SILICON IN THE ROOTS OF HIGHER PLANTS

Silicon (Si) distribution in the roots of Sorghastrum nutans (L.) Nash and Sorghum bicolor (L.) Moench. was investigated by means of the electron-probe microanalyzer and scanning electron microscope. In both species, Si was confined to the inner tangential wall of the tertiary-phase endodermal cells in the form of nodular silica aggregates of similar morphology and X-ray intensity. The results are compared to those for six closely related genera, as well as to studies of Si in the roots of species of other tribes of the family Poaceae. The various types of root deposits occurring in the family are described, and their relationships discussed. It is concluded that the type of Si distribution exhibited is determined largely by the phylogenetic status of the genus, rather than by the basic pattern of root anatomy.     

THE INFECTION OF PLANTS BY VIRUSES THROUGH ROOTS

Roots of young tomato plants became infected when inoculated with tomato bushy stunt, tobacco mosaic, and potato X viruses. Root infections also occurred when these viruses were added to soil or culture solutions in which plants were growing.
The viruses were sometimes localized around their initial entry points in roots; sometimes they invaded the root system but not the shoots, and sometimes they produced full systemic infection of roots and shoots. In some experiments, but not all, systemic infections were more frequent when the upper tap root or superficial roots were inoculated than when fibrous roots were inoculated.
In both tomato and potato, virus X spread from diseased to healthy plants sharing the same culture solution, if their roots were in contact, but not otherwise. Infection of the roots of potato plants by inoculation, produced only one plant with virus-infected haulms, although several had infected tubers.     

罗汉果皂甙的含量测定

从罗汉果中提取强甜味剂罗汉果皂甙,并进行了初步分离,以香草醛－高氯酸比色法测定了大中小三种罗汉果中总皂甙的含量,经方差分析,大、中罗汉果总皂甙含量无显著差异,而小果皂甙含量大于中、小中果,提取单位皂甙所需原材料价格以小果为低。若将其作为甜味剂开发使用,以小果最为经济。为开发利用商品性差、价格低的小果,提供了实验研究依据和开发利用途径。     

THE ROLE OF ROOTS IN THE NUTRITION OF AQUATIC VASCULAR PLANTS

Rooted stems of three aquatic species were cultured in a two-compartment apparatus which allowed the upper and lower portions of the stem to be kept in different nutrient solutions. P³² was supplied to either the upper or lower compartment. At the end of a 10-day growth period, the specific activity of phosphate was determined in axillary shoots which developed during the course of the experiment from buds in the upper compartment. The results indicated that most of the phosphate in these shoots was not absorbed from the ambient medium but was derived from the rooted stem base in the lower compartment (over 90 % in Myriophyllum brasiliense, 59 % in M. spicatum, and 74 % in Elodea densa). These results give a very different but probably more accurate picture of phosphate absorption in rooted aquatic vascular plants than short-term experiments, in which phosphate is readily taken up from the ambient medium by leaves of M. spicatum and E. densa. In M. brasiliense the amount of phosphate translocated is related to the mass of roots present. Evidence is presented that normal growth of axillary shoots occurs even when all mineral ions have to be obtained by translocation from the lower compartment.     

UPTAKE AND TRANSLOCATION OF TI FROM NANOPARTICLES IN CROPS AND WETLAND PLANTS

Bioavailability of engineered metal nanoparticles affects uptake in plants, impacts on ecosystems, and phytoremediation. We studied uptake and translocation of Ti in plants when the main source of this metal was TiO₂ nanoparticles. Two crops (Phaseolus vulgaris (bean) and Triticum aestivum (wheat)), a wetland species (Rumex crispus, curly dock), and the floating aquatic plant (Elodea canadensis, Canadian waterweed), were grown in nutrient solutions with TiO₂ nanoparticles (0, 6, 18 mmol Ti L^?1 for P. vulgaris, T. aestivum, and R. crispus; and 0 and 12 mmol Ti L^?1 for E. canadensis). Also examined in E. canadensis was the influence of TiO₂ nanoparticles upon the uptake of Fe, Mn, and Mg, and the influence of P on Ti uptake. For the rooted plants, exposure to TiO₂ nanoparticles did not affect biomass production, but significantly increased root Ti sorption and uptake. R. crispus showed translocation of Ti into the shoots. E. canadensis also showed significant uptake of Ti, P in the nutrient solution significantly decreased Ti uptake, and the uptake patterns of Mn and Mg were altered. Ti from nano-Ti was bioavailable to plants, thus showing the potential for cycling in ecosystems and for phytoremediation, particularly where water is the main carrier.     

三七环二肽成分

从三七(Panax notoginseng)的根中分离得到14个环二肽成分,通过波谱解析其结构分别鉴定为环-(亮氨酸-苏氨酸)(1)、环-(亮氨酸-异亮氨酸)(2)、环-(亮氨酸-缬氨酸)(3)、环-(异亮氨酸-缬氨酸)(4)、环-(亮氨酸-丝氨酸)(5)、环-(亮氨酸-酪氨酸)(6)、环-(缬氨酸-脯氨酸)(7)、环-(丙氨酸-脯氨酸)(8)、环-(苯丙氨酸-酪氨酸)(9)、环-(苯丙氨酸-丙氨酸)(10)、环-(苯丙氨酸-缬氨酸)(11)、环-(亮氨酸-丙氨酸)(12)、环-(异亮氨酸-丙氨酸)(13)、环-(缬氨酸-丙氨酸)(14)。其中化合物1为新化合物,化合物4～10为新天然化合物,化合物2～3、11～14为已知化合物;化合物2和11、3和4、12和13分别为一对混合物,比例分别为2：1、1：1和2：1。     

西归的化学成分研究

从云南特产菜蔬西归(伞形科植物西藏凹乳芹Vicatia thibetica de Boiss．的根)中分离鉴定了8个化合物,分别为伞形花内酯(umbelliferone,1),佛手柑内酯(bergapten,2),阿魏酸(ferulic acid,3),芹菜素(apigenin,4),β-谷甾醇(psitosterol,5),胡萝卜甙(daumsterol,6),d-甘露醇(d-mannitol,7),蔗糖(sucrose,8),这8个化合物均为首次从该植物中分离得到。     

藏药迷果芹根中的化学成分

从藏药迷果芹(Sphallerocarpus gracilis)的根中首次分离到6个化合物,经MS,NMR等光谱技术鉴定,结合化学反应,确定了其结构分别为xanthalin(1),3-O-angeoylhamaudol(2),isoimperatorin(3),aviprin(4),4′-O-β-D-glucopyranosy-5-O-methylvisamminol(5)和daucosterol(6)。     

西洋参根中人参黄酮苷的分离鉴定

利用大孔吸附树脂柱及葡聚糖凝胶C 2 5柱层析 ,首次从西洋参根中分离并鉴定出黄酮类成分———人参黄酮苷 ,并对其进行了结构鉴定。为人参与西洋参的鉴别提供了又一成分区别点     

臭瓜根的化学成分

自臭瓜(Cucurbila foetidissima Hbk)根的石油醚、乙酸乙酯提取物,分离鉴定了六个化合物,葫芦素B(cucurbitacin B)Ⅰ、拜俄尼酸(bryonolic acid)Ⅱ、22氢化Δ~(7(8))菠甾醇(22-dihydro-spinasterol, 24α-ethyl-5α-cholesta-7-en-3β-ol)Ⅲa、菠甾醇(24α-ethyl-5α-cholesta-7,trans-22-dien-3β-ol)Ⅲb、22氢化Δ~(7(8))菠甾醇葡萄糖甙(22-dihydrospinasterol, 24α-ethyl-5α-cholesta-7-en-3-O-β-D-glucoside)Ⅳa、菠甾醇葡萄糖甙(24α-ethyl-5α-cholesta-7,trans-22-dien-3-O-β-D-glucoside)Ⅳb。