Micropropagation of Calluna vulgaris cv. ‘H.E. Beale’

Axillary shoot producing cultures were obtained from microcuttings and shoot tips of Calluna vulgaris cv. H.E. Beale. For cultures derived from microcuttings the highest multiplication rate of 38 shoots (5 mm or longer) was obtained on a reduced salt medium with the addition of 0.5 mgl^-1 2-isopentenyladenine (2iP) during an 8 week subculture. For shoot tip derived cultures 0.2 mgl^-1 6-benzyladenine (BA) was the best cytokinin and led to a multiplication rate of 26 for a 6 week subculture. The addition of 1 g/l casein hydrolysate to a multiplication medium enhanced shoot proliferation in presence of 0.5 mgl^-1 BA.Despite various auxin treatments shoots formed no roots in vitro but rooted readily if transferred to a peat substrate ex vitro. A high rooting percentage (80%) was also obtained with shoots taken from the end of a multiplication phase and rooted directly. An additional subculture on low auxin containing media before transfer to peat substrate is recommended because the shoot condition can be improved in this way. A high number of rooted plantlets was produced, so the methods described will allow mass propagation.     

Micropropagation of Plumbago rosea Linn.

Multiple shoot formation from the medicinal plant Plumbago rosea Linn. was induced on callus from stem segments on Murashige & Skoog media containing auxin and cytokinin. 2,4-D (2.5 mg l^-1) and kinetin (1.5 mg l^-1) added to the media gave best callus production, while BAP (2 mg l^-1) plus NAA (1.0 mg l^-1) induced shoot formation from that callus. Numerous shoots with roots could be produced by transferring shoots to media containing IBA (1.5 mg l^-1). Regenerated plantlets were transferred to pots and 60% survived.     

Tree replacement patterns in subalpine Abies-Betula forests,Wolong Natural Reserve,China

Vegetation in canopy gaps of two old-growth Abies-Betula forest stands, one with bamboo the other without, was measured. The structure of gap vegetation at each site was used to derive tree replacement probabilities. Transition probabilities indicate different tree replacement trends in forests with bamboo compared to those without. Projected compositions show Betula to be the most abundant species in bamboo stands while Abies remains most abundant where bamboo was absent. A dense bamboo sward seems to reduce the probability of Abies filling gaps by inhibiting establishment and growth of seedlings. Bamboo preempts space after canopy gap formation by increasing shoot production which reduces opportunities for establishment and growth of other woody species. Differences in dispersal ability and longevity of Abies and Betula appear to be important factors contributing to their coexistence forests with a small canopy gap disturbance regime.     

Bamboo germplasm screening with nuclear restriction fragment length polymorphisms

Summary Bamboo species are difficult to identify because flowering material is seldom available and taxonomy is of necessity based on vegetative characters. To evaluate the utility of restriction fragment length polymorphism (RFLP) analysis in bamboo systematics and germplasm screening, a library of random genomic probes from a Phyllostachys nigra PstI library was constructed. Probes from the library were used to screen bamboo germplasm consisting mostly of temperate bamboos of the genus Phyllostachys. RFLP variation was abundant, and species-specific patterns were readily obtained. Chloroplast DNA showed little variation among the bamboo accessions analyzed.     

中国小竹鼠生态的初步研究

小竹鼠在我国仅分布于云南西部热带亚热带地区。主要生活于山坡稀树灌丛、阔叶林、橡胶园及居民点附近。在盈江县分布于海拔300-950米地带。取食、休息、繁殖主要在洞道内。洞系由洞口、取食道、趋避道、窝及“厕所”组成。食物主要有棕叶芦、芦竹及三叶橡胶等18种,尤喜食橡胶树主根,因而对橡胶树危害很大。13号标本中雌7雄6。在盈江每胎2-3只,以2只为多。成年小竹鼠过独居生活,雌雄各有自己的洞系。     

The effect of drought on levels of abscisic acid,cytokinins, gibberellins and ethylene in aeroponically-grown sunflower plants

Abscisic acid (ABA), cytokinins and gibberellin-like substances (GAs) were extracted from the roots and shoots of 17-day-old sunflower seedlings which had been droughted or were unstressed. Plants were grown in an aeroponic chamber which allowed for good control over degree of water stress and easy access to roots. Following methanolic extraction of lyophilized material, cytokinins were separated from the acidic growth-regulators on a cellulose PO₄ cationic exchange column. The cytokinins were analysed by paper chromatography and HPLC and the soybean hypocotyl section assay. Semipurified acidic regulators were chromatographed on SiO₂ columns and HPLC and aliquots assayed with the dwarf rice cv. Tan-ginbozu bioassay for GAs. Fractions known to contain ABA were purified by sequential reverse-phase HPLC of the acid and then of the methyl ester forms followed by quantitation as Me-ABA on GLC-EC. ABA losses were measured by using an internal standard [³H]-ABA). Ethylene production was also monitored in stressed and unstressed seedlings.The effect of drought on GAs and ethylene was minimal. The ABA levels were markedly higher in droughted plants. Stressed roots had 32 times more ABA than controls. The levels of cytokinins in the shoots of droughted plants were about half those in unstressed shoots, and qualitative differences occurred in the roots. Under stress a large peak of activity was present similar to zeatin glucoside which was not present in the unstressed condition. The results are discussed in relation to drought-effects on metabolism.     

In vitro regeneration of plantlets in Fagraea fragrans Roxb. — a tropical tree

Different vegetative parts of Fagraea fragrans Roxb., a valuable timber tree of South East Asia, were used as explants in in vitro studies.Nodal segments showed the best growth response as numerous adventitious shoots were regenerated in MS medium supplemented with Benzyl adenine (BA, 8.8 um) and 2,4-dichlorophenoxyacetic acid (2,4-D, 0.5 um). Shoot buds also developed from the leaf and root segments that were subcultured. The detailed process of callus growth and differentiation leading to the formation of whole plantlets is described. Uniform plantlets obtained could be transplanted successfully in soil.     

A simple,rapid protocol for adventitious shoot development from mature cotyledons of glycine max cv bragg

Mature soybean cotyledons (Maturity group VII) were cultured on modified MS containing 0–2.5 μM indole-butyric acid (IBA); 0–10 μM 6-benzylaminopurine (BAP) and 0.7% agar. Embryonic axes of explants were removed prior to culture initiation and cultures were incubated at 24°C with 45–50 μE. s⁻¹.M⁻² of mixed irradiance with 16 h photoperiod. Shoot proliferation occurred at 0–2.5 μM IBA and 5–10 μM BAP, while in the presence of 2.5 μM IBA alone, only roots developed. Abnormal shoots were produced with 2.5 μM IBA and 5–7.5 μM thidiazuron. Adventitious shoot development started 7–14 d after culture initiation in the region where the embryonic axis was previously attached to the cotyledon and shoots were visible within 28 days. The presence of the embryonic axis inhibited shoot morphogenesis. The shoots were rooted on half strength MS inorganic salts plus vitamins, 2% sucrose, 0.5 μM NAA acid or 2.5–5 μM IBA, or 5–10 μM IAA, and 0.7% agar. Rooted plants were acclimatized under a mist in the greenhouse. This simple, rapid,in vitro adventitious shoot development protocol could be adapted for transformation/regeneration studies in soybean. Trade and company names are used in the publication solely to provide specific information. Mention of a trade or company name does not constitute a warranty or an endorsement by the U.S. Department of Agriculture to the exclusion of other products or organizations not mentioned.     

四川王朗自然保护区大熊猫主食竹——缺苞箭竹(Fargesia denudat)不同发育时期酯酶和α-淀粉酶同工酶的研究

通过聚丙烯酰胺凝胶电泳,对生长在亚高山地带的大熊猫主食竹的实生苗、成竹和开花竹中不同发生年龄鞭系,以及同一鞭系内一系列生长年龄竹株作了酯酶、α-淀粉酶同工酶的比较研究。结果表明,同一竹种的不同发生年龄鞭系之间叶酯酶电泳类型存在明显差异,而同一鞭系内α-淀粉酶同工酶的变化表现与竹株生长年龄有关。由此认为,上述同工酶系统可以用作竹类无性系发育分析的生理指标。