Abstract: In the C4 plant maize, three photosynthetic cell types differentiate: C4 bundle sheath, C4 mesophyll, and C3 mesophyll cells. C3 mesophyll cells represent the ground state, whereas C4 bundle sheath and C4 mesophyll cells are specialized cells that differentiate in response to light-induced positional signals. The Golden2 (G2) gene regulates plastid biogenesis in all photosynthetic cells during the C3 stages of development. However, G2 function is specifically committed to the differentiation of bundle sheath cell chloroplasts in C4 leaf blades. In this article, we report the isolation of G2-like (Glk) genes from maize and rice, providing evidence for a family of Glk genes in plants. The expression profiles of the rice Glk genes suggest that these genes may act redundantly to promote photosynthetic development in this C3 species. In maize, G2 and ZmGlk1 transcripts accumulate primarily in C4 bundle sheath and C4 mesophyll cells, respectively, suggesting a specific role for each gene in C4 differentiation. We show that G2 and ZmGLK1 both can transactivate reporter gene transcription and dimerize in yeast, which supports the idea that these proteins act as transcriptional regulators of cell-type differentiation processes.

Abstract: ;positive regulator commonly involved in the tolerance to cold and salt/drought. We carried out in situ detection of the transcript and immunolocalization of the protein. In the wild-type rice plants under both stress conditions, OsCDPK7 was expressed predominantly in vascular tissues of crowns and roots, vascular bundles and central cylinder, respectively, where water stress occurs most severely. This enzyme was also expressed in the peripheral cylinder of crown vascular bundles and root sclerenchyma. Similar localization patterns with stronger signals were observed in stress-tolerant OsCDPK7 over-expressing transformants with the cauliflower mosaic virus 35S promoter. The transcript of a putative target gene of the OsCDPK7 signaling pathway, rab16A, was also detected essentially in the same tissues upon salt stress, suggesting that the OsCDPK7 pathway operates predominantly in these regions. We propose that the use of the 35S promoter fortuitously strengthened the localized expression of OsCDPK7, resulting in enhancement of the stress signaling in the inherently operating regions leading to improved stress tolerance.

Abstract: The present study describes the anatomical structure of calyx and leaf glands in Galphimia brasiliensis and analyzes the mechanism of secretion. The glands are marginal and suprabasal, cup-shaped, sessile, and scarcely visible with the naked eye. Light microscopy reveals the following features: a thin, smooth cuticle; unistratified secretory cells; subglandular parenchyma; and vascular bundle supply composed of phloem and xylem with abundant druses of calcium oxalate. Transmission electron microscopy reveals the presence of secretory cells with conspicuous nuclei, dense cytoplasm, lipid droplets, numerous vesicles, mitochondria, Golgi, rough endoplasmic reticulum (RER), and elongated plastids with osmiophilic contents. The secretion reaches the apoplastic space and accumulates beneath the cuticle. Finally, the viscous, translucent exudate is eliminated by mechanical rupture of the cuticle. Histochemical analysis confirms that lipids are the main constituent. Small amounts of polysaccharides were also identified.

Abstract: Cell extension in the mesocotyl elongation zone (MEZ) of maize (Zea mays L.) seedlings is inhibited by light. The growth inhibition by blue light in the MEZ was reversible upon transfer to darkness. This experimental system was used for investigating the modification of mechanical cell-wall properties and the role of cell-wall lignification in cell elongation. The occurrence of lignin in the cortex and vascular bundle tissues of the MEZ was demonstrated by the isolation of diagnostic monomers released after thioacidolysis of the cell walls. Concomitantly with the inhibition of growth, blue light induces an increase in cell-wall stiffness (tensile modulus) as well as an increase in extractable lignin in the outer MEZ tissues (cortex + epidermis). Both effects are reversed when growth is resumed in the MEZ in darkness after a period of growth inhibition induced by 3 h light. In the vascular bundle light produces no comparable change in lignin content. Appearance and disappearance of phenylpropanoid material in MEZ cell walls in the light, or in darkness following a brief light treatment, respectively, can be visualized under the fluorescence microscope by characteristic changes in autofluorescence of tissue sections upon excitation with UV radiation. It is concluded from these results that light-induced lignification of primary walls is involved in cell-wall stiffening and thus inhibition of elongation growth in the MEZ of maize seedlings. Resumption of growth upon redarkening may be initiated by wall loosening in the uppermost MEZ region which displaces the lignified cell walls towards the lower mesocotyl region.

Abstract: Minor-vein ultrastructure and sugar export were studied in mature summer and winter leaves of the three broadleaf-evergreen species Ajuga reptans var. artropurpurescens L., Aucuba japonica Thunb. and Hedera helix L. to assess temperature effects on phloem loading. Leaves of the perennial herb Ajuga exported substantial amounts of assimilates in form of raffinose-family oligosaccharides (RFOs). Its minor-vein companion cells represent typical intermediary cells (ICs), with numerous small vacuoles and abundant plasmodesmal connectivity to the bundle sheath. The woody plants Hedera and Aucuba translocated sucrose as the dominant sugar species, and only traces of RFOs. Their minor-vein phloem possessed a layer of highly vacuolated cells (VCs) intervening between mesophyll and sieve elements. Depending on their location and ontogeny, VCs were classified either as companion or parenchyma cells. Both cell types showed symplasmic continuity to the adjacent mesophyll tissue although at a lower plasmodesmal frequency compared to the Ajuga ICs. p-Chloromercuribenzenesulfonic acid did not reduce leaf sugar export in any of the plants, indicating a symplasmic mode of phloem loading. Winter leaves did not show symptoms of frost injury, and the vacuolar pattern in ICs and VCs was equally prominent in both seasons. Starch accumulation as a result of reduced phloem loading was not observed to be triggered by low temperature. In contrast, high amounts of starch were found in mesophyll and bundle-sheath cells of summer leaves. Physiological data on season-dependent leaf exudation showed the maintenance of sugar export in cold-acclimated winter leaves.

Abstract: In order to estimate whether cytosolic glutamine synthetase (GS1; EC 6.3.1.2) is partly coupled to the reaction of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) in developing organs of rice (Oryza sativa L.), we compared the expression pattern of transcripts and proteins for GS1 and PAL in the tissue sections from leaf blades at various stages of development. In immature vascular bundles of unexpanded leaf blades, GS1 mRNA was mainly detected in xylem parenchyma cells, mestome-sheath cells, and sclerenchyma cells. PAL transcripts were also accumulated in these cell types. Vascular bundles in midribs of immature leaf blades contained mRNAs and proteins for both GS1 and PAL abundantly in sclerenchyma cells, although distribution of these two proteins was not completely overlapped. In immature vascular bundles in midribs, lignin deposition was observed in cell walls of xylem parenchyma cells, mestome-sheath cells and sclerenchyma cells. These results implied that a part of GS1 in unexpanded leaf blades is possibly involved in reassimilation of ammonia released from PAL reaction during the lignin production.

Abstract: In the leaves of the NAD-malic enzyme (NAD-ME)-type C4 dicot Amaranthus viridis L., there are chloroplasts in the vascular parenchyma cells (VPC), companion cells (CC), ordinary epidermal cells (EC), and guard cells (GC), as well as in the mesophyll cells (MC) and the bundle sheath cells (BSC). However, the chloroplasts of the VPC, CC, EC, and GC are smaller than those of the MC and BSC. In this study, the accumulation of photosynthetic and photorespiratory enzymes in these leaf cell types was investigated by immunogold labelling and electron microscopy. Strong labelling for phosphoenolpyruvate carboxylase was found in the MC cytosol. Weak labelling was observed in the CC and GC cytosol. Labelling for pyruvate, Pi dikinase occurred to varying degrees in the chloroplasts of all cell types except CC. Labelling for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase was detected in the chloroplasts of all cell types except MC. For both NAD-ME and the P-protein of glycine decarboxylase, intense labelling was found in the BSC mitochondria; weaker labelling was recognized in the VPC mitochondria. These data indicate that when not only the MC and BSC but also the other leaf cell types are included, the cell-specific expression of the enzymes in C4 leaves becomes more complex than has been known previously. These findings are discussed in relation to the metabolic function of epidermal and vascular bundle cells.

Abstract: Maize leaf blades differentiate dimorphic photosynthetic cell types, the bundle sheath and mesophyll, between which the reactions of C(4) photosynthesis are partitioned. Leaf-like organs of maize such as husk leaves, however, develop a C(3) pattern of differentiation whereby ribulose bisphosphate carboxylase (RuBPCase) accumulates in all photosynthetic cell types. The Golden2 (G2) gene has previously been shown to play a role in bundle sheath cell differentiation in C(4) leaf blades and to play a less well-defined role in C(3) maize tissues. To further analyze G2 gene function in maize, four g2 mutations have been characterized. Three of these mutations were induced by the transposable element Spm. In g2-bsd1-m1 and g2-bsd1-s1, the element is inserted in the second intron and in g2-pg14 the element is inserted in the promoter. In the fourth case, g2-R, four amino acid changes and premature polyadenylation of the G2 transcript are observed. The phenotypes conditioned by these four mutations demonstrate that the primary role of G2 in C(4) leaf blades is to promote bundle sheath cell chloroplast development. C(4) photosynthetic enzymes can accumulate in both bundle sheath and mesophyll cells in the absence of G2. In C(3) tissue, however, G2 influences both chloroplast differentiation and photosynthetic enzyme accumulation patterns. On the basis of the phenotypic data obtained, a model that postulates how G2 acts to facilitate C(4) and C(3) patterns of tissue development is proposed.

Abstract: The subcellular compartmentation of β-glucosidase was studied in rye, maize and wheat seedlings by immunocytochemical methods. For detection, we used a 10 nm gold-labeled secondary antibody, and results were observed using transmission electron microscopy. In all three species, β-glucosidase was found in plastids, cytoplasm and cell walls. In rye, gold particles were seen on cell walls and cytoplasm in epidermal cells of the root tip and shoot, in bundle sheath cells of the shoot and in all cells, except the vascular bundle cells of the coleoptile. Gold labeling was also observed in plastids of the bundle sheath cells of rye shoot tips and in cortical cells of root tips. In wheat, gold labeling was observed on cell walls and cytoplasm of epidermal cells in the shoot base and coleoptile, and on cell walls and plastids in epidermal cells of the root tip. In maize, gold labeling was mainly found in plastids or proplastids in vascular bundle cells and bundle sheath cells of the shoot, in bundle sheath cells of the coleoptile and in epidermal cells of the root. Some gold particles were also found in cell walls and cytoplasm of stomatal guard cells of the shoot base and vascular bundle cells of the shoot tip and in the cell walls of bundle sheath cells of the shoot tip and root tip epidermal cells. Results are discussed in relation to the role of β-glucosidase in hydroxamic acid release and overall defense mechanism of monocotyledons.

Abstract: In leaves of the maize tangled1 (tan1) mutant, clusters of bundle sheath (BS)-like cells extend several cells distant from the veins, in association with the single layer of BS cells around the vein. We show that the BS-like cell clusters in tan1 leaves result from the continued division of cells in the procambial/BS cell lineage that do not divide further in wild-type leaves. The ectopic BS-like cells accumulate the BS marker NADP-dependent malic enzyme but not the mesophyll cell marker phosphoenolpyruvate carboxylase, and exhibit thickened walls, suggesting that they differentiate as C4-type BS cells. We propose that bundle sheath cell fate can be conferred on some derivatives of procambial cell divisions in a manner that is heritable through multiple cell divisions and is position-independent.

Abstract: The phloem is a highly specialized long distance transport tissue in vascular plants. Despite detailed knowledge of the development and ultrastructure of phloem tissue in a wide variety of plant species, surprisingly little is known about the mechanisms and regulation of phloem transport. The main

Abstract: Rb(+) as a tracer for K(+) was used to test the hypothesis that uptake of K(+) from xylem vessels of small veins into the symplast of maize leaves occurs at the xylem/bundle sheath cell interface. 22.5 min after immersing cut leaves into 20 mM RbCl+1 mM KCl, Rb(+) appeared in the cells of the leaves. Sections of these leaves were freeze-dried. In cryo-thin sections (5 microm), (85)Rb(+) and (41)K(+) content was determined by laser microprobe mass analysis with a large resolution of about 1 microm. Determining the ratio of (85)Rb(+) to (41)K(+) in the cell walls and cytosols of bundle sheath cells, mesophyll cells, and in the cells between the xylem elements resulted in the following picture: In small veins, Rb(+) entered the symplast directly at the xylem/bundle sheath cell interface.

Abstract: The infection process of Phomopsis helianthi and the specific degradation of infected tissue were studied in detail using light and transmission electron microscopy. In comparison with other vascular pathogens, the infection and degradation process was in some aspects different. The favourite tissue for the pathogen to grow in was the phloem, Parenchymatic cells in and around vascular bundles were extremely sensitive to infection long before hyphae arrived, probably due to a toxin. In the parenchymatic cells the first changes were visible at the chloroplasts where electron-dense material accumulated in the thylakoid space. The chloroplast stroma changed contrast and later the whole cytoplasm also appeared electron dense. In the vascular bundles, first the phloem was destroyed and then hyphae invaded the adjacent mesophyll, the cambium, and finally the vessel elements. In particular, the compact mesophyll of the midvein was severely affected. Vessel elements were lined with electron-dense material and some were filled with flocculent material. Severe wall destruction indicated the action of a complete set of cell wall-degrading enzymes before hyphae entered the tissue; it always started at the innermost wall layer. Wall degradation in vascular tissue and adjacent parenchyma with intercellular spaces was different. Before the degradation of the protoplasts started, the cell walls were completely metabolized and only the secondary walls of the vessels resisted for longer. There were no host-cell reactions visible that could be interpreted as a defence reaction.

Abstract: C4 photosynthesis incorporates novel leaf anatomy, metabolic specialisations and modified gene expression. C4 plants typically possess a distinctive Kranz leaf anatomy consisting of two photosynthetic cell types. These are bundle sheath (BS) cells that surround the vascular centres, and mesophyll (M) cells that, in turn, surround the BS cells. A more rare form uses compartmentalisation of dimorphic chloroplasts within a single cell type. In C4 leaves, these structural frameworks functionally separate two sets of carboxylation and decarboxylation reactions. Selective expression of key photosynthesis genes in BS and M cells leads to specific accumulation of key photosynthetic enzymes which catalyse different sets of cell-type-specific reactions, enabling these plants to assimilate atmospheric CO2 with very high efficiency. For some plants, C4 photosynthesis has facilitated their adaptation to arid conditions, high temperatures and marginal environments. Understanding the basis of this pathway has applications for improvements in agricultural productivity and alternative fuel development. Key Concepts C4 photosynthesis is a carbon concentration mechanism used by some plants to improve the efficiency of photosynthetic carbon fixation. C4 photosynthesis incorporates modified leaf morphology, separation of carboxylation and decarboxylation/refixation steps of carbon assimilation, and specialised patterns of cell-type-specific gene expression. The leaves of most C4 plants possess a Kranz-type anatomy consisting of bundle sheath and mesophyll cells. A more rare form of this pathway, called single-cell C4, uses partitioning of dimorphic chloroplasts to separate different sets of reactions within a single leaf cell type. In C4 leaves, Rubisco is localised only within internalised bundle sheath cells, or internalised chloroplasts, to protect from atmospheric O2 and limit the oxygenase activity of this enzyme. The initial carbon assimilation enzyme in these leaves is PEPCase, which incorporates CO2 but not O2. Reactions of C4 pathway work as a pump to concentrate CO2 in the vicinity of the internalised Rubisco enzyme. These reduce or eliminate photorespiration, thereby enhancing photosynthetic efficiency. C4 plants are more efficient than C3 plants under arid conditions, including high temperatures and water stress. C4 plants show increased efficiency of water and nitrogen use, allowing them to outcompete C3 plants in marginal environments. Bioengineering of C4 characteristics into C3 species has the potential to improve photosynthetic efficiency in crop plants used for food and biofuel. Keywords: photosynthesis; carbon fixation; leaf anatomy; bundle sheath cells; mesophyll cells; photorespiration, evolution; environmental adaptability; cytology; C4 variations; C4 enzymes; gene regulation; biotechnology

Abstract: Structure and development of vascular cambium was studied histologically in the stem of Celosia argentea L. and Aerva sanguinolenta (L.) BLUME (Amaranthaceae). In both the species secondary growth resulted in the development of successive rings of cambia. The cambium is storied consisting only of fusiform initials giving rise to rayless vascular tissues at least in the early part of secondary growth. In the later part of the secondary growth, development of vertically elongated rays were observed in Celosia argentea. Each successive ring of cambium developed from the axial parenchyma at a distance of about four to six cell layers external to the phloem produced by the previous cambium. Functionally the cambium was bi-directional producing xylem centripetally and phloem centrifugally. Developmentally each cambium ring was divided into two distinct types : i. small segments of cambium producing conducting elements of xylem and phloem, and ii. wider segments of cambium giving rise to thick-walled conjunctive tissues centripetally and thin-walled parenchyma centrifugally in Aerva sanguinolenta and thin-walled parenchyma on both xylem and phloem side in Celosia argentea. This variation in cambial behavior resulted in the formation of successive rings of xylem alternating with phloem and axial parenchyma in Aerva sanguinolenta and vascular bundles embedded in ground mass of axial parenchyma in Celosia argentia.

Abstract: A multidisciplinary approach-anatomy, histochemistry and phytochemistry-was used to investigate the leaf structure, the content and the storage location of barbaloin in the leaves of Aloe vera L. var. chinensis (Haw.) Berg. Xeromorphic characteristics including secondary thickened epidermal cell walls, thicker cuticle, ambiguous differentiation of spongy and palisade tissues in the chlorenchyma, and well_developed aquiferous tissue could be seen in the leaves. Several large parenchymatous cells were observed at the phloem pole of the first ring of vascular bundles. The secondary ring of vascular bundles in the leaf base and the stomata, which are surrounded by five cells, have some classification significance in this species. The density of vascular bundles, the content of barbaloin and the intensity of histochemical reaction differed among leaf numbers L1 (annual leaf), L2 (biennial leaf), L3 (triennial leaf) and L4 (quadrennial leaf), and in different parts of the leaf. These three factors were highest in the youngest leaf, L1, and top parts of all the leaves and lowest in the basal parts and the oldest leaf, L4. The density of vascular bundles had a positive correlation to the content of barbaloin. The histochemical results revealed that the small sheath cells that surrounded the bundles might be the location of barbaloin synthesis and the large parenchymatous cells beneath the sheath might be the storage places of this metabolite.

Abstract: A comparative anatomical study was made of the genus Passerina comprising 20 species and four subspecies, most of which are endemic to southern Africa. It showed that anatomical variation is useful in species recognition and classification. Anatomical characters typical of Thymelaeaceae and displayed in Passerina include isobilateral leaves, a papillate cuticular membrane, mucilaginous epidermal cell walls, a parenchymatous bundle sheath and extraxylary sclerenchyma fibres. Vascular bundles of the leaf lack intraxylary phloem. Characters common to Passerina are inverse-dorsiventral and epis- tomatic leaves, inverted palisade parenchyma and an abaxial hvpodermal sclerenchymatous sheath. Orientation of the main vascular bundle in relation to the epidermis and mesophyll allows the recognition of four leaf structural types and ten states, according to which all species can be characterized and grouped. Functionally many anatomical features of the leaf in Passerina are interpreted as adaptations to the Mediterranean climate of the Cape Floristic Region, where most species occur.

Abstract: Anatomical investigation has been made on the stem and root of Sesbania sesban at different stages of growth. Xylem has been found to be the first vascular tissue to differentiate. The root is tetrflrch with four strands of xylem and four strands of phloem. One strand of xylem alternates with one strand of phloem. The epidermis is single layered. Beneath the epidermis there are cortex with some tannin cells. The cambium appears at the basal part of the root and gradually it extends towards the root apex. The phellogen appears in the deeper cortex and produced 8–12 layers of cork cells and 4–6 layers of phelloderm. In the stem, the epidermis is single layered. Beneath the epidermis there are 9–10 layers of cortex with lots of tanniniferous cells. The vascular bundles are of two types, small and large with bundle caps. In the large vascular bundle, the primary phloem consists of a number of sieve elements while in the small bundle there are parenchymatous tissue with or without functional sieve element. The large vascular bundle con tains 5–7 strands of xylem while the small bundle contains 1 or 2. Thli cambium differentiates in between xylem and phloem of the primary structures of the stem. It becomes active and gives rise to secondary phloem and secondary xlyem. The vessels are small and big. The smaller vassels lie in between or among the vessels. Most of the vessels are in pairs. Among the elements of secondary phloem, axial parenchyma has been found to occupy the major area. The periderm develops one after another from deeper cortex.

Abstract: Laccases (EC 1.10.3.2) are blue copper oxidases that are found in a large variety of living organisms including bacteria, fungi, insects and plants 1. , 2. , 3. . To date their role in these organisms has not yet been clearly established. In higher plants, based on their capacity to oxidize monolignols in vitro and localization at the cell wall, laccases are considered candidate enzymes in the ultimate step in lignification. In order to provide functional evidence to support or refute this hypothesis, four lines of antisense poplars, each corresponding to a different gene, were obtained. Although none of the lines exhibited significant differences in either lignin content or composition, one line, lac3AS, is characterized by a two to three-fold increase in soluble phenolics and perturbations in cell adhesion of xylem fibers. The fact that several laccases from Zinnia (8 out of the 9 obtained) are heavily induced at the onset of lignification during the formation of tracheary elements (TEs) further suggest then involvement of laccases in secondary cell wall formation. In order to make a quantitative leap in our understanding of lignification and vascular development, we are currently developing two strategies that will lead to the identification of new genes involved in these plant–specific processes. Firstly, we have constructed a “late xylogenesis” cDNA library by suppression subtractive hybridization (SSH) from differentiating TEs of Zinnia. Approximately 75% of the 800 clones obtained appear to be differentially expressed during TE formation. A limited number of differentially expressed clones were randomly chosen and sequenced. Among them, known molecular markers of late xylogenesis including a cysteine protease and an endonuclease were identified, demonstrating the quality of the library. Massive sequencing and the determination of detailed expression profiles of these cDNAs are now underway. Secondly, we have screened T-DNA tagged Arabidopsis mutants (Versailles collection) for atypical vascular patterns in floral stems. One of these mutants, hca, for high cambial activity, is characterized by the formation of a continuous ring of vascular tissue as opposed to the discrete vascular bundles typically observed in Arabidopsis. The identification of the gene responsible for this phenotype is now underway.

Abstract: Characteristics of photosynthate translocation, partitioning and sugar accumulation were investigated in developing fruit of satsuma mandarin ( Citrus unshiu Marc.). In 14 C tracing experiment, the source leaf next to a sample fruit was exposed to 14 CO 2 under daylight for 1 h, then allowed to stay in ambient air for 5 h, 23 h or 47 h. Peel, vascular bundles and phloem free tissues in the fruit quarter directly aligned with the source leaf were isolated by dissection for chemical and radioactivity analysis. Radioactivity was quantified after separation and extraction of the tissues in boiling 80% ethanol. The following results were obtained. ⑴ Sugar content of the fruit tissues increased with fruit development. In the peel, nearly equal amounts (in mg/g FW) of sucrose, fructose and glucose occurred in the peel and the accumulation patterns of these sugars were quite similar. In other tissues, however, sucrose level was substantially or moderately higher than that of total hexoses (Fig.1). ⑵ Over 50% of the photosynthates transported to fruit was found in juice sac at the primary stage of fruit enlargement, stage of rapid fruit enlargement and fruit coloring. At the full ripe stage, however, the amount of photosynthate obtained by juice sac was about the same as that entering peel, vascular bundle and segment epidermis (Fig.2). ⑶Specific 14 C radioactivity acquired by juice sac markedly decreased with fruit development, especially at the latest stage (Fig.3). ⑷ Specific 14 C radioactivity ratios of vascular bundle to segment epidermis and segment epidermis to juice sac considerably increased with the progress of fruit development, the latter ratio being much higher (Table 1). This result suggests that postphloem assimilate transport was the limiting step in the pathway for assimilate transfer into juice sac. ⑸The fact that a certain percentage of 14 C sugars recovered in juice sacs was sucrose indicates that although photosynthates were partially hydrolyzed during their transfer into juice sac, at least part of photosynthates in the form of sucrose could still enter the juice sacs unchanged (Table 2).

Abstract: The characters of vascular bundle in neck panicle and grain filling of intersubspecific heavy panicle hybrid rice (IHPHR) were studied. The results were as follows: The IHPHR had more vascular bundles, much larger areas of single vascular bundle, much larger areas of all vascular bundles, much larger areas of all phloem and much larger areas of all xylem in neck panicle than intervarietial hybrid rice (IHR), which increased the number of the second branches and the number of grains in second branch and enlarged the panicle of IHPHR. IHPHR had a lower burdened capacity of spikelet number and matter to fill the grains in the conducting tissue than IHR. So, IHPHR had not only larger panicle but also normal grain filling and heavier panicle. IHPHR overcame the main physiological barriers of intersubspecific hybrid rice-large panicle but limited flow of photosynthetic product to the panicle that led to poor grain plumpness. The results also indicated that the breeding of IHPHR was a effective measure for the rice breeding of super high yield.

Abstract: The climatic indexes were calculated at variant elevation accor ding to the method of ecoclimatelogy.The morphological and anatomic leaf characteristics and their main affecting ecological factors of Larix chinensis,which distributes at 3 000～3 400 m in Taibaishan Mountain of Qinling Mountains,was studied by using the method of multivariate statistic.The morphological indexes are leaf thick,leaf number of every leaf brunch,and ratio between length and broad of leaf.The anatomic indexes are cuticle thick,upper epidermis thick,lower epidermis thick,endodermis thick,thick of transfusion tissue and vascular bundle,tracheid diameter,and ratio between thick of transfusion tissue and vascular bundle and leaf thick.The results showed following points.① Baileys index was essential factor that affected the ratio between length and broad of leaf and the epidermis cuticle thick of leaf of Larix chinensis.The ratio between length and broad of leaf tended to increase and the epidermis cuticle thick of leaf gradually getting thinner with the increasing of Baileys index.② The annual precipitation was essential factor affecting other morphological anatomic indexes.With the increasing of annual precipitation,these characteristics tended to be shorter or thinner.They are the leaf number of every brunch leaves,the leaf thick,the trachied diameter,the thick of transfusion tissue and vascular bundle of leaf,the endodermis thick,and the ratio between thick of transfusion tissue and vascular bundle and leaf thick.But the lower and upper epidermis thick of leaf was increasing gradually.③ The thick of mesophyll between lower and upper epidermis and endodermis in leaf middle,which were not obviously related to environmental factors,probably were more conservative character.

Abstract: The results of structural botanical experiment of nutritive organs of Dendrobium candidum show:the leaf is of isobilateral;the stoma is of quadrilataral,only distributes in lower epidermis;there are alternating bigger vieins and smaller ones in the mesophyll;there are many polyhedral or ellipsoidal cells and irregular cells full of particulate matter and a few of slimy cells containing needle crystals in the ground tissue;collateral closed bundles scattered in it;the velamen of underground root consists of 6～7 layers of cells,while the velamen of air root consists of only 4 layers of cells;each of the exodermis,endodermis and pericyle consists of a layer of sclerenchymal cells and parenchymal passage cells;radial vascular bundle of the root is of tenarch there is a big and evident pith in the middle part