TIME-LAPSE PHOTOGRAPHIC OBSERVATIONS OF MORPHOGENESIS IN ROOT NODULES OF COMPTONIA PEREGRINA (MYRICACEAE)

Seedlings of the sweet fern Comptonia peregrina (L.) Coult. were grown aeroponically with their roots bathed in a nutrient mist lacking nitrogen except for 10 ppm N at the outset. The initiation and early development of root nodules capable of fixing atmospheric nitrogen were recorded with time-lapse photography through early development to the establishment of highly branched, roughly spherical nodules. In Comptonia multiple primary nodule lobes are formed at or near the site of infection with as many as 10 primary lobes occurring together. On the shoulders of the swollen primary lobes new primordia develop, forming secondary nodule lobes, which may persist without nodule root elongation, giving a coralloid appearance. The tips of the lobes may elongate, forming nodule roots which grow vertically upward, or, if disturbed, in random orientation. Nodule roots occasionally form lateral roots. The root axis upon which the nodule forms undergoes secondary thickening on the proximal side of the nodule attachment; the distal portion of the root shows no secondary thickening and later atrophies. Thus, nodules are perennial structures on a woody root system. The endophyte infects and occupies the basal cortical tissues of the primary nodule lobes and successive nodule lobes as they are formed, being restricted to the swollen bases and not infecting the elongate nodule roots. Development of the nodule is interpreted in terms of complex host-endophyte interactions involving the initiation of multiple primordia forming nodule lobes, the active inhibition of nodule lobes and finally nodule root elongation. Anatomical evidence for the endogenous origin of nodule primordium formation substantiates the view obtained from time-lapse photomacrography.     

THE DEVELOPMENT OF ISOLATED ROOTS OF COMPTONIA PEREGRINA (MYRICACEAE) IN CULTURE

Seedling roots of the sweet fern Comptonia peregrina (L.) Coult. were excised aseptically and cultured in a modified Bonner-Devirian liquid nutrient medium. Root elongation was very slow in the basic medium which contained inorganic salts, B-vitamins, trace elements and 4 % sucrose. The addition of plant hormones including gibberellic acid, indoleacetic acid, and zeatin, alone or in combinations, had little effect on growth. Myoinositol at 10 or 100 ppm doubled the rate of elongation. The effect of this sugar alcohol could not be replaced by scyllitol, D-sorbitol, D-mannitol or by increasing the sucrose concentration. Subcultured root tips showed progressively less elongation in successive transfers. Secondary thickening of the roots, especially in the basal half, occurred in initial passages and in subcultured roots without added hormones. Root buds also occurred spontaneously especially in the basal portions of cultured roots, both in first and in successive passages. An anatomical analysis showed that these buds were endogenous, arising from a secondary cortex of pericyclic origin.     

OXYGEN CONCENTRATION WITHIN THE NITROGEN-FIXING ROOT NODULES OF MYRICA GALE L.

Microelectrodes were used to study the oxygen concentration within Myrica gale L. nodules. Low oxygen concentrations were found only in the region of the mature, nitrogen-fixing endophyte, and appeared to correspond to clusters of infected host cells. The oxygen concentration in the remainder of the nodule was much higher. Interconnected intercellular air spaces were demonstrated by infiltration with India ink. Infiltration of the spaces with water greatly reduced oxygen concentration throughout the nodule, indicating that they function in supplying oxygen to the infected cells and remainder of the nodule. These results differ from those found previously for soybean nodules and provide evidence that legume and actinorhizal nodules have different mechanisms for protecting nitrogenase from oxygen.     

沙棘共生固氮根瘤及其内生弗兰克氏菌

用透射电镜研究了中国沙棘（Ｈｉｐｐｏｐｈａｅ ｒｈａｍｎｏｙｄｅｓ Ｌ．）根瘤的超微结构。它的侵梁细胞位于皮层中部,非侵染细胞与之间排列,富含多酚和淀粉粒。在根瘤的发育过程中,具有以下特征：（１）早期侵染细胞中具有核仁联合体;（２）由内生菌丝趋核生长而形成的核膜内陷处,有许多核孔出现;（３）在中期侵染细胞的内生菌丝和泡囊的荚膜附近,有成束的微管存在;（４）在４、５月瘤样的维管束细胞、非侵染细胞及早     

A QUANTITATIVE ANALYSIS OF FEMALE GAMETOPHYTE DEVELOPMENT IN FIELD- AND GREENHOUSE-GROWN PLANTS OF GLYCINE MAX AND PHASEOLUS AUREUS (PAPILIONACEAE)

A statistical analysis of size for the megasporocyte, functional megaspore, and 2-, 4-, 8-nucleate, and mature female gametophytes for Glycine max and Phaseolus aureus grown in the field and greenhouse was accomplished from measurements of the length, width, and length and width intercepts for each stage. The greatest increase in mean length for Phaseolus in the greenhouse and Glycine in the field takes place between the 2- and 4-nucleate stages. In alternate environments, the two genera show the greatest increase between the functional megaspore and 2-nucleate stage. Greater similarity between the genera than shown by each genus in the two environments was also found for other features, viz., the largest mean length and width attained by each stage, the least increase in mean length and width and the overlap in confidence intervals for length and length intercepts between successive stages, and changes in the width intercept as a percent of total width as the ovule becomes campylotropous. T tests at the 0.05 level reveal significant differences between greenhouse and field plants in Phaseolus for length of the megasporocyte and 8-nucleate stage and length and length intercept of the 2- and 4-nucleate stages. In Glycine, differences appear for the length and both intercepts of the megasporocyte and the length intercepts of the mature stage. The similarity of Glycine in one environment to Phaseolus in the other coupled with the differences of statistical significance for each genus in the two conditions suggest that environment does have a pronounced effect on female gametophyte development. Statements to the contrary in previous reports to include one on these genera are correct for the qualitative aspects of development investigated, but they cannot be extended in all respects to the quantitative analysis of growth reported here. The differences recorded suggest caution in the choice of material for comparative studies. For embryological data, especially those of a quantitative nature, to be fully useful in taxonomic assessments, material for all taxa should be collected from natural habitats.     

INITIATION AND DEVELOPMENT OF ROOT NODULES OF CASUARINA (CASUARINACEAE)

Roots of seedlings of the “beefwood” tree, Casuarina cunninghamiana Miq. grown in nitrogen-free nutrient solution were inoculated with a suspension prepared from crashed root nodules taken from mature plants. Marked deformation of root hairs was evident but no infection threads were observed in root hairs. The mode of infection remains undetermined. Root nodules were initiated within three weeks and thereafter numerous upward-growing nodule roots developed from each nodule. Nodules in this symbiotic nitrogen-fixing plant resulted from an infection caused by an unidentified actinomycete-like soil microorganism. Anatomical analysis of nodule formation showed that nodules are the result of repeated endogenous lateral root initiations, one placed upon another in a complexly branched and truncated root system. The endophyte-infected cortical tissues derived from successive root primordia form the swollen nodular mass. Nodule roots develop from nodule lobes after escaping from the initial inhibitory effects of the endophyte. Included is a discussion of the anatomical similarities between nodules of Casuarina which produce nodule roots and those of Alnus which form coralloid nodules usually lacking nodule roots.     

棕尾别麻蝇(Sarcophaga peregrina)幼虫与蛹血淋巴凝集素的纯化与特性

用亲和层析法纯化了棕尾别麻蝇幼虫和蛹血淋巴凝集素。以兔红细胞吸附幼虫血淋巴凝集素为抗原制备的抗体、球球蛋白和甲状腺蛋白等三种亲和层析吸附剂纯化得到的幼虫凝集素是相同的,其分子量73kD左右。用甲状腺球蛋白为亲和配基纯化的蛹血淋巴凝集素由二种亚基组成,其分子量分别为30和32kD。幼虫和蛹血淋巴凝集素活性的抑制糖明显不同：乳糖、岩藻糖和N－乙酰半乳糖胺对幼虫血淋巴凝集素活性有抑制作用;而甘露糖胺、半乳糖胺和葡萄糖胺则对蛹血淋巴集素有一定抑制。而且,用兔红细胞吸附幼虫血淋巴凝集素为抗原制备的抗血清对蛹的凝集素活性无交叉反应,表明这两种凝集素是不相同的。虽然本文所纯化的麻蝇蛹血淋巴凝集素的分子量和Komano等报道的麻蝇蛹以及幼虫体壁 伤害诱导的凝集素SPL相同,但其糖的抑制特性有明显差异。     

PHB颗粒在红豆草根瘤细菌发育中的动态变化

红豆草根瘤胞间隙和侵入线中另有个别细菌含有PHB颗粒,而且数量很少,一个细菌通常仅有一个。随着细菌被从侵入线中释放到寄主细胞中,这些PHB颗粒立即消失。幼龄细菌不含PHB颗粒,成熟细菌一般也不含这种内含物。当细菌衰老时,它们又再度出现,并大量增加,而后很快减少,直至完全消失。从未发现这种颗粒存在于解体细菌中,尽管它们处于各种不同的解体状态。PHB颗粒在细菌发育中的变化表明,它的多少不仅与根瘤细菌发育密切有关,而且也受制于根瘤品种。     

ELECTRON TRANSPORT SYSTEMS OF RHIZOBIUM GROWN IN NODULES AND IN LABORATORY MEDIUM

The electon transport systems of Rhizobium japonicum were studied,comparing cells harvested from effective nodules with thosefrom artificial culture. Participation of the cytochrome systemwas confirmed in both forms of cells. Absorption peaks of thecytochromes of cultured cells were a, b, c type, resemblingthose of Bacillus subtilis, yeast and mammalian tissue. Cytochromea could not be detected in the absorption spectrum of symbioticcells, although the CO binding difference spectrum showed apeak at about 438 mµ, which can be attributed to a componenta₃ or a₁. CO difference spectrum also showed a shoulder at about416 mµ. Cells cultivated under the insufficient supply of oxygen showedthe cytochrome absorption spectrum closely resembled that ofsymbiotic cells. Diaphorase activity was lower in symbioticcells. These results are considered to be due to the insufficientsupply of oxygen within nodule tissue. Succinate oxidation bythe symbiotic cell paniculate was shown to be carbon monooxideresistant. NADH₂ oxidation by the supernatant fraction of symbioticcells was accelerated by flavin mononucleotide, 2, 6-dichiorophenolindophenol, methylene blue and vitamin K₃. ¹Present address: Faculty of Agriculture, Tôhoku University,Sendai. ²Present address: Central Agricultural Experiment Station, Kitamoto.     

STRUCTURE AND GERMINATION OF BLASTOCLADIELLA EMERSONII RESISTANT SPORANGIA

Resistant sporangia of Blastocladiella emersonii were induced by the addition of bicarbonate, potassium chloride, sodium chloride, or ammonium chloride to the medium and by the exposure of the zoospores to ultraviolet irradiation. Mature resistant sporangia induced by all of these conditions exhibit similar areolate wall pitting. Under suitable conditions resistant sporangia in all cases examined germinated with the cracking of the outer sporangial wall, with the formation of exit tubes by the inner sporangial wall, and with the cleavage and release of zoospores through discharge papillae formed in the tips of the exit tubes.     

玉米内生杀虫工程菌对玉米螟的离体及活体生物测定

12#Bt/CXC是以能定植在玉米维管束系统的内生菌I>Clavibacter xyli subsp.Cynodon—tis(CXC)为宿主菌,将Bt urstaki的δ—内毒素基因cryIA?整合到其染色体上形成的内生工程菌。以玉米螟Ostrinia furnacalis Guenee为供试昆虫的生测结果表明：在同一浓度下,12^#菌株对玉米螟的毒力均高于野生型Bt菌株HD73和空白对照(最低浓度除外)。浓度最高时12^#处理的死亡率为63%,而m工73为53%,死亡率与浓度呈正相关,相关系数r₁₂^#大于r_HD—73。在用12^#Bt/CXC接种玉米的活体生测中,人工接虫4周后检测,注射接种法效果明显优于种子处理法。不同浓度的注射接种处理,玉米螟幼虫减少率最低70%,最高可达96%,与未处理对照相比差异显著。12#菌剂处理后对玉米螟的生长发育也有抑制作用,虫体重减轻26.4%～44.5%,处理株虫龄平均为2龄,而对照株为4龄。     

大叶相思的结瘤固氮和吸氢酶活性

本文报道大叶相思的结瘤固氮和氢酶活性的研究结果。大叶相思结瘤状况与其他含羞草亚科的树种相似,刚形成的幼瘤为单生球状或椭圆形,以后顶端伸长或分叉,呈分叉状、姜状和扇状。同一植株的不同成熟度根瘤的固氮活性也不同,成熟壮瘤固氮活性最高,幼瘤次之,衰老瘤最低。不同立地条件下种植的大叶相思根瘤固氮活性虽有差异,但生长在pH4.7的酸性红壤中的大叶相思,根瘤固氮活性仍具有较高水平。大叶相思根瘤固氮活性也有明显的季节变化,夏秋较高,春冬较低。根瘤离体后7小时内固氮活性变化不大,甚至在离体后21小时内仍维持一定水平的固氮活性。大叶相思根瘤具有吸氢酶,其吸H_2活性在最初3小时内随时间延长而升高,3—7小时内仍维持一定水平。在根瘤固氮系统中注入外源分子H_2,可提高固氮酶活性,外源H_2最适浓度为7.5％。由于其根瘤具有催化吸收分子H_2的氢酶系统,能吸收利用固氮反应所放出的大量H_2,因而能更有效地利用光合产物于固氮过程。大叶相思根瘤离体后能较长时间维持高的固氮活性水平,可能与其吸H_2酶系统有关。     

灰金合欢根瘤类菌体繁殖及其宿主细胞的超微结构

根瘤细胞早期发育阶段,以宿主细胞器和根瘤菌转化类菌体的数量增多为特征。随后类菌体增殖到填满宿主细胞内的大部分区域。各个类菌体周膜内含有1至几个类菌体。晚期共生发育阶段,类菌体细胞结构和宿主细胞器数量发生了变化。文中还讨论了根瘤的共生固氮作用。     

GROWTH OF COLPOMENIA PEREGRINA (PHAEOPHYCEAE) IN CULTURE: EFFECTS OF SALINITY,TEMPERATURE AND DAYLENGTH1

Increases in size of Colpomenia peregrina (Sauv.) Hamel microthalli were determined at six different combinations of salinity and temperature under laboratory conditions. Microthalli grown at low salinity (15%) did not have a growth rate significantly different from microthalli grown at high salinity (30%). However, more macrothalli were produced in higher salinity media. Fewer macrothalli were produced at lower temperatures. Growth of C. peregrina microthalli was also determined at six different combinations of daylength and temperature. Microthalli under 15:9 h (LD cycle) did not have a growth rate significantly different from microthalli under 9:15 h LD. However, more macrothalli were produced under long day conditions. Of the three different temperatures utilized (5, 13 and 20° C) only 5° C produced significantly different growth rates. Low temperature reduced growth to such an extent that macrothalli of a size that could be recognized in the field took approximately two months to produce in culture. These results may explain the seasonal presence/absence of the delophycean phase of C. peregrina in the field. Zoospore survivorship and macrothallus production of C. peregrina in culture indicated that both PES and an artificial medium were suitable for the laboratory cultivation of this plant.     

豆科根瘤拟菌体周膜来源和扩增方式的多样性

豆科植物根瘤内的共生拟菌体需有周膜包围。田菁［Ｓｅｓｂａｎｉａ ｃａｎｎａｂｉｎａ （Ｒｅｔｚ．） Ｐｅｒｓ．］、大豆［Ｇｌｙｃｉｎｅ ｍ ａｘ （Ｌ．） Ｍｅｒｒ．］和豌豆（Ｐｉｓｕｍ ｓａｔｉｖｕｍ Ｌ．）的根瘤拟菌体周膜内有多个拟菌体。在周膜形成和周膜内的拟菌体由１ 个到多个的根瘤发育过程中,要有大量的膜来源和周膜的扩增才能适应这种生理变化。同一种根瘤内周膜扩增有周膜间的镶嵌融合,周膜与内质网及其小泡、小液泡膜融合等多种方式。细胞化学表明：周膜、质膜和内质网膜具有相同型的ＡＴＰ酶,周膜是一种嵌合膜,与质膜、内质网膜和液泡膜有共性。最后对周膜来源和扩增方式多样性的生理意义进行了讨论     

根瘤菌在宿主细胞内的存在形式及其命运

根瘤菌在根瘤宿主细胞内有两种形式：一种为拟菌体、被宿主细胞来源的财膜包裹;另一种为自由生活的营养细胞。前者色大多数,后者只有少数。随着根瘤的衰老,其命运是：拟菌体及其宿主细胞同时衰老以致最终解体,拟菌体不能再入土壤复生;以自由生活的营养细胞形式存在的细菌,不随其宿主细胞的解体而亡,可回复到土壤,一方面在豆科植物和土壤之间循环,一方面维持根瘤菌在土壤中天然的群体生态平衡。