ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00400.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe sieve‐element characters of 40 species from all families making up the monocotyledon order Zingiberales have been studied by transmission electron microscopy. While phloem‐proteins are a typical component of all eight families, the Zingiberaceae are characterized by nondispersive protein bodies derived from nuclear crystals. The sieve‐element plastids are of the form‐P2cs, i.e. contain cuneate protein crystals (as typical of all monocotyledons) and starch grains, those of the family Musaceae have protein filaments in addition (form‐P2cfs). The exclusiveness of the form‐P2c(f)s plastids contributed to the homogeneity of the order and its distinctness among other monocotyledon taxa. When diameters of the sieve‐element plastids from leaf phloem are compared, in the “banana group” the family averages of the Strelitziaceae and the Lowiaceae have, respectively, maximum and minimum values and are clearly different from those in the Musaceae, the family in which they have been included previously. In the “ginger group”, the family averages of the Zingiberaceae, Costaceae, and Marantaceae are close to the order average, with only Cannaceae having minimum values. A comparison of species averages, however, reduces the size differences between families: the value forRavenala(Strelitziaceae) is close to those of the five Musaceae tested, and that ofGlobba(Zingiberaceae) even slightly lower than the sp

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00401.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn the parenchyma cells of 1‐d‐old dark‐grown rye coleoptiles (Secale cereale) proplastids occurred which sometimes contained starch grains. During coleoptile growth in darkness starch‐filled amyloplasts are formed from the preexisting proplastids. No prolamellar bodies were observed in the stroma of the plastids of the etiolated coleoptile. After irradiation of 3‐d‐old etiolated coleoptiles with continuous white light three different types of plastids occurred. In the epidermal cells proplastids were observed. The parenchyma cells below the stomata of the outer epidermis (above the two vascular bundles) contained mature, spindle‐shaped chloroplasts with a well‐developed thylakoid system. In the parenchyma cells that surround the vascular bundles amyloplasts with some thylakoid membranes (chloroamyloplasts) occurred. The mesophyll cells of the primary leaves of dark‐grown seedlings contained etioplasts with large prolamellar bodies. In the primary leaves of irradiated plants chloroplasts similar to those of the parenchyma cells of the coleoptile were observed. Our results show that the rye coleoptile, which grows underground as a heterotrophic organ, is capable of developing mature chloroplasts upon reaching the light above the soil surface. The significance of this expression of photosynthetic capacity for the carbon economy of the developing seed

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00402.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe effects of methylglyoxal‐bis(guanylhydrazone) (MGBG), an inhibitor of polyamine biosynthesis were studied on tuberization and cellular polyamine content usingin vitro Solanum tuberosum(cv Binjte) plants.When MGBG was added to the culture medium, it produced a partial inhibition of the growth of stems and leaves; it totally blocked rhizogenesis and strongly stimulated tuber formation. Morphogenetic effects of MGBG were correlated to a 40 % decrease in free putrescine, spermidine, spermine content of the leaves and to a 28 % decrease in spermidine titer of the stems. In the tubers, this inhibitor did not change the free polyamine titer but increased by up to 85 % the titer of conjugated putrescine, spermidine, spermine. When the plants were grown in the dark, MGBG produced, like benzyladenine, a stimulation of the rate of tuberization and enhanced the content of conjugated polyamines in the tuber.These results support the hypothesis that polyamines play an important role in the morphogenesis of potato plants. The role of polyamine conjugation in tuber development is discusse

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00403.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe touch‐induced free coiling response ofBryonia dioicatendrils is accompanied by the differentiation of supporting tissue at the ventral side of the organ, becoming the inner (concave) side of the coiled tendril. As part of this process, the Bianconi plate, a continuous sclerenchyma sheath stretching along the ventral face of the five bicollateral vascular bundles, becomes strongly lignified. During this reaction, the extractable activity of phenylalanine ammonia‐lyase in the tendrils increases four‐ to five‐fold, while the amount of PAL, as demonstrated by immunoblotting, remains unchanged. This touch‐induced process can also be elicited by airborne application of methyl jasmonate. The PAL inhibitor, 2‐aminoindan‐2‐phosphonic acid (AIP) completely inhibits both the touch‐ and methyl jasmonate‐induced deposition of lignin‐like material in the Bianconi plate, but has no effect on coiling. From these results, it can be concluded that the cessation of growth at the ventral side of a free‐coiling tendril is not due to induced lignification but rather, lignification seems to serve the function of increasing the mechanical strengt

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00404.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractFour species belonging to theLecanora subfuscagroup (Lecanoraceae, lichenized Ascomycotina) and containing the 2,5,7‐trichloro‐3‐O‐methylnorlichexanthone chemosyndrome are described:L. elixiiLumbsch,L. epibryonAch.,L. mayrhoferiLumbsch spec. nov. andL. parmelinoidesLumbsch spec. nov. The species, which are interpreted as being closely related, can be distinguished by a combination of subtle morphological and anatomical cha

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00405.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe zygomyceteGeosiphon pyriformeis the only known endocyanosis of a fungus. TheNostocspp. filaments are included in photosynthetically active and nitrogen fixing, multinucleated bladders, which grow on the soil surface. The spores of the fungus are white or slightly brownish. They are about 250 μm in diameter and develop singly on hyphal ends or, less frequently, intercalarly. The wall of the spores consists of a thin innermost layer, a laminated inner layer with a thickness of about 10–13 μm, and an evanescent outer layer. The laminated layer is composed of helicoidally arranged microfibrils, and is separated from the evanescent outer layer by a thin electron‐dense sublayer. Polarisation microscopy indicates the occurrence of chitin. Shape and wall ultrastructure of theGeosiphonspores and their cytoplasm resemble that ofGlomusspores, but are different from that of other genera of the Glomales and Endogonales. Germination occurs by a single thick hyphal outgrowth directly through the spore wall. Like various AM forming fungi,Geosiphon pyriformecontains endocytic bacteria‐like organisms, which are not surrounded by a host membrane. Our observations indicate thatGeosiphonis a potential AM

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00406.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe water fluxes and the CO2exchange of three leaf succulents,Othonna opima, Cotyledon orbiculataandSenecio medley‐woodii, with different leaf anatomy, growth form and CO2fixation pathways (C3, CAM) were monitored with a gas exchange cuvette which was combined with a potometric system to quantify water uptake. Measurements, which are primarily valid for plants with a sufficient water supply, were made during 6 to 10 consecutive days under constant experimental conditions. Water uptake for 24 h exceeded water loss by transpiration only for aS, medley‐woodiiplant with 10 expanding but only 7 mature leaves. In this case the gained water evidently is put into leaf expansion. All other plants showed balanced transpiration and water uptake rates.O. opimaandC. orbiculatahave a similar life form, similar water storage volumes and the same natural habitat but their diurnal water uptake patterns differ significantly. In the C3plantO. opimawater uptake increased when the transpiration increased or transpiration rates were higher than uptake rates and vice versa. On the contrary the CAM plantC. orbiculatatranspired during the dark period at constant or decreasing rates but showed steadily increasing uptake rates.Senecio medley‐woodii‐andC. orbiculataare CAM plants with similar diurnal water uptake patterns with its maximum in uptake during or towards the end of the CO2dark fixation period. Water uptake ofC. orbiculatawas at its minimum at the end of the light period despite transpiration being maximal. The results were discussed considering the different CO2fixation pathways. In the investigated CAM succulents,C. orbiculataandS. medley‐woodii, the CAM influenced water uptake throughout the whole day and not only during the CO2dark fixati

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00407.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractCambium samples ofThuja occidentalisL. were collected at five different times, covering spring reactivation and early and late resting period, and used for sucrose determinations. Fragments of the different cell types ‐ xylem ray, cambial initials, sieve‐elements including phloem parenchyma cells, phloem ray ‐ were dissected from freeze‐dried radial sections and analyzed individually. Results show large differences in sucrose concentrations in the different cell types of the cambial layer. In addition, each cell type also shows seasonal fluctuations in sucrose content, whose amplitudes and patterns of variation appear specific for the particular ce

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1994.tb00408.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY