Abstract: Plants perceive environmental signals such as day length and temperature to determine optimal timing for the transition from vegetative to floral stages. Arabidopsis flowers under long-day conditions through the CONSTANS (CO)–FLOWERING LOCUS T (FT) regulatory module. It is thought that the environmental cues for photoperiodic control of flowering are initially perceived in the leaves. We have previously shown that GIGANTEA (GI) regulates the timing of CO expression, together with FLAVIN-BINDING, KELCH REPEAT, F BOX protein 1. Normally, CO and FT are expressed exclusively in vascular bundles, whereas GI is expressed in various tissues. To better elucidate the role of tissue-specific expression of GI in the flowering pathway, we established transgenic lines in which GI is expressed exclusively in mesophyll, vascular bundles, epidermis, shoot apical meristem, or root. We found that GI expressed in either mesophyll or vascular bundles rescues the late-flowering phenotype of the gi-2 loss-of-function mutant under both short-day and long-day conditions. Interestingly, GI expressed in mesophyll or vascular tissues increases FT expression without up-regulating CO expression under short-day conditions. Furthermore, we examined the interaction between GI and FT repressors in mesophyll. We found that GI can bind to three FT repressors: SHORT VEGETATIVE PHASE (SVP), TEMPRANILLO (TEM)1, and TEM2. Finally, our chromatin immunoprecipitation experiments showed that GI binds to FT promoter regions that are near the SVP binding sites. Taken together, our data further elucidate the multiple roles of GI in the regulation of flowering time.

Abstract: Summary The hydraulic conductivity of the leaf vascular system (Kleaf) is dynamic and decreases rapidly under drought stress, possibly in response to the stress phytohormone ABA, which increases sharply in the xylem sap (ABAxyl) during periods of drought. Vascular bundle-sheath cells (BSCs; a layer of parenchymatous cells tightly enwrapping the entire leaf vasculature) have been hypothesized to control Kleaf via the specific activity of BSC aquaporins (AQPs). We examined this hypothesis and provide evidence for drought-induced ABAxyl diminishing BSC osmotic water permeability (Pf) via downregulated activity of their AQPs. ABA fed to the leaf via the xylem (petiole) both decreased Kleaf and led to stomatal closure, replicating the effect of drought. In contrast, smearing ABA on the leaf blade, while also closing stomata, did not decrease Kleaf within 2–3 h of application, demonstrating that Kleaf does not depend entirely on stomatal closure. GFP-labeled BSCs showed decreased Pf in response to ‘drought’ and ABA treatment, and a reversible decrease with HgCl2 (an AQP blocker). These Pf responses, absent in mesophyll cells, suggest stress-regulated AQP activity specific to BSCs, and imply a role for these cells in decreasing Kleaf via a reduction in Pf. Our results support the above hypothesis and highlight the BSCs as hitherto overlooked vasculature sensor compartments, extending throughout the leaf and functioning as ‘stress-regulated valves’ converting vasculature chemical signals (possibly ABAxyl) into leaf hydraulic signals.

Abstract: The primary inflorescence stem of Arabidopsis thaliana is rich in lignified cell walls, in both vascular bundles and interfascicular fibres. Previous gene expression studies demonstrated a correlation between expression of phenylpropanoid biosynthetic genes and a subset of genes encoding ATP-binding cassette (ABC) transporters, especially in the ABCB/multi-drug resistance/P-glycoprotein (ABCB/MDR/PGP) and ABCG/pleiotropic drug resistance (ABCG/PDR) subfamilies. The objective of this study was to characterize these ABC transporters in terms of their gene expression and their function in development of lignified cells. Based on in silico analyses, four ABC transporters were selected for detailed investigation: ABCB11/MDR8, ABCB14/MDR12, ABCB15/MDR13, and ABCG33/PDR5. Promoter::glucuronidase reporter assays for each gene indicated that promoters of ABCB11, ABCB14, ABCB15, and ABCG33 transporters are active in the vascular tissues of primary stem, and in some cases in interfascicular tissues as well. Homozygous T-DNA insertion mutant lines showed no apparent irregular xylem phenotype or alterations in interfascicular fibre lignification or morphology in comparison with wild type. However, in abcb14-1 mutants, stem vascular morphology was slightly disorganized, with decreased phloem area in the vascular bundle and decreased xylem vessel lumen diameter. In addition, abcb14-1 mutants showed both decreased polar auxin transport through whole stems and altered auxin distribution in the procambium. It is proposed that both ABCB14 and ABCB15 promote auxin transport since inflorescence stems in both mutants showed a reduction in polar auxin transport, which was not observed for any of the ABCG subfamily mutants tested. In the case of ABCB14, the reduction in auxin transport is correlated with a mild disruption of vascular development in the inflorescence stem.

Abstract: The phloem unloading pathway remains unclear in fruits of Cucurbitaceae, a classical stachyose-transporting species with bicollateral phloem. Using a combination of electron microscopy, transport of phloem-mobile symplasmic tracer carboxyfluorescein, assays of acid invertase and sucrose transporter, and [14C]sugar uptake, the phloem unloading pathway was studied in cucumber (Cucumis sativus) fruit from anthesis to the marketable maturing stage. Structural investigations showed that the sieve element–companion cell (SE–CC) complex of the vascular bundles feeding fruit flesh is apparently symplasmically restricted. Imaging of carboxyfluorescein unloading showed that the dye remained confined to the phloem strands of the vascular bundles in the whole fruit throughout the stages examined. A 37 kDa acid invertase was located predominantly in the cell walls of SE–CC complexes and parenchyma cells. Studies of [14C]sugar uptake suggested that energy-driven transporters may be functional in sugar trans-membrane transport within symplasmically restricted SE–CC complex, which was further confirmed by the existence of a functional plasma membrane sucrose transporter (CsSUT4) in cucumber fruit. These data provide a clear evidence for an apoplasmic phloem unloading pathway in cucumber fruit. A presumption that putative raffinose or stachyose transporters may be involved in soluble sugars unloading was discussed.

Abstract: Early events in NaCl-induced root ion and water transport were investigated in maize (Zea mays L) roots using a range of microelectrode and imaging techniques. Addition of 100 mm NaCl to the bath resulted in an exponential drop in root xylem pressure, rapid depolarization of trans-root potential and a transient drop in xylem K(+) activity (A(K+) ) within ∼1 min after stress onset. At this time, no detectable amounts of Na(+) were released into the xylem vessels. The observed drop in A(K+) was unexpected, given the fact that application of the physiologically relevant concentrations of Na(+) to isolated stele has caused rapid plasma membrane depolarization and a subsequent K(+) efflux from the stelar tissues. This controversy was explained by the difference in kinetics of NaCl-induced depolarization between cortical and stelar cells. As root cortical cells are first to be depolarized and lose K(+) to the environment, this is associated with some K(+) shift from the stelar symplast to the cortex, resulting in K(+) being transiently removed from the xylem. Once Na(+) is loaded into the xylem (between 1 and 5 min of root exposure to NaCl), stelar cells become more depolarized, and a gradual recovery in A(K+) occurs.

Abstract: Sensing pH and sucrose concentration (with a preference for pH values of 7.0-7.5 and sucrose concentrations of approximately 400 mmol l(-1)) enables aphids to recognise sieve tubes inside vascular bundles. However, it is still unclear how aphids find their way to the vascular bundles. Membrane potentials in the cortex of Vicia faba stems were measured along a radial transect from the epidermis to the sieve elements and there was no gradient detected that could be used by aphids to guide their stylets to the sieve elements. Additionally, aphids did not demonstrate a preference between artificial diets with low or high levels of dissolved oxygen, making it unlikely that oxygen gradients in the cortex assist orientation towards the phloem. Tracks of salivary sheaths indicate that aphids search for vascular bundles in a radial direction (perpendicular from the stem surface to the vascular bundle) with regular side punctures in a pre-programmed fashion. Optical examination and electrical penetration graph (EPG) recordings suggest that aphids (Megoura viciae) probe the vacuolar sap of cortex cells. Acidic pH (5.0-5.5) and low sucrose concentrations in vacuoles, therefore, may provoke aphids to retract their stylets and probe the next cell until a favourable cell sap composition is encountered. The importance of sucrose as a cue was demonstrated by the experimental manipulation of Ricinus communis plants that cause them to transport hexoses instead of sucrose. Aphids (Aphis fabae) ingested less phloem sap of plants transporting hexoses compared with plants transporting the normal sucrose. The proposed rejection-acceptance behaviour provides a universal plant-directed mode of how aphids orientate their stylets towards the phloem.

Abstract: Little is known about the translocation of proteins and other macromolecules from a host plant to the parasitic weed Phelipanche spp. Long-distance movement of proteins between host and parasite was explored using transgenic tomato plants expressing green fluorescent protein (GFP) in their companion cells. We further used fluorescent probes of differing molecular weights to trace vascular continuity between the host plant and the parasite. Accumulation of GFP was observed in the central vascular bundle of leaves and in the root phloem of transgenic tomato plants expressing GFP under the regulation of AtSUC2 promoter. When transgenic tomato plants expressing GFP were parasitized with P. aegyptiaca, extensive GFP was translocated from the host phloem to the parasite phloem and accumulated in both Phelipanche tubercles and shoots. No movement of GFP to the parasite was observed when tobacco plants expressing GFP targeted to the ER were parasitized with P. aegyptiaca. Experiments using fluorescent probes of differing molecular weights to trace vascular continuity between the host plant and the parasite demonstrated that Phelipanche absorbs dextrans up to 70 kDa in size from the host and that this movement can be bi-directional. In the present study, we prove for the first time delivery of proteins from host to the parasitic weed P. aegyptiaca via phloem connections, providing information for developing parasite resistance strategies.

Abstract: Based on the high density of plasmodesmata interconnecting the intermediary cells and their neighboring phloem parenchyma or bundle-sheath cells, and based on the insensitivity to the sucrose transport inhibitor p-chloromercuribenzenesulfonic acid (PCMBS), cucurbits have been concluded to be symplastic loaders. In the present study, we identified and characterized the full-length sequence of sucrose transporter gene (CmSUT1) from melon (Cucumis melo L. cv. Hale's best jumbo). In vitro experiments confirmed that the identified gene product has sucrose transporter activity in baker's yeast. Healthy and cucumber mosaic virus (CMV)-infected melon plants were employed to examine sucrose transporter activity in planta. Pretreatment with PCMBS inhibited loading of newly fixed ¹⁴CO₂ into minor veins of CMV-infected plants. Moreover, CMV infection caused significant increase in CmSUT1 transcripts expression, mainly in vascular bundles of minor veins, which was associated with elevated sucrose content in phloem sap collected from source-leaf petioles. We propose that cucurbit plants contain the machinery for apoplastic phloem loading and that CMV infection causes a quantitative shift in the mode by which photoassimilates are loaded into the sieve tube.

Abstract: The analysis of rapid responses in the transcriptome of Arabidopsis roots to a decreased iron (Fe) supply was studied using DNA microarrays and revealed candidate genes with putative roles in Fe homeostasis. In addition to the frequently reported induction of gene activity in response to Fe deficiency, the expression of a number of putative cationic metal transporters was found to rapidly decrease in response to Fe deficiency. In this report we have investigated a small family of five nodulin-like genes that show protein sequence similarity to AtVIT1 and likely have a function in regulation of Fe homeostasis. DNA microarray analysis showed a rapid decrease in transcript abundance for nodulin-like1 (At1g21140), nodulin-like2 (At1g76800), and nodulin-like21 (At3g25190). This decrease was significant after 6 h of Fe deficiency and persisted at least to 72 h. Nodulin-like3 (At3g43630) and Nodulin-like4 (At3g43660) did not respond to the Fe concentration in the microarray analysis. The nodulin-like family encoded presumptive membrane proteins with five calculated transmembrane domains, and all members had significant protein sequence homology to the vacuolar Fe transporters AtVIT1 and ScCCC1p. Homologs of all five nodulin-like genes were found in both di- and monocotyledon plants, as well as in Physcomitrella and Chlamydomonas. Promoter-β-glucuronidase (GUS) assays showed expression of the nodulin-like1 gene in roots, hypocotyls, and expanded cotyledons of two-week-old Arabidopsis seedlings with the greatest activity associated with the vascular bundle and the root stele. In the absence of Fe,GUS activity was greatly reduced and was only weakly visible in the stele and vascular bundle. In an attempt to identify the function of these nodulin-like proteins, we isolated knockout mutants for nodulin-like3 and nodulin-like21 from available T-DNA insertion lines. Although these mutants did not show dramatic changes in growth or in their ability to grow on Fe-deficient media or media containing from 5 to 120 μM Fe, the nodulin-like3 mutant had a significantly higher Fe concentration in the shoots and both nodulin-like3 and nodulin-like21 mutants had significantly decreased Fe in the roots. These results were taken as an indication, that some members of this nodulin-like family were directly involved in Fe homeostasis in plants.

Abstract: In this study, anatomical structures of the petiole of 7 taxa viz., Glechoma hederacea L., Origanum vulgare L., Scutellaria salviifolia Bentham, Ajuga reptans L., Prunella vulgaris L., Lamium purpureum L. var. purpureum, Salvia verbenaca L., Salvia viridis L., Salvia virgata Jacq., belonging to the Lamicaceae family were examined and compared. In all the studied taxa, some differences were found in the petiole shape, arrangement and number of vascular bundles, hair types and the presence of collenchyma. G. hederaceae, S. virgata and O. vulgare consist of a total of 3 vascular bundles, with a big bundle in the middle of the petiole and a single small vascular bundle in each corner. P. vulgaris has 5 vascular bundles. S. verbenaca has a total of 11 vascular bundles, with a big bundle positioned in the middle. L. purpureum L. var, purpureum consists of 4 vascular bundles. S. salviifolia has 3 vascular bundles. A. reptans has a total of 9 vascular bundles, with 1 big bundle in the middle. S. viridis consists of 7 vascular bundles. Petiole has glandular and eglandular hairs. Eglandular hairs consist of capitate hairs, whereas peltate hairs are only found in S. salviifolia.

Abstract: Genus Suaeda (family Chenopodiaceae, subfamily Suaedoideae) has two structural types of Kranz anatomy consisting of a single compound Kranz unit enclosing vascular tissue. One, represented by Suaeda taxifolia, has mesophyll (M) and bundle sheath (BS) cells distributed around the leaf periphery. The second, represented by Suaeda eltonica, has M and BS surrounding vascular bundles in the central plane. In both, structural and biochemical development of C 4 occurs basipetally, as observed by analysis of the maturation gradient on longitudinal leaf sections. This progression in development was also observed in mid-sections of young, intermediate, and mature leaves in both species, with three clear stages: (i) monomorphic chloroplasts in the two cell types in younger tissue with immunolocalization and in situ hybridization showing ribulose bisphosphate carboxylase oxygen-ase (Rubisco) preferentially localized in BS chloroplasts, and increasing in parallel with the establishment of Kranz anatomy; (ii) vacuolization and selective organelle positioning in BS cells, with occurrence of phosphoenolpyruvate carboxylase (PEPC) and immunolocalization showing that it is preferentially in M cells; (iii) establishment of chloroplast dimorphism and mitochondrial differentiation in mature tissue and full expression of C 4 biochemistry including pyruvate, Pi dikinase (PPDK) and NAD-malic enzyme (NAD-ME). Accumulation of rbcL mRNA preceded its peptide expression, occurring prior to organelle positioning and differentiation. During development there was sequential expression and increase in levels of Rubisco and PEPC followed by NAD-ME and PPDK, and an increase in the 13 C/ 12 C isotope composition of leaves to values characteristic of C 4 photosynthesis. The findings indicate that these two forms of NAD-ME type C 4 photosynthesis evolved in parallel within the subfamily with similar ontogenetic programmes.

Abstract: Only a few species of aphids induce galls. Among these, Paracletus cimiciformis, Forda marginata, Forda formicaria, Geoica utricularia and Baizongia pistaciae induce galls on Pistacia terebinthus leaflets. Prior to present study the author examined microscopically P. terebinthus leaflets. He also studied the microscopic morphology of galls induced by the five species mentioned above. A clear microscopic difference between these galls is that in the wall of galls induced by the genera Paracletus and Forda a single vascular bundle is seen. The interpretation is that these galls are laminae of the modified leaflets. However, in the walls of the galls induced by the genera Geoica and Baizongia, two vascular bundles are observed. In the present paper a study of the early stages of development of galls produced by G. utricularia is described. The study was designed to explain the origin of the two vascular bundles present in the walls of these galls. The findings indicate that the aphid induces a massive development of the two vascular bundles present in the midvein of the leaflets of P. terebinthus: the main vascular bundle and the small supernumerary vascular bundle. Both these extremely developed vascular bundles occupy the walls of the galls induced by G. utricularia.

Abstract: The present study deals with the microscopical and macroscopical investigation on leaves, petioles and stems of Madhuca longifolia Fam. Sapotaceae. Madhuca longifolia commonly known as ‘Mahua’ is an important plant used against various disorders in indigenous system of medicine such as hepatoprotective, antipyretics, anti-Inflammatory, antiulcer, analgesic, anthelmintic, anti-diabetic and in wound healing activity. The transverse section of leaf shows epidermis single layered on both the surfaces and covered with thin cuticle, cortex, pith, vascular region with xylem and phloem. Leaves consists uniseriate type of trichomes. The paracytic types of stomata are present in both lower and upper surface of leaves. The transverse section of Petiole shows single layered epidermis covered with cuticle, vascular bundles, xylem surrounded by the phloem. The transverse section of stem shows cork, cortex, xylem, phloem and pith. The powder microscopy shows paracytic stomata, uniseriate and covering type of trichomes, parenchymatous cells and fragments of vascular tissue. The quantitative microscopical studies of leaf were also carried out and various leaf content such as palisade ratio, vein islet number, vein termination number, stomata number, stomatal index.

Abstract: Stem anatomy and the development of intraxylary phloem were investigated in six to eight years old Coccinia indica L. (Cucurbitaceae). Secondary growth in the stems was achieved by the normal cambial activity. In the innermost part of the thicker stems, xylem parenchyma and pith cells dedifferentiated into meristematic cells at several points. In some of the wider rays, ray cells dedifferentiate and produce secondary xylem and phloem with different orientations and sometimes a complete bicollateral vascular bundle. The inner cambial segments of the bicollateral vascular bundle (of primary growth) maintained radial arrangement even in the mature stems but in most places the cambia were either inactive or showed very few cell divisions. Concomitant with the obliteration and collapse of inner phloem (of bicollateral vascular bundles), parenchyma cells encircling the phloem became meristematic forming a circular sheath of internal cambia. These internal cambia produce only intraxylary secondary phloem centripetally and do not produce any secondary xylem. In the stem, secondary xylem consisted mainly of axial parenchyma, small strands of thick-walled xylem derivatives, i.e. vessel elements and fibres embedded in parenchymatous ground mass, wide and tall rays along with exceptionally wide vessels characteristic of lianas. In thick stems, the axial parenchyma de-differentiated into meristem, which later re-differentiated into interxylary phloem. Fibre dimorphism and pseudo-vestured pits in the vessels are also reported.

Abstract: Phloem loading is the process by which photoassimilates synthesized in the mesophyll cells of leaves enter the sieve elements and companion cells of minor veins in preparation for long distance transport to sink organs. Three loading strategies have been described: active loading from the apoplast, passive loading via the symplast, and passive symplastic transfer followed by polymer trapping of raffinose and stachyose. We studied phloem loading in Amborella trichopoda, a premontane shrub that may be sister to all other flowering plants. The minor veins of A. trichopoda contain intermediary cells, indicative of the polymer trap mechanism, forming an arc on the abaxial side and subtending a cluster of ordinary companion cells in the interior of the veins. Intermediary cells are linked to bundle sheath cells by highly abundant plasmodesmata whereas ordinary companion cells have few plasmodesmata, characteristic of phloem that loads from the apoplast. Intermediary cells, ordinary companion cells, and sieve elements form symplastically connected complexes. Leaves provided with 14CO2 translocate radiolabeled sucrose, raffinose, and stachyose. Therefore, structural and physiological evidence suggests that both apoplastic and polymer trapping mechanisms of phloem loading operate in A. trichopoda. The evolution of phloem loading strategies is complex and may be difficult to resolve.

Abstract: Six species/cultivars were selected for the comparative anatomical studies of leaf in the genus Rosa from Faisalabad and adjoining administrative districts. The most widely cultivated R. damascena showed some specific anatomical modifications in leaves such as thick leaves (lamina), thick upper epidermis, large palisade cells, wide protoxylem vessels, large phloem area and large and more stomata particularly on adaxial epidermis. This species showed reduced cortical cell area, lower epidermis thickness, spongy cell area, vascular bundle area and metaxylem area. These characteristics indicated ecological success of this species to a variety of environmental types. The second most widely cultivated species, R. bourboniana ‘Gruss-an-Teplitz’ showed thick leaves (lamina), large cortical cell area, large vascular bundle area, large metaxylem vessels and large phloem area. All the Rosa species/cultivars showed great diversity in leaf tissue architecture, which are the indicators of distribution and ecological success of the genus Rosa in the Punjab plains, particularly Faisalabad environments.

Abstract: Phytohormones are indispensable factors regulating plant cell dedifferentiation. In this paper, different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin (KIN) were incorporated in the culture medium and the anatomy of dedifferentiated cells prior to callus formation from Arabidopsis thaliana petiole explants was examined. The results indicated that the cytoplasm of parenchyma cells in the vascular bundle gradually became denser with time of culture only if 2,4-D was included in the medium. The WUSCHEL (WUS) gene was expressed in derivative cells of the vascular bundle after culture for 24 h in the presence of 2,4-D and there was no obvious signal in these cells of cultured petioles with KIN alone. These results suggest that 2,4-D plays an important role in the process of dedifferentiation of vascular bundle cells in Arabidopsis petioles and KIN has no obvious effect on it.

Abstract: In the present study, the leaves of 18 Scorzonera L. (Asteraceae) taxa were studied by LM in order to assess anatomical variations that may serve as distinguishing characters and to evaluate their significance for the genus by numerical analysis. All the investigated species can be divided into distinct groups according to mesophyll and midrib structure. Firstly they can be divided in two groups based on presence/absence of cavity on midrib. Secondarily two main vascular bundle types can be identified in transverse sections according to the presence or absence of secretory cells in phloem. Principal component analysis (PCA) showed that width of the palisade tissue beneath the upper epidermis, rate of spongy to the mesophyll (w/w), average number of epidermal cells for both sides and average number of stomata on upper side are the most important characters in explaining the total variations.

Abstract: Med8, a subunit of mediator complex, has proved to possess crucial functions in many organisms from yeast to human. In plant, the med8 mutant of Arabidopsis thaliana displayed delayed anthesis and increased number of leaves during the vegetative period. However, the roles of Med8 in other flowering plants are still unknown. To investigate the function of Med8 ortholog in tobacco (Nicotiana tabacum L.; named as NtMed8), we created transgenic tobacco plants with repressed NtMed8 expression mediated by RNA interference (RNAi). Compared with the wild type, the NtMed8-RNAi plants exhibited: more leaves with smaller but thicker blades; larger cells and vascular bundles with lower stomata density in leaves; swelled chloroplasts with thicker and lumen-enlarged thylakoids; weaker root system with fewer lateral roots; larger flowers and floral organs; flowering earlier under long day, but later under short day conditions; and male sterile with larger but less germinable pollens. In addition, quantitative RT-PCR indicated that NtMed8 is expressed in both vegetative and floral tissues. Subcellular localization analysis by transient expression of fusion protein in Nicotiana benthamiana leaves showed that NtMed8 was located in both plasma membrane and nucleus. These results suggest that NtMed8 plays important roles in both vegetative and reproductive development, and the function of Med8 appears to be, at least partially, conserved in flowering plants.

Abstract: Bundle sheath (BS) strand cells and BS thylakoids from C4 plants represent a unique system for various studies using a combination of physiological, biochemical, and molecular approaches. We have developed procedures for mechanical disruption of leaf tissues in order to isolate metabolically active bundle sheath strand cells and thylakoids practically free from cross-contamination coming from mesophyll cells. The procedures are described in detail together with useful practical suggestions. Using mechanical disruption we have shown the supramolecular organization of the dimeric LHCII-PSII in BS thylakoids of maize.

Abstract: Context: Kranz anatomy of locally developed sugarcane cultivars were studied in relation to C4 vascular arrangement. Objective: The objective of this study was to make gross cross-sectional anatomy and quantitative assessment of the anatomic traits of the leaf-blade and midrib of the sugarcane cultivars. Materials and Methods: Leaf blade and leaf sheath of two sugarcane cultivars Ishurdi 20 and Ishurdi 32 were used as the materials. Free hand section with appropriate stain were used. Sections were studied using an advanced biological system microscope fitted with motic camera. Anatomic traits were studied through motic image plus J 1.0 software using Macintosh computer. Results : Three sized vascular bundles and significant differences in distance between those vascular bundles were noted. Ishurdi 32 possessed two sized vascular bundles. Large vascular bundles characters by two large metaxylem vessels on either side of protoxylem. Phloem well developed. Intermediate and small bundles lack metaxylem vessels and protoxylem, but have metaphloem with thick and thin walled sieve tubes. Bundle sheaths have extended to upper and lower epidermis but for small bundle it is extended to abaxial epidermis. Vascular bundles are almost completely surrounded by chlorenchymatous bundle sheath and associated with hypodermal sclerenchyma on both abaxially and adaxially except small blade bundles which associated with the abaxial sclerenchyma. Bundle sheath cells were smaller in large and larger in other two types of vascular bundle. An inner mestome sheath with thickened walls is always present round the phloem and metaxylem around all or part of the xylem in large and intermediate bundles. In small bundles mestome sheath is altogether absent. Bulliform cells with varied area were present on the adaxial epidermis opposite to small vascular bundles. Midrib anatomy consists of central large vascular bundles lacking bundle sheath cells pushed deep inside parenchymatous hypodermis from abaxial hypodermal sclerenchyma girders. Lack of Kranz traits, and bundle sheath cells have transformed into sclerenchymatous bundle cover. Central mid-rib large bundle flanked by 3-10 small bundles on either side of midrib which have Kranz system of anatomy. Midrib region have continuous hypodermis consists of sclerenchyma cells and it is few layer (Ishurdi 32) to multilayer (Ishurdi 20). Conclusion : Kranz system with well developed bundle sheath associated with Kranz mesophil in the leaf blade were observed but Kranz tissue absent in midrib region. Large and small vascular bundles alternate all alone the leaf blade. Bulliform cell well develop indicates zeric adaptation. Two cultivars differ in respect of quantitative expression of Kranz tissue. Keywords : Sugarcane cultivar; Kranz tissue; bulliform cells; mestome sheath. DOI: http://dx.doi.org/10.3329/jbs.v18i0.8778 JBS 2010; 18(0): 66-73

Abstract: Holocalyx balansae Micheli belongs to the Fabaceae family and is called pau-alecrim in Portuguese. In folk medicine, it is indicated to treat heart, hepatic and digestive upsets, as well as being considered anti-septic and diaphoretic. This work aimed to study the morpho-anatomy of the leaf and stem of this native medicinal species, in order to increase knowledge of the Brazilian flora and to contribute to pharmacognostic quality control. Samples of mature leaves and young stems were fixed and either sectioned free-hand or embedded in glycol-methacrylate and sectioned by microtome, then stained. Microchemical tests and scanning electron microscopy were also performed. The leaves are alternate, compound and paripinnate, and the leaflets have a lanceolate shape. Anomocytic and anisocytic stomata are found exclusively on the abaxial surface. The mesophyll is dorsiventral and the midrib, in cross-section, is flat on both sides, showing one collateral vascular bundle, encircled by a sclerenchymatic and crystalliferous sheath. The rachis and petiole present a collateral vascular bundle with a centric arrangement. The stem presents phellogen localized superficially. In the vascular cylinder, there is a sclerenchymatic sheath and continuous phloem and xylem cylinders, both traversed by narrow rays. Prismatic crystals of calcium oxalate are present in the leaf and stem.

Abstract: Some weeds treated with the recommended dose rates of glyphosate recover after the application. An explanation of this phenomenon is needed to avoid incomplete control and the potential spread of resistance. The distributions of glyphosate and of shikimate levels within treated plants were therefore analysed, and plant reactions were investigated via histological examinations. It was found that glyphosate was translocated from Amaranthus palmeri leaves to roots within 48 h following treatment. Changes in the phloem of different weed species became visible after 3 days. After 4 days, shikimate accumulation was highest in stem tips and decreased towards the base of plants. Necrosis of pith cells started at the same time. Yellowing of leaves, stem curvature and wilting were observed after 1 week. Herbicide-induced polyphenols and lignin in the intercellular space suggest that glyphosate phytotoxicity is not based solely on the shikimate pathway. It seems to be linked to the decay of vascular tissues and of pith, but not to the transport of glyphosate into apical meristems. Meristematic tissue surrounding the pith survived and gave rise to new buds in Amaranthus plants. These findings are important for the characterisation of plants that escape herbicide treatment and for the search for new control tools.

Abstract: The characteristics of vascular system were investigated within a spikelet of wheat (Triticum aestivum L. var. PBW-343). The results divulged that the vascular system of florets 1 and 2 was more conducive to precipitation of photo-assimilates than floret 3 or 4. The whole pervading vascular system in floret 1 and 2 possibly pumped more assimilates as compared to floret 3 or other florets. The pattern seemed to be similar in all the segments of spikelets within the same ear. Further it was elucidated that floret number 3 which possessed smaller grains had longer and slender vascular bundles which probably resisted the movement of assimilates.

Abstract: In maize (Zea mays L., cv. Voronezhskaya-76) seedlings subjected to salinity, the values of indicators of stress response development (contents of proline and lactate, activity of peroxidase) were higher in the cells of mesophyll than in the bundle sheath. At short-term NaCl (150 mM) action, the main reactions of the total adaptation syndrome were located in the cell of mesophyll. At salinity, substantial rearrangements of the isoenzyme composition of the malate dehydrogenase (MDH) system main enzymes occurred, which determined cell energization, the synthesis of reducing equivalents, maintenance of the osmotic balance, and functioning of the Hatch-Slake cycle. The changes in some intermediate concentrations and MDH-system enzyme functioning occurring under stress conditions permit a suggestion that, in maize tissues subjected to salt stress, an additional metabolic pathway related to aspartate synthesis and transport is induced.

Abstract: The cyclitols: d-pinitol, d-chiro-inositol are naturally present in the tissues of Lupinus angustifolius. The effect of these cy- clitols on the behaviour of the pea associated clone of Acyrthosiphon pisum during various stages of probing was studied. The main stage of probing studied was the stylet penetration in mesphyll and vascular bundle. d-pinitol, d-chiro-inositol and their mixture were exogenously applied to pea Pisum sativum explants and the aphid probing behaviour was evaluated using the Electrical Penetration Graph technique (EPG). Feeding of peas with cyclitols at a concentration of 10 mM, caused a selective accumulation of d-pinitol and d-chiro-inositol in stems, leaf petioles, and leaf blades. In aphid bodies, both cyclitols were traced, respectively, to the host plant treat- ment. The new cyclitols in pea tissues did not significantly affect the total duration and frequency of aphid activities during probing in peripheral as well as vascular tissues. However, the aphid behaviour on cyclitol-treated plants as compared to their behaviour on the control was slightly altered. Non-probing and probing in mesophyl prevailed among aphid activities during the initial period of stylet penetration. Aphids on d-pinitol+d-chiro-inositol-treated plants reached phloem vessels relatively later than aphids on the con- trol and d-chiro-inositol plants. There were recurrent switches between E1 (salivation) and E2 (sap ingestion) patterns in some aphids during the phloem phase on d-pinitol and d-pinitol+d-chiro-inositol - treated plants. This may reflect difficulties in the uptake of the phloem sap, and point to lupin cyclitols as being responsible, at least in part, for the rejection of L. angustifolius as a host plant by the pea clone of A. pisum.

Abstract: One of the most important characteristics that determines the quality of forages is their digestibility. Certain structural characteristics of the vegetative organs, such as a high percentage of cells with lignified walls, might limit digestibility. Leaf and stem histological characteristics related to digestibility were examined for nine wild Lathyrus species closely related to cultivated species. The recommended characteristics for plants that could be used as forage on their own are: a small number of stem vascular bundles, a relatively small proportion of stem sclerenchyma and sclerenchymatous parenchyma tissue, thin leaflet cuticle, a small number of leaf vascular bundles, and large mesophyll and epidermal cells. According to the results of the analyses, species with favourable histological characteristics were L. palustris, L. sphaericus and L. aphaca, while the species with the highest proportion of thick-walled cells, unsuitable for use as forage, were L. pratensis, L. niger and L. tuberosus.