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.

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.

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.