Somaclonal variation for some morphological traits, herb yield, essential oil content and essential oil composition in an Indian cultivar of rose-scented geranium

Somaclonal variation for plant height, plant spread, leaf shape, leaf size, leaf form, herb yield, essential oil content and 10 important constituents of the essential oil was studied in an Indian cultivar, ‘Bourbon’ of rose‐scented geranium (Pelargonium graveolens). Significantly larger variance was observed among in vitro‐regenerated plants of the SC1 generation (first generation following an in vitro phase) than among parental plants raised from stem cuttings for herb yield, plant height, leaf size, essential oil content, and for the contents of cis‐rose oxide, trans‐rose oxide, isomenthone and 10‐epi‐γ‐eudesmol in the essential oil. Plants of the SC₁ generation showing values beyond the higher or lower limit (depending on the trait) of the range observed among parental plants for different traits were developed into clones by their multiplication through stem cuttings, and evaluated again in the SC₂ generation (second generation following the in vitro phase). Somaclones selected for plant spread, and for the contents of linalool and trans‐rose oxide in their essential oils did not breed true in the SC₂ generation. However, for the remaining traits studied, 13–100% of the selected clones retained their selected traits in the SC₂ generation, suggesting that the changes in these somaclones were due to genetic causes.     

Management of Two Potentially Iron Toxic Benchmark Wetlands Using Integrated Approach for Rice Production in Nigeria

To manage iron toxic rainfed lowlands on a sustainable basis for rice production, a trial was conducted using an integrated approach (i.e. tolerant genotype and fertilizer nutrients). This trials involved two rice cultivars ITA 212 and Suakoko 8 in two cropping seasons (1994 and 1995) and on two potentially iron toxic soil types with excessively high active Fe contents of between 4.43 % and 5.15 %, respectively, located in two agro‐ecological zones in Nigeria. The effects of fertilizer nutrients (N, P, K, Zn, N+P, N+K, N+Zn, N+P+K, N+P+K+Zn and control) were evaluated on the grain yield (GY) and nutrient uptake (leaf analyses) of the rice plants using stepwise multiple regression analysis (SMRA). Results showed that these soils are acidic and had sub‐optimal macronutrient and micronutrient contents coupled with excessively high active Fe (Fe_H) of between 4.43 % and 5.15 %. Fertilizer nutrients N+K, N+P+K and N+P+K+Zn consistently appeared to result in higher GY compared to others on both soil types. Plant analysis of both rice cultivars showed no apparent deficiencies in elemental composition with regard to macronutrients and micronutrients. Results of SMRA showed that tissue K, Zn and Mg contents were significantly related (P < 0.01) to the GY of the two rice cultivars.     

Silicon Application in Cultivated Rices (Oryza sativa L and Oryza glaberrima Steud) Alleviates Iron Toxicity Symptoms Through the Reduction in Iron Concentration in the Leaf Tissue

Iron (Fe) toxicity is a constraint commonly encountered in waterlogged conditions. Under anaerobic conditions, reduced Fe is massively absorbed by plants and may induce the generation of reactive oxygen species. This oxidative stress is responsible for physiological perturbations, growth reduction and yield losses. Rice is known as a silicon (Si) accumulator. Although Si is not considered as essential, it is known to play a beneficial role in the resistance to biotic and abiotic stresses through diverse and sometimes unknown mechanisms. The aim of this study was to determine the alleviation of Fe toxicity through Si application in different genotypes. Therefore, cultivars of both cultivated rice species (Oryza sativa and Oryza glaberrima) and lines from a segregating population issued from a cross between IR64 (O. sativa subsp. indica) and Azucena (O. sativa subsp. japonica) were grown in hydroponics under standard or excessive Fe(II) conditions, with or without the addition of Si. The application of Si on Fe‐treated plants strongly alleviated Fe toxicity symptoms. The reduced Fe uptake by Si‐treated plants suggested that an avoidance mechanism would be involved in this alleviation. Moreover, an additive effect of the Si and Fe treatments on the absorption of other nutrients by plants was revealed. These promising results gave insights into the understanding of rice resistance mechanisms to Fe toxicity, opening new perspectives in its management through Si fertilization. Finally, plant response to Si application was greatly influenced by the genotype. Thus, selection of stronger Si‐accumulating varieties could also be of valuable interest in the improvement of rice resistance to Fe toxicity.     

The effect of in vivo and in vitro applications of ethrel and GA<Subscript>3</Subscript> on sex expression in bitter melon (<Emphasis Type="Italic">Momordica charantia</Emphasis> L.)

Bitter melon (Momordica Charantia L.) is an important vegetable crop with nutritional and medicinal qualities. As a member of cucurbitaceae it is monoecious with varying proportions of staminate and pistillate flowers. This study was undertaken to determine the effects of various applications of ethrel and gibberellic acid (GA₃) on sex modification in M. charantia. In the first set of experiments, various concentrations of hormones were added to the seed germination medium, in the second, adult plants growing in the field were sprayed with aqueous solutions of ethrel or GA₃ three times at three-day intervals. The number and sex of open flowers was recorded daily for 60 days after the first flower opened and total number of staminate and pistillate flowers was calculated at the end of the experiment. The highest frequency (29.5%) of pistillate flowers was observed in plants treated with 500 ppm ethrel at germination. Similarly, spraying of adult plants with 100 ppm GA₃ increased the proportion of pistillate flowers to 26% relative to 15% in untreated controls. Both ethrel and GA₃ induced significantly higher number of pistillate flowers than control. In vitro hormone application during seed germination was much more successful than spraying of field grown plants.     

小麦根系在不同铁营养水平条件下的蛋白质组差异表达分析

为了探究小麦根际不同铁水平对根系基因表达的调控,采用小麦‘北农9549’为材料,进行缺铁胁迫和胁迫后恢复铁供应等不同处理,用双向电泳的方法分离蛋白,对比分析不同处理间根系蛋白质表达的差异。结果表明,缺铁处理植株与正常供铁的植株相比,缺铁条件下生长的小麦根系有137个蛋白点的表达水平变化具有显著差异（P<0.05）,其中76个蛋白点发生大于2倍的显著上调表达,另有61个蛋白点发生大于2倍的显著下调表达。上述经过铁饥饿的小麦根系恢复正常铁供应2周后,与自始至终正常供铁的根系相比,有150个蛋白点的表达水平变化具有显著差异（P <0.05）,其中78个蛋白点发生大于2倍的显著上调表达,另有72个蛋白点发生大于2倍的显著下调表达,本试验结果表明,缺铁会引起小麦根系表达大量特异性蛋白。     

Effect of Prohexadione Calcium on Growth Components and Endogenous Gibberellins Contents of Rice (Oryza sativa L.)

Prohexadione calcium (Pro‐Ca) is a novel plant growth regulator that inhibits the late stages of gibberellins (GAs) biosynthesis in plants, thus reducing the vegetative growth of the plant. Pro‐Ca was applied to field‐grown rice cultivar Ilpumbyeo to evaluate its effect on growth and yield components and endogenous GAs, when applied at different rates and timings. This study illustrated that Pro‐Ca application decreased the internode length, stem length, panicle length, shoots fresh weight and stem lodging index, while stem breaking force was increased in all treatments. The effect of Pro‐Ca was more pronounced in 20 ppm concentration than 10 ppm. The number of panicles m⁻², ripened grain ratio and 1000 grain weight and milled rice yield parameters, increased with the application of Pro‐Ca, though the number of grains per panicle decreased insignificantly. The endogenous bioactive GA₁ contents significantly decreased with the application of Pro‐Ca, as the GA biosynthesis was interrupted at later stages, when GA₂₀ conversion to GA₁ was blocked, thus drastically reducing GA₁ and GA₈ levels, but only insignificant changes were observed for intermediates from GA₁₂ to GA₂₀. The levels of the endogenous GAs in rice shoots were measured by GC‐MS‐SIM using ²H₂‐labelled GAs as internal standards. Present results also illustrated that early application of Pro‐Ca was more effective than its late application for effective control of different growth parameters and thus reducing lodging in rice plants.     

A Robertsonian translocation from Thinopyrum bessarabicum into bread wheat confers high iron and zinc contents

Development of wheat–alien translocation lines has facilitated practical utilization of alien species in wheat improvement. The production of a compensating Triticum aestivum–Thinopyrum bessarabicum whole‐arm Robertsonian translocation (RobT) involving chromosomes 6D of wheat and 6E^b of Th. bessarabicum (2n = 2x = 14, E^bE^b) through the mechanism of centric breakage–fusion is reported here. An F₂ population was derived from plants double‐monosomic for chromosome 6D and 6E^b from crosses between a DS6E^b(6D) substitution line and bread wheat cultivar ‘Roushan’ (2n = 6x = 42, AABBDD) as female parent. Eighty F₂ genotypes (L1–L80) were screened for chromosome composition. Three PCR‐based Landmark Unique Gene (PLUG) markers specific to chromosomes 6D and 6E^b were used for screening the F₂ plants. One plant with a T6E^bS.6DL centric fusion (RobT) was identified. A homozygous translocation line with full fertility was recovered among F₃ families and verified with genomic in situ hybridization (GISH). Grain micronutrient analysis showed that the DS6E^b(6D) substitution line and T6E^bS.6DL stock have higher Fe and Zn contents than the recipient wheat cultivar ‘Roushan’.     

植物铁素(Fe)营养的生理研究进展

铁(Fe)是植物体内发现最早和含量最高的必需微量元素,参与许多生理过程和代谢途径,缺铁将严重影响其生长发育和产量品质。植物源食物中的Fe是动物和人类获取Fe的主要途径,摄入不足将损害其健康。为了充分了解Fe在植物体内的代谢生理,推动富Fe植物的培育和富Fe食物的研发,本文归纳了土壤和植物体内Fe的含量、形态及比例,总结了植物体内Fe的分布与功能,比较了植物应对少量可溶性Fe环境下的不同高效吸收策略,分析了Fe在细胞内和长距离运输中的调控机制。在此基础上,针对以往研究中存在的不足提出展望,认为今后应更多地关注：不同物种间的Fe代谢途径的差异及分子机理、Nramp家族基因如何调控植物缺Fe的吞噬机制、质体中铁蛋白(Fer)的氧化沉淀与还原释放机制和提高植物体内Fe含量及生物有效性的生物强化措施。     

Photosynthetic Acclimation and Productivity of Mungbean Cultivars under Elevated CO2 Concentration

Mungbean [Vigna radiata (L.) Wilczek] cultivars (Pusa Baisakhi, PS 16 and P 105) were grown in field at atmospheric (360 ± 10 ppm, AC) and elevated CO₂ (650 ± 50 ppm, EC) concentrations inside open top chambers for entire period of growth and development till maturity. Leaf net photosynthesis rate (P_N) of AC and EC grown plants when compared at same CO₂ concentration showed no significant down‐regulation of P_N in EC plants. In cv. P 105, even up‐regulation of P_N was observed in EC plants. Mungbean cultivars accumulated assimilates in the leaves during the day mostly in the form of starch. Nodule number and weight were also higher in EC plants. The positive effect of elevated CO₂ on P_N, dry‐matter production and seed yield was better expressed in cv. P 105 having greater podding ability.     

Cotton Leaf Senescence can be Delayed by Nitrophenolate Spray Through Enhanced Antioxidant Defence System

Leaf senescence is an oxidative process, and most of the catabolic processes involved in senescence are propagated irreversibly once initiated. An experiment was conducted to test the hypothesis that nitrophenolates (Atonik, a plant growth regulator) spray can delay the leaf senescence through reduced oxidative damage. Atonik 3.75 g a.i. ha^?1 was sprayed during boll filling stage on cotton, and the senescence process was evaluated by quantifying total chlorophyll contents, photosynthetic rate, Fv/Fm ratio, various reactive oxygen species (ROS) content, antioxidant content and antioxidant enzyme activity from 90 days after sowing (DAS) to 130 DAS. The result indicated that nitrophenolate spray reduced the hydrogen peroxide (H₂O₂), superoxide anion (O₂^?) accumulation, lipid peroxidation (malondialdehyde), lipoxygenase activity and membrane permeability over unsprayed control. The antioxidant enzyme activity (superoxide dismutase, SOD; ascorbate peroxidase, APX; peroxidase, POX; glutathione peroxidase, GSH‐Px) were significantly increased by the nitrophenolate spray. POX (118.1 %) and GSH‐Px (143.3 %) activities were enhanced to a higher level compared to APX (8.5 %) activity at 130 DAS. Enhanced accumulation of ascorbate (144.9 %), phenol (154.7 %) and proline (50 %) was seen in nitrophenolate‐sprayed plants compared with unsprayed control plants at 130 DAS. Ascorbate content is increased by higher dehydroascorbate reductase enzyme activity. Ascorbate was thus able to replenish reducing equivalents to phenoxyl radicals resulting in an increase in phenolic compounds. The increased phenolic acid content may be involved in scavenging the ROS produced during senescence process. The higher level of reduced ascorbate and low level of endogenous H₂O₂ in the leaves may be the prerequisite for delayed leaf senescence in the nitrophenolate‐sprayed plants. Based on the present work, it can be concluded that nitrophenolate‐sprayed plants can postpone the leaf senescence by peroxide/phenolic/ascorbate system which is involved in scavenging the ROS produced during leaf senescence.     

Development of breeding populations from interspecific hybrids between Trifolium repens L. and T. occidentale Coombe

Trifolium occidentale is a diploid wild relative of T. repens (white clover) with adaptation to dry, saline coastal habitats. Transfer of drought and salt‐tolerant adaptive traits to white clover could be potentially valuable if interspecific hybridization can be achieved efficiently and leads to fertile hybrid populations. To achieve hybridization, 4x plants of T. occidentale were generated. Efficient techniques for generation of 4x plants and their identification using dry pollen shape are described. Interspecific 4x F₁ plants were achieved without embryo rescue. F₂ populations and first backcross hybrids to white clover were also efficiently achieved. Although male and female fertility were lower than in white clover, they were adequate to produce large amounts of seed from small numbers of inflorescences. Thus, early generation interspecific hybrid prebreeding populations can be readily developed, opening the way for transfer of traits from T. occidentale to white clover.     

Cultivar Specific Response of CO2 Fertilization on Two Tropical Mung Bean (Vigna radiata L.) Cultivars: ROS Generation,Antioxidant Status,Physiology, Growth,Yield and Seed Quality

Increasing atmospheric carbon dioxide concentration (CO₂) is an important component of global climate change that will have a significant impact on the productivity of crop plants. In recent years, growth and yield of agricultural crop plants have been shown to increase with elevated CO₂ (EC) and have enticed considerable interest due to variation in the response of crop plants. In this study, comparative response of two mung bean cultivars (HUM‐2 and HUM‐6) was evaluated against EC at different growth stages under near‐natural conditions for two consecutive years. The plants were grown in ambient as well as EC (700 ppm) in specially designed open‐top chambers. Under elevated CO₂, marked down‐regulation of reactive oxygen species (ROS) levels, membrane disruption and activities of superoxide dismutase and catalase were noticed in both the cultivars, but the extent of reduction was more in HUM‐6. As compared to ambient CO₂, EC increased total chlorophyll, photosynthetic rate, growth and yield parameters. Cultivar‐specific response was noticed as HUM‐6 showed higher increase in yield attributes than HUM‐2. Under CO₂ treatment, soluble protein and reducing sugars decreased while total soluble sugars and starch showed an opposite trend. Principal component analysis showed that both the cultivars responded more or less similarly to EC in their respective groupings of physiological and growth parameters, but the magnitude of ROS and antioxidative enzymes was variable. The experimental findings depict that both the cultivars of mung bean showed contrasting response against EC and paved the way for selecting the suitable cultivar having higher productivity in a future high‐CO₂ environment.     

外源一氧化氮供体SNP对水稻叶片中由硒引起的脂质过氧化的调节作用

一氧化氮(nitric oxide, NO)是植物中一种重要的信号分子, 在诱导种子萌发, 影响植物生长发育, 促进植物细胞衰亡等方面发挥着重要作用。然而对于外源NO是否参与了Se诱导的脂质过氧化调节过程仍不为人知。我们研究了0.2 μmol L^-1和20 μmol L^-1Na₂SeO₃及一氧化氮供体硝普钠(sodium nitroprusside, SNP)处理对水稻叶片叶绿素、H₂O₂和硫代巴比妥酸反应产物(Thiobarbituric Acid Reactive Substances, TBARS)含量, 愈创木酚过氧化物酶(guaiacol peroxidase, GPX)、超氧化物歧化酶(superoxide dismutase, SOD)、过氧化氢酶(catalase, CAT)以及抗坏血酸过氧化物酶(ascorbate peroxidase, APX)活性等生理生化指标的影响。结果表明, 1 μmol L^-1SNP处理促进GPX、APX和CAT活性, 缓解膜脂过氧化, 降低TBARS含量;显著提高0.2 μmol L^-1Na₂SeO₃处理下水稻叶片中叶绿素含量。在20 μmol L^-1Na₂SeO₃处理下, 外加1 μmol L^-1SNP更加显著促进GPX和CAT活性, 与此同时明显降低20 μmol L^-1Na₂SeO₃处理引起的H₂O₂含量上升, 并降低TBARS含量。NO对植物中由Se引起的脂质过氧化具有调节作用。     

Physiological processes associated with salinity tolerance in an alfalfa half‐sib family

We previously reported an alfalfa half‐sib family, HS‐B, with improved salt tolerance, compared to parental plants, P‐B. In this study, we conducted additional experiments to address potential physiological mechanisms that may contribute to salt tolerance in HS‐B. Vegetatively propagated HS‐B and P‐B plants were treated with a nutrient solution (control) or a nutrient solution containing NaCl (EC = 12 dS/m). Shoots and roots were harvested at various time points after treatment for quantification of proline, soluble sugar, and H₂O₂ using spectrophotometers. Subcellular localization and quantification of Na in roots were conducted using a Na⁺‐specific dye under a confocal microscope. HS‐B produced 86 and 89% greater shoot and root dry biomass, respectively, compared to parental plants, P‐B, under salinity in the greenhouse. Under saline conditions the HS‐B shoots accumulated 115% and roots 55% more soluble sugars than P‐B counterparts. The non‐saline HS‐B shoots, however, showed 72% less soluble sugars than the non‐saline P‐B plants. Under saline conditions HS‐B accumulated 39% less proline in shoots, while roots accumulated 56% more proline, compared to their P‐B parents. HS‐B plants also showed a greater reduction of stomatal conductance under mild saline stress. HS‐B shoots and roots contained 3–4 times less reactive oxygen species (H₂O₂) after salt treatment compared to P‐B plants. Sodium localization and distribution analysis using Na⁺‐specific dye revealed HS‐B plants accumulated 88% and 48% less Na⁺ in stele and xylem vessels compared to P‐B. The study provides insights into the potential mechanisms that may contribute to salt tolerance in HS‐B: maintaining RWC by accumulating soluble sugars while reducing transpiration, maintaining healthy status by reducing oxidative stresses, and preventing salt toxicity by reducing accumulation of Na⁺ inside root cells and xylem.     

Quality retention of oyster mushrooms (Pleurotus florida) by a combination of chemical treatments and modified atmosphere packaging

Three preservation techniques, chemical treatment, modified atmosphere packaging (MAP) and low temperature storage were used to improve physico-chemical attributes of oyster mushrooms. Mushrooms were treated with a solution of sorbitol (0.05%, w/v), citric acid (3%, w/v) and CaCl₂ (1%, w/v). Chemically treated mushrooms were packed under two different gas compositions. Physico-chemical, textural and sensory properties of the samples were assessed during storage at 4 °C for 25 d. Chemical treatment of mushrooms followed by modified atmosphere packaging using 10% O₂ and 5% CO₂ provided better retention of quality characteristics and received higher sensory ratings compared to other samples, resulting in a storage life of 25 d. Material with this treatment underwent minimal changes in weight, pH and TSS. Radical scavenging activity and total polyphenol contents were retained at 85 and 91% levels, respectively. Control samples without chemical treatment and with chemical treatment, kept under similar packaging conditions, underwent spoilage after 5 and 15 d, respectively.     

Rapid generation cycling of an F2 population derived from a cross between Lens culinaris Medik. and Lens ervoides (Brign.) Grande after aphanomyces root rot selection

Cultivated lentil (Lens culinaris Medik.) is susceptible to aphanomyces root rot (ARR), whereas partial resistance is present in wild lentil including Lens ervoides (Brign.) Grande. Approximately six generations of selfing are required to fix a desired trait in a population, which usually requires 2 years in a breeding programme, so the primary objective was to develop a rapid generation cycling (RGC) technique that achieves this goal in 1 year. Rapid generation cycling was then tested on an F₂ population (LR‐59) derived from a L. culinaris × L. ervoides cross in combination with a reliable ARR screening technique, which generates a wide range of disease severities conducive to selection. Phenotyping of an F₂ population of more than 1,200 plants resulted in scores ranging from 2.4 to 4.0 on a scale from zero to five. Plants with scores lower than 4.0 were selected for advancement for five generations using a modified single‐seed descent method, optimum growing conditions, 20‐hr photoperiod and harvest of immature seeds. Seeds were germinated in a 100 μM gibberellin solution. Average generation length after phenotyping was 56 days resulting in five generations within approximately 300 days. Using a modified inoculation protocol, ARR phenotyping of the F₇ population resulted in scores ranging from 1.4 to 4.0. This inexpensive, nonsterile speed breeding protocol saves 1 year in the development of lentil varieties with improved ARR resistance.     

Individual reaction of <Emphasis Type="Italic">Capsicum</Emphasis> F<Subscript>2</Subscript> hybrid genotypes in anther cultures

The present study evaluated the individual plants reaction of F₂ hybrid generation of C. annuum: ATZ1 × PO and ATZ1 × CDT as well as two interspecific hybrids: C. frutescens × C. annuum ATM1 and C. frutescens × C. chinense on androgenesis conditions in in vitro anther cultures. The experiment was carried out following a modified method of Dumas de Vaulx et al. (Agronomie 1:859–864, 1981). There were demonstrated clear differences in the effectiveness of androgenesis both between the pepper hybrid forms as well as among individual plants of all the genotypes tested. The highest effectiveness of androgenic embryos development was observed for the cultivated form of C. annuum: (ATZ1 × PO)F₂. Anthers of most of the plants of this hybrid produced embryos at the level higher than 5%, while in anther cultures of the second C. annuum hybrid (ATZ1 × CDT)F₂ almost 3-fold fewer embryos and plants were produced. Anthers isolated from flower buds of interspecific hybrids formed much lower number of embryos. A positive reaction was recorded for five hybrid plants of (C. frutescens × C. annuum ATM1)F₂, while in case of (C. frutescens × C. chinense)F₂ androgenic embryos were obtained from anthers of two plants. Only in the case of a one of these plants did the effectiveness of androgenesis exceed 5%. The ploidy level of the regenerants was determined by flow cytometry. Among the regenerants there were observed both haploid forms and the plants with the diploid number of chromosomes.     

Exogenous Abscisic Acid Application During Grain Filling in Winter Wheat Improves Cold Tolerance of Offspring's Seedlings

Low temperature seriously depresses seed germination and seedling growth in winter wheat (Triticum aestivum L.). In this study, wheat plants were sprayed with abscisic acid (ABA) and fluridone (inhibitor of ABA biosynthesis) at 19 days after anthesis (DAA) and repeated at 26 DAA. The seeds of those plants were harvested, and seed germination and offspring's seedling growth under low temperature were evaluated. The results showed that exogenous ABA application decreased seed weight and slightly reduced seed set and seed number per spike. Under low temperature, seeds from ABA‐treated plants showed reduced germination rate, germination index, growth of radicle and coleoptile, amylase activity and depressed starch degradation as compared with seeds from non‐ABA‐treated plants; however, activities of the antioxidant enzymes in both germinating seeds and seedling were enhanced from those exposed to exogenous ABA, resulting in much lowered malondialdehyde (MDA) and H₂O₂ concentrations and production rate. In addition, the maximum quantum efficiency of photosystem II was also enhanced in ABA‐treated offspring's seedlings. It is concluded that exogenous ABA treatment at later grain‐filling stage could be an effective approach to improve cold tolerance of the offspring during seed germinating and seedlings establishment in winter wheat.     

Cadmium Enhances Generation of Hydrogen Peroxide and Amplifies Activities of Catalase, Peroxidases and Superoxide Dismutase in Maize

Maize (Zea mays L. cv. 777) plants grown in hydroponic culture were treated with 50 μm CdSO₄. Growth and metabolic parameters indicative of oxidative stress and antioxidant responses were studied in leaves of plants treated with Cd. Apart from increasing lipid peroxidation and H₂O₂ accumulation, supply of Cd suppressed growth, fresh and dry mass of plants and decreased the concentrations of chloroplastic pigments. The activities of catalase (CAT; EC 1.11.1.6), peroxidase (POD; EC 1.11.1.7), ascorbate peroxidase (APX; EC 1.11.1.11) and superoxide dismutase (SOD; EC 1.15.1.1) were increased in plants supplied 50 μm Cd. Localization of activities of isoforms of these enzymes (POD, APX and SOD) on native gels also revealed increase in the intensities of pre‐existing bands. Stimulated activities of CAT, POD, APX and SOD in maize plants supplied excess Cd do not appear to have relieved plants from excessive generation of reactive oxygen species (ROS). It is, therefore, concluded that supply of 50 μm Cd induces oxidative stress by increasing production of ROS despite increased antioxidant protection in maize plants.     

Novel variation for the tocopherol profile in a sunflower created by mutagenesis and recombination

α‐Tocopherol is the main tocopherol in sunflower seeds (>90%). Because it exerts a weak antioxidant action in vitro, its partial replacement by other tocopherols is an important breeding objective in this crop. The objective of this research was to develop novel tocopherol profiles in sunflower through mutagenesis and genetic recombination. Seeds of four ‘Peredovik’ accessions were used for chemical mutagenesis with ethyl methane sulfonate (EMS). Single‐seed screening in the M₂ generation resulted in two M₂ seeds, derived from different M₁ plants, with increased γ‐tocopherol contents of 19.2% and 96.7%, respectively. M₃ progeny from the M₂ seed with the 96.7% content bred true for high c‐tocopherol content, containing more than 90%γ‐tocopherol. M₃ progeny from the M₂ seed with only 19.2%γ‐tocopherol segregated in a range from 0 to 84.6%. Selection for high c‐tocopherol content produced an M_4:5 line, designated IAST‐1, with a stable high concentration of γ‐tocopherol. Crosses between IAST‐1 and T589, with an increased b‐tocopherol content, produced F₂ segregants with trans‐gressive levels of up to 77%β‐tocopherol or up to 68% d‐tocopherol. Both novel tocopherol profiles were confirmed in the F₃ generation.