Gravimorphism in rice and barley: Promotion of leaf elongation by vertical inversion in agravitropically growing plants

We have compared shoot responses of agravitropic rice and barley plants to vertical inversion with those of normal ones. When rice plants were vertically inverted, the main stems of a japonica type of rice, cv. Kamenoo, showed negative gravitropism at nodes 2–15 of both elongated and non-elongated intermodes. However, shoots of lazy line of rice, lazy-Kamenoo, bent gravitropically at nodes 11–15 only elongated internodes but not at nodes 2–10 of non-elongated ones. Thus, shoots of Kamenoo responded gravitropically at all stages of growth, whereas shoots of lazy-Kamenoo did not show gravitropic response before heading. In Kamenoo plants, lengths of both leaf-sheath and leaf-blade were shortened by vertical inversion, but those of the vertically inverted plants of lazy-Kamenoo were significantly longer than the plants in an upright position. When agravitropic and normal plants of barley were vertically inverted, the same results as in rice were obtained; elongation of both leaf-sheath and leaf-blade was inhibited in normal barley plants, Chikurin-Ibaragi No. 1, but significantly stimulated in agravitropic plants ofserpentina barley. These results suggest that vertical inversion of rice and barley plants enhances the elongation growth of leaves in the absence of tropistic response.     

冷杉属植物叶角质层内表面的观察及其系统学意义

在扫描电镜下,比较观察了冷杉属全世界36种2变种的叶角质层内表面的结构特征,根据叶角 质层内表面胞间凸缘特征的显著差异,将冷杉属植物归为4类:(1)直且发达的单凸缘;(2)双凸缘; (3)不发达的单凸缘;(4)弯曲且发达的单凸缘。并发现这四种凸缘类型在冷杉属中的分布格局与该 类植物的地理分布具有相关性。根据所观察的结果和前人的属下分类系统以及化石资料,认为北美西部是现代冷杉属植物的一个多样性中心。     

Exploration of the Effective Location of Surface Oxygen Defects in Graphene‐Based Electrocatalysts for All‐Vanadium Redox‐Flow Batteries

Oxygen functional groups play a key role in vanadium redox reactions. To identify the effective location of oxygen functionalities in graphene‐based nanomaterials, a selectively edge‐functionalized graphene nanoplatelet (E‐GnP) with a crystalline basal plane is produced by a ball‐milling process in the presence of dry ice. For comparison, the reduced graphene oxide (rGO) that contains defects at both edges and in the basal plane is produced by a modified Hummers' method. The location of defects in the graphene‐based nanomaterials significantly affects the electrocatalytic activity towards vanadium redox couples (V²⁺/V³⁺ and VO²⁺/VO₂ ⁺). The improved activity of these nanoplatelets lies in the presence of oxygen defects at the edge sites and higher crystallinity of basal planes than in rGO. This effective location of oxygen defects facilitates fast electron‐transfer and mass‐transport processes.     

The integration of cell proliferation and growth in leaf morphogenesis

A number of recent publications have assessed the outcome on leaf development of targeted manipulation of cell proliferation. The results of these investigations have awakened interest in the long-standing debate in plant biology on the precise role of cell division in morphogenesis. Does cell proliferation drive morphogenesis (cell theory) or is it subservient to a mechanism which acts at the whole organ level to regulate morphogenesis (organismal theory)? In this review, the central role of growth processes (distinct from cell proliferation) in morphogenesis is highlighted and the limitations in our understanding of the basic mechanisms of plant growth control are highlighted. Finally, an attempt is made to demonstrate how sequential local co-ordination of growth might provide an interpretation of some of the recent observations on cell proliferation and leaf morphogenesis.     

Estimation of big sagebrush leaf area index with terrestrial laser scanning

Accurate monitoring and quantification of the structure and function of semiarid ecosystems is necessary to improve carbon and water flux models that help describe how these systems will respond in the future. The leaf area index (LAI, m² m⁻²) is an important indicator of energy, water, and carbon exchange between vegetation and the atmosphere. Remote sensing techniques are frequently used to estimate LAI, and can provide users with scalable measurements of vegetation structure and function. We tested terrestrial laser scanning (TLS) techniques to estimate LAI using structural variables such as height, canopy cover, and volume for 42 Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis Beetle & Young) shrubs across three study sites in the Snake River Plain, Idaho, USA. The TLS-derived variables were regressed against sagebrush LAI estimates calculated using specific leaf area measurements, and compared with point-intercept sampling, a field method of estimating LAI. Canopy cover estimated with the TLS data proved to be a good predictor of LAI (r² = 0.73). Similarly, a convex hull approach to estimate volume of the shrubs from the TLS data also strongly predicted LAI (r² = 0.76), and compared favorably to point-intercept sampling (r² = 0.78), a field-based method used in rangelands. These results, coupled with the relative ease-of-use of TLS, suggest that TLS is a promising tool for measuring LAI at the shrub-level. Further work should examine the structural measures in other similar shrublands that are relevant for upscaling LAI to the plot-level (i.e., hectare) using data from TLS and/or airborne laser scanning and to regional levels using satellite-based remote sensing.     

栽培植物群落组建理论的研究

栽培植物是人工种植的植物。按照集合程度 ,可分为个体、群体和群落三大层次。个体是单个植物体。群体是同类植物个体的集合体。群落是异类植物群体的集合体。在大面积生产上主要种植植物群体。然而 ,在生产条件和生态条件优越的情况下 ,植物群落则具有更大的生产潜力。自从立体农业在我国兴起以来 ,种植业正向着植物群落生产方向发展 ,如何组建高产高效的植物群落已成为一项迫切需要研究的问题。本文总结了 40多年来立体种植研究的理论部分 ,为植物群落生态工程提供科学依据。1　群体组合1 .1　群体组合原则1 .1 .1　形态基本相同　植物个…     

Leaf thickness and UV-B absorbing pigments of plants in relation to an elevational gradient along the Blue Mountains,Jamaica

Terrestrial plant species vary widely in their adaptation to (increasing) solar UV-B radiation. Among the various responses of higher plants to enhanced UV-B are increasing leaf thickness and increasing concentrations of UV-B absorbing compounds. In some (UV-B resistant) plant species increased leaf thickness and UV-B absorbance may form part of mechanisms protecting plants from UV-B damage. However, in UV-B sensitive plant species leaf thickness and UV-B absorbance may increase as well with enhanced UV-B radiation. In the latter case however, this response cannot prevent plant damage and disturbance. In the present field study the relationship between these plant parameters and a natural elevational UV-B gradient on the tropical island of Jamaica was described. Four plant species of the Blue Mountain Tropical Montane Forest, occurring on open forest sites along the roadside and paths were studied along an elevational gradient. Plant species studied are Redbush (Polygonum chinense), Wild ginger (Hedychium gardneranum), John Crow Bush (Bocconia frutescens) and White clover (Trifolium repens). The elevational sites were at 800, 1000, 1200, 1400 and 1600 m above sea level. Leaf thickness was measured of leaves of intact plants around midday in the field. Leaf disks (5 mm) were sampled and extracted with a methanol/HCl mixture. UV-B absorption of these leaf extracts was measured spectrophotometrically. For all species leaves from higher elevations were thicker than those from lower elevations. In addition, the absorption of UV-B of leaf extracts increased with increasing elevations. It is assumed that the calculated gradient of the UV-B_BE from 800 m above sea level: 9.45 kJ m^-2 day^-1 to 9.75 kJ m^-2 day^-1 at 1600 m is related to the measured increase of leaf thickness and UV-B absorbing compounds. The responsiveness of these plant parameters to the elevational gradient does not necessarily imply that the plant species are UV-B resistant. One possibility is that the species studied, which are growing on open, disturbed sites on the forest floor and along mountain-roads, are relatively sensitive to UV-B. In addition to clear sky conditions, mist and clouds occur frequently in this tropical mountane forest at Jamaica. Also, the low nutrient status of the soil (low pH, nutrient deficiency) and the high content of polyphenols in leaves of many plant species of the tropical montane rain forest may relate to the marked response of the species studied with increasing elevation. Abbreviations: asl – above sealevel, UV-B – ultraviolet-B radiation (280–320 nm), TMCF – Tropical Montane Cloud Forest.     

Micromorphology of Leaf Epidermis of Chimonobambusa (Bambusoideae)

Micromorphological characters of leaf epidermis of 27 published species of Chimonobambusa Makino were examined by both light and scanning electron microscopes (Table 1). On the adaxial surface, bulliform cells are of irregular or tetragonal shape and in 2-- 3 rows between veins; stomata rare. On the abaxial surface, intercostal long cells are of thin and sinuous wall; short cells solitary, paired, or 3 to several in a row on veins; silica bodies narrow tall or saddle like; bicellular hairs common, with the basal cell slightly longer than or as long as the distal cell; hooks elliptic and apiculate, common in some species and rare in the others; papillae numerous, those overarching stomata showing different patterns (Plates 1, 2). The examined species exhibit three types of leaf epidermis (Table 2 ): 1, papillae widely spread, 4 rod- like papillae overarching the individual stomata, hooks common, including all the six examined species of Sect. Qiongzhuea and 9 species of Sect. Oreocalamus; 2, papillae around stomata only (with the exception of C. microfloscula), the 4 papillae branched or curved, plus several small ones, forming an arciform cover over the individual stomata, hooks sparse, including 7 species of Sect. Oreocalamus and 1 species of Sect. Chimonobambusa; 3, papillae overarching stomata intermediate between the other two types, with the other characters similar to type 1, including 2 species of Sect. Chimonobambusa and 2 species of Sect. Oreocalamus. The three types more or less correspond to the current classification of the genus based on gross morphology, but since Sect. Oreocalamus showed all the three types and type 3 was somewhat intermediate between the other two, present data support a broad sense of the genus Chimonobambusa, and the three sections proposed by Ohrnberger (1990) are to some extent acceptable. The results support the removing of C. luzhiensis from Sect. Qiongzhuea, but reassignment of C. metuoensis to Sect. Qiongzhuea cannot be confirmed. In addition, the leaf epidermis is of diagnostic value at species level. The data support the inclusion of C. linearifolia in C. angustifolia, but do not support that of C. rivularis in C. lactistriata, nor of C. yunnanensis and C. tuberculata in C. armata (Ohrnberger, 1990). In fact, C. yunnanensis, C. tuberculata and C. lactistriata, in addition to C. hirtinoda, are similar to C. qudrangularis in both leaf and gross morphological characters; so is C. pachystachys to C. utilis, C. neopurpurea to C. marmorea, and maybe C. rigidula to C. szechuanensis. They are possibly sister-species.or even conspecific, respectively. The various specific papillate patterns are characteristic of bamboo taxa, andinvestigation of wider samples will be of great interest in bamboo systematics.     

GC-MS分析甜菊叶的挥发性成分

甜菊(Stevia rebaudianum Bertohi)叶经固相微萃取(SPME)和同时蒸馏萃取(SDE),用气相色谱/质谱法(GC-MS)检测其挥发性成分.从甜菊叶中共检出101种化学物质,其中从SPME萃取物中检出67种,SDE萃取物中检出80种,二者共有组分46种.主要成分为反式-α-香柠檬烯、β-蒎烯、石竹烯氧化物、匙叶桉油烯醇、橙花叔醇等,其主要成分与菊科(Compositac)其他植物的明显不同.     

Spatially Resolved Sulphur K-edge XANES Spectroscopy for in situ Characterization of the Fungus–plant Interaction Puccinia triticina and Wheat Leaves

An innovative application of X‐ray absorption near edge structure (XANES) spectroscopy for the characterization of interactions of biotrophic plant pathogens with their hosts as exemplified by Puccinia triticina colonizing wheat leaves is described. Spatially resolved, synchrotron radiation‐based XANES spectroscopy was used for the detection of changes in sulphur metabolism induced by leaf rust infections. A significant accumulation of sulphate occurred at the site of the sporulating urediniosori of P. triticina. Compared with non‐infected leaf areas, minor changes in the spectra were observed for the non‐visibly colonized tissue neighbouring the rust sori. As the spectra for isolated urediniospores and the healthy leaf areas did not match the spectra of the urediniosori, a significant impact of the biotrophic pathogen on sulphur metabolism of wheat has been demonstrated. Spatially resolved XANES spectroscopy will extend the range of qualitative and quantitative methods for in situ investigations of host–pathogen interactions, thus contributing to enlarge our knowledge about the metabolism of diseased plants.