Genetic change in the waxy trait of barley under the influence of wild type DNA. Analysis of the composition of starch and the electrophoretic spectrum of caryopsis hordein from altered plants and the retention of these changes to the fourth generation

Injection of DNA isolated from the wild type of barley into grains of recipient mutant plants (waxy mutants) at the milk stage of maturity leads to a change in starch synthesis; type of spikes and hordein composition. In the first generation of injected plants the wild type starch synthesis was observed in some separate plants (these observations were made at a haploid level in pollen cells). In the second generation of transformed plants along with the change in starch and hordein synthesis a modification of the type of spikes was also revealed. Recipient plants had six-rowded (hexastichous) spikes, and donor plants--two rowded (distichous) spikes. Disc-electrophoresis of hordeins of the wild type barley (Yuzhny var.), hordeins of the waxy mutant (defected in synthesis of normal starch) and barley plants transformed under the action of wild type exogenous DNA reveals differences in the protein spectrum between donor, recipient and transformants. In the second generation in many of the transformed plants starch synthesis reverted to the recipient mutant type. Simultaneously a reversion of hordein composition to the initial mutant type was observed, and the distichous pikes became hexastichous. Analysis of the components of starch revealed that donor plant that have amilose and amilopectin in starch, and the recipient plants that lack amilose, can be distinguished by the spectra of light absorption of starch. For characterizing these differences the plot of absoprtions at 490 versus that at 590 nm was used. The tangens of angles of these curves for the waxy mutant were equal to 1.05 +/- 0.07 and 1.81 +/- 0.04 for the wild type barley. All transformants have a 1.78 ratio and for revertants this value was 1.02.     

Genetic modification of the waxy character in barley after an injection of wild-type exogenous DNA. Analysis of the second seed generation

Preparations of the DNA extracted from the endospermal milk and leaves of normal distichous barley plants were injected into the grains of hexastichous barley at a milk-ripeness stage and carrying waxy mutation (i.e. having defective synthesis of amylose). Restoration of normal starch synthesis in plant cells was considered as an indication of the changes produced by the exogenous DNA. In normal barley, starch contains amylose and amylopectin and is stained blue-to-black in an iodine solution, whereas in the waxy mutant, starch has no amylose and is stained red-to-brown. To exclude any relationship of dominance the analysis was carried out at a haploid level, that is on the pollen harvested from the injected plants. This approach had the additional advantage of allowing us to work with individual cells instead of whole plants or their organs. Upon injection of the preparations of wild-type DNA a certain fraction of plants showed changes toward wild type. The seeds obtained from the altered plants were sown and the progeny examined. It was established that in the second generation most plants returned to the recepient type. A detailed analysis of the progeny of plant No. 506/19, in the first generation of which almost all pollen (over 99.5%) was of wild type, showed that in these plants the alterations were considerably more stable, only one fifth or one sixth of plants returning to the original recipient type. In half of the progeny of plant No. 506/19 the starch was of the donor type, and in 30% of the plants, as in the first generations, the bulk of the polen (99.98%) was stained black by iodine. In the second generation, segregation of plants for starch staining differed from the Mendelian one, which is probably indicative of non-chromosomal localization of the genetic determinants brought along with the injected DNA. Concurrent with the alterations of the starch structure, alterations of the type of spike (hexastichous barley plants modified distichous ones) were observed in those plants whose pollen became predominantly or wholly normal. Also, delayed manifestation of the synthesis of normal starch was noted. Certain plants which did not show any changes in the first generation yielded wild-type pollen grains in the second generation.     

Genetic modification of the waxy character in barley under the action of exogenous DNA of the wild variety

Genetic transformation was studied on spring barley mutants carrying the recessive mutant allele of waxy locus.Analysis of the pollen grains of 38 control plants that were not subjected to any treatment showed that in the whole sample there was no mutant grain that stained black with iodine. It is also indicative of the genotypical purity of the original waxy plants.After mechanical damage (puncture in the top and in the side of a grain) there were 5 pollen grains fo wild type among 124000 mutant grains. Injection of grains with 2 μl distilled water led to the emergence of pollen grains that stained black at a frequency similar to that after puncture. The overall frequency of wild barley pollen grains for all control variants was 2.2·10⁻⁵.The frequencies of wild-type pollen grains were practically the same after injections of DNA from E. coli, extensively deproteinized highly polymeric DNA from barley leaves or slightly deproteinized low polymeric DNA from barley endospermal material.There was no marked increase of the wild pollen frequency after the injection of slightly deproteinized low polymeric DNA from the endospernal material (2.2·10⁻⁵ in the control versus 3.7·10⁻⁵ in the experiment).The analysis of the material for the amount of altered pollen grains in invidual plants also unequivocally demonstrated significant differences between the control and the experiment. In the first four variants there was no plant having over these altered pollen grains among the 2500 mutant grains examined. In the variants with injections of barley DNA differing in the extent of deproteinization and in polymerisation only in one case (of low polymeric slightly deproteinized DNA) there were no plants with many altered pollen grains. In all the other variants there were plants having much pollen of wild type.The largest number of plants with a great many affected pollen grains occurred in the variant with highly polymeric DNA from the endospermal material not subjected to deproteinization with chloroform and isoamyl alcohol.     

Barley HvPAPhy_a as transgene provides high and stable phytase activities in mature barley straw and in grains

The phytase purple acid phosphatase (HvPAPhy_a) expressed during barley seed development was evaluated as transgene for overexpression in barley. The phytase was expressed constitutively driven by the cauliflower mosaic virus 35S‐promoter, and the phytase activity was measured in the mature grains, the green leaves and in the dry mature vegetative plant parts left after harvest of the grains. The T₂‐generation of HvPAPhy_a transformed barley showed phytase activity increases up to 19‐fold (29 000 phytase units (FTU) per kg in mature grains). Moreover, also in green leaves and mature dry straw, phytase activities were increased significantly by 110‐fold (52 000 FTU/kg) and 57‐fold (51 000 FTU/kg), respectively. The HvPAPhy_a‐transformed barley plants with high phytase activities possess triple potential utilities for the improvement of phosphate bioavailability. First of all, the utilization of the mature grains as feed to increase the release of bio‐available phosphate and minerals bound to the phytate of the grains; secondly, the utilization of the powdered straw either directly or phytase extracted hereof as a supplement to high phytate feed or food; and finally, the use of the stubble to be ploughed into the soil for mobilizing phytate‐bound phosphate for plant growth.     

CdCl<Subscript>2</Subscript>-induced morphogenetic variation of <Emphasis Type="Italic">Triticum aestivum</Emphasis> cultivars

The effect cadmium chloride on released local cultivars of soft spring wheat (Triticum aestivum) has been studied under laboratory and field conditions in order to widen the variation spectrum of this plant. It has been found that treatment of grains with a 0.01% aqueous solution of CdCl₂ induces the appearance of tall, strong plants with productive bushiness in the M1 generation that are characterized by various morphological changes: elongated ears, scales, and grains; increased number of grains per ear and mass of 1000 grains; anthocyan pigmentation of the stem and leaf axil; etc. Study of meiosis showed chromosome aggregation, displacement of the mitotic spindle of the metaphase plate, and empty (sterile) cells in anaphases (AI and AII). The altered characters of M₁ plants are preserved in the M₂–M₄ generations.     

Effects of Age and Environment on Net Assimilation Rate of Barley

To distinguish between the effects of age and environment onnet assimilation rate (E) of barley (var. Brant) grown in theopen in pots at Ottawa, E was measured outdoors (treatment N)and on similar plants transferred to a constant environmentfor the 2 weeks during which E was determined (treatment T).During June and July, E of treatment N decreased by 77 per cent.;for treatment T this fall increased to 90 per cent, of the initialvalue. E and average day and night temperatures were greaterin the constant environment than outdoors in early June, andin July they were greater outdoors. Incident light energy wasalways greater outdoors. Thus, the fall in E with age was partiallymasked outdoors by an increase caused by the improvement inenvironmental conditions during the experiment. Plants grown continuously in the constant environment had lowerE, greater leaf area and dry weight, and ears emerged earlierthan plants of similar age that had been transferred for 2 weeksto the constant environment from outdoors. E of plants growncontinuously in the constant environment decreased with time,both when the pots were moved away from the light panel to maintaina constant light intensity at the base of the youngest leafand when the pots remained stationary so that the plants grewtowards the lights. After ears emerged, E for treatments N and T was measured onplants whose ears were shaded to prevent them photosynthesizing.Photosynthesis in the ear accounted for 19 per cent, of thefinal ear dry weight during the first 2 weeks after emergence,12 per cent, during the 3rd and 4th, and 3 per cent, duringthe 5th and 6th weeks. Shading had no effect on weight of plantparts other than ears and had similar effects outdoors and inthe constant environment.     

A protocol for the efficient screening of putatively transformed plants forbar,the selectable marker gene,using the polymerase chain reaction

Amplification of thebar gene usingTaq DNA polymerase in PCR is often not successful, possibly due tobar's high GC content. We describe a PCR protocol in which reliable amplification at a sensitivity of one gene copy per genome (in this study, barley) present in the reaction was achieved using a novel pair of primers and Expand^tm High Fidelity DNA polymerase mix (Boehringer Mannheim). This method should allow for rapid screening of plants putatively transformed withbar.     

Variation in monoculture and in mixture for grain yield and other characters in spring barley

Fourteen north-west European spring barley cultivars were grown alone or in binary mixtures sampled according to a partial diallel scheme. On the basis of the association between cultivars in mixture and monoculture, three groups of characters were distinguished. Group A characters, plant height, ear weight/tiller, grain yield/tiller, number of grains/tiller and 1000-grain weight, showed strong positive associations between performance in monoculture and mixture. Group B characters, number of tillers/plant and harvest index showed incomplete positive associations, while for group C characters, dry matter/plant, ear weight/plant, grain yield/plant and number of grains/plant, associations were weak or non-existent. Compound characters in group C showed less genetic variation in monoculture and lower general competitive effects in mixture than component characters in groups A or B. These results clearly indicate that while selection for grain yield and other characters on a per plant basis (group C characters) is confounded by intergenotypic competition, characters such as the yield components number of grains/tiller and 1000-grain weight (group A characters) are hardly affected in this range of cultivars. Selection for opposing group A characters may start in the F₂ generation, while any selection for group B and C characters should be delayed until later generations. The merits of indirect selection for yield using visual assessment of yield components are discussed. Separate analyses obtained by the inclusion of spring wheat cv. Timmo in monoculture and in the set of mixtures indicated that the use of spring wheat plants to minimise intergenotypic competition ranges from superfluous (group A characters) to useless (group C characters). A large degree of mixture advantage and the lack of complementary dominance and suppression between competitor and associate was attributed to the relatively low density of plants in the experiment which, though suitable for single plant selection, is not typical of normal seed rates for cropping.     

Inhibition by 1-beta-D-arabinofuranosylcytosine of the incorporation of N-acetylneuraminic acid into glycolipids and glycoproteins of hamster embryo cells

1-β-D-Arabinofuranosylcytosine which interferes with DNA synthesis in bacteria and mammalian cells and brings about transformation of hamster embryo fibroblasts, has been found to inhibit the incorporation of N-Acetylneuraminic acid into glycolipids and glycoproteins of both normal and transformed hamster embryo cells in tissue culture. Three hours after commencement of treatment (10^?3M ara-C), incorporation of [¹⁴C] thymidine into DNA was inhibited by 95 per cent, while incorporation of [³H] D-glycosamine (precursor of sialic acid) into glycolipids and glycoproteins was inhibited by 85 per cent. At 24 hours, the inhibition of incorporation of the two labelled components was 83 and 80 per cent respectively. In homogenates of both cell types, incorporation of [¹⁴C] N-acetylneuraminic acid was competitively inhibited by ara-CMP. Ara-C was found to have no effect on the incorporation of [¹⁴C] choline into phospholipids of cells grown in tissue culture. These results suggest that interference with DNA synthesis by ara-C may not be the only factor involved in cell transformation by this substance.     

Immunological evidence for transfer of the barley nitrate reductase structural gene to Nicotiana tabacum by protoplast fusion

Summary A protoplast fusion experiment was designed in which the selectable marker, nitrate reductase (NR), also served as a biochemical marker to provide direct evidence for intergeneric specific gene transfer. NR-deficient tobacco (Nicotiana tabacum) mutant Nia30 protoplasts were the recipients for the attempted transfer of the NR structural gene from 50 krad -irradiated barley (Hordeum vulgare L.) protoplasts. Barley protoplasts did not form colonies and Nia30 protoplasts could not grow on nitrate medium; therefore, selection was for correction of NR deficiency allowing tobacco colonies to grow on nitrate medium. Colonies were selected from protoplast fusion treatments at an approximate frequency of 10^-5. This frequency was similar to the Nia30 reversion frequency, and thus provided little evidence for transfer of the barley NR gene to tobacco. Plants regenerated from colonies had NR activity and were analyzed by western blotting using barley NR antiserum to determine the characteristics of the NR conferring growth on nitrate. Ten plants exhibited tobacco NR indicating reversion of a Nia30 mutant NR locus. Twelve of 26 regenerated tobacco plants analyzed had NR subunits with the electrophoretic mobility and antigenic properties of barley NR. These included plants regenerated from colonies selected from 1) co-culturing a mixture of Nia30 protoplasts with irradiated barley protoplasts without a fusion treatment, 2) a protoplast fusion treatment of Nia30 and barley protoplasts, and 3) a fusion treatment of Nia30 protoplasts with irradiated barley protoplasts. No barley-like NR was detected in plants regenerated from a colony that grew on nitrate following selfed fusion of Nia30 protoplasts. Because tobacco plants expressing barley-like NR were recovered from mixture controls as well as fusion treatments, explanations for these results other than protoplast fusionmediated gene transfer are discussed.     

Determination of Nitrate Reductase Activity in Barley Leaves and Roots

The inactivation of nitrate reductase in the leaves and rootsof barley (Hordeum vulgare L. cv. Mazurka) during and afterextracting was investigated. At 0 °C in the absence of casein,25 per cent of ‘total’. i.e. maximal in vitro, nitratereductase activity was lost during the 2 min extraction process,followed by a slower loss of activity while the extract wasstored in ice. Activity was maintained by adding a minimum of1 per cent casein to the extraction medium containing 0·1M phosphate (pH 7·5), 1 mM EDTA and 1 mM dithiothreitol.Nitrate reductase was stable for several hours in these extracts,but declined in a first order manner in the absence of dithiothreitol.Casein also prevented the initial loss while making root extracts,but had less effect during storage. Using casein and thiols, nitrate reductase activity in light,(as product of maximal in vitro rates and wt g^–1) in leaveswas 98 per cent of the total activity in 31-day-old plants grownwith full nutrient in water culture and 60-day-old field-grownplants receiving no fertilizer. Field-grown plants, however,exhibited only 17 per cent of the activity of culture-grownplants. Nitrate reductase in leaves of barley plants grown in waterculture had a diurnal rhythm. During the first 3 h of the lightperiod, activity increased to 1·3 x the ‘dark’value. This was followed by a temporary decrease and then byanother increase to a maximum of 1·7 x the ‘dark’value, occurring about 8 h after illumination. Activity thendecreased during the rest of the light period and in darkness. Hordeum vulgare L., barley, nitrate reductase     

VARIATION IN POLLEN SIZE,FERTILIZATION ABILITY,AND POSTFERTILIZATION SIRING ABILITY IN ERYTHRONIUM GRANDIFLORUM

The mean volume of pollen grains and total pollen production varied both within and among plants of Erythronium grandiflorum. The second flowers of two-flowered plants tended to produce smaller and fewer grains than first flowers, but there was no overall relationship between mean pollen grain size and production per flower. I evaluated the effects of pollen size differences within and among plants on two components of male reproductive success: pollen tube growth and postfertilization siring ability. Pollen tubes grown in media were longer for second flowers, but were not correlated with the mean size of pollen grains, suggesting that (1) internal resource content of pollen (i.e., carbohydrates plus lipids) was not associated with the hydrated size of pollen, and that (2) pollen from second flowers contained more resources. I analyzed the growth rate and the fertilization ability of pollen growing in styles. Growth rate differed among donors and recipients, but no effects of pollen or donor characters (i.e., pollen production, grain size, and flower position) were detected. In single donor pollinations, pollen size was negatively correlated with fertilization ability across donors, and positively correlated with postfertilization siring ability of donors. A second experiment used pairs of donors; within-plant differences in pollen size and flower position had effects similar to the single donor experiment on fertilization ability, but among-plant differences were not significant. The results corroborate earlier experiments that suggest that the growth of pollen tubes in the style is probably controlled by the recipient, since donor characters had minimal effects on pollen fertilization ability. Postfertilization siring ability was not affected by within-plant differences in mean grain size and production. For among-donor differences, the number of seeds set for each donor was positively correlated with the mean grain volume, and when a donor producing large pollen fertilized ovules in an ovary, there was increased seed abortion for seeds in the same ovary sired by a second donor. In addition, the total number of seeds produced by a fruit was decreased when both donors had large pollen, apparently due to increased postfertilization abortion. Postfertilization processes appear to be influenced by paternal differences that are expressed through competition among developing seeds for maternal resources.     

Effects of Drought on Partitioning of Nitrogen in Two Wheat Varieties Differing in Drought-tolerance

A model was constructed to describe the translocation and partitioningof nitrogen on the seventh day after anthesis for well-wateredand droughted plants of two wheat varieties (Triticum aestivumL. cv. Warigal and Condor). The glasshouse-grown plants weredetillered so that a simplified model could be derived for themain stem. A 9-d drought treatment was imposed just after anthesisand this coincided with the period of endosperm cell divisionin the grains. Warigal, which had a higher grain yield thanCondor under drought, absorbed up to 15-times more nitrogenand translocated 1.5-fold more nitrogen to the shoot via thexylem. In both varieties, nitrogen redistributed from vegetativeorgans accounted for more than 60 per cent in control and 70per cent in droughted plants of the nitrogen needed for eargrowth. The net loss of nitrogen increased by 4-3 per cent inthe leaves, but decreased by 60 per cent in the stem under drought.Stem and roots appeared to play an important role in the nitrogeneconomy of droughted plants: less nitrogen was translocateddirectly to the grains from the senescing leaves and 40–60per cent more nitrogen was translocated to the roots. Nearlyall the nitrogen reaching the roots in the phloem was reloadedinto the xylem stream and translocated back to the shoot. Thetransfer of nitrogen through the stem was reduced under droughtand this resulted in a constant C:N ratio of the grains whichmay be important in the regulation of endosperm cell division. Triticum aestivum L., wheat, drought, nitrogen, senescence, translocation     

Degradation of DNA and endonuclease activity associated with senescence in the leaves of pea of normal and aphyllous genotypes

Senescence and wilting of the leaves of pea (Pisum sativum L.) of normal (AfAf) and aphyllous (afaf) genotypes were accompanied by DNA degradation. In young (12th–9th) subapical leaves of AfAf plants, total DNA was high-polymeric; in the 6th leaf, DNA degradation was appreciable; and in the 4th and 3rd leaves, hydrolysis of DNA was pronounced. Similar degradation of DNA was also observed in senescing leaves of aphyllous plants, but there it started later than in the plants of normal type. The extent of DNA degradation was closely related to the elevation of total nuclease activity in pea leaves associated with the age. The leaves of plants of different genotypes distinctly differed in the activity of acid and alkaline nucleases. Senescence of the leaves was accompanied by the induction of Ca²⁺-and Mg²⁺-dependent nucleases with mol wts of 42, 37, 34, 26, and 21 kD. In different stages of leaf senescence, different sets of nucleases were detected.     

二棱啤酒大麦杂种一代及其亲本主要性状的灰色系统分析

研究采用灰色关联分析方法,对20组二棱型啤酒大麦杂种一代及其亲本的7个主要性状之间的关联系数、关联度和关联序进行了分析。结果表明：在关联度和关联序中,大麦的穗粒数、穗粒重,千粒重分别与穗长这一性状的关联度最大,关联序中穗长全排在首位;而穗粒数,穗粒重,千粒重分别与有效穗数这一性状的关联度最小,关联序中有效穗数全排在末位,为了提高单株产量应注意协调好有效穗数与穗长这一对主要矛盾明确各性状对籽粒产量所起的直接和间接作用及其相对重要性,确定主攻方向,配制各种优势组合。为大麦亲本选配提供科学依据。从而达到二棱型啤酒大麦预期的育种目标。     

Rice can acclimate to lethal level of salinity by pretreatment with sublethal level of salinity through osmotic adjustment

The physiological ability to adapt for various environmental changes is known as acclimation. When exposed to sublethal level of stress, plants develop the ability to withstand severe stress, as acquired tolerance. The present study was conducted to explicate the physiological basis of acquired tolerance in rice. Rice seedlings (variety IR 20) were grown in half strength Hoagland solution, and after 22nd day, they were kept in half strength Hoagland solution containing 50 mM NaCl (sublethal dose) for 7 days followed by half strength Hoagland solution containing 100 mM NaCl (lethal dose) for another 7 days. The non-pretreated 29 days old rice seedlings maintained in half strength Hoagland solution were directly transferred to half strength Hoagland solution containing 100 mM NaCl (lethal dose) solution for 7 days. The control plants were maintained in half strength Hoagland solution without NaCl. Various morphological and physiological parameters were recorded on 29th and 36th days old seedlings from control, pretreated and non-pretreated plants. The results revealed significant reduction in growth parameters (shoot length, root length, leaf area and total dry matter production) of non-pretreated plants below that of pretreated plants. The pretreated plants showed increased values to the extreme of 19.8 per cent in leaf water potential (ψ_w), 9 per cent in relative water content (RWC), 26 per cent in photosynthetic rate (P _N), 28 per cent in leaf stomatal conductance, and 47 per cent in chlorophyll a over non-pretreated plants. The same trend was also observed in chlorophyll a/b ratio (6.6%) and F _v/F _m ratio (19.3%). However, a reverse trend was seen in F _o value. The pretreated plants showed improved ionic regulation as evident from low Na⁺, Cl⁻ and high K⁺ contents, which is attributed to enhanced plant water status and photosynthesis. Both pretreated and non-pretreated plants had higher contents of osmolytes viz., sucrose, leaf soluble sugars and proline contents than control plants. However, starch content revealed an inverse trend. Therefore, the present study reveals that rice can acclimate to lethal dose of salinity stress by pretreatment with sublethal dose of NaCl. Section Editor: J. M. Cheeseman     

CO<Subscript>2</Subscript> exchange and structural organization of chloroplasts under hypothermia in potato plants transformed with a gene for yeast invertase

Growth, CO₂ exchange, and the ultrastructure of chloroplasts were investigated in the leaves of potato plants (Solanum tuberosum L., cv. Désirée) of wild type and transformed with a gene for yeast invertase under the control of patatin class I B33 promoter (for apoplastic enzyme) grown in vitro on the Murashige and Skoog medium supplemented with 2% sucrose. At a temperature of 22°C optimal for growth, the transformed plants differed from the plants of wild type in retarded growth and a lower rate of photosynthesis as calculated per plant. On a leaf dry weight basis, photosynthesis of transformed plants was higher than in control plants. Under hypothermia (5°C), dark respiration and especially photosynthesis of transformed plants turned out to be more intense than in control material. After a prolonged exposure to low temperature (6 days at 5°C), in the plants of both genotypes, the ultrastructure of chloroplasts changed. Absolute areas of sections of chloroplasts and starch grains rose, and the area of plastoglobules decreased; in transformed plants, these changes were more pronounced. By some ultrastructural characteristics: a reduction in the cold of relative total area of sections of starch grains and plastoglobules (in percents of the chloroplast section area) and in the number of granal thylakoids (per a chloroplast section area), transformed plants turned out to be more cold resistant than wild-type plants. The obtained results are discussed in connection with changes in source-sink relations in transformed potato plants. These changes modify the balance between photosynthesis and retarded efflux of assimilates, causing an increase in the intracellular level of sugars and a rise in the tolerance to chilling.     

Effect of Post-anthesis Drought on Cell Division and Starch Accumulation in Developing Wheat Grains

Wheat plants (Triticum aestivum L., cv. Warigal) were subjectedto 20 d of water deficit during the period of endosperm celldivision. Drought accentuated the differences in final grainweight between spikelets and between grains within spikelets.The distal grains of top spikelets were most affected by drought.The maximum number of endosperm cells was, respectively, 30and 40 per cent lower in basal grains and distal grains of draughtedplants. In basal grains of middle spikelets, the number of largestarch granules per cell was unaffected but the number of smallstarch granules per cell was 45 per cent lower in grains ofdraughted plants. The initiation of small starch granules wasmore affected than cell division because severe water deficitoccurred earlier during the former process than the latter.Final dry weight appeared to correlate well with the maximumnumber of endosperm cells, but depended also on the number ofstarch granules per cell. Consequently, the amount of dry matterper cell was not constant in both treatments. The concentration of sucrose per endosperm cell was lower onlyin the droughted distal grains of top spikelets. The supplyof sucrose to endosperm cells did not regulate the initiationof small starch granules. Triticum aestivum L., wheat, drought, grain growth, cell division, starch     

Variation ofHelminthosporium resistance and biochemical and cytological characteristics in somaclonal generations of barley

SC₂ and SC₃ progenies of nineteenin vitro regenerated barley plants (SC₁) from resistant calli selected against purified culture filtrate ofHelminthosporium sativum and one parent ‘Dissa’ genotype were studied for stability of resistance and protein, soluble protein, maltose and saccharose contents. Cytological studies were also carried out on the SC₃ generation. Stability of resistance toHelminthosporium sativum was found in 50% of the somaclonal lines. Significant variation among different somaclonal lines and among different callus lines from which the plants were regenerated were found for yield, disease score and biochemical characters assessed except saccharose content in the somaclonal lines. Significant increase and decrease over the donor parent for most of the characters were obtained. Cytological abnormalities such as multilobed nuclei, multinucleate cells, abnormal anaphase and mixoploidy were also observed.     

An observation study of airborne pollen fall in Didim (SW Turkey): years 2004–2005

Pollen grains in the atmosphere of Didim, collected using a Durham sampler, were investigated in 2004 and 2005. Weekly pollen grains per square centimetre were calculated. Over a period of 2 years, 17,518 pollen grains/cm² belonging to 40 taxa and unidentified pollen grains were recorded. In 2004, 9,879 pollen grains were counted per cm², and in 2005 the value was 7,639 per cm². The majority of pollen grains investigated were Pinus spp. (45.58%), Cupressaceae/Taxaceae (13.49%), Olea spp. (9.19%), Platanus spp. (7.62%), Gramineae (6.33%), Pistacia spp. (4.34%), Morus spp. (3.81%), Quercus spp. (2.02%), Abies spp. (1.39%), and Plantago spp. (1.11%). During the month of April, 40.46% of total pollen grains were recorded. According to our results, pollen season durations for the dominated pollen grains in Didim were: the 7th–33rd weeks for Pinus spp., nearly the whole year except summer for Cupressaceae/Taxaceae, the 17th–29th weeks for Olea spp., the 10th–24th weeks for Platanus spp., the 8th–46th weeks for Gramineae, the 8th–20th weeks for Pistacia spp., the 11th–21st weeks for Morus spp., the 17th–21st weeks for Quercus spp., the 9th–27th weeks for Abies spp., and the 7th–26th weeks for Plantago spp.