Abstract: The occurrence of fungicidal, elemental S is well documented in certain specialized prokaryotes, but has rarely been detected in eukaryotes. Elemental S was first identified in this laboratory as a novel phytoalexin in the xylem of resistant genotypes of Theobroma cacao , after infection by the vascular, fungal pathogen Verticillium dahliae . In the current work, this phenomenon is demonstrated in a resistant line of tomato, Lycopersicon esculentum , in response to V. dahliae . A novel gas chromatography-mass spectroscopy method using isotope dilution analysis with 34 S internal standard was developed to identify unambiguously and quantify 32 S in samples of excised xylem. Accumulation of S in vascular tissue was more rapid and much greater in the disease-resistant than in the disease-susceptible line. Levels of S detected in the resistant variety (approximately 10 μg g −1 fresh weight excised xylem) were fungitoxic to V. dahliae (spore germination was inhibited >90% at approximately 3 μg mL −1 ). Scanning electron microscopy-energy dispersive x-ray microanalysis confirmed accumulation of S in vascular but not in pith cells and in greater amounts and frequency in the Verticillium spp.-resistant genotype. More intensive localizations of S were occasionally detected in xylem parenchyma cells, vessel walls, vascular gels, and tyloses, structures in potential contact with and linked with defense to V. dahliae. Transient increases in concentrations of sulfate, glutathione, and Cys of vascular tissues from resistant but not susceptible lines after infection may indicate a perturbation of S metabolism induced by elemental S formation; this is discussed in terms of possible S biogenesis.

Abstract: We have identified a drought-inducible gene, designated as SoDip22, in sugarcane leaves. The cDNA encoded a hydrophilic protein with a calculated molecular mass of 15.9 kDa and the amino acid sequence was similar to that of ABA, stress and ripening-inducible protein from various plant species. ABA or mannitol-treatment of the detached leaves also induced SoDip22 expression. Stepwise homogenization of the stressed leaves showed that SoDip22 is localized in bundle sheath cells. These results suggest that SoDip22 functions to adapt to drought stress in the bundle sheath cell, and that the signaling pathway for the induction is, at least in a part, mediated by ABA.

Abstract: Hybrid lethality, a type of reproductive isolation, is a genetically controlled event appearing at the seedling stage in interspecific hybrids. We characterized the lethality of F 1 hybrid seedlings from Nicotiana gossei Domin and Nicotiana tabacum cv Bright-Yellow 4 using a number of traits including growth rate, microscopic features of tissues and cells, ion leakage, DNA degradation, reactive oxygen intermediates including superoxide radical (O 2 − ) and hydrogen peroxide (H 2 O 2 ), and expression of stress response marker genes. Lethal symptoms appeared at 4 d after germination in the basal hypocotyl and extended toward both the hypocotyl and root of the plants grown at 26°C. Microscopic analysis revealed a prompt lysis of cell components during cell death. Membrane disruption and DNA degradation were found in the advanced stage of the lethality. The death of mesophyll cells in the cotyledon was initiated by the vascular bundle, suggesting that a putative factor inducing cell death diffused into surrounding cells from the vascular tissue. In contrast, these symptoms were not observed in the plants grown at 37°C. Seedlings grown at 26°C generated larger amounts of reactive oxygen intermediate in the hypocotyl than those grown at 37°C. A number of stress response marker genes were expressed at 26°C but not at 37°C. We proposed that a putative death factor moving systemically through the vascular system induced a prompt and successive lysis of the cytoplasm of cells and that massive cell death eventually led to the loss of the hybrid plant.

Abstract: We have isolated and characterized a Lotus japonicus gene (Ljsbp) encoding a putative polypeptide with striking homology to the mammalian 56-kDa selenium-binding protein (SBP). cDNA clones homologous to LjSBP were also isolated from soybean, Medicago sativa, and Arabidopsis thaliana. Comparative expression studies in L japonicus and A. thaliana showed that sbp transcripts are present in various tissues and at different levels. Especially in L japonicus nodules and seedpods and A. thaliana siliques, sbp expression appears to be developmentally up-regulated. sbp Gene transcripts were localized by in situ hybridization in the infected cells and vascular bundles of young nodules, while in mature nodules, low levels of expression were only detected in the parenchymatous cells. Expression of sbp transcripts in young seedpods and siliques was clearly visible in vascular tissues and embryos, while in embryos, low levels of expression were detected in the root epidermis and the vascular bundles. Polyclonal antibodies raised against a truncated LjSBP recombinant protein recognized a polypeptide of about 60 kDa in nodule extracts. Immunohistochemical experiments showed that accumulation of LjSBP occurred in root hairs, in the root epidermis above the nodule primordium, in the phloem of the vasculature, and abundantly in the infected cells of young nodules. Irrespective of the presence of rhizobia, expression of SBP was also observed in root tips, where it was confined in the root epidermis and protophloem cells. We hypothesize that LjSBP may have more than one physiological role and can be implicated in controlling the oxidation/reduction status of target proteins, in vesicular Golgi transport, or both.

Abstract: The tropical nitrogen-fixing tree, Casuarina glauca Sieb. ex Spreng. was genetically transformed using Agrobacterium tumefaciens C58C1(pGV2260; pBIN19GUSINT). We report on the expression pattern conferred by the cauliflower mosaic virus (CaMV) 35S promoter in transgenic C. glauca plants grown in vitro, and for one year in a greenhouse. Histochemical assays in shoots from in vitro plants revealed β-glucuronidase (GUS) staining in apical and axillary buds, and in nearly all tissues near the base of the stem. In roots, the CaMV 35S drove strong GUS expression in the apex and vascular tissue. In 1-year old plants grown in a greenhouse, the CaMV 35S promoter was highly active, except in peripheral suberized tissues. Transgenic C. glauca plants were nodulated by the actinomycete Frankia. Histochemical assays on vibratome sections of transgenic nodules demonstrated intense GUS activity in the vascular bundle, the phellogen, and in strands of uninfected cells filled with polyphenols. GUS expression was undetectable in Frankia-infected cells.

Abstract: The vascular tissue of higher plants is organized into a continuous and unified system that undergoes a transition between two highly differentiated structures, the root and the shoot. This transition was studied in tomato by investigating the genetic basis of morphological variation between Lycopersicon esculentum and L. hirsutum LA407. Our analysis concentrated on morphology in stem cross sections, and we detected heritable genetic differences in an inbred backcross population having L. esculentum as the recurrent parent and LA407 as the donor parent. Inbred backcross line (IBL) 2353 contained a donor segment from chromosome 2 and retained features of the LA407 stem vascular morphology. Marker-trait analysis of vascular structure in a cross between IBL 2353 and L. esculentum showed significant (0.0001 ≤ P ≤ 0.0375) associations between markers on chromosome 2 and the size of primary vascular bundles, the shape of the vascular system, and the thickness of the secondary vascular tissue. Families with LA407 DNA for the markers on chromosome 2 had larger primary vascular bundles, more developed secondary vascular tissue, and a triangular vascular shape. These results suggest that the distal portion of chromosome 2 in LA407 contains a locus or loci affecting vascular morphology and development.

Abstract: Two genes (TaLTP1 and TaLTP2) encoding lipid transfer proteins (LTPs) were isolated from a cDNA library constructed from leaf tissue harvested from 4-week-old seedlings of a wheat-rye near-isogenic line (NIL) involving a translocation of rye chromosome 2RL with wheat 2BS. The spatial and temporal patterns of expression of TaLTP1 and TaLTP2 were examined by Northern blot analysis and in situ hybridization. Both TaLTP1 and TaLTP2 contained a 270-bp open reading frame and encoded a putative LTP precursor molecule of 90 amino acids. Expression of the two LTPs was detected in leaves, stems, and crowns of the NILs but not in the roots. The expression levels of TaLTP1 and TaLTP2 remained constant in response to cold and ABA treatments over a period of 24 h but increased 3 days after the initiation of drought stress. An in situ hybridization study indicated that TaLTP1 was expressed in the cells within the vascular bundles of leaves and in the tissue layers between the vascular bundles in the crowns of the control and drought-treated plants. Expression of TaLTP1 in the tissue layers between the vascular bundles was higher in the drought-treated plants than in the control plants. The results suggested that high levels of expression of TaLTPs in the tissue layers between the vascular bundles might play a role in the drought tolerance response of the wheat crown.

Abstract: Temperature change induces morpho-physiological responses, whose significance for plant function under this modified environmental condition is mostly unclear. Plastic responses to temperature changes from optimal (25°C) to chilling (5°C) conditions or vice versa, as compared with constant temperature treatments, were studied in spring and winter wheat. Plants grown at 5°C had smaller leaves, less stomata and larger root systems than their counterparts grown at 25°C. Plants at 5°C therefore had larger effective root : shoot ratio, defined as the ratio between total area of roots and stomata. Spring and winter cultivars differed in root growth, leaf growth and stomatal frequency following a shift in temperature. Nevertheless, both cultivar types reached similar effective root : shoot ratios, which were typical for each temperature. We also found changes in leaf thickness, transverse vascular bundle area and xylem : phloem ratios. Shifting temperature triggered rapid changes in leaf and root carbohydrate content and osmotic potential. Our results suggest that temperature-induced plasticity may play a role in ameliorating possible water deficits caused by large soil-air temperature differentials in natural environments.

Abstract: Interruption of the vascular bundles of Zinnia internodes induced transdifferentiation of cells into tracheary elements (TEs) or sieve elements (SEs) within 4 d of wounding. The early stage of the regeneration processes was analyzed using two molecular marker genes, TED3 and ZeHB3, which are expressed specifically in TE precursor cells and immature phloem cells, respectively. An increase in the numbers of TED3 and ZeHB3 mRNA-expressing cells always preceded an increase in the numbers of TEs and SEs formed. The earliest sign of vascular differentiation was the appearance 24 h after wounding of a layer(s) of TED3 mRNA-expressing cells in the inter- and intrafascicular cambial-like regions along the severed vascular bundles. In contrast, the number of ZeHB3 mRNA-expressing cells decreased dramatically along the severed bundles 24 h after wounding, and increased again 36 h after wounding. These results clearly indicate that xylem and phloem differentiation are not synchronized during vascular regeneration. Treatment with 10 - 3 M colchicine abolished the expression of ZeHB3 mRNA in pith parenchyma, but not TED3 mRNA; this suggests that cell division is a prerequisite for the transdifferentiation of pith parenchymal cells into immature phloem cells expressing ZeHB3. In contrast, transdifferentiation of pith parenchymal cells to TE precursor cells does not require preceding cell division. However, the inhibition of cell division prevented the formation of both radial files of TEs and the cambial-like layer(s) of TED3 mRNA-expressing cells, and, ultimately, vascular regeneration altogether. These results imply that wound-induced cambial-like activity in and between severed vascular bundles is essential for vascular regeneration.

Abstract: Different effects of Acremonium strictum from Cameroon on maize cultivars Ndock 8701, CMS 8704 and CMS 8501 were investigated. Observations of symptoms and re-isolation of the pathogen showed that the disease causes chlorosis, leaf necrosis, stem necrosis, barren plants and wilting symptoms. Reduction in growth and yield is demonstrated. In the cultivar Ndock 8701 the pathogen showed systemic development in the host tissues with inter- and intracellular colonization of the vascular bundle and adjacent tissues including the protoxylem lacuna, xylem vessels, metaxylem, sieve tubes, protophloem and metaphloem. Gels and gums were observed in the maize xylem vessels after fungal invasion and are part of the host defence response. Coloration corresponding to acidic carbohydrates and phenolic compounds was recorded. This is the first demonstration of the pathogenic nature of A. strictum in maize from Cameroon as well as the observation of gels and gums. This pathogen must be regarded as important considering its interaction in maize.

Abstract: We investigated the function of the auxin-regulated cell wall gene DC 2.15, a member of a small gene family, present in Daucus carota (L.) and other plants. Cultured cells derived from carrot hypocotyls transformed by the DC 2.15 cDNA in antisense direction were ten-fold longer than wild-type cells, indicating a function of the corresponding protein in suppression of cell expansion. The analysis of carrot plants expressing the DC 2.15 gene in antisense direction showed that the corresponding protein and/or related proteins probably are involved in leaf and vascular bundle development. The antisense plants generally displayed a retarded growth phenotype and delayed greening in comparison to wild-type plants. The asymmetric architecture of the wild-type leaves was degenerated in the DC 2.15 antisense plants and the leaves showed a torsion within and along their major vein. The vascular bundles showed a lowered ratio of the phloem/xylem area in cross sections of the leaf middle vein whereas the bundle sheath and the cambium showed no obvious phenotype. Expression of a promoter-GUS construct was found primarily in vascular bundles of stems, leaves and in the nectar-producing flower discs. The observed pleiotropic antisense phenotype indicates, by loss of function, that one or several related cell wall proteins of this gene family are necessary to realize several complex developmental processes.

Abstract: The leaf mine in Richterago riparia is caused by a lepidopteran larva (lepidopteronome). The leaves of R. riparia show campdodrome venation; the epidermis is unistratified, with stomata and glandular trichomes in adaxial and abaxial surfaces. The mesophyll is bilateral and the vascular system is collateral. During the formation of the mine, the larva consumes the chlorenchyma of the mesophyll and the smaller vascular bundles (veins of third and fourth orders). Structural alterations in the tissues of the host plant were not observed, except for the formation of a wound meristem and the presence of cells with phenolic substances next to the mine. Three cephalic exuviae of the miner were found in the mesophyll. This lepidopteronome is parenchymatic and the epidermis remains intact, but forms a protective layer for the mining insect.

Abstract: Cysteine synthase and alliinase (alliin-lyase) are terminal enzymes responsible for synthesis of cysteine and degradation of alliin (S-alk(en)yl-cysteine sulfoxide), respectively, in Allium plants. We determined the intercellular localization of cysteine synthase and alliinase using antibodies against these proteins. Cysteine synthase was predominantly localized in bundle sheath and phloem cells of three Allium plants, A. tuberosum, A. cepa and A. sativum. Lower amounts could be detected in mesophyll cells. Alliinase was almost exclusively localized in bundle sheath cells of the three Allium species. These results suggest the importance of bundle sheath cells for both synthesis and degradation of sulfur-containing compounds in Allium plants.

Abstract: Summary. The structure of the 7 th , 8 th and 12 th leaf of maize plants (Zea mays L. cv. Knezha-611, 2L) grown under conditions of 80%, 60% and 40% of full moisture content has been studied. Data from anatomical analysis show that the gradual depletion of soil moisture does not provoke substantial histological changes. Analysis of the leaves’ ultrastucture reveals that the water deficit (at 40% of soil moisture content) caused a typical destruction of thylakoids in the mesophyll chloroplasts. Chloroplasts in the bundle sheath show greater structural plasticity and stability. Functional differences between the studied tissues are probably the most important pre-requisite for the structurally different response of the plastid apparatus.

Abstract: Rapidly developing tumours at hypocotyls of Ricinus communis, induced by Agrobacterium tumefaciens strain C58, were characterized by strong differentiation of vascular bundles and their functional connection to the host bundles. The stem/tumour interface showed increased xylem, with numerous vessels accompanied by multiseriate unlignified rays. To know how nutrients efficiently accumulate in the tumour sink tissue, cell electropotentials (E(m)) in cross-sections were mapped. The measured cells were identified by injected Lucifer Yellow. Xylem and phloem parenchyma cells and stem/tumour-located rays hyperpolarized to E(m) values of about -170 mV, which suggest high plasma membrane proton pump activities. Rapidly dividing cells of cambia or small tumour parenchyma cells had low E(m). The tumour aerenchyma and the stem cortex cells displayed values close to the energy-independent diffusion potential. The lowest values were recorded in stem pith cells. Cell K(+) concentrations largely matched the respective E(m). The pattern of individual cell electropotentials was supplemented by whole organ voltage measurements. The voltage differences between the tumour surface and the xylem perfusion solution in stems attached to the tumours, the trans-tumour electropotentials (TTP), confirm the findings of respiration-dependent and phytohormone-stimulated high plasma membrane proton pump activity in intact tumours, mainly in the xylem and phloem parenchyma and ray cells. TTPs were inhibited by addition of NaN(3), CN(-) plus SHAM or N(2) gas in the xylem perfusion solution and by external N(2) flushing. The data provide functional evidence for the structural basis of priority over the host shoot in nutrient flow from the stem to the tumour.

Abstract: The results indicated that higher K~(+), Na~(+), Ca~(2+), Mg~(2+) and Cl~(-) were distributed in the vascular bundle sheath cells than in mesophyll cells and epidermal bulliform cells of the swamp ecotype Higher Ca~(2+) was found in the bulliform cells than in mesophyll cells and vascular bundle sheath cells, higher Mg~(2+) in the mesophyll cells and higher K~(+), Na~(+) and Cl~(-) in the vascular bundle sheath cells of the dune ecotype Higher Na~(+) and Mg~(2+) was determined in the mesophyll cells than in the bulliform cells and vascular bundle sheath cells, and higher K~(+), Ca~(2+) and Cl~(-) in the vascular bundle sheath cells of the light salt meadow ecotype In the heavy salt meadow ecotype, higher Na~(+) and Mg~(2+) were accumulated in the bulliform cells than in mesophyll cells and vascular bundle sheath cells, but higher K~(+), Ca~(2+) and Cl~(-) in the pesophyll cells

Abstract: A DNA having the promoter activity of OsSUT1 gene; a transgenic plant capable of specifically expressing a desired foreign gene in the vascular bundle or the phloem by using the above DNA as a promoter, etc. A DNA having the promoter activity of OsSUT1 gene is isolated from a rice (Oryza sativa L.) genomic library. This DNA has a promoter sequence exerting a phloem-specificity and growth time-specificity in its base sequence represented by SEQ ID NO:1. A transgenic plant expressing a desired foreign gene specifically to the phloem or to the vascular bundle is constructed by ligating the foreign gene to the downstream of the promoter DNA and then inserting it into genome.

Abstract: Anatomical investigation were made on the stem and root of Sesbania rostrata at different stages of growth. Xylem was found to be the first vascular tissue to differentiate. The root was tetrarch with four strands of xylem and four strands of phloem. One strand of xylem alternated with one strand of phloem. The epidermis was single layered. Beneath the epidermis there were cortex with some tannin cells. The cambium appeared at the basal part of the root and graduaHy it extending towards the root apex. The phellogen appeared in the deeper cortex and produced 45 layers of cork cells and 2–4 layers of phelloderm. In the stem, the epidermis Was single layered. Beneath the epidermis there were 10–12 layers of cortex with lots of tanniniferous cells. The vascular bundles were of two types, small and large with bundle caps. In the large vascular bundle, the primary phloem consisted of a number of sieve elements while in the small bundle there were parenchymatous tissue with or without functional sieve element. The large vascular bundle contained 5–7 strands of xylem while the small bundle contained 1 or 2. The cambium differentiated in between xylem and phloem of the primary structures of the stem. It became active and gave rise to secondary phloem and secondary xylem. The vessels were small and big. The smaller vessels lay in between or among the big vessels. Most of the vessels were solitary. Among the elements of secondary phloem, axial parenchyma was found to occupy the major area. The periderm developed one after another from deeper cortex.

Abstract: Tugarinovia mongolica has a tubular stylar nectary located at the base of the style.The nectary, which lacks special vascular bundleis,is composed of secretory epidermis and nectariferous tissue. Stomata are present in the epidermis and there are well developed space under them.The basal cells of the nectary are adjacent to the vascular bundle of the style. During the development of nectary, both the structure and content of cell change regularly. The pre nectar is provided by the vascular bundle at the base of the style. Nectar is formed in nectariferous tissue,and it is excreted from the stoma. The relationship between the structure of the nectary and evolution is discussed.

Abstract: It was shown that the heritabilities of spikelets per panicle, primary branch number, secondary branch number and numbers of large, small vascular bundles in neck-panicle were above 70%, while numbers of large and small vascular bundles in second internode, above 50%. The numbers of genetic factors involved in above-mentioned traits were more than 6.0. According to estimated coefficients of skewness (g_(1)) and kortosis (g_(2)) of the traits, complementary interactions were detected for the traits, i.g., primary branch number, number of small vascular bundles in neck-panicle and number of large vascular bundles in second internode. Genic interactions were not found for spikelets per panicle, secondary branch number, number of large vascular bundles in neck-panicle and numbers of small vascular bundles in second internode. Ratio of numbers of large to small vascular bundles in neck-panicle and ratio of number of large vascular bundles in second internode to that in neck-panicle can show better the subspecific characteristics of material studied and may be used in classification of indica and japonica subspecies for reference.