ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00507.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYThe diploid annualMicroseris pygmaeais the only Chilean species of the genus and is closely related toM. bigeloviiandM. elegansof California. It must have reached Chile by long‐distance dispersal from California and have gone through a single‐plant bottleneck before becoming established. Previous data on iso‐enzyme alleles and morphology have separated coastal from inland populations and suggested that range expansion took place by stepwise founder effects creating a set of nested monophyletic groups of populations. Here, we test this hypothesis on 10 strains from nine representative populations using nuclear DNA fragments amplifiedin vitrofrom short arbitrary primers (RAPDs) as characters. We obtained 208 amplification products with 24 primers. Of these, 91 were shared by all strains, 93 were informative. The data confirm that coastal and inland populations form two distinct monophyletic groups, but show relatively weak differentiation within each of these groups indicating some gene flow and recombination among neighbouring populations. Homoplasy in the data due to all possible sources including faults in band interpretation is estimated at about 10%. A cladogram of the two genetically most divergent strains ofM. pygmaea, M. bigeloviiandM. elegansshows that each species is monophyletic but does not suggest any closer association betweenM. pygmaeaand one of its possible ancestral sp

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00508.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYDifferent species of the genusCucumiswere characterized with molecular markers. Highly repetitive satellite DNA and different elements of the middle repetitive ribosomal RNA genes were used as hybridization probes. The RFLP analyses and hybridizations with different satellite DNAs and rDNA probes confirmed the division of the genusCucumisinto an African and an Asian subgenus and revealed thatC. meloof the African subgenus is more closely related toC. sativusandC. hardwickiiof the Asian subgenus than toC. anguriawhich also belongs to the African subgenus.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00509.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYThe genomic relationships betweenThinopyrum bessarabicum2n= 14,T. junceiforme2n= 28,T. sartorii2n= 28 andT. junceum2n= 42 were determined by computer‐aided karyotype analysis. The results revealed that the genome ofT. bessarabicumis similar to one of the two nearly identical genomes ofJ. junceiformeand the genome designationsJj1Jj1andJj1Jj1Jj2Jj2are proposed for the two taxa respectively. The chromosome complement ofT. junceiformeis found very similar to that ofT. sartoriifor which the genome designationJj1Jj1Jj3J3is advocated, while both taxa are characterized as segmental allotetraploids.Thinopyrum junceumis characterized as segmental allohexaploid with the genome designationJj1Jj1Jj(2)Jj(2)Jj(3)Jj(3). Furthermore, the examined taxa ofT. junceumpolyploid complex are considered as separate biological species and it is suggested that they have modified versions of the same basic genom

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00510.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYTissue‐cultured plants are different from normal plants because of the environmental conditions in a tissue‐culture container. Together with the water retention capacity (WRC) of the headspace in a container, the gas composition is responsible for a divergent physiological behaviour. By controlling the WRC of the headspace the physiology and anatomy of tissue‐cultured plants can be improved to resemble normal plants.During culturein vitrounder our conditions, the CO2‐level showed a typical circadian shift depending upon illumination, but was always higher than the normal atmospheric concentration. Carbon accumulating in tissue‐cultured plantsin vitrooriginated both from headspace‐CO2and sucrose in the culture medium. The evolution of photosynthesis during the acclimatization process allowed the determination of the condition of the plant and indicated the occurrence of stress after planting and after transfer from weaning to normal

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00511.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYAn increasing number of ornamental crops are being multipliedin vitro. In this article, the application of meristem culture to plants free from viruses is reviewed and is shown to be useful and cost‐effective. First, a literature survey is given on results of meristem culture applied to ornamentals and on damage due to virus diseases. Secondly trials and results with lily,AlstroemeriaandDelphiniumand their viruses are discussed.Virus‐free plants have a considerable surplus value compared with infected plants. Additional advantages are that a virus‐free crop cannot be a source of contamination for other varieties of the same crop, and that there are no phytosanitary limitations. Virus‐free does not mean resistant, however, and re‐infection is possible, but can be prevented by strict measures.Meristem culture applied toin vitrocultures of lily,AlstroemeriaandDelphiniumalways yielded a much lower amount of virus‐free plantlets than the usual procedure, i.e. meristem culture applied to plants grown in the

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00512.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYIn this study, the content of active internal indolebutyric acid (IBA) and of IBA‐derived indoleacetic acid (IAA) was related to adventitious root formation on the stem base of microcuttings of apple. Maximum root formation was obtained after an incubation of 3 days on medium supplemented with 32 μmIBA or 5 days on medium containing 3·2 or 10 μmof the hormone. Two to three weeks after the start of the auxin treatment, the maximum root number was attained. The absorbed IBA‐3H accumulated predominantly in the bottom 1 mm of the stem, i.e. the location where the roots emerge. The metabolism of [3H]‐IBA was examined in this part of the apple shoots in relation to adventitious root formationin vitro.The internal content of free IBA (IBAint) corresponded to about 60% of the IBA concentration in the medium from 6 h to 3 days of incubation. The internal content of IBA‐derived IAA (IAAint) was about 15% of the IBA concentration in the medium. At incubation periods of 2 and 3 days the shorter period required a higher IBAintand IAAintcontent to produce the same amount of roots. This observation indicates that in those cases, the mode of action of IBA in root formation resembles a dose effect of the active auxin components in the stem base. Over the whole range of experimental conditions (6–120 h, 0·1–32 μm), however, the product of incubation time and exogenous concentration or internal content of auxins was not related to the number of roots.The percentage of label recovered in the IBAintand IAAintfractions was the same at suboptimal and optimal IBA concentrations for root formation, and did not change between 0·7 and 3 days after auxin addition. Therefore, root formation was not related to a specific type of

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00513.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYIn many crops, it is important to control dormancy and/or apical dominance during micropropagation. The regulation of dormancy was studied in bulblets of lily, buds of apple and quince, and seeds ofAgrostemma githago. The development of dormancy was enhanced by choosing the appropriate tissue‐culture conditions, in particular temperature, and inhibited by application of fluridone, an inhibitor of abscisic‐acid (ABA) synthesis. For the maintenance of dormancy, continuous synthesis of ABA was required. Dormancy was broken by treatment with gibberellins, or by cold storage under humid conditions. Apical dominance was studied in apple. As a pretreatment with fluridone promoted the outgrowth of axillary buds, ABA may also play a role in the development of apical domina

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00514.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYPlantlets ofCalathea ornatarooted at frequencies varying between 75 and 100% irrespective of the presence of 6‐benzylaminopurine (BAP) or indolebutyric acid (IBA). After transfer to soil all plants grew rapidly with the exception of BAP‐rooted plants, probably because these plants lacked lateral roots. Plantlets ofMalusshowed slightly improved rooting and considerably improved survival at increasing sucrose concentration from 20 to 30 gl−1during multiplication. Their survival and performance after planting in soil depended upon the number of roots formed in rooting medium. Elevated CO2‐levels (800 ml m−3) during acclimatization increased survival rate and plant height of rooted and non‐roote

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00515.x

年代:1992

数据来源: WILEY

摘要:

SUMMARYPlantlets ofLilium speciosumregeneratedin vitroconsist of scales that may or may not bear a leaf. We studied the effects of several physical, nutritional and hormonal factors on dry‐matter partitioning between bulbs and leaves. Both absolute bulb weight and relative bulb weight (bulb weight as a percentage of plant weight) were determined.High temperature, culture in the dark and high osmolarity promoted relative bulb weight. Day‐length had no effect. Amongst the nutritional factors sucrose promoted relative bulb weight. High concentration of MS‐nutrients caused an increase in bulb fresh weight only. Bulb formation was under control of abscisic acid (ABA): ABA added to the medium completely blocked leaf formation, whereas fluridone, an inhibitor of ABA‐synthesis, inhibited bulb formation. Paclobutrazol (PP333) blocked leaf formation completely. The PP333‐effect was reversed by gibberellins A4+7. Cytokinin (6‐benzylaminopurine), auxin (indoleacetic acid), ethylene and methyl jasmonate ha

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1992.tb00516.x

年代:1992

数据来源: WILEY