The effect of in planta TIBA and proline treatment on somatic embryogenesis of sugar beet (Beta vulgaris L.)

The effect of in planta TIBA and L-proline onin vitro seedlings and cell culture of sugar beet was investigated. Sterilized seeds were grownin vitro on 1/2 MS medium supplemented with 0 or3 mg/l TIBA. Calli obtained on young leaves cultured on MS medium containing 1 mg/l BAP, were used for the initiation of cell suspension cultures using MS basal composition supplemented with 0 or 50 mM proline. Aliquots of 1 ml from cell suspension culture were inoculated onto the first somatic embryo induction MS medium containing TIBA 0.5 mg/l, BAP 1.0 mg/l, and proline at 0 or 50 mM. After three weeks of culture, embryogenic calli were transferred to the second embryo induction medium supplemented with NAA and BAP at 0.2 and 0.5 mg/l, respectively. The frequency of somatic embryos of calli obtained from in plantaTIBA together with proline treatments on average was20 which was higher than that of the other treatments. This revised version was published online in July 2006 with corrections to the Cover Date.     

Response of Rice (Oryza sativa L.) Tillering to Sub-ambient Levels of Ultraviolet-B Radiation

The negative impact of enhanced ultraviolet‐B (UV‐B) radiation has been demonstrated for rice, but few studies have examined the effects of low UV‐B radiation on rice growth and physiology. The objective of this study was to determine the effects of low UV‐B radiation on rice physiology with special emphasis on tiller initiation and development in two popular US rice cultivars, ‘Cocodrie’ and ‘Clearfield 161 (CL161)’. Plants received no natural UV‐B radiation because of the UV‐absorption characteristics of the greenhouse glass, hence UV‐B was artificially supplied by supplemental UV‐B lighting. Plants were grown in soil collected from research plots, and were exposed to UV‐B radiation of 0, 4 (sub‐ambient) or 8 kJ m⁻² day⁻¹ (ambient) for 29 days in one experiment and 87 days in a second experiment. ‘Cocodrie’ had no differential response among 0, 4 and 8 kJ m⁻² day⁻¹ UV‐B treatments for all the parameters measured except for plant height, which showed 5% decrease at ambient UV‐B conditions. For ‘CL161’ sub‐ambient UV‐B radiation exposure decreased vegetative tiller production (25%) and total panicle dry weight (15%). The decrease in tiller production was not due to a decrease in carbohydrate content or increase in auxin content under the low UV‐B radiation.     

不同脱萼剂对库尔勒香梨石细胞、木质素及其关键合成酶的影响

为了揭示使用脱萼剂和植物三碘苯甲酸(TIBA)对果实石细胞的影响,以库尔勒香梨为试材,采用间苯三酚染色法研究石细胞变化情况,同时测定果实石细胞含量、木质素含量及其关键合成酶活性。结果表明:经脱萼剂与TIBA处理的库尔勒香梨果实脱萼率均提高,且脱萼剂效果更加明显,但在盛花后110 d脱萼剂与TIBA处理的石细胞含量均高于对照,且在果实成熟期即盛花后145 d均显著高于对照,TIBA处理的石细胞含量始终高于脱萼剂处理。综上,脱萼剂与TIBA处理虽可使果实脱萼率增加,但同时造成果实的石细胞含量增加,影响果实口感,综合考虑推荐在生产中使用脱萼剂更有利于保证库尔勒香梨果实品质。     

Micropropagation of orchids: A review on the potential of different explants

Orchids are among the most diverse of the flowering plant families, with over 800 described genera and 25,000 species. Orchids are prized for their beautiful long lasting flowers exhibiting an incredible range of diversity in size, shape and colour. Today growing orchids is more than just a hobby, it is an international business covering around 8% of the world floriculture trade and has the potential to alter the economic landscape of a country. Large-scale multiplication of exquisite and rare hybrids using tissue culture techniques has helped orchids occupy a position as one of the top ten cut flowers. As orchids are outbreeders, their propagation using seeds leads to the production of heterozygous plants. Hence, protocols providing regeneration from various vegetative parts of the plants are needed. Though orchid micropropagation has shown spectacular development in the recent years, the wide spread use of micropropagation is believed to be still limited due to problems like exudation of phenolics from explants, transplantation to field, somaclonal variation etc. We endeavour to include the major investigations on explant-based orchid tissue culture starting from the pioneering works of Rotor [Rotor, G., 1949. A method of vegetative propagation of Phalaenopsis species and hybrids. Am. Orchid Soc. Bull. 18, 738–739] followed by Morel [Morel, G., 1960. Producing virus-free cymbidiums. Am. Orchid Soc. Bull. 29, 495–497] and Wimber [Wimber, D.E., 1963. Clonal multiplication of cymbidiums through tissue culture of the shoot meristem. Am. Orchid Soc. Bull. 32, 105–107] to date.     

生长抑制剂对大叶黄杨形态及光合作用的影响

目的]探究抑制剂对大叶黄杨生长的抑制作用以及对其叶片形态和光合作用的影响,为灌木绿篱的化学修剪提供技术指导。[方法]在北京林业大学林场苗圃采用3种生长抑制剂(多效唑(PP_(333))、三碘苯甲酸(TIBA)以及脱落酸(ABA))对密植成绿篱状的1年生大叶黄杨扦插苗进行叶面喷施,对其生长、叶片形态及光合作用等指标进行测定。[结果]3种抑制剂均有矮化植株、抑制新梢生长的作用,矮化效果最佳、抑制作用最强的为PP_(333),且高浓度PP_(333)对于高生长的抑制作用持效性较长。叶宽、叶厚以及叶面积在短期PP_(333)处理下高于对照。PP_(333)能提高大叶黄杨净光合速率,主要通过增加叶厚、气孔导度、叶肉导度及叶绿素含量来实现,并且PP_(333)使蒸腾速率提高的同时降低了水分利用效率。TIBA有显著减小叶长、叶宽的作用,但能使叶厚增加,且随浓度的增加作用效果增强,主要通过减小叶面积,降低叶肉导度、气孔导度、胞间CO_2浓度及叶绿素含量来降低净光合速率。ABA能增加叶面积(10 mg·L~(-1)处理除外)、叶长以及减小叶片厚度,通过抑制气孔导度、叶肉导度、叶绿素含量降低净光合速率。TI-BA及ABA均通过降低蒸腾速率,使水分利用效率提高。[结论]3种抑制剂均有矮化植株、抑制新梢生长的作用,并且影响叶片发育,进而影响叶片光合作用,且800 mg·L~(-1)的多效唑对大叶黄杨具有较好的正向作用。