Studies on the long-day inhibition of flowering in Xanthium and Kalanchoe

It is well known in short-day plants that a leaf held in non-inductive photoperiods inhibits flowering when interposed between the induced leaf and the apical meristem, in an analogous manner to the basal half of a leaf induced by short-day in its distal half. This has often been explained by the inhibiting leaf or basal part of an induced leaf becoming the major source of carbohydrates to the apex, rather than the induced leaf itself; i.e. by preventing thus the co-transported stimulus from reaching the apex. Experiments with Kalanchoe blossfeldiana Poellniz and Xanthium strumarium L. in which carbon dioxide levels were lowered or increased, or 3-(3,4-dichlorophenyl)-1,1-dimethylurea injected, or sugar fed to the petioles of a debladed interposed leaf, or night-breaks given as well as other photoperiodic treatments, all pointed to 'carbohydrate diversion' not being the major cause of failure of the short-day stimulus reaching the target apex. It is tentatively concluded that instead an inhibitory action occurs in the vascular passage of the stimulus preventing co-transport with the carrier molecule.     

沙葱叶基愈伤组织原生质体再生体系的建立

沙葱是一种具有抗旱抗寒、抗病性和适应性强等生理特性的荒漠植物.为开发利用其固有的遗传资源,本研究利用细胞工程技术建立了沙葱(Allium mongolicum Regel)叶基愈伤组织原生质体的分离、培养和植株再生实验体系.研究结果表明,酶法分离原生质体的产率和分裂频率明显取决于用于制各原生质体的愈伤组织的状态.转代培养7～10d的松软愈伤组织可分离出大量有活性的.在附加2.0mg/L2,4-D、0.2mg/L激动素、500 mg/L水解乳蛋白、0.4 mol/L甘露醇和2%蔗糖的MS培养基中进行液体浅层培养,4～5 d后出现第一次原生质体分裂;7～10d出现第二次分裂.结果显示原生质体的分裂频率大约为5%;4周后,可见到小愈伤组织.当将原生质体分裂形成的愈伤组织转移到附加2.0mg/L6-苄氨基嘌呤(或激动素)和0.4mg/L萘乙酸(NAA)的MS固体培养基上,并在低光照条件下培养后,从愈伤组织上分化出了不定芽,进而发展成小植株,并移栽成活.本研究对沙葱抗逆遗传品质用于经济植物遗传改良的研究奠定了可行的实验基础.     

野生沙葱的资源分布与保护利用

分析了野生沙葱的资源分布、生态适应性、营养价值、研究与利用现状,提出了在全国范围内进行沙葱资源的分布范围、分布类型、种源特征、遗传变异、群落特征及其演替规律的调查与确定,建立沙葱的种质资源库和数据库,全面开展不同种源沙葱的迁地保护、生态适应性、保护生物学及人工优质丰产栽培技术研究等一系列保护、利用的思路与措施。     

荒漠植物梭梭和沙拐枣光合作用、蒸腾作用及水分利用效率特征

运用开放式气体交换LI-6400便携式光合作用测定系统,研究了梭梭(Haloxylonammodendron)和沙拐枣(Calligonummongolicum)的净光合速率(Pn)、蒸腾速率(E)及水分利用效率(WUE)特征。结果表明:梭梭和沙拐枣在湿润状况下的Pn日变化呈单峰型,梭梭低于沙拐枣,日平均分别为19.60±0.12μmol·m-2·s-1和24.06±0.50μmol·m-2·s-1;E也是梭梭低于沙拐枣,日平均分别为5.53±0.08mmol·m-2·s-1和8.21±0.26mmol·m-2·s-1;WUE则不同,日平均梭梭高于沙拐枣,分别为3.28±0.05mmolCO2·mol-1H2O和2.84±0.06mmolCO2·mol-1H2O。WUE年均值也是梭梭高于沙拐枣,二者最高值都出现在9月,次高值出现在7月,WUE的高低变化与年降水量的高低分布一致。在湿润和干燥两种状况下,梭梭和沙拐枣Pn对光强的响应表明,水分条件好时Pn明显增大,光能利用率提高。从湿润状况时的净光合速率、光饱和点和CO2补偿点,以及干燥状况时也具有低CO2补偿点,确定梭梭和沙拐枣具有C4光合途径。     

荒漠植物梭梭和沙拐枣的花环结构及C4光合特征

 为了探讨梭梭（Haloxylon ammodendron）和沙拐枣（Calligonum mongolicum）适应高温强光荒漠环境的光合作用机构及特征,通过对其同化枝的解剖结构观察,δ13C值分析,以及气体交换测定表明：二者均具有花环结构(Kranz anatomy),肉细胞（Mesophyll cell）呈栅栏状,其内侧是维管束鞘细胞（Bundle sheath cell）,小维管束与维管束鞘细胞相接。在栅栏组织和贮水组织中,梭梭具有形状巨大的含晶细胞;沙拐枣具有大量的粘液细胞。梭梭和沙拐枣同化枝的δ13C值分别为-14.3‰和-14.8‰,在不同生长季节和土壤水分条件下,二者的δ13C值变化在-14‰到-16‰之间。梭梭和沙拐枣的CO2补偿点分别为2 μmol•mol－1和4 μmol•mol－1,光饱和点分别为1 660和1 756 μmol•m－2•s－1,表观光合量子效率分别为0.044和0.057 mol CO2•mol－1 photons。这表明,广泛分布于我国荒漠地区的木本植物梭梭和沙拐枣为C4植物,其光合途径不随生长季节和水分条件的变化而改变。     

Transition from primary dormancy to secondary dormancy in cocklebur seeds

Abstract The transition from primary dormancy to secondary dormancy was examined using upper cocklebur (Xanthium pennsylvanicum Wallr.) seeds. The non-after-ripened seeds with primary dormancy responded to chilling, anoxia, KCN, and NaN₃ with an increase in germination. However, their maximal responses to these treatments only occurred after a period of water imbibition, probably a reflection of the increasing growth potential of the axial tissue which was accompanied by the increase in the capacities of respiration and ethylene production. On the other hand, the establishment of secondary dormancy was accompanied by a decrease in respiration and ethylene production of seeds, and in the growth potential of both axial and cotyledonary tissues. The decrease in growth potential of these tissues occurred regardless of whether they were excised from after-ripened seeds or non-after-ripened seeds. It is inferred that the primary dormancy of cocklebur seeds is a state maintained in un-germinated seeds for a long time through a spontaneous transition to secondary dormancy.     

鄂西北产苍耳子甲醇粗提物抑菌活性及其清除DPPH能力的初步评价

采用生长速率法、孢子萌发法及DPPH自由基清除法,对产自鄂西北的野生植物苍耳子粗提物体外抑菌活性及抗氧化性进行了初步测定.结果表明,苍耳子甲醇粗提物对绿色木霉、黄瓜灰霉菌、黑曲霉、终极腐霉、尖镰孢菌黄瓜专化型五种病原真菌均有一定的抑制作用,其中无论是抑制菌丝生长还是孢子萌发,均对黑曲霉显示出了显著的抑制活性.实验结果也...     

苍耳属一新变种——一室苍耳

本变种与原变种(Xanthium sibi ricum Patrin)及近无刺苍耳(var.subinerme(winkl.)w idder.)的主要不同在于前者雌性头状花序中,内层总苞片结合成卵形囊状体,有1小花;成熟的总苞体1室, 1瘦果,顶端只有1喙,总苞体连同喙部长约10~13mm,宽约3~6mm,被较稀疏的倒钩刺,顶端1/3近无刺。     

蒙古口蘑驯化栽培成功

在观察研究蒙古口蘑生态的基础上,通过菌种分离、驯化,选出87-B-2优良菌株。在以马粪、麦秸等配制的发酵料进行瓶栽、箱栽试验的基础上,1990年用床式栽培方法驯化栽培成功蒙古口蘑。     

The presence of two types of β-cyanoalanine synthase in germinating seeds and their responses to ethylene

Germinating seeds of many species contain two types of β-cyanoalanine synthase (CAS, EC 4.4.1.9) that convert HCN to β-cyanoalanine. One is cytoplasmic CAS (cyt-CAS), which is precipitated by 50 to 60% (NH₄)₂SO₄ and has a pH optimum of 10.5. Cytoplasmic CAS is present at high levels in dry seed and its activity does not increase during imbibition. The activity of cyt-CAS is not affected by exogenously applied ethylene (C₂H₄), except in rice ( Oryza sativa cv. Sasanishiki). The second type of CAS found in seed is mitochondrial CAS (mit-CAS), which is precipitated by 60 to 70% (NH₄)₂SO₄ and has a pH optimum of 9.5. Mitochondrial CAS is present at low levels in dry seed, and its activity increases greatly during imbibition in the seeds of all species tested. Exposure to C₂H₄ stimulated mit-CAS activity in seeds of rice, barley ( Hordeum vulgare cv. Hadakamugi). cucumber ( Cucumis sativus cv. Kagafushinari) and cocklebur ( Xanthium pennsylvanicum ). The increase in the mit-CAS activity in cocklebur in response to C₂H₄ commenced alter a lag period of 2 to 3 h when the duration of soaking was short (16 h), but commenced without a lag period when the seeds were soaked for three months. Application of both chloramphenicol and cycloheximide to the axial and cotyledonary tissues of cocklebur seeds strongly inhibited growth as well as the increase in mit-CAS activity. It is postulated that the mit-CAS is synthesized de novo during imbibition and that its activity is regulated by C₂H₄, CO₂ which also promotes seed germination in some species, was ineffective m stimulating mit-CAS activity in cocklebur seeds.