Opening keynote presentation at the 7th International Symbiosis Congress (Kraków, Poland, July 2012), which was dedicated to the memory of Lynn Margulis, outstanding scientist. It is particularly appropriate that this tribute appears in this journal based in Cracow, for shortly before her passing, she told me how very much she looked forward to coming to the Jagiellonian University in Cracow, “the great city of Copernicus”, as the invited keynote speaker to this Congress. DZ
We used cytological and embryological methods to study reproductive cycle stages in Cerasus fruticosa Pall., Cerasus × eminens (Beck) Buia and Cerasus × mohacsyana (Kárpáti) Janchen from SW Slovakia, focusing on development of the male and female reproductive organs, fertilization processes and embryo formation. We found that reproductive potential was reduced by synergistic effects of negative biotic and abiotic factors. Despite the presence of degenerated, deformed pollen grains and their great variability of shape and size, a sufficient amount of normally developed viable pollen grains developed in anthers of C. fruticosa and C. × mohacsyana. Disturbed microsporogenesis in C. × eminens led to significantly lower production of viable pollen grains. We did not observe serious disturbances during megasporogenesis and megagametogenesis. Lower fruit set was caused by degeneration of ovules as a result of unsuccessful pollination, fertilization failure, or embryo degeneration during its initial development.
We used artificial hybridization to study the crossability of the noble fir (Abies procera) with Manchurian fir (A. holophylla) and Caucasian fir (A. nordmanniana), and found compatibility between A. procera of North American origin and the Asian species A. holophylla as evidenced by the 14% fraction of filled seeds obtained in A. procera × A. holophylla crossing. Crossing of A. procera with the Mediterranean species A. nordmanniana failed completely, producing only empty seeds.
We made interspecific crosses to facilitate the introgression of desirable traits of Allium roylei into the Alliumcepa genome. After hand-pollination, 906 interspecific F1Allium cepa × A. roylei plants were obtained by in vitro culture via embryo rescue. Nuclear DNA analysis showed that 97.6% of the regenerants were interspecific F1Allium cepa × A. roylei hybrids. Genomic in situ hybridization (GISH) showed that each hybrid had 16 chromosomes, eight of which were identified as A. cepa and eight as A. roylei chromosomes.
We used DPPH scavenging assays to study the antioxidant activity of three native Polish species of blackberry leaves (Rubus kuleszae Ziel., R. fabrimontanus (Sprib.) Sprib. and R. capitulatus Utsch.). All the studied extracts (methanolic, water, methanolic-water) showed high DPPH free radical scavenging activity (IC50 450.0-186.0 μg/ml). The most effective of the studied species was Rubus kuleszae. Total content of phenolic compounds (70.50-136.04 mg GAE/g) and phenolic acids (14.70-38.26 mg CAE/g) was determined spectrophotometrically. Antioxidant activity correlated positively with total content of phenolic compounds and phenolic acids.
We studied the effect of qualitative and quantitative variation of saponin content in foliar tissues of four European alfalfa (Medicago sativa L.) cultivars (Radius, Sapko, Sitel, Radius line 1) on pea aphid (Acyrthosiphon pisum Harris) development, and the effect of aphid infestation on alfalfa saponin content. Aphids (adult apterae, larvae, and adult alatae) were counted on 3-, 6- and 9-month-old plants (before the first, second and third cutting). Thin-layer chromatography was used to detect and estimate the quantity of the following saponins: 3GlcA, 28AraRhaXyl medicagenic acid; 3Glc, 23Ara, 28AraRhaXylApi zanhic acid (zanhic acid tridesmoside); and 3RhaGalGlcA soyasapogenol B (soyasaponin I). Radius, Sapko, and Sitel contained all three saponins but Radius line 1 did not contain zanhic acid tridesmoside or medicagenic acid glycoside. Saponin content was highest in Radius and lowest in Radius line 1. Regardless of the cultivar, saponin content was higher in aphid-infested than uninfested plants. For all sampling dates, aphid numbers were highest on Radius line 1 and lowest on Radius; that is, aphid numbers were inversely related to saponin content. Alfalfa has a herbivoreinduced defense. Saponin levels increase in the foliage of infested alfalfa. Attempts of plant breeders to reduce saponin content in order to increase alfalfa digestibility for livestock might make the plants more susceptible to aphids and other pests.
The influence of ambient solar UV-A or UV-B radiation on growth responses was investigated in three varieties of cotton (Gossypium hirsutum L.) after exclusion of solar UV-A/B radiation: JK-35, IH-63 and Khandwa-2. Cotton plants were grown from seeds in UV-exclusion chambers lined with selective UV filters to exclude either UV-B (280-315 nm) or UV-A/B (280-400 nm) from the solar spectrum under field conditions. Excluding UV-B and UV-A/B significantly increased plant height, leaf area and dry weight accumulation in all three varieties of cotton. The varieties differed considerably in their sensitivity to ambient UV-A/B. Khandwa-2 was most sensitive and JK-35 least sensitive to ambient solar UV. We monitored the activity of the antioxidant enzymes superoxide dismutase (SOD), ascorbic acid peroxidase (APX), glutathione reductase (GR) and guaiacol peroxidase (GPX), as well as the level of the antioxidant ascorbic acid (ASA), in primary leaves of the most UV-sensitive variety (Khandwa-2). The level of UV-B-absorbing substances was significantly decreased by exclusion of solar UV-B and UV-A/B. Exclusion of solar UV decreased the activity of all the antioxidant enzymes monitored and the level of ascorbic acid versus control plants (+UV-A/B) grown under filters transparent to solar UV. Reduction of the antioxidant defense after UV exclusion indicates that ambient solar UV exerts significant stress and induces some reactive oxygen species to accumulate, which in turn retards the growth and development of cotton plants. Ambient solar UV stresses cotton plants, shifting their metabolism towards defense against solar UV. Exclusion of solar UV eliminates the need for that defense and leads to enhancement of primary metabolism.
This study investigated the quantitative anatomy of photosynthetic tissues (leaf mesostructure) of wild ginseng Panax ginseng C.A. Mey. (Araliaceae) plants from different natural habitats. The structural and functional traits of the photosynthetic apparatus shown to be especially elastic were mesophyll cell volume (Cv >40%) and traits related to filling of the leaf with cells and plastids (Cv≥21%). P. ginseng possesses relatively few cells per leaf area (44.6-107.2 103/cm2) and chloroplasts (1.7-4.9 106/cm2). Also low are the values of such integral indexes as relative surface of mesophyll cells (Ames/A, 2.78-5.28) and relative surface of chloroplasts (Achl/A, 1.9-3.2). The leaf mesostructure of wild ginseng shows traits of a plant typically found in shady forest habitats. The photosynthetic apparatus of ginseng adapts to various habitat conditions on the level of leaf mesostructure, through structural transformations of mesophyll tissue, such as changes in the number and size of cells and chloroplasts and also the integral surface indexes Achl/A and Ames/A.
The flowers of Polemonium caeruleum are protandrous. The nectary is in the form of a rim encircling the ovary. Secreted nectar accumulates in a chamber located at the bottom of the floral tube and is protected by dense staminal hairs. The nectary tissue is not vascularized, but is supplied by vascular strands that occur near the base of the nectary and which directly supply the stamens. Nectar is secreted via modified stomata located on the upper part of the rim, particularly on the adaxial surface. The number of stomata and the volume and sugar concentration of nectar are greater during the female stage than during the male stage. In both stages, however, the nectar is sucrose-dominant. This paper shows that in P. caeruleum the nectar sugars are not a direct product of current photosynthesis, since plastids of nectary cells are devoid of chlorophyll. The main source of sugars in secreted nectar is the phloem sap, together with starch that accumulates in the nectary cells during the male stage and is then rapidly hydrolyzed during the female stage.
We studied the embryology of Withania somnifera (L.) Dunal by light microscopy in order to reveal specific embryological features of the genus, and compared the results with embryological data on other members of the family Solanaceae. The key embryological characters of W. somnifera include dicotyledonous-type anther wall formation, simultaneous cytokinesis in pollen mother cells, binucleate tapetal cells, 2-celled mature pollen, anatropous, tenuinucellate and unitegmic ovules, polygonum-type embryo sac formation, the presence of an endothelium, and cellular endosperm formation. We give the first report of the dicotyledonous mode of anther wall formation (previously described as basic type) for the species. Comparative study suggests that anther wall formation, number of nuclei in tapetal cells, number of cells in mature pollen, mode of embryo sac formation and endosperm development are the most variable embryological features in Solanaceae. Some of these embryological features of W. somnifera should be of value for comparative study of related species and their phylogenetic relationships within the family.
SDS-PAGE electrophoresis was used to study the effect of NaCl on protein expression in two cultivars of tomato (Solanum lycopersicum L.): Edkawi (salt-tolerant) and Castle rock (salt-sensitive). Five-day-old seedlings were grown on MS agar media supplemented with 0, 50, 100, 150, 200 and 300 mM NaCl. Two days after treatment the seedlings were examined to determine the effect of salt on their growth and to relate that to protein banding variations. Gel analysis showed differences in at least 4 protein bands with molecular weights at 20, 25, 45 and 65 kDa. These proteins were induced in the 50 mM NaCl treatment in the salt-sensitive cultivar, then decreasing to undetectability at higher concentrations. In the salt-tolerant cultivar, most of the proteins exhibited a more or less steady expression pattern and maintained expression through the 200 mM NaCl treatment. All proteins gave weak or no expression signals at 300 mM NaCl, the treatment that proved lethal. Differentially expressed bands were identified using MALDI-TOF mass spectrometry. The putative function of each identified protein in relation to salt stress is discussed.
We examined the response of plants of various crop and weed species to cyanamide in order to evaluate allelochemical- mediated interactions between the species. We studied germination and seedling growth in the common weeds Galium aparine L. and Amaranthus retroflexus L., and the crops Zea mays L., Triticum aestivum L., Lactuca sativa L., Solanum lycopersicum L. and Sinapis alba L. as acceptor plants. Concentration-dependent phytotoxic effects of cyanamide were noted during seed germination and in the root and shoot growth of the tested plants. The monocotyledonous plants generally were less sensitive to cyanamide treatment. Seed germination and seedling growth of the dicotyledonous plants were strongly inhibited by the allelochemical at both tested concentrations (1.2 mM, 3 mM). We conclude that cyanamide has potential for use as a natural herbicide only in specific field systems of cyanamide-tolerant monocotyledonous crops accompanied by cyanamide-sensitive dicotyledonous weeds.
We analyzed DNA damage, mitotic activity and polyploidization in Crepis capillaris callus cells during short- and long-term in vitro culture, and the influence of plant growth regulators on these processes. Changes in the concentration of growth regulators altered the stability of callus. The level of DNA damage was highly dependent on the growth regulator composition of the medium. Cytokinin at high concentrations damaged DNA in the absence of auxin. Short- and long-term callus differed in sensitivity to growth regulators. Mitotic activity changed when callus was transferred to medium with modified growth regulators. Callus cell nuclear DNA content increased with age and in response to plant growth regulators. Hormones played a role in the genetic changes in C. capillaris callus culture. We demonstrated the usefulness of C. capillaris callus culture as a model for analyzing the effect of culture conditions, including plant growth regulators, on genetic stability.
Using four Polish Vicia faba L. minor cultivars (Bronto, Dino, Tibo, Nadwiślański) we obtained callus from epicotyl fragments collected from 7- and 14-day-old seedlings and from cotyledonary nodes of immature seeds. Callus induction efficiency varied from 81% to 97% depending on the origin of the explant. Shoots regenerated only from the cotyledonary nodes of all tested cultivars. On average, 50% of the explants grown on MS medium containing 1.0 mg dm-3 NAA, 0.5 mg dm-3 BAP, 0.25 mg dm-3 GA3, 1.0 g dm-3 casein hydrolysate, 750 mg dm-3 inositol, 3% sucrose and 0.4% agar were able to regenerate shoots. The number of calluses regenerating shoots was highest from explants collected from fruiting nodes 6 to 9. Decapitation of donor plants increased the percentage of calluses regenerating shoots. On half-strength MS medium with 2 mg dm-3 NAA and on 1/2 MS alone, 11% of the shoots rooted; on 1/2 MS with 1 g dm-3 AC, 8.0% rooted. The regenerants were transferred to Perlite with Hoagland medium and acclimated. Ten percent of the regenerated plants survived the acclimation process, flowered and produced seeds.
Metallothioneins are low-molecular-weight proteins capable of covalently binding heavy metal ions due to the presence of many cysteine residues in their sequences. We analyzed the predicted amino acid sequences of 19 metallothionein (7 from Arabidopsis thaliana and 12 from Oryza sativa) and their promoter sequences in silico in order to determine the potential regulatory cis-elements present in the promoters of metallothionein genes, from which it is possible to determine the putative functions of these genes. The PlantCARE and PLACE databases provided information about the putative regulatory elements in the metallothionein promoters. Metal response element sequences were found in the promoters of eleven O. sativa and two Arabidopsis metallothionein genes. Copper response elements were identified in both model plants, usually in many copies, particularly in O. sativa. Both the high cysteine content and the presence of metal response motifs in the promoters support the suggestion that metallothioneins play a key role in metal detoxification. The most common putative element in the analyzed promoters was CIRCADIAN, which was present in five A. thaliana and eight O. sativa sequences. The methyl jasmonate response sequence, root-specific expression element and drought response element were found only in O. sativa metallothioneins. Light and low temperature response elements, biotic and abiotic stress elements, an abscisic acid-responsive element and an ethylene-responsive element occur in selected metallothionein promoters of both species. A few promoters have putative organ- and cell-specific regulatory elements. The presence of many different motifs in the promoters of the Arabidopsis and O. sativa genes implies that metallothioneins are general stress response proteins with many important functions in plants, including regulation of their normal development and adaptation to changing environmental conditions.
We used germination tests to assess the frequency of polyembryony in 9 asparagus cultivars with a high propensity to produce double embryos with different ploidy levels: Alpha, Andreas, Boonlim, Cipres, Eposs, Helios, Limbras, Ravel and Sartaguda. Twin embryos inside a single seed were found in 3 cultivars: Eposs 2n, Ravel 2n and Sartaguda 2n, at 0.60% frequency (15 seeds with twin embryos out of 2500 seeds). Of 30 obtained seedlings, 14 were separated diploid-diploid twins, 6 were conjoined diploid pairs, 8 were separated diploid-haploid and 2 were diploid-haploid pairs conjoined in the hypocotyl region. Some embryos showed unilateral dominance of one embryo (size and shape). The haploid status of the smallest embryo was confirmed by chromosome number (n=x=10) and flow cytometry (nuclear C DNA amount 1.95 pg). The haploid obtained in this manner possessed enough vegetative vigor to undergo chromosome doubling.
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