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401.
A.J. Rescia M.F. Schmitz P. Martín de Agar C.L. de Pablo J.A. Atauri F.D. Pineda 《植被学杂志》1994,5(4):505-516
Abstract. Changes in land use, particularly the type of forest management, and their spatial pattern, especially woody plant diversity, were related to each other in an area in the Basque region (Spain). The number and diversity of boundaries between landscape patches is related to the development of the spatial complexity of the landscape, C(s), measured in bits and defined as: C(s) = H(b) H(l), where H(b) is the boundary diversity H(1) the spatial heterogeneity generated by these boundaries. As to the vegetation types, changes in land use over the last 50 yr have resulted in a less diversified and more fragmented landscape, especially on a small scale. Forest plantation has become the predominant land use. The frequency of land use changes is studied regarding its influence on the present levels of woody plant diversity. 相似文献
402.
Lourdes Castelblanque Begoña García-Sogo Benito Pineda Vicente Moreno 《Plant Cell, Tissue and Organ Culture》2010,100(1):107-112
A simple and efficient protocol for plant regeneration from protoplasts of the potted plant Kalanchoe blossfeldiana Poelln. is reported. Mesophyll protoplasts were isolated from axenic leaves after a preculture. The enzymatic digestion of
the tissue with a solution containing 0.4% Cellulase Onozuka R-10 and 0.2% Driselase yielded 6.0 × 105 protoplasts per gram fresh weight after density gradient purification. Protoplasts were cultured in the dark at an initial
density of 1 × 105 protoplasts per milliliter in a liquid medium with 320 mM mannitol, 130 mM sucrose, 2.3 μM 2,4-dichlorophenoxy acetic acid
(2,4-D), 5.4 μM 1-naphthaleneacetic acid (NAA) and 2.2 μM 6-benzyladenine (BA). Cell wall regeneration was observed within
4 days of culture and cell division began after 5–7 days. When cultured in a liquid medium with 5.4 μM NAA and 8.9 μM BA,
protoplast-derived colonies proliferated until small visible calli, and adventitious buds appeared after transfer to photoperiod
conditions. Developed shoots were rooted on a solid medium supplemented with 0.6 μM indole-3-acetic acid (IAA) and successfully
established under greenhouse conditions. The process required 4 months from isolation to rooted plants and the best conditions
found gave a plant regeneration efficiency of 6.4 plants per 1 × 105 protoplasts. This is the first protocol reported for plant regeneration from protoplasts for a Crassulaceae family species. 相似文献
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405.
The enzyme p‐hydroxyphenylpyruvate dioxygenase (HPPD) is very important in prenylquinone biosynthesis in all photosynthetic organisms. In this study, we present the functional characterization and expression analysis of HPPD from the unicellular green alga Chlamydomonas reinhardtii P. A. Dang. Recombinant HPPD1 enzyme was purified and characterized. Kinetic analysis revealed a Km of 49 μM for p‐hydroxyphenylpyruvate, similar to other HPPDs. The size of HPPD subunit was estimated as 47 kDa by SDS‐PAGE, in accordance with the predicted molecular size after HPPD1 cDNA sequence. However, native HPPD1 enzyme showed an apparent molecular mass of 188 kDa and a homotetrameric structure, which suggests a reconsideration of the idea that all eukaryotic HPPDs have a homodimeric structure while all prokaryotic HPPDs are homotetramers. Expression analysis by Northern blot revealed that hppd1 expression is strongly up‐regulated by low temperature and poorly regulated by high temperature, darkness, or moderate light changes, suggesting that Chlamydomonas HPPD may play an important role in the synthesis of tocopherols and/or plastoquinones under stress conditions in the physiological context of the adaptation to growth at low temperatures. 相似文献