tip and shoot, in bundle sheath cells of the shoot and in all cells, except the vascular bundle cells of the coleoptile. Gold labeling was also observed in plastids of the bundle sheath cells of rye shoot tips and in cortical cells of root tips. In wheat, gold labeling was observed on cell walls and cytoplasm of epidermal cells in the shoot base and coleoptile, and on cell walls and plastids in epidermal cells of the root tip. In maize, gold labeling was mainly found in plastids or proplastids in vascular bundle cells and bundle sheath cells of the shoot, in bundle sheath cells of the coleoptile and in epidermal cells of the root. Some gold particles were also found in cell walls and cytoplasm of stomatal guard cells of the shoot base and vascular bundle cells of the shoot tip and in the cell walls of bundle sheath cells of the shoot tip and root tip epidermal cells. Results are discussed in relation to the role of β -glucosidase in hydroxamic acid release and overall defense mechanism of monocotyledons.     

热激诱导的玉米幼苗耐热性及其与脯氨酸的关系

研究了热激对玉米幼苗耐热性的效应及其与脯氨酸的关系。结果表明,培养2.5 d的玉米幼苗经过42℃热激4 h并于26.5℃下恢复4 h后,提高了玉米幼苗在48℃下的存活率,并且热激及其后的恢复过程中都表现出脯氨酸的积累。不同浓度的外源脯氨酸预处理也可提高玉米幼苗内源脯氨酸的水平和抗氧化酶抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)、过氧化物酶(GPX)的活性,从而提高玉米幼苗在高温胁迫下的存活率。这些结果暗示热激过程中脯氨酸的积累所诱发的抗氧化酶活性的增强可能是热激诱导的玉米幼苗耐热性形成的生理基础之一。     

Comparative salt tolerance in triticale,wheat and rye during germination

Summary Differences in salt tolerance of wheat and barley have been observed but knowledge of such differences in triticale (X Triticosecale Wittmack) cultivars is of potential importance. Effects of six salinity levels (0 to 2% NaCl) on germination of triticales Beagle and 6TA 131 in comparison to wheat and rye were determined at 15–20°C. Beagle triticale and rye showed similar trends in germination reduction as salinity increased from 0 to 1.5% NaCl and exhibited fairly high salt tolerance. However, 6TA 131 triticale and wheat showed a significant drop in germination even at 0.5% NaCl concentration and were more susceptible to salt injury.     

转基因玉米双抗12-5-21的抗虫性及对草甘膦的耐受性

[目的]评价转cry1Ab/cry2Aj和G10evo-epsps基因玉米双抗12-5的杂交后代双抗12-5-21对亚洲玉米螟、黏虫、棉铃虫的抗性及对目标除草剂草甘膦的耐受性.[方法]分别在6叶期和花丝期、6叶期、花丝期对亚洲玉米螟、黏虫、棉铃虫进行田间人工接虫;自然条件下,收获期剖秆调查双抗12-5-21对鳞翅目害虫...     

玉米、小麦、水稻原生质体制备条件优化

玉米Zea mays L.、小麦Triticum aestivum L.、水稻Oryza sativaL.是三大重要粮食作物,对其原生质体制备条件的优化具有重要意义.以玉米(综3)、小麦(中国春)、水稻(日本晴)10日龄幼苗为材料,研究了叶肉细胞原生质体分离过程中的酶浓度、酶解时间和离心力大小等因素对产量和活力的影响.结果表明:酶浓度和酶解时间对原生质体产量影响显著,随着酶解液浓度和酶解时间的提高,原生质体产量增加,但细胞碎片同时增多.水稻经真空处理后,原生质体产量大幅度提高.通过正交实验设计得出如下结果:玉米叶肉细胞原生质体分离的最佳条件为:纤维素酶1.5％,离析酶0.5％,50 r/min酶解7h,100×g离心2 min收集,原生质体产量为7×106/g FW;小麦叶肉细胞原生质体分离的最佳条件为:纤维素酶1.5％,离析酶0.5％,50 r/min酶解5h,100×g离心2 min收集,原生质体产量为6×106/g FW;水稻叶肉细胞原生质体分离的最佳条件为:纤维素酶2.0％,离析酶0.7％,50 r/min酶解7h,1 000×g离心2 min收集,得到的原生质体产量为6×106/g FW.通过二乙酸荧光素染色发现原生质体活力均在90％以上.用PEG-Ca2+介导法将含有绿色荧光蛋白的质粒转化入原生质体,转化率可达50％ ～80％.     

The effect of wheat cytoplasm on the synthesis of wheat x rye hybrids

Summary Four nuclear genotypes of Triticum aestivum L., each substituted into the cytoplasm of T. timococcum Kostoff, Aegilops ventricosa Tausch and T. timopheevi Zhuk., were crossed with four homozygous Secale cereale L. inbred lines to produce 48 alloplasmic octoploid primary triticales. Crossability, embryo differentiation, amphihaploid plantlet recovery in vitro, and response to colchicine treatment were investigated. It was found that in general the effects of the wheat cytoplasm on the characteristics studied were of equal importance as those of the wheat and the rye nuclear genotypes. Cytoplasm can be regarded as an additional source of variation in the synthesis of primary triticales. Cross-compatibility in wheat x rye hybrids appeared to be determined by specific parental genotypes and their nucleo-cytoplasmic interactions rather than by any general compatibility of particular nuclear genotypes and/or cytoplasms.     

Mixotrophic productivity of the marine diatom Phaeodactylum tricornutum cultured with soluble fractions of rye,wheat and potato

The marine microalga Phaeodactylum tricornutum was cultured semi-continuously with the soluble fractions of wheat, rye and boiled potato flours. Fifteen percent of the culture volume was renewed every 3 d. The cell productivities were 0.9×109 cells/l/d, 1.1×109 cells/l/d and 2.6×109 cells/l/d for wheat, rye and potato respectively. The productivity of the autotrophic control was 1.0×109 cell/l/d. When a soluble fraction of raw potato was added, the productivity was enhanced to 4.1×109 cells/l/d, 2.4 times higher than the autotrophic culture. The high productivity of P. tricornutum with the soluble fractions of Solanum tuberosum suggests its usefulness as a source of nutrients for the production of microalgal biomass.     

Tissue localization of β-glucosidase in rye, maize and wheat seedlings

The localization of β -glucosidase was determined at the tissue level in roots and shoots of rye, wheat and maize seedlings, using an immunohistochemical approach with antibodies directed against purified maize β -glucosidase as the primary antibody. In the roots, the β -glucosidase was found in the epidermis and the underlying cell layer. In the leaves, staining was seen in the epidermis (rye and wheat) and nearby vascular tissue (rye, wheat and maize). In all 3 species, β -glucosidase activity was highest in the coleoptile. Here the enzyme was restricted to the epidermis in wheat and to cells near the vascular tissue in maize, but was found in the whole tissue, except the vascular tissue, in rye. Maize, wheat and rye all contain hydroxamic acid glucosides and results are discussed in relation to a proposed role of β -glucosidase as part of a defense system releasing hydroxamic acid aglucone upon herbivore attack, pathogen penetration or aphid infestation.     

Role of rye chromosomes in improvement of zinc efficiency in wheat and triticale

Using the disomic wheat-rye addition lines (Triticum aestivum L., cv. Holdfast-Secale cereale L., cv. King-II) and an octoploid triticale line (xTriticosecale Wittmark L. "PlutoxFakon") as well as the respective wheat and rye parents, greenhouse experiments were carried out to study the role of rye chromosomes on the severity of Zn deficiency symptoms, shoot dry matter production, Zn efficiency, shoot Zn concentration and Zn content. Plants were grown in a Zn-deficient calcareous soil with (10 mg Zn kg-1 soil) and without Zn supply. Zinc efficiency was calculated as the ratio of dry weight produced under Zn deficiency to the dry weight produced under Zn fertilization. In the experiments with addition lines, visual Zn deficiency symptoms were slight in the rye cultivar King-II, but were severe in the wheat cultivar Holdfast. The addition of rye chromosomes, particularly 1R, 2R and 7R, into Holdfast reduced the severity of deficiency symptoms. Holdfast showed higher decreases in shoot dry matter production by Zn deficiency and thus had a low Zn efficiency (53 %), while King-II was less affected by Zn deficiency and had a higher Zn efficiency (89 %). With the exception of the 3R line, all addition lines had higher Zn efficiency than their wheat parent: the 1R line had the highest Zn efficiency (80 %). In the experiment with the triticale cultivar and its parents, rye cv. Pluto and wheat cv. Fakon, Zn deficiency symptoms were absent in Pluto, slight in triticale and very severe in Fakon. Zinc efficiency was 88 % for Pluto, 73 % for triticale and 64% for Fakon. Such differences in Zn efficiency were better related to the total amount of Zn per shoot than to the amount of Zn per unit dry weight of shoot. Only in the rye cultivars, Zn efficiency was closely related with Zn concentration. Triticale was more similar to rye than wheat regarding Zn concentration and Zn accumulation per shoot under both Zn-deficient and Zn-sufficient conditions.The results presented in this study show that rye has an exceptionally high Zn efficiency, and the rye chromosomes, particularly 1R and 7R carry the genes controlling Zn efficiency. To our knowledge, the result with triticale and its rye parents is the first report showing that the genes controlling Zn efficiency in rye are transferable into wheat and can be used for development of new wheat varieties with high Zn efficiency for severely Zn-deficient conditions.     

A segment of rye chromosome 1 enhances growth and embryogenesis of calli derived from immature embryos of wheat

Summary The influence of the short arm of rye chromosome 1 (1RS) from Secale cereale var. Imperial on the growth and differentiation of callus cultures from wheat Triticum aestivum var. Chinese Spring immature embryos was analysed. This chromosome arm was found to stimulate both embryogenesis and the rate of growth of calli. Recombinant lines carrying segments of 1RS were used to delineate the regions of 1RS responsible for the tissue culture effects. The enhancement of embryogenesis and the stimulation of growth were shown to be associated with two distinct genetic regions of the chromosome arm; the former is located between the centromere and the Sec 1 locus, while the latter is situated in the immediate vicinity of the Sec 1 locus.     

High yield isolation of mesophyll protoplasts from wheat, barley and rye

Efficient procedures are described for high-yield isolation of mesophyll protoplasts from spring wheat ( Triticum aestivum L. cv. Glenlea), winter wheat ( Triticum aestivum L. cv. Frederick), barley ( Hordeum vulgare L. cv. Bruce) and rye ( Secale cereale L. cv. Puma). Factors such as plant age, composition of the incubation medium during isolation, purification procedures and culture medium affect protoplast yield, viability and metabolic competence, as measured by light-dependent CO₂ fixation. Optimal osmolarity of the isolation medium was equivalent to 1.8 times that measured in the leaves of all plant material used. The presence of 2 m M ascorbic acid in the preincubation and isolation medium increased the yield by 50% and conserved viability and metabolic competence. The protoplasts were stable for up to 48 h without loss of either viability or of original activity of CO₂ fixation, which was in the order of 100 μmol CO₂ (mg chl)⁻¹h⁻¹.
In our MC-56 liquid medium these protoplasts regenerated cell walls within 72 h and a few divided.     

The interrelationship of growth and frost tolerance in winter rye

The reduction in growth of winter cereals that occurs in the fall is thought to be required for the development of frost resistance. In the present study, the interrelationship of freezing tolerance and growth was examined by raising winter rye ( Secale cereale cv. Puma) plants at 20/16°C (day/night) and at 5/3°C under 8-, 16- and 24-h daylengths to vary growth rates and frost tolerance. Temperature and irradiance were quantified as thermal time, photothermal time and photosynthetic photon flux and examined by multiple linear regression in order to determine their effects on growth and frost tolerance of rye shoots. At low temperature, both growth and frost tolerance were markedly influenced by daylength and irradiance. Plants grown at 5/3°C with a short daylength accumulated shoot dry weight and increased frost tolerance at a greater rate per unit photothermal time or photon flux than plants grown at longer daylengths. Moreover, 5/3°C plants grown with a 16-h day grew more slowly and were less frost tolerant than plants grown with a 24-h day. We conclude that the interrelationship between growth and frost tolerance is a quantitative one. Frost tolerance is induced only by low temperature, but the development of forst tolerance is dependent upon both irradiance, which affects the amount of photoassimilate available, and daylength, which may affect the partitioning of photoassimilates between growth and frost tolerance.     

黑麦中与耐盐性相关的cDNA片段的克隆与序列分析

SI800(Salt Induced 800 bp,SI800)为我们用mRNA差别显示技术在盐胁迫的黑麦幼苗叶片中分离到的一个盐胁迫应答cDNA片段。利用低熔点琼脂糖凝胶电泳方法纯化了该片段,并将其连接到pGEM—T easy vector上转化大肠杆菌JM 109,获得30个阳性克隆子,经过酶切和PCR双重鉴定后,选取2个阳性克隆子进行了测序,结果表明,SI800长735 bp,GenBank B last结果显示,该片段与细菌中的阿卓糖酸氧化还原酶基因的部分区段有较高的同源性。     

镉胁迫下玉米幼苗生理生态的变化

用不同浓度Cd2 + 处理玉米种子 ,在室内常规培养 ,研究了种子萌发和幼苗生理生态的变化。结果表明 ,镉影响玉米种子的萌发和幼苗的生长。当Cd2 + 浓度高于 5 0mg·L-1时 ,显著抑制种子的发芽率 ;随Cd2 + 浓度的增加 ,根系长度和侧根数减小 ;在Cd2 + 浓度小于 5mg·L-1时 ,镉刺激苗高和根系及地上部干物质量增加 ,当Cd2 + 浓度超过相应浓度时 ,苗高和根系及地上部的生长量随Cd2 + 浓度提高而降低。镉胁迫下幼苗根系活力和叶绿素含量明显降低 ,根内丙二醛含量增加。镉影响玉米幼苗对矿质元素的吸收。根系和茎叶中Ca、Mg、Fe、Cu的吸收量随Cd2 + 浓度提高而增加 ,K、Zn的吸收量随Cd2 + 浓度提高而减少。     

污水与镉复合胁迫对玉米幼苗代谢物的影响

运用GC-MS技术结合AMDIS软件对代谢物种类、含量及其代谢途径进行分析,研究污水与镉复合胁迫对玉米幼苗代谢物的影响.共鉴定出50种代谢物.在镉单一胁迫下,玉米幼苗苹果酸含量降低,柠檬酸含量升高,植株体内三羧酸循环稳定;在污水与镉复合胁迫下,柠檬酸和苹果酸含量均显著增加,复合胁迫阻碍了三羧酸循环的正常进行.镉单一胁迫和污水与镉复合胁迫均导致葡萄糖含量显著下降,与抗逆相关的物质腐胺、脯氨酸、肌醇和γ-氨基丁酸含量均显著升高,表明光合作用受到抑制,但以复合胁迫的变化更为明显.表明污水与镉复合胁迫对玉米幼苗代谢物影响的作用机制主要是通过阻碍三羧酸循环和抑制光合作用进行.     

Changes in glutathione and phytochelatins in roots of maize seedlings exposed to cadmium

The effects of excess Cd on the contents of free cysteine, total glutathione and phytochelatin (PC) were measured in roots of intact maize seedlings. Exposure to 3 /tmM Cd for 15 min caused PCs to appe substrates for formation of longer PCs. Total glutathione levels declined with PC synthesis, free cysteine contents changed little. The reactions to excess Cd differed along the length of roots. In the 1 cm apical region a high production of PCs occurred with a moderate loss of total glutathione. In the mature region, PC content was 2.5-fold less than in apices, several unidentified thiols accumulated, and total glutathione levels declined drastically. Exposure to 0.05 μM Cd for 24 h induced PCs, the contents rose as Cd concentrations were increased. The roots produced PCs in excess of that required to chelate the Cd present, as if some PCs were compartmentalized or had not yet formed Cd-PC complexes. Phytochelatin formation was stimulated most effectively by Cd, less by Zn and Cu and negligibly by Ni. Total glutathione declined with Cd and Zn exposure, however, with excess Cu the roots contained 45% more total glutathione than did the controls.