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991.
Graham R. Powell 《Trees - Structure and Function》1991,5(2):107-116
Summary Shoot systems developed over 3 successive years were investigated on 55 understorey Tsuga canadensis (L.) Carr. trees. Paired comparisons of preformed-leaf content of terminal buds and numbers of leaves produced on new shoots showed that neoformed leaves were produced in large numbers. Parent-shoot character was not useful in predicting numbers of preformed leaves, was better related to total leaves produced, but left the majority of the variation unexplained. This reflected the capacity of any terminal bud to produce a shoot with more or less neoformation, depending on conditions for growth. All shoots over 6 cm long produced sylleptic shoots that bore from two to many leaves and were arranged in a mesitonic pattern along the parent. Some of the longer sylleptic shoots produced lateral buds or second-order sylleptic shoots. Monopodial second-year extensions of sylleptic-shoot axes followed an acrotonic pattern, as did proleptic shoots from the few lateral buds borne on the parent shoots. Such lateral buds were more frequent on shorter parent shoots: they typically occurred near the proximal and distal ends. Duration of shoot extension was positively correlated with shoot length: terminal buds became evident as shoot extension neared cessation. 相似文献
992.
In order to test whether an increased export of carbohydrates by leaves and starch mobilization are critical for floral transition
in Arabidopsis thaliana, the Columbia ecotype as well as its starchless mutant pgm and starch-in-excess mutant sex1 were investigated. Induction of flowering was achieved by exposure of plants to either one long day (LD) or one displaced
short day (DSD). The following conclusions were drawn: (i) Both the pgm and sex1 mutants have a late-flowering phenotype in days shorter than 16 h. (ii) When inductive treatments cause a large percentage
of induced plants, there is always a large, early and transient increase in carbohydrate export from leaves. By contrast,
when an inductive treatment results in only a low percentage of induced plants (pgm plants exposed to one DSD), the export of carbohydrates from leaves is not increased, supporting the idea that phloem carbohydrates
have a critical function in floral transition. (iii) Starch mobilization is not required to obtain an increased carbohydrate
export when induction is by one LD (extended period of photosynthesis), but is absolutely essential when induction is by one
DSD (period of photosynthesis unaffected). (iv) Floral induction apparently increases the capability of the leaf phloem-loading
system.
Received: 27 August 1997 / Accepted: 6 March 1998 相似文献
993.
Growth performance of an inland population of Plantago maritima in response to nitrogen and salinity
The inland distribution of Plantago maritima in Ireland and Britain is strongly western and generally associated with base-rich soils or with flushes in more acidic upland soils. Plants from an eastern Irish salt marsh and from an inland population growing on shallow calcareous soils in east County Clare, Ireland, were grown in culture solutions with a range of seawater dilutions (10–100%) and nitrogen (2.8–140 ppm N) concentrations added as ammonium nitrate. A low nitrogen supply (2.8 ppm N) resulted in very low dry matter production but with increased nitrogen, plant growth increased, even of inland population plants in 50% seawater. Some inland plants survived 100% seawater, but growth was much reduced. The relatively high salinity tolerance of this inland population is discussed.Nomenclature follows Flora Europaea (Tutin et al., 1964–80) for angiosperms, Watson (1968) for bryophytes and Hawksworth et al. (1980) for lichens.Thanks are due to the Central Marine Services Unit and Michael Coughlan, Microbiology Department at University College Galway for Mullaghmore soil nitrogen analyses. 相似文献
994.
叶芽花芽需热量差异导致植物先花后叶 总被引:1,自引:0,他引:1
为探究植物先花后叶的影响因素,本研究以1963—1988年间北京地区杏和山桃展叶和始花物候资料及相应的日最高、最低温度数据为基础,利用偏最小二乘回归法确定杏和山桃叶芽及花芽的需冷期和需热期,进而利用动态模型和生长度小时模型分别估算叶芽和花芽的需冷和需热量。结果表明,依据长期物候观测资料,利用偏最小二乘回归法进行植物需冷和需热量的估算非常有效。先花后叶植物叶芽和花芽需冷量几乎相同,需热量的差异是导致植物先花后叶的主要原因。杏和山桃花芽的需热量分别为2829.7±876.2和1457.2±581.2生长度小时,而相应叶芽需热量却是花芽的两倍之多。基于物候观测的重要性及实用性.中国物种水平上的地面观测应得到进一步深入发展。 相似文献
995.
采后衰老进程在很大程度上受到内源和外源激素的影响。抑制拟南芥中磷脂酶Dα1(phospholipaseDtxl,PLDod)的表达后,使得外源脱落酸(abscisic acid,ABA)和乙烯加速的离体叶片衰老过程在一定程度上得到了缓解。然而,内源激素在这个过程中的作用尚不清楚。本研究对比分析了野生型和PLDα1缺失型两种基因型拟南芥叶片在3种不同人工老化过程中(离体诱导的、外源ABA和乙烯促进的衰老过程),内源ABA,茉莉酸甲酯(methyl jasmonate,MeJA)、吲哚乙酸(indole-3-acetic acid,IAA)、玉米素核苷(zeatin riboside,ZR)和赤霉素(gibberellic acid,GA,)的含量变化。这5种激素对3种不同衰老处理方式的响应模式表明了人工老化过程存在着两个不同阶段,并且在衰老早期每种激素的变化模式相同。PLDα1功能缺失使得激素加速的衰老过程得以延缓,这与内源ABA、MeJA、ZR和IAA的含量变化有关。而与GA、的含量变化无关。同时,ZR和IAA的变化模式也说明了这两种激素的变化可能是缺失PLDα1延缓激素加速的衰老过程这一事件的原因而非结果。 相似文献
996.
Securing food production for the growing population will require closing the gap between potential crop productivity under optimal conditions and the yield captured by farmers under a changing environment, which is termed agronomical stability. Drought and salinity are major environmental factors contributing to the yield gap ultimately by inducing premature senescence in the photosynthetic source tissues of the plant and by reducing the number and growth of the harvestable sink organs by affecting the transport and use of assimilates between and within them. However, the changes in source–sink relations induced by stress also include adaptive changes in the reallocation of photoassimilates that influence crop productivity, ranging from plant survival to yield stability. While the massive utilization of -omic technologies in model plants is discovering hundreds of genes with potential impacts in alleviating short-term applied drought and salinity stress (usually measured as plant survival), only in relatively few cases has an effect on crop yield stability been proven. However, achieving the former does not necessarily imply the latter. Plant survival only requires water status conservation and delayed leaf senescence (thus maintaining source activity) that is usually accompanied by growth inhibition. However, yield stability will additionally require the maintenance or increase in sink activity in the reproductive structures, thus contributing to the transport of assimilates from the source leaves and to delayed stress-induced leaf senescence. This review emphasizes the role of several metabolic and hormonal factors influencing not only the source strength, but especially the sink activity and their inter-relations, and their potential to improve yield stability under drought and salinity stresses. 相似文献
997.
《Bioorganic & medicinal chemistry letters》2014,24(7):1677-1680
A series of 2,5-substituted-1,3,4-oxadiazole/thiadiazole sulfone derivatives were synthesized and evaluated for their antibacterial activities against rice bacterial leaf blight and leaf streak caused by Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicolaby via the turbidimeter test in vitro. Antibacterial bioassay results indicated that most compounds demonstrated good inhibitory effect antibacterial bioactivities against rice bacterial leaf blight and leaf streak. Among the title compounds, compound 6c demonstrated the best inhibitory effect against rice bacterial leaf blight and leaf streak with half-maximal effective concentration (EC50) values of 1.07 and 7.14 μg/mL, respectively, which were even better than those of commercial agents such as Bismerthiazol and Thiediazole Copper. In vivo antibacterial activities tests at greenhouse conditions demonstrated that the controlling effect of compounds 6c (43.5%) and 6g (42.4%) against rice bacterial leaf blight were better than those of Bismerthiazol (25.5%) and Thiediazole Copper (37.5%). 相似文献
998.
Leaf Senescence and GABA Shunt 总被引:1,自引:0,他引:1
Leaf senescence is highly regulated and complex developmental process that involves degradation of macromolecules as well as its
recycling. Senescence process involves loss of chlorophyll, degradation of proteins, nucleic acid, lipid and mobilization of nutrients
through its transport to the growing parts, developing fruits and seeds. Nitrogen is the most important nutrient to be recycled in
senescence process. GABA-transaminase (γ-aminobutyric acid) is found to play very important role in nitrogen recycling process
through GABA-shunt. Therefore, it is of interest to review the significance of GABA shunt in leaf senescence. 相似文献
999.
Yuehua Sun Yanling Zhao Xiaojuan Wang Guirong Qiao Guoliang Chen Ye Yang Jing Zhou Liang Jin Renying Zhuo 《Acta Physiologiae Plantarum》2009,31(1):33-41
The aim of this work is to develop a method of plant regeneration from leaf explants of Platanus occidentalis L. successfully. Woody plant medium (HortScience 16:453–459, 1981) and Murashige and Skoog (Physiol Plant 15:473–497, 1962)
medium were used as induced and rooted basal medium, respectively. The effects of combinations of 6-BA, IBA, NAA and KT with
different concentrations on adventitious bud regeneration from P. occidentalis leaf explants were compared. The results showed that the highest shoot regeneration frequency (90%) and maximum number (13.72 ± 0.44)
of shoots per explant was recorded on WPM medium supplemented with 22.20 mmol l−1 6-BA and 0.49 mmol l−1 IBA. A 40-day-old explants were much more productive for shoot formation than others in this study. The regenerated shoots
were cultured on MS medium supplemented with 1.33 mmol l−1 6-BA, 0.16 mmol l−1 NAA and 2% (w/v) adenine, after 2-week shoots were transferred to 1/2 MS medium supplemented with 0.49 mmol l−1 IBA for rooting. Hardened plantlets via acclimatization were transferred to pots and transplanted to the soil finally. To
ascertain whether tissue culture had effects on the genetic stability of plantlets regenerated, the genetic diversity was
assessed using RAPD marker. A total of 96 bands ranging from 0.5 to 2.2 kb with an average of 6.4 bands per primer, were obtained
using 15 primers. Amplified products exhibited few of polymorphic patterns across all the plants of P. occidentalis and the overall frequency of detection of somaclonal polymorphisms was lower than 0.0104%.
Yuehua Sun, Yanling Zhao, and Xiaojuan Wang contributed equally to this work. 相似文献
1000.
Nadia Corp Hitoshige Hayaki Takahisa Matsusaka Shiho Fujita Kazuhiko Hosaka Nobuyuki Kutsukake Michio Nakamura Miho Nakamura Hitonaru Nishie Masaki Shimada Koichiro Zamma William Wallauer Toshisada Nishida 《Primates; journal of primatology》2009,50(2):184-189
In 1998, four chimpanzees in the Mahale Mountains National Park, Tanzania, were observed wiping their mouths with non-detached
leaves or stalks of grass, or rubbing their mouths with a tree trunk or branch, especially while eating lemons. The number
of mouth-wiping/rubbing individuals increased to 18 in 1999. By 2005, 29 chimpanzees were documented wiping/rubbing their
muzzles in this way. Although it is difficult to determine whether the chimpanzees acquired this behavior as a result of trial
and error or social learning, the fact that chimpanzees at other sites perform this behavior with detached leaves or leafy
twigs much more often than with intact items suggests the possibility that cleaning with intact plant parts at Mahale spread
via social learning. 相似文献