Litchi trees (Litchi chinensis cv. nuomoci) were sprayed with 0.5mg/l (T1), 0.75mg/l (T2), 1.0mg/l (T3) of brassinolide and withwater (CK) as the control group before anthesis. The enzyme activities of pectin methyesterase (PME), polygalacturonase (PG), cellulase (CX) and the content of water-soluble pectin, protopectin and calcium in the fruit pericarp were studied in order to investigate the effect of brassinolide on litchi pericarp during its development. Content of water-soluble pectin remained at a higher concentration during early stages of development of treated fruit compared to control fruit. Protopectin content increased during fruit development and reached a peak after 58 days of anthesis. PME and PG activities both increased and showed the same trend under T1, T2 and T3 as the concentrations of pectin and protopectin. Calcium concentration of fruit pericarp was higher in treated fruit than control fruit and showed significant dosage response. CX activity was inhibited by brassinolide treatment. The brassinolide reduced fruit cracking compared to the control. The results showed that brassinolide sprayed before anthesis may play an important role in increasing the commercial value of litchi fruits.

In order to determine the response of pollen to UV-B irradiation and cumulative effects of UV-B exposure time on pollen germination and tube growth, 19 taxa of higher plants were investigated in vitro concerning the exposure of pollen grains to two levels of enhanced ultraviolet-B (UV-BBE) (280-320nm, 350 and 500mW:m2 biologically effective UV-B radiation) simulating 8 and 21% stratospheric ozone depletion in Lanzhou, China (36.04°N, 1550 m) and to no UV-B (control group). Compared with the control, enhanced UV-B radiation significantly inhibited pollen germination and tube growth in most species. Higher UV-B flux rate caused a greater inhibitory effect than lower UV-B radiation level. Several taxa exhibited insensitivity of pollen germination and tube growth to UV-B and were even stimulated by UV-B. Reduction in pollen germination rates and tube growth increased with longer exposure time and this indicated a cumulative effect of UV-B radiation. It is concluded that changes in pollen susceptibility to UV-B would lead to severe ecological consequences under natural conditions.

Two Chinese cultivars of Glycine max, namely Heidou and Jindou, were exposed to ambient and supplemental levels of ultraviolet-B (UV-B) radiation simulating a 24% depletion in stratospheric ozone over a 9-week growing period at an outdoor experimental site. Enhanced UV-B irradiation significantly reduced leaf, stem and root biomass, and plant height in the Heidou cultivar. These changes were associated with a diminished photosynthetic (net CO2) rate, stomatal conductance, transpiration rate and water use efficiency, and accompanied by decreased foliar chlorophyll a and b, and total carotenoid concentrations and elevated foliar flavonoid levels. In contrast, the Jindou cultivar displayed only a significantly reduced stem mass and stomatal conductance, but no changes in pigment composition under elevated UVB. The greater tolerance of elevated UV-B exposures by the Jindou cultivar was attributed partly to its higher foliar flavonoid content, smaller leaf size, thicker leaf cuticle and scabrous (hairy) lamina. Nevertheless both the Heidou cultivar and the less UV-B sensitive Jindou cultivar displayed an altered carbon isotope composition (d13C) in their tissues following exposure to elevated UV-B. Such carbon isotope composition changes in plant tissues suggested a means of early detection of photosynthetic disruption in plants with anticipated increase in UV-B due to stratospheric ozone depletion.

A psychrotolerant bacterium, designated strain Tibet-IIU11T, was isolated from the Qinghai-Tibet Plateau permafrost region, China. A taxonomic study was conducted using a polyphasic approach, with determination of physiological and biochemical properties and phylogenetic analysis based on 16S rRNA gene sequences. The novel isolate was found to belong to the genus Hymenobacter and was distinct from the recognized species of this genus. The major fatty acids were iso-C15: 0 (24.5%), summed feature 3 (C16: 1v7c and/or iso C15: 0 2-OH; 20.0%), summed feature 4 (iso-C17: 1 I and/or anteiso-C17: 1 B; 14.0%), C16: 1v5c (12.7%) and anteiso-C15: 0 (8.4%). Phosphatidylethanolamine and an unknown aminophospholipid were predominant in the polar lipid profile. The quinone system consisted exclusively of menaquinone MK-7 and sym-homospermidine was the major polyamine present. These chemotaxonomic traits are in good agreement with the characteristics of the genus Hymenobacter. The assignment of the novel isolate to this genus was further supported by a DNA G+C content of 60 mol%. On the basis of the polyphasic evidence presented in this study, it is proposed that strain Tibet-IIU11T (5DSM 18569T5CGMCC 1.6365T) represents a novel species, Hymenobacter psychrotolerans sp. nov.

The seeds of Limonium aureum (L.) Hill. were dried from 8.92% to 2.88% moisture content in a desiccating container with silica gel. After ultra-drying the seeds were accelerated aged (50℃, 1 month), and some physiological indices, including the electrical conductivity, dehydrogenase activity, superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), ascorbate peroxidase (APX), catalase (CAT), volatile aldehydes and malondialdehyde (MDA) were tested. The results indicated that dehydrogenase, POD, SOD, GR, APX and CAT activities of the ultra-dry seeds were higher than the control seeds, while volatile aldehydes and malondialdehyde were lower than the control group. The results suggest that ultra-drying is beneficial for maintaining the vigor of L. aureum seeds at a high level. Thus, L. aureum seeds could be stored under ultra-dry conditions.

The stomatal characteristics, length and dry weight as well as stable carbon isotope composition (d13C) of needles and tree rings of Qinghai spruce (Picea crassifolia) at different altitudes in the Qilian mountains were investigated. The results showed that stomatal density, distribution pattern on epidermis, and length and dry weight of needles all increased with altitude below 3,000m. In contrast, these parameters all decreased with increasing altitude above 3,000m. Furthermore an assay of tree rings showed that near 3,000m in altitude was the optimum zone for growth and development of Qinghai spruce. Although atmospheric CO2 concentration influences stomatal density, the effects of many environmental factors, such as temperature, light and rainfall, could obscure the effects of changes in atmospheric CO2 concentration on stomatal density at altitudes higher than the optimum for growth. The correlation of stomatal density with atmospheric CO2 concentration and d13C of Qinghai spruce needles was significant below 3,000m, but was insignificant above 3,000m altitude. The d13C value of needles, however, was negatively correlated with atmospheric CO2 concentrations. Therefore, the influence of altitude should be considered in research on plant physiological ecology and the relationship of stomatal density with d13C value or atmospheric CO2 concentration.

The roles of reactive oxygen species (ROS) and nitric oxide (NO) in ethylene synthesis induced by UV-B radiation (280-320 nm) in Maize (Zea mays L. Yuyu No. 22) seedlings were investigated. UV-B radiation resulted in the increase in ROS, NO and ethylene production. Repression of the UV-B-induced ethylene by inhibitors of ethylene synthesis did not affect the accumulation of UV-B-induced O2·−, H2O2 and NOS. In contrast, scavenging UV-B-induced O2·−, H2O2 and NO production resulted in the repression of UV-B-induced ethylene. Furthermore, exogenous O2·− and NO promoted the UV-B-induced ethylene accumulation. The results indicated that ROS and NO played an important role in UV-B-induced ethylene synthesis in maize seedlings. Experiments with related inhibitors suggested that NO was riginated from NOS, not from NR, and ROS was not from NADPH oxidase. A synergistic effect in promoting the accumulation of UV-B-induced ethylene between NO and ROS (mainly O2·−) was found.

The properties of microsomal membranes in spring wheat leaves (Triticum aestivum L. cv. Ganlong No.92-005) exposed to (0) control, 22 21 8.64 (T) and 11.2kJ m day (T) biologically effective UV-B irradiation (UV-B ) were studied under greenhouse conditions. These 1 2 BE irradiance levels correspond to a decrease in the stratospheric ozone of ø12.5 and 20%, respectively, for a clear solstice day at Lanzhou (36.048N, 1550 m), China. Compared with controls, the content of malondialdehyde (MDA) increased by 70.8% in T and 83.8% in Ton 1 2 the 7th day of the radiation, and the IUFA (index of unsaturated fatty acids) decreased, indicating peroxidation of lipid acids. Simultaneously, a drastic decrease of phospholipid content after 21 days and an increase of membrane lipid microviscosity on UV-B irradiation were also found, suggesting a reduction in the fluidity of membrane lipids. Ethylene emission by the microsomal membrane, in the presence of exogenous 1-aminocyclopropane-1-carboxylic acid was higher in the wheat seedlings after 7, 14 and 21 days' irradiation 21 than in the controls. These changes were correlated with a rise in lipoxygenase activity. Membrane-bound enzymes (Ca-ATPase and 21 Mg-ATPase) were promoted by UV radiation in the first 7 days and significantly decreased after 14 and 21 days' treatment in comparison to control. Our results suggest that UV-B radiation may cause changes in structural complexity and function of microsomal membranes in spring wheat leaves.

Ammopiptanthus mongolicus (Maxim.ex Kom.) Cheng f., an ancient relic of the Tertiary Period, is a rare and endangered species of Fabaceae in Mid-Asia desert and has been listed as one of primary protection plants by the Chinese government. Because of its high value of study and ecological usefulness in defending desert, this plant has been called 'live fossil'. Using the leaves of A. mongolicus derived from water-stressed and water-supplemented environments at Shapotou in the south-east edge of Tengger Desert, seasonal changes of caloric values and osmotica, including free amino acids, total soluble sugar (TSS), sucrose, glucose and inorganic cations have been studied in this paper. The results showed that the main substances involved in osmotic adjustment varied with growth periods and between samples. At the early period it was soluble sugar mainly, and at the late period, besides soluble sugar, potassium and free amino acid (especially proline) also functioned. The higher levels of osmotica content (especially concentrations of total soluble sugar, sucrose, proline and potassium) and caloric values have been found in water-stressed plants rather than in irrigated ones.

The effects of ultraviolet-B (UV-B) radiation on stem elongation growth, xyloglucan-degrading activity, the rate of nitric oxide (NO) release and nitric oxide synthase (NOS) activity were evaluated in stems of pea (Pisum sativum L.) seedlings during a 5 days growth period. UV-B radiation significantly induced NOS activity and promoted NO release subsequently inhibited xyloglucan-egrading activity which led to the inhibition of pea stems elongation. Similarly, exogenous NO donation to the rhizospheric zone of pea seedlings imitated the responses of stems to UV-B radiation. NOS inhibitor (LNNA) and NO scavenger (PTIO) had the opposite responses to UV-B radiation: decrease NO release, increase xyloglucan-degrading activity and stems elongation. The results indicated that reduction of stems length caused by UV-B radiation was possibly achieved through modification of the mechanical properties of cell wall polysaccharides, which was probably mediated by the change of xyloglucan-degrading activities in cell walls and NO might be as a signal regulating the xyloglucan-degrading activities in cell walls. In addition, the difference of NOS origin between graminaceous plants and dicots was discussed.