Seasonal Changes in the Cytokinin Content of Ginkgo biloba Leaves

Young growth-chamber-grown cotton plants were subjected to a series of eight periods of soil water stress, which served as a preconditioning treatment. After preconditioning, water was withheld and changes in the stomatal resistance and leaf water potential were determined and compared with similar well watered control plants. The stomatal response of stress preconditioned plants adjusted such that the diffusion resistance of the lower surface of the leaf did not reach a value greater than 20 s cm^?1 until the leaf water potential dropped 14 bars below that required to reach the same resistance on previously unstressed plants. The resistance—leaf water potential relation for the adaxial surface was unaltered by the preconditioning treatment. Adjustment of the osmotic potential of the guard cells on the abaxial surface provides at least a partial explanation of this change in response. The lack of adjustment of stomatal response on the adaxial surface of the leaves was correlated with a lack of adjustment in osmotic potential of guard cells on that surface.     

Occurrence of a Cytokinin Glucoside in the Leaves and in Honeydew of Salix babylonica

Honeydew and leaf extracts from Salix babylonica indicate that large quantities of cytokinin are present in the leaves and are transported through the phloem of this plant during late autumn. The active compound in the extracts could be hydrolysed with β-glucosidase, whereafter it showed the same chromatographic behaviour as zeatin. It is proposed that cytokinins in the leaves are converted to the glucoside and then redistributed to the rest of the plant organs where it is stored.     

The Effect of 1-Naphthaleneacetic Acid on the Endogenous Cytokinin Content of Aseptically Cultured Bark Segments of Salix babylonica

The formation of an undifferentiated wound callus from the cambialregion of bark explants of Salix babylonica was accompaniedby an increase in the endogenous cytokinin levels of the tissueduring the first six days of culture. Treatment of the explantswith 1-naphthaleneacetic acid decreased the level of extractablecytokinin. This decrease was not accompanied by a reductionin the cell number nor in the growth of the explants as reflectedby changes in dry weight. The significance of these findingsis discussed with reference to the known effects of auxin oncytokinin synthesis and degradation. (Received May 23, 1981; Accepted August 11, 1981)     

柳树叶浸提液对蛋白核小球藻的化感作用

通过对蛋白核小球藻进行细胞密度的测定,分析了不同浓度的柳树(Salix babylonica)叶浸提液对蛋白核小球藻(Chlorella pyrenoidosa)生长和细胞形态的影响。结果表明：柳树叶浸提液对蛋白核小球藻具有化感作用,不同浓度的浸提液化感作用强度不同;作用96 h的半效应浓度(EC₅₀,_{96 h}值)为11.82 g·L^-1,较低浓度(10和20 g·L^-1)浸提液对蛋白核小球藻表现出先抑制后促进的作用特性,而较高浓度（30 g·L^-1）浸提液则始终表现出抑制效果;10、20和30 g·L^-1浸提液对蛋白核小球藻的最大抑制率分别为37.5%、39.3%和56.5%;柳树叶浸提液作用下,部分蛋白核小球藻细胞平均颗粒体积增大,颜色变透明,膨胀后溶解;低浓度浸提液处理组少数细胞聚集在一起,高浓度浸提液处理组细胞大量聚集,形成多细胞群体,多数沉于瓶底,沉降性能增强。     

Changes in the Chlorophyll Content and Cytokinin Levels in the Top Three Leaves of New Plant Type Rice During Grain Filling

This paper reports the ways that the differences in leaf senescence are related to grain filling, grain yield, and the dynamics of cytokinins (CKs) in the top three leaves of four field-grown new plant type (NPT) rice, a tropical japonica developed at the International Rice Research Institute, Philippines, to increase the yield potential of rice. The chlorophyll content in leaves decreased from flowering to maturity in all the NPT lines, whereas the grain filling percentage was higher in the fast-senescing NPT line than in slow-senescing NPT line. Grain yield was positively correlated with senescence in the flag leaf. Rapid changes in the CK levels were recorded in the leaves of the fast-senescing line, whereas the CK levels were relatively stable in leaves of the slow-senescing line, suggesting that the dynamics of CKs in the fast-senescing line are vital for fast senescence. There were no significant changes in bioactive CKs, CK O-glucosides (storage CKs), and cis-zeatin derivatives in different leaves of the slow-senescing NPT line between 0 and 3 weeks after flowering, suggesting that the content of these CKs is relatively stable during grain filling. A progressive increase in levels of bioactive CKs was positively correlated with gradual accumulation of CK N-glucosides (inactive CKs) in the top three leaves of the slow-senescing NPT line, whereas the decrease of bioactive CKs in the flag leaf of the fast-senescing line was accompanied by accumulation of CK O-glucosides. These results suggest that there is a higher rate of biosynthesis and/or import of bioactive CKs as well as their turnover which may favor delay of leaf senescence in the slow-senescing NPT line.     

Changes in Endogenous Cytokinin Levels During Abscission and Senescence of Streptocarpus Leaves

The cytokinin levels of butanol and aqueous extracts of proximalportions of Streptocarpus leaves showed very little change duringthe summer and early autumn months, whereas those of the distalportions changed markedly. These changes appear to be closelyrelated to the formation of abscission layers and the subsequentsenescence of the distal part of the leaves. It is postulatedthat the increase in butanol-soluble cytokinins during Januarymay induce abscission, while the decrease in February appearsto be directly related to senescence of the distal portionsof the leaves.     

Cu2+胁迫对2种速生柳幼苗生长及生理特性的影响

以营养溶液中培养的‘苏柳172’(Salix jiangsuensis CL J-172)和垂柳(Salix babylonica Linn)幼苗为材料,分析它们在不同浓度Cu2+溶液(0、20、40、80、100、200、300μmol.L-1)下的生长以及部分生理指标的变化,以明确2种速生柳树用于植物修复的潜力。结果显示:2种柳树幼苗的生物量、叶片色素含量、根系活力以及根系形态的各指标都随Cu2+浓度的增加而显著降低。它们叶片SOD和POD活性以及脯氨酸含量随Cu2+浓度的增加呈先上升后下降的趋势,‘苏柳172’和垂柳中SOD活性在Cu2+浓度为20μmol.L-1时最大,其POD活性分别在Cu2+浓度为100和40μmol.L-1时达到最大,而其脯氨酸含量在Cu2+浓度为200μmol.L-1时达到最大。可见,2种柳树生长均受到Cu2+胁迫的抑制,它们能够在一定程度上通过增加保护酶活性和脯氨酸含量来提高对Cu2+的耐受性,且‘苏柳172’对Cu2+的忍耐力强于垂柳。     

Life cycle of Melampsora coleosporioides,a leaf rust of Salix babylonica in Japan

Melampsora coleosporioides produces uredinia and telia on the leaves of Salix babylonica. Since the life cycle of this fungus is largely unknown, inoculation experiments were conducted to find alternate host plants. Results showed that M. coleosporioides can use Corydalis incisa as a spermogonial and aecial host. The morphological characteristics of the spermogonial and aecial states of the fungus are first described. Furthermore, field observations and histological studies demonstrated that the fungus was able to overwinter in twigs of S. babylonica and produced urediniospores in early spring. Thus, the leaf rust occurs on S. babylonica every year and alternation with the spermogonial and aecial host is not necessary.     

The Effect of Ringing on Cytokinin Distribution in Salix baylonica

Although quantitative differences were observed in the cytokinin content of mature leaves and bark of Salix babylonica it would appear as if these tissues contained the same cytokinin complement. Ringing resulted in a decrease in the level of cytokinins in the leaves and an increase in the bark, both above and below the girdle. In the leaves the decrease was due mainly to a drop in the level of those compounds that co-chromatographed with the cytokinin glucosides. These compounds were also almost undetectable in the bark above the girdle, where callus was formed. The observed increase in the cytokinin content of the bark above the girdle was due to higher activity in those parts of the chromatograms where zeatin and zeatin riboside occurred. Ringing stimulated the growth of lateral buds below the girdle. These developing buds as well as the bark below the girdle contained very high levels of cytokinins that cochromatographed with zeatin and zeatin riboside.     

苯酚废水对垂柳叶片光合生理参数的影响

为探讨垂柳(Salix babylonica)对苯酚污染物的耐受程度及其应用于苯酚污染环境修复的可行性,了解苯酚胁迫对垂柳光合作用生理过程的影响与限制机理,采用水培模拟胁迫实验方法,在5种苯酚溶液浓度(50、100、200、400和800mg·L–1)下,测定垂柳植株叶片光合气体交换及叶绿素荧光参数。结果表明,苯酚对垂柳光合作用具有显著的抑制作用,表现为叶片净光合速率(Pn)、最大光合速率(Pnmax)、光合量子效率(Φ)、PSII最大和实际光化学效率(Fv/Fm和ФPSII)等均明显下降。苯酚胁迫浓度越高,对垂柳光合作用的抑制程度越大;苯酚胁迫限制光合作用主要由非气孔因素引起。将垂柳用于苯酚污染的水体环境修复时,苯酚浓度应在200 mg·L–1以下,否则垂柳的光合作用效能会明显降低。垂柳光合作用生理活性耐受苯酚胁迫的极限浓度还需进一步实验研究。     

Transcriptome sequencing and EST-SSR marker development in Salix babylonica and S. suchowensis

Tree Genetics &; Genomes - The aim of this study was to explore the prospects of integrating simple sequence repeat (SSR) or microsatellite marker data into a geographical information system to...     

柳树叶浸提液对四尾栅藻生长特性及光合效率的影响

以四尾栅藻（Scenedesmusquadncauda）为研究对象,应用柳树（sn如babylonica）叶浸提液研究了其对四尾栅藻密度、细胞形态、叶绿素含量及光合效率的影响。结果表明：各浓度柳树叶浸提液处理组四尾栅藻密度均低于对照组,且较高浓度浸提液处理组藻密度更低。浓度为10g／L、20g／L和30g／L的柳树叶浸提液对四尾栅藻的最大抑制率分别为47．0％、54．6％和62．3％。根据浓度一效应关系方程,计算出对应的柳叶浸提液96h对四尾栅藻的半效应浓度（EC,。值）为23．32g/L.加入柳树叶浸提液后,四尾栅藻细胞边缘变得不规则,细胞体变透明,部分细胞溶解。在柳树叶浸提液作用下四尾栅藻叶绿素a含量始终保持在很低的水平。lO∥L、20∥L和30∥L处理组叶绿素含量最低分别为173．12t,g／L、124．18斗∥L、37．62斗g／L。实验开始第ld后各浓度柳树叶浸提液处理组Fv／Fm显著下降（P〈0．01）,第24d柳树浸提液浓度效应较为明显,大致是浸提液浓度越高,四尾栅藻PSⅡ最大光合效率越低。     

Light-dark modulation of hydroxycinnamate: CoA ligase activity from stems of Salix babylonica cultivated in vitro

Plantlets of Salix babylonica cultivated in vitro were used to study the regulation of the lignification process. The hydroxycinnamate: CoA ligase activity of the stems was shown to be controlled by light. During photoperiodic cycles, photocontrol also occurred and induced a diurnal oscillation of enzyme activity. The oscillation was maintained in continuous light and to a certain extent in continuous darkness.Abbreviations D darkness - L light - PAL phenylalanine ammonia-lyase     

豆腐木叶果胶含量的动态变化规律研究

测定了不同季节豆腐柴木叶中的果胶含量,并研究了不同叶位豆腐木果胶含量的变化规律.结果表明,豆腐木叶中的果胶含量在6～8月呈上升趋势,8月最高,9月开始下降.不同叶位果胶含量中,第3、5、6叶位的豆腐木叶片果胶含量较高,第5叶最高.     

科尔沁沙地黄柳气孔导度和水分状况随季节和地形的变化特征①

黄柳叶片气孔导度在上午８时后即呈下降趋势,下表皮气孔导度大于上表皮。干旱季节上下表皮气孔日间开启程度不同,下表皮气孔受环境因子的影响较大;湿润季节则相同。不同季节气孔导度值不同,下表皮气孔对季节变化反应灵敏。不同季节黄柳体内水分状况参数值不同,在５、６月份抗旱性最强;沙丘不同部位各参数值亦不相同,在沙丘中部和丘脚抗旱性最强,而在丘顶水分状况最好。湿润的７月黄柳一日内各时刻的膨压值均大于０,说明经期     

科尔沁沙地黄柳气孔导度和水分状况随季节和地形的变化特征

黄柳叶片气孔导度在上午8时后即呈下降趋势,下表皮气孔导度大于上表皮。干旱季节上下表皮气孔日间开启程度不同,下表皮气孔受环境因子的影响较大;湿润季节则相同。不同季节气孔导度值不同,下表皮气孔对季节变化反应灵敏。不同季节黄柳体内水分状况参数值不同,在5、6月份抗旱性最强;沙丘不同部位各参数值亦不相同,在沙丘中部和丘脚抗旱性最强,而在丘顶水分状况最好。湿润的７月黄柳一日内各时刻的膨压值均大于0,说明虽然此期间水势随环境条件和气孔调节有所升降,但未影响植株的正常生长。     

Seasonal Changes in the Composition and Content of Dehydrins in Winter Wheat Plants

Seasonal changes in the pattern and content of dehydrins in winter wheat (Triticum aestivum) plants grown under field and laboratory conditions were studied by one-dimensional PAGE and immunochemical methods. During hardening, plants accumulated dehydrin-like polypeptides with mol wts of 209, 196, 66, 50, and 41 kD. In winter, low-molecular-weight dehydrins with mol wts of 24, 22, 17, 15, and 12 kD were synthesized and accumulated as well. Their content dropped sharply in spring when plants became unhardened. Accumulation/disappearance of these proteins corresponded to the fluctuations in wintering plant frost tolerance before winter and in spring. It is assumed that both high- and medium-molecular-weight dehydrins are involved in plant stress responses and adaptation, whereas low-molecular-weight dehydrins are evidently involved only in the process of low-temperature adaptation.