四川省都江堰龙池地区苔藓植物染色体的研究

报道了四川省都江堰市龙池地区６种苔藓植物配子体的以体研究结果,５种材料均取其生长点或茎尖,观察和计数了细胞有丝分裂中期的染色体数,１．中华扁萼苔（Ｒａｄｕｌｌａｃｈｉｎｅｎｓｉｓ Ｓｔｅｐｈ．ｖａｒ．ｒｏｐｔｕｄｉｓｔｉｐａ）ｎ＝８;２．蛇苔（Ｃｏｎｏｃｅｐｈａｌｕｍ ｃｏｎｉｃｕｍ（Ｌ．）Ｄｕｎ．）＝９;３．长齿匍灯藓（Ｐｌａｇｉｏｍｎｉｕｍ ｄｒｕｍｍｏｎｄｉｉ （Ｂｒｕｃｈ．＆ Ｓｃｈｉｍｐ     

Desiccation and cryopreservation of actively-growing cultured plant cells and protoplasts

Actively-growing cultured cells of Pogonatum and Polytrichum were desiccated and cryopreserved. Although Pogonatum was slightly more tolerant to desiccation, both species were cryopreserved with >90% survival rate. An examination of isolated protoplasts revealed that differences in desiccation tolerance were likely dependent on levels of injury of plasma membranes. Trehalose and sucrose provided some protective effects during protoplast desiccation, but mannitol and glucose were less effective when Pogonatum protoplasts were directly desiccated and preserved at various temperatures. The effectiveness of glucose was enhanced when combined with culture medium components.     

Physiological responses of Pogonatum cirratum subsp. fuscatum living in different habitats to simulated nitrogen deposition

The effects of nitrogen (N) deposition on Pogonatum cirratum (Sw.) Bird. subsp. fuscatum (Mitt.) Hyvoenen, a species of moss widely distributed in South China, were investigated. Plots subjected to a gradient of N treatments were established in 3 habitats with different illumination and humidity conditions. N was sprayed onto plots with NH₄NO₃ solutions, at doses equivalent to 20, 40 and 60 kg N ha^?1, in 4 applications during May 2006 and January 2007. The results suggest that high N deposition affects both carbon (C) and N metabolism of P. cirratum subsp. fuscatum, as well as the interaction between them. On the other hand, the sensitivity of the moss varied according to the humidity and light conditions. Moss in a habitat with high humidity and moderate light was more tolerant to an N deposition increase than moss in a habitat with low humidity and low light, as the latter was extremely sensitive to an increase in N deposition.     

黔西南红土型金矿硬叶小金发藓对几种金属元素的吸收、富集特征

利用原子吸收法测定黔西南红土型金矿硬叶小金发藓(Pogonmon neesii(C.Muell)Dozy)植株及其土壤中的Au、Pb、Cu、、Zn、Ca、Mg、Hg和As等8种金属元素含量,并分析它们之间的相关性及植物对金属的富集能力.结果表明:硬叶小金发藓体内的金属元素含量普遍较高,对不同金属元素的吸收、富集具有较大的差异,Ca-Mg呈极显著正相关,Cu-Zn、Hg-As呈显著正相关.该植物对Hg和As均具有强烈的富集作用.     

Physiological responses of Pogonatum cirratum subsp. fuscatum living in different habitats to simulated nitrogen deposition

The effects of nitrogen (N) deposition on Pogonatum cirratum (Sw.) Bird. subsp. fuscatum (Mitt.) Hyvoenen, a species of moss widely distributed in South China, were investigated. Plots subjected to a gradient of N treatments were established in 3 habitats with different illumination and humidity conditions. N was sprayed onto plots with NH₄NO₃ solutions, at doses equivalent to 20, 40 and 60 kg N ha^?1, in 4 applications during May 2006 and January 2007. The results suggest that high N deposition affects both carbon (C) and N metabolism of P. cirratum subsp. fuscatum, as well as the interaction between them. On the other hand, the sensitivity of the moss varied according to the humidity and light conditions. Moss in a habitat with high humidity and moderate light was more tolerant to an N deposition increase than moss in a habitat with low humidity and low light, as the latter was extremely sensitive to an increase in N deposition.     

Comparative morphological and photosynthetic studies on three Malaysian species of Pogonatum from habitats of varying light irradiances

Abstract

Comparative morphological and physiological studies were carried out on three species of Malaysian Pogonatum collected from habitats exposed to different light intensities ranging from 28±4 W/m² for P. cirratum subsp. macrophyllum (Dozy & Molk.) Hyvönen, to 230±39 W/m² for P. subtortile (Müll.Hal.) A. Jaeger to 751±45 W/m² for P. neesii (Müll.Hal.) Dozy. Total chlorophyll and beta-carotene content were higher in P. cirratum subsp. macrophyllum and P. subtortile than in P. neesii when calculated on a fresh weight basis. However, soluble protein content was higher in the sun species compared to its shade-adapted counterparts, and the soluble protein to total chlorophyll ratio was highest in P. neesii. The chloroplasts in the leaves of P. cirratum subsp. macrophyllum were significantly larger than those in the other two species, and had more grana and thylakoids per chloroplast profile. The numbers of starch grains in P. cirratum subsp. macrophyllum and P. subtortile were more than double that observed in P. neesii. Morphological studies of the leaves showed specific differences in the shapes and heights of the lamellae found on the adaxial surfaces of the leaves. The lamellae of P. cirratum subsp. macrophyllum were rudimentary whilst those of P. subtortile were 2–3 cells high and P. neesii possessed lamellae 5–7 cells high. These findings indicate a direct correlation between the height of the lamellae and the light irradiances received by the plants. Determination of the in vitro Photosystem II photochemical rates, with an oxygen electrode, of chloroplasts isolated from these plants, showed that P. neesii and P. subtortile exhibited higher rates than P. cirratum subsp. macrophyllum. Similarly in vivo light saturation studies with an infrared gas analyzer showed that CO₂ assimilatory rates were highest in P. neesii, even at low light intensities, suggesting a relationship between photosynthesis and light irradiance in these mosses that is different from vascular plants.     

Nuclear and Organelle DNA Replication during Spore Germination in Bryophytes and Equisetum

In contrast to ferns, the spore nuclei of the moss, Funaria hygrometrica, are in the G₂ phase. They do not incorporate the thymidine analogue BUdr before the first mitosis. When spores germinate in the presence of aphidicolin, an inhibitor of the (nuclear) DNA polymerase alpha, they give rise to two-celled, negatively phototropic protonemata, consisting of relatively long and thin cells. Determinations of nuclear DNA content further confirm the presence of G₂-nuclei in Funaria spores. Spores of Pogonatum urnigerum and of Equisetum hyemale likewise contain G₂-nuclei, as shown by BUdr incorporation or experiments with aphidicolin, respectively. In germinating Funaria spores, the organelle DNA is synthesized very early and independent of nuclear DNA. A gradient in replication of organelle DNA is found only in the long tip cells which are formed in the presence of aphidicolin.