Effect of Polyamines on Chlorophyll and Protein Contents, Photochemical Activity, and Energy Transfer in Detached Wheat Leaves during Dark Incubation

Spermine as compared to putrescine or spermidine retarded the loss of chlorophyll and protein contents to a greater extent in wheat primary leaves during dark incubation. Activities of whole chain electron transport, photosystem (PS) 1 and PS2, and absorbed excitation energy distribution in favour of PS 1 were protected by these amines in valency dependent manner during 72-h dark incubation.     

Nitrate reductase activity (in vivo and in vitro) of ditelosomic stocks of wheat (Triticum aestivum L.)

The nitrate reductase activities (NRA) of 31 ditelosomic stocks were compared with that of the control plant [Chinese Spring (CS) euploid], using in vivo and in vitro assay procedures that had been optimized with respect to the euploid. Fourteen stocks exhibited significant differences in in vivo NRA from that of the euploid; the effect of removal of a chromosome arm was always to increase NRA. Eight of these stocks showed similar effects in vitro, although in three, a casein-sensitive factor had to be eliminated before the difference was expressed. Homoeologous group effects were evident among ditelosomics of groups 2, 4, and 7, while for three chromosomes (2D, 7A, and 7B), removal of either arm resulted in a similar increase in NRA in vivo and probably in vitro.P. W. Jones was supported by a Science Research Council C.A.S.E. award with the Plant Breeding Institute, Cambridge, U.K.     

Development of microsporesin vivo andin vitro inBrassica napus L.

Summary Populations of highly homogeneous uninucleate and binucleate microspores ofBrassica napus cv. Topas were obtained by bud selection and percoll fractionation. The development of the uninucleate and the binucleate microspores in culture was compared to thosein vivo using the fluorochrome DAPI to stain DNA. The major developmental pathway of the uninucleate microsporesin vitro resulted in embryo formation. The characteristic of this pathway was that the first division produced two diffusely stained nuclei and subsequent divisions gave rise to a multinucleate embryoid. The second pathway which occurred in a small number of the uninucleate microspores led to callus formation. The majority of the binucleate microsporesin vitro followed the developmental pattern of their counterpartsin vivo and were not embryogenic. The embryogenic binucleate microspores produced embryos through the divisions of the vegetative nucleus.Plant Research Centre Contribution # 1147     

Effect of nickel on antioxidative enzyme activities, proline and chlorophyll contents in wheat shoots

Effect of two Ni concentrations (10 and 200 μM) on growth, Ni accumulation, chlorophyll and proline contents, relative water content (RWC) as well as the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione S-transferase (GST) were studied in shoots of wheat plants. Treatments caused a considerable accumulation of Ni in the shoots. However, exposure of plants to 10 μM Ni did not lead to significant alterations in shoot growth except for a slight increase in fresh mass. The other parameters studied were not affected by treatment of plants with 10 μM Ni. In contrast, 200 μM Ni caused inhibition of shoot growth, a decline in RWC and chlorophyll content, accumulation of proline and occurrence of visible symptoms of Ni toxicity. The activities of SOD and CAT decreased in response to 200 μM Ni. Conversely, several-fold enhancements of POD and GST activities were observed following the 3^rd day of 200 μM Ni treatment.     

An improved medium for in vitro grain development from detached wheat spikelets

Wheat spikelets detached from the spike at anthesis were cultured on solidified media and successfully produced mature grains. These grains resembled normal grains and contained well-developed, embryos. Lower concentrations of glutamine favored dry weight increase in developing grains. Such grains were indistinguishable from grains from greenhouse-grown plants in germination on moist blotting sheets. The technique of individual spikelet culture can be used to study physiology and development of wheat grains and kernels and to study host-pathogen interactions in wheat floret diseases such as Karnal bunt.     

An efficient method for in vitro regeneration from immature inflorescence explants of Canadian wheat cultivars

Fertile, green plants were regenerated from immature inflorescence explants from each of four Canadian wheat cultivars. The cultivars were representative of four classes of Canadian wheat. Explants from immature inflorescences of three size ranges were cultured on two types of media: MSI/MSR, which contains 1650 mg l^-1 NH₄NO₃and sucrose as a carbon source, and BII/BIR, which contains 250 mg l^-1 NH₄NO₃and maltose as a carbon source. Regeneration from all cultivars was significantly better on BII/BIR media than on MSI/MSR media. On BII/BIR media, `AC Karma', `Plenty', and `Fielder' gave the highest number of shoots per 10 explants, where the explants were derived from immature inflorescences 5.1 to 10.0 mm in length. 'Columbus' did not regenerate on MSI/MSR medium, and regenerated poorly on BII/BIR medium. Differences were found between cultivars with regard to the number of regenerant plants produced with the best treatments: `Plenty' produced 16.1 shoots per 10 explants, `AC Karma' 12.4, `Fielder' 6.4, and `Columbus' 2.2.     

Effect of bioaccumulation of cadmium on biomass productivity,essential trace elements,chlorophyll biosynthesis,and macromolecules of wheat seedlings

Soil contamination with heavy metals has become a worldwide problem, leading to losses in agricultural yield and hazardous human health effects as they enter the food chain. The present investigation was undertaken to examine the influence of cadmium (Cd²⁺) on the wheat (Triticum aestivum L.) plant. Cd²⁺ accumulation and distribution in 3-wk-old seedlings grown in nutrient medium containing varying concentrations of Cd²⁺ (control, 0.25, 0.50, 1.0, 2.5, and 5.0 mg/L) was monitored. The effect of varying Cd²⁺ concentrations up to 21 d on biomass productivity, plant growth, photosynthetic pigments, protein, amino acids, starch, soluble sugars, and essential nutrients uptake was studied in detail to explore the level up to which the plant can withstand the stress of heavy metal. Plants treated with 0.5, 1.0, 2.5, and 5.0 mg/L Cd²⁺ showed symptoms of heavy-metal toxicity as observed by various morphological parameters which were recorded with the growth of plants. The root, shoot-leaf length and the root, shoot-leaf biomass progressively decreased with increasing Cd²⁺ concentration in the nutrient medium. Cd²⁺ uptake and accumulation was found to be maximum during the initial growth period. Cd²⁺ also interfered with the nutrients uptake, especially calcium (Ca²⁺), magnesium (Mg²⁺), potassium (K⁺), iron (Fe²⁺), zinc (Zn²⁺), and manganese (Mn²⁺) from the growth medium. Growth reduction and altered levels of major biochemical constituents such as chlorophyll, protein, free amino acids, starch, and soluble sugars that play a major role in plant metabolism were observed in response to varying concentrations of Cd²⁺ in the nutrient medium. In the present study, the effects of Cd²⁺ on growth, biomass productivity, mineral nutrients, chlorophyll biosynthesis, protein, free amino acid, starch, and soluble sugars in wheat plants was estimated to establish an overall picture of the Cd²⁺ toxicity at structural and functional levels.     

Germination ofMusa velutina seeds: Comparison ofin vivo andin vitro systems

Summary In the genusMusa, germination is extremely variable and relatively difficult. Even more difficulties are faced when producing hybrids. The seed yield of hybrids in breeding programs is usually low and often, to ensure the viability and survival of seeds, it is necessary to attempt to germinate a large excess of these seeds. In this context,in vitro embryo culture might be an invaluable tool for obtaining desirable hybrid plants in a short time. Seeds ofMusa velutina were sown in seed trays in a peat-based mixture. Thein vivo seed germination reached 78% but only after 9 mo. Because of this delayed and intermittent germination, embryos were excised from seeds and inoculated onto half-strength Murashige and Skoog (1962) medium, with or without supplementation with various concentrations of gibberellic acid. Light and dark conditions were also used to test their effect on embryo germination. After 2 wk, 82% of embryos germinated in the dark on medium containing 0.1 μM gibberellic acid. Addition of gibberellic acid increased the shoot length and root number over the gibberellic acid-free treatment. Similarly, dark conditions gave a significant increase over light conditions for all the parameters except root number where light or dark conditions did not make any difference. Thus, the present study highlights the importance of various components of thein vitro culture ofMusa embryos and the advantage over direct use of greenhouse-sown seeds both in terms of the time taken to germinate and the final percentage.     

Heat-induced accumulation of chloroplast protein synthesis elongation factor, EF-Tu, in winter wheat

Chloroplast protein synthesis elongation factor, EF-Tu, has been implicated in heat tolerance in maize (Zea mays). Chloroplast EF-Tu is highly conserved, and it is possible that this protein may be of importance to heat tolerance in other species including wheat (Triticum aestivum). In this study, we assessed heat tolerance and determined the relative levels of EF-Tu in mature plants (at flowering stage) of 12 cultivars of winter wheat experiencing a 16-d-long heat treatment (36/30 degrees C, day/night temperature). In addition, we also investigated the expression of EF-Tu in young plants experiencing a short-term heat shock (4h at 43 degrees C). Heat tolerance was assessed by examining the stability of thylakoid membranes, measuring chlorophyll content, and assessing plant growth traits (shoot dry mass, plant height, tiller number, and ear number). In mature plants, relative levels of EF-Tu were determined after 7 d of heat stress. High temperature-induced accumulation of EF-Tu in mature plants of all cultivars, and a group of cultivars that showed greater accumulation of EF-Tu displayed better tolerance to heat stress. Young plants of all cultivars but one did not show significant increases in the relative levels of EF-Tu. The results of the study suggest that EF-Tu protein may play a role in heat tolerance in winter wheat.     

Effect of Nitrogen and Water Stress on Photosynthesis and Nitrogen Content in Wheat

The relationships between photosynthesis, leaf nitrogen content and water stress were studied in ten genotypes of wheat differing in the presence of dwarfing genes. Net photosynthetic rate (P_N) was mostly higher at ear emergence stage than at anthesis stage. P_N decreased with water stress (leaf water potential from –2.0 to –2.5 MPa), and with reduced leaf N content in all genotypes studied. Among the various genotypes, single dwarf and wild types showed higher P_N rate and maintained higher leaf N content under different N doses and water supply as compared to the other types studied.     

The effect of glucose-6-phosphate isomerase genotype onin vitro specific activity andin vivo flux inMytilus edulis

Four samples of the musselMytilus edulis were taken between 1984 and 1987 from Stony Brook, New York, and used to study the glucose-6-phosphate isomerase (GPI) polymorphism in this species.In vitro specific activity andin vivo flux measured in the same animals were found to be significantly correlated. A significant effect of GPI genotype on flux was observed in one of the samples; overall, significant evidence of effect of genotype on enzyme activity was also obtained. GPI activities of common genotypes tend to deviate less from the population mean than those of rare (frequency less than 5%) genotypes. This suggests the possibility that rare GPI genotypes are rare as a consequence of having biochemical properties that deviate from an optimum level and, therefore, having a lower fitness. In support of this hypothesis, we found in one of our samples that shell length is a concave function of GPI activity with an intermediate optimum activity level. The financial support provided to P.J.N.S. by the Luso-American Educational Commission (Fulbright Program), the Instituto Nacional de Investigacao Científica (Portugal), and the Faculdade de Ciências da Universidade de Lisboa during several stages of this research is gratefully acknowledged. Financial support from the Ministerio de Educatión y Ciencia (Spain) in the form of a postdoctoral Fulbright/MEC fellowship to M.S. is also gratefully acknowledged. Research was supported by National Science Foundation Grant BSR-8415060 to R.K.K. This is contribution No. 736 from the Program in Ecology and Evolution, State University of New York at Stony Brook. On leave from Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande C2, Lisboa, Portugal.     

In vivo andin vitro investigations on rotenoids fromIndigofera tinctoria and their bioefficacy against the larvae ofAnopheles stephensi and adults ofCallosobruchus chinensis

Various plant parts ofIndigofera tinctoria L. were collected separately at different growth stages and analysed for their rotenoid content. The total rotenoid content decreased with age; among the plant parts, maximum content was in leaves and minimum in stem. The identity of different rotenoids was confirmed by melting point, mixed melting point, UV and infrared spectral studies, and gas-liquid chromatography. Six rotenoids (deguelin, dehydrodeguelin, rotenol, rotenone, tephrosin and sumatrol) were isolated, identified and quantified invivo. The static cultures ofIndigofera tinctoria were established from seeds on RT medium, and maintained for a period of six months by frequent subculturings. Only four rotenoids were present in callus cultures; sumatrol and tephrosin were absent. The maximum content was found in eight week old tissue after fresh subculturings and minimum at 2 weeks. The toxicological studies ofin vivo andin vitro extract against the pulse beetle(Callosobruchus chinensis) and mosquito(Anopheles stephensi) larvae, showed that rotenoids were more effective against mosquito larvae thanCallosobruchus chinensis. Extracts from callus was more effective against both the test animals than that from plant parts.     

Effect of hypobaric conditions on ethylene evolution and growth of lettuce and wheat

Elevated levels of ethylene occur in enclosed crop production systems and in spaceflight environments, leading to adverse plant growth and sterility. There are engineering advantages in growing plants at hypobaric (reduced atmospheric pressure) conditions in biomass production for extraterrestrial base or spaceflight environments. Objectives of this research were to characterize the influence of hypobaria on growth and ethylene evolution of lettuce (Lactuca sativa) and wheat (Triticum aestivum). Plants were grown under variable total gas pressures [from 30 to 101 kPa (ambient)]. In one study, lettuce and wheat were direct seeded, germinated and grown in the same chambers for 28 d at 50 or 101 kPa. Hypobaria increased plant growth and did not alter germination rate. During a 10-day study, 28-day-old lettuce and 40-day-old wheat seedlings were transplanted together in the same low and ambient pressure chambers; ethylene accumulated in the chambers, but the rate of production by both lettuce and wheat was reduced more than 65% under 30 kPa compared with ambient pressure (101 kPa). Low O2 concentrations [partial pressure of O2 (pO2) = 6.2 kPa] inhibited ethylene production by lettuce under both low (30 kPa) and ambient pressure, whereas ethylene production by wheat was inhibited at low pressure but not low O2 concentration. There was a negative linear correlation between increasing ethylene concentration and decreasing chlorophyll content of lettuce and wheat. Lettuce had higher production of ethylene and showed greater sensitivity to ethylene than wheat. The hypobaric effect on reduced ethylene production was greater than that of just hypoxia (low oxygen).     

The chromosomal location of factors determining the presence of phenolic compounds in wheat (Triticum aestivum L.)

Summary Using thin-layer chromatography and nulli-tetrasomic and ditellosomic series of Triticum aestivum L. cv. Chinese Spring, it has been possible to relate the phenolic compounds found in adult plant leaves and 12 day-old seedling leaves with the chromosomes or chromosome arms 1 B, 2 BL, 3 BL, 5 A, 6 AL, 7 B and 7 DS.     

Effects of Water Deficit during Germination of Wheat Seeds

Germinating seeds of spring wheat (Triticum aestivum L.) were tolerant to dehydration up to the 4^th day following imbibition and from the 5^th day the seedling survival decreased. Dehydration also inhibited the rate of seed dry mass depletion and seedling dry matter accumulation and increased the content of soluble sugars both in grain and seedlings. Glucose supplied either to dry seeds or to 4-d-old seedlings increased survival of dehydrated seedlings. In contrast, exogenously supplied non-readily metabolizable sorbose and mannose suppressed seedling survival.     

Effect of heavy metals on isoperoxidases of Wheat

The influence of increasing concentrations of copper, zinc, lead, nickel, chromium and cadmium on 14-day-old seedlings of wheat (Triticum aestivum L. cv. Vergina) was studied. Plants were grown in 1/10 strength Rorison’s nutrient solution with increasing concentrations of each of the metals added separately. The toxicity of metals depressed shoot growth but the most evident symptoms were on roots. The concentration of each metal which caused inhibition of root growth was chosen to study the influence of metals on isoperoxidases of wheat shoots. The concentrations employed did not alter the number of peroxidase bands but almost in all cases enhanced the intensities of bands of pH 4.0-4.2 and 5.0-5.4, while they decreased the intensities of bands of pH 4.2-4.6 and 5.4-6.5. The similar effects of the different heavy metals employed may suggest similarity in metal action on wheat isoperoxidases. The increased intensities of peroxidase bands may be considered as an indication of enhanced senescence caused by the heavy metal treatments. Generally, our results suggest that the heavy metals employed have caused complex changes on the multiple forms of peroxidases.     

In vitro microspore reaction of different German wheat cultivars

Summary The in vitro microspore androgenesis reaction of 25 commercial German spring (including 4 Triticum durum) and 50 winter wheat cultivars was investigated. Tremendous genotypical differences were found in microspore response. The best-responding winter wheat cultivai, Florida, is characterized by the presence of a 1B/1R wheat-rye translocation chromosome. The significance of this finding and other genetic systems for future use of haploids in plant breeding is discussed.