Transformation of<Emphasis Type="Italic"> Kalanchoe blossfeldiana</Emphasis> with <Emphasis Type="Italic">rol-</Emphasis>genes is useful in molecular breeding towards compact growth

Dwarf genotypes of the economically important flowering potted plant Kalanchoe blossfeldiana were developed by molecular breeding. Root inducing (Ri)-lines were regenerated by applying CPPU to the hairy roots, which were produced by inoculating leaf explants with a wild-type Agrobacterium rhizogenes strain ATCC15834. Amplification by polymerase chain reaction (PCR) and Southern blot analysis confirmed the presence of T-DNA in the Ri-lines. Six Ri-lines were characterised in a greenhouse trial revealing that several morphological traits changed with respect to ornamental value such as plant height, number of lateral shoots, leaf size, leaf number, flower size and number of flowers. The Ri-lines differed in their degree of Ri-phenotype, and the internodes of the Ri-lines were clearly shorter, giving a compact growth habit compared to control plants. Time to anthesis was the same in Ri-line 331 as in control plants and delayed by only 3 days in Ri-line 306 as compared to control plants. A compact plant without delayed flowering can be assumed to be valuable for further breeding.     

3种入侵植物叶片挥发物对旱稻幼苗根的影响

入侵植物通过化感作用对入侵地的生态系统构成了严重的威胁,影响了入侵域农作物的生产。采用石蜡切片技术,利用光学显微镜进行观察,研究了不同质量浓度的黄顶菊、三叶鬼针草、胜红蓟3种入侵植物的叶片挥发物对旱稻幼苗初生根的结构以及根系发育的影响,结果表明:低质量浓度(5g)的三叶鬼针草和胜红蓟叶片挥发物对根皮层起抑制作用,低质量浓度(5g)的三叶鬼针草挥发物对维管柱有促进作用,而黄顶菊挥发物对髓腔影响比较大,表现为低浓度抑制,高浓度促进;20g质量浓度的三种入侵植物叶片挥发物对旱稻幼苗初生根结构影响最大,均出现结构上的变异;对侧根的发育随浓度的增加而呈现明显的抑制作用,20g质量浓度时没有侧根的发生。表明入侵植物对受体植物根结构的影响随植物种类和挥发物浓度的不同而有不同的特点。     

根施甜菜碱对镍胁迫下小麦幼苗生长生理的影响

以普通小麦品种‘轮选988’为材料,采用溶液培养法,研究了根施不同浓度甜菜碱(1.0、2.0、3.0、4.0、5.0、10.0、15.0、20.0mmol·L~(-1))对镍(100μmol·L~(-1) NiSO_4)胁迫下小麦根系生长的影响,以及4.0mmol·L~(-1)甜菜碱处理镍胁迫幼苗根系相关抗逆生理生化指标的变化。结果表明:(1)与不施加镍对照相比,镍胁迫下小麦幼苗的根长、株高、鲜重和干重分别显著降低了14.7%、11.7%、15.0%和16.7%。(2)与单独镍胁迫处理相比,小麦幼苗的根长、株高、鲜重和干重均随着根施甜菜碱的浓度逐渐增加且呈先升后降的趋势,并以4.0mmol·L~(-1)外源甜菜碱处理效果较佳。(3)与单独镍胁迫处理相比较,在4.0mmol·L~(-1)外源甜菜碱处理下,小麦幼苗根系超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性分别升高了284.7%、40.3%、82.9%和20.4%,超氧阴离子自由基(O-·2)含量、过氧化氢(H_2O_2)含量和丙二醛(MDA)含量分别显著降低了50.6%、38.4%和40.6%,可溶性糖含量及游离脯氨酸(Pro)含量分别显著降低了19.2%、45.4%,而根系活力大幅上升了358.0%。研究认为,根施适宜浓度外源甜菜碱可显著增强小麦幼苗根系的抗氧化能力,恢复根系活力,从而有效减弱镍胁迫对小麦幼苗生长的伤害。     

INFLUENCE OF DIFFERENT SALT MARSH PLANTS ON HYDROCARBON DEGRADING MICROORGANISMS ABUNDANCE THROUGHOUT A PHENOLOGICAL CYCLE

The influence of Juncus maritimus, Phragmites australis, and Triglochin striata on hydrocarbon degrading microorganisms (HD) in Lima River estuary (NW Portugal) was investigated through a year-long plant life cycle. Sediments un-colonized and colonized (rhizosediments) by those salt marsh plants were sampled for HD, total cell counts (TCC), and total petroleum hydrocarbons (TPHs) assessment. Generally, TCC seemed to be markedly thriving by the presence of roots, but without significant (p > 0.05) differences among rhizosediments. Nevertheless, plants seemed to have a distinct influence on HD abundance, particularly during the flowering season, with higher HD abundance in the rhizosediments of the fibrous roots plants (J. maritimus <P. australis <T. striata). Our data suggest that different plants have distinct influence on the dynamics of HD populations within its own rhizosphere, particularly during the flowering season, suggesting a period of higher rhizoremediation activity. Additionally, during the vegetative period, plants with fibrous and dense root system tend to retain hydrocarbons around their belowground tissues more efficiently than plants with adventitious root system. Overall results indicate that fibrous root plants have a higher potential to promote hydrocarbons degradation, and that seasonality should be taken into account when designing long-term rhizoremediation strategies in estuarine areas.     

Mercury in Plants from Fields Surrounding a Contaminated Channel of Ria de Aveiro,Portugal

Samples of plants and soil were collected in March and June 1995 at 12 sites in fields surrounding the Estarreja Channel (Ria de Aveiro), where the mercury-rich effluent of a chlor-alkali plant has been discharged since the 1950s. Mercury concentrations in soil ranged from 0.64 to 182 μ g g^?1. The highest values were attributed to soil contaminated with sediments dredged from the Estarreja Channel. Plant roots contained between 0.03 and 3.2 μ g g^?1 of total mercury, and there is evidence that root systems uptake mercury from the soil. The linear relationship between mercury concentrations in the roots of Holcus lanatus and in soil over a wide range of mercury concentrations suggests that mercury uptake depends on the element's concentration in the soil. The ratio root:soil concentrations for the analyzed plants varied between 0.003 and 0.199, indicating varying mercury uptake by the root systems. Levels of mercury in the aerial parts of plants showed no clear relationship with the values found in soil or in roots, presumably being influenced mostly by the atmospheric deposition of airborne particles or absorption of atmospheric mercury.     

Rhizosecretion of recombinant proteins from plant hairy roots

Rhizosecretion of a target protein in the hydroponic medium provides an alternative manufacturing platform that simplifies the downstream purification procedure and increases protein yield. In order to increase the production rates of rhizosecreted proteins, we have exploited the ability of Agrobacterium rhizogenes to induce the formation of large amounts of root tissue on transgenic tobacco plants engineered to secrete a model recombinant protein, human secreted alkaline phosphatase (SEAP). The secretion of SEAP from hairy roots induced on the stems of transgenic tobacco plants was 5–7 times higher than that from adventitious transgenic roots.Abbreviations mRNA Messenger RNA - Ri Root-inducing - SEAP Secreted alkaline phosphataseCommunicated by W. Harwood     

Formation of cluster roots and mycorrhizal status of Comptonia peregrina and Myrica pensylvanica in Maine, USA

Extent of cluster (proteoid) root formation in the field was examined in relation to availability of P and successional status of the site in two actinorhizal, N₂-fixing shrubs. Comptonia peregrina (L.) Coult. and Myrica pensylvanica Loisel. In C. peregrina cluster roots were present at all 13 sites and comprised between 0.2 and 19% of total fine root dry weight. Cluster root formation was most extensive at recently disturbed sites and was negatively correlated with cover of associated woody species (r =−0.85), litter depth (r =−0.81) and available (extractable) soil P (r =−0.75). In M. pensylvanica cluster roots were present at all 11 sites and comprised between 6 and 20% of total fine root dry weight. On mineral soils (n = 6), extent of cluster root formation was negatively correlated (r =−0.86) with cover of associated woody species and with litter depth (r =−0.78; P = 0.07). Comptonia peregrina and M. pensylvanica lack functional mycorrhizae at these sites because only intracellular infections were found and these lacked arbuscules. None of 22 non-N₂-fixing, dominant woody species associated with C. peregrina and M. pensylvanica formed cluster roots. Cluster roots probably allow C. peregrina and M. pensylvanica to obtain sufficient P from nutrient-poor soils in the absence of functional mycorrhizae. Extensive cluster root formation on disturbed, early successional sites may aid these species in colonizing these sites because they have to form only one symbiosis (with Frankia ) and not two (with Frankia and a mycorrhizal fungus).     

甲醛胁迫下四种盆栽植物的生理动态反应

选择巢蕨(Neottopteris nidus)、巴西铁(Dralaena fragrans)、虎尾兰(Sansevieria trifasciata)和黑美人(Aglaonema commutatum)4种室内盆栽植物作为典型的试验材料,以15 mg·m-33甲醛分别进行熏蒸处理,测定单位干物质甲醛的吸收量、相对电导率、丙二醛含量和叶绿素含量等,以研究这些植物在甲醛胁迫下的生理动态反应。结果表明:在甲醛胁迫的4 d时间内,巢蕨和巴西铁的单位干物质甲醛吸收量均在第3天达到峰值,而黑美人和虎尾兰则一直在缓慢增加,其中以巢蕨吸收的量最多,巴西铁单位干物质甲醛吸收量最少; 4种植物的相对电导率、丙二醛的含量均随甲醛胁迫时间的增加而增加,以巢蕨的相对电导率最高,虎尾兰最低,但巴西铁的丙二醛的含量最高,巢蕨最低; 4种植物的叶绿素含量均随甲醛胁迫时间的增加而降低,其中黑美人降低幅度最高,虎尾兰最低。     

中水浇灌对3种绿地植物若干生理指标的影响

中水灌溉是缓解城市供水紧张和减少污水排放量的有效措施。通过短期盆栽试验和长期大田调查相结合的方法,以清水灌溉为对照;选用绿地植物台湾草、金叶假连翘和黄金榕为研究对象;以植物叶片中超氧化物歧化酶、过氧化物酶活性、丙二醛、脯氨酸含量、总叶绿素含量和叶片细胞膜透性6个生理指标作为评价。结果表明,在短期盆栽试验中,中水灌溉的三种植物叶片中总绿素含量显著高于对照,中水灌溉的台湾草叶片中的超氧化物歧化酶活性显著高于对照,其余指标差异不显著;长期大田调查的三种植物的6种指标在中水灌溉下与对照之间差异均不显著。     

紫外辐射增加对植物生长及某些生理代谢的影响

本文就紫外线辐射增加对植物生长发育、生理特性和作物产量等方面的影响进行了论述。