摘要:

A controlled crossing program resulted in the production of four interspecific and three intergeneric hybrids among species ofAstersect.OxytripoliumandMachaeranthera. Meiotic analysis revealed stronger degrees of genome homology in some of the intergeneric hybrids than in some of the interspecific hybrids. The significance of these results to the taxonomy ofAsterandMachaerantherawas considered and the result was the transfer ofAster sonoraetoMachaeranthera.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06049.x

出版商:Wiley    

年代:1978

数据来源: WILEY

摘要:

Cultivated varieties (cvs) of the avocado(Persea americana)originate by selfing, hybridization or chance selections, and are then propagated by grafting. The mesocarps of a given cv are consequently all genetically identical. Mesocarp gene‐enzyme systems were examined by starch gel electrophoresis and were found to be highly polymorphic. Alcohol dehydrogenase, phosphoglucomutase, glutamic‐oxaloacetic transaminase and leucine aminopeptidase are coded by 10 genes with 20 condominant alleles. ‘Seedling’ populations have been produced by selfing or by hybridizing cvs. Seedlings were found to segregate in normal Mendelian fashion for any gene for which the parent or parents were heterozygous. No isozyme evidence contradicted the reported parentage of several cvs of hybrid or selfed origin. Outcrossing, as indicated by the presence of a non‐parental isozyme, was detected among the seedlings of a supposed selfed population. To our knowledge, this is the first report of molecular genetics and of the genetics of any single‐gene character for the avocado. Possible applications are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06050.x

出版商:Wiley    

年代:1978

数据来源: WILEY

摘要:

The capitate‐sessile and capitate‐stalked glands of the glandular secretory system inCannabis, which are interpreted as lipophilic type glandular hairs, were studied from floral bracts of pistillate plants. These glands develop a flattened multicellular disc of secretory cells, which with the extruded secretory product forms the gland head and the auxiliary cells which support the gland head. The secretory product accumulates beneath a sheath derived from separation of the outer wall surface of the cellular disc. The ultrastructure of secretory cells in pre‐secretory stages is characterized by a dense ground plasm, transitory lipid bodies and fibrillar material, and well developed endoplasmic reticulum. Dictyosomes and dictyosome‐derived secretory vesicles are present, but never abundant. Secretory stages of gland development are characterized by abundant mitochondria and leucoplasts and by a large vacuolar system. Production of the secretory product is associated with plastids which increase in number and structural complexity. The plastids develop a paracrystalline body which nearly fills the mature plastid. Material interpreted as a secretion appears at the surface of plastids, migrates, and accumulates along the cell surface adjoining the secretory cavity. Extrusion of the material into the secretory cavity occurs directly through the plasma membrane‐cell wall barrier.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06051.x

出版商:Wiley    

年代:1978

数据来源: WILEY

摘要:

Penetrating palladium probes were placed in the stem and leaf ofKalancho'ë blossfeldiana. The electropotentials arising in the probes at the wound site were continuously monitored during the subsequent healing process. The potential change was always in the positive going direction, beginning at an average of 320 millivolts and stabilizing at an average of 601 millivolts relative to a standard hydrogen electrode. The healing process can be divided into two distinct phases: an initial phase of approximately 6 hr duration in which the potential rises rapidly and a second phase extending to approximately dusk on the third day in which the potential rises at a substantially lower rate. There is also a definite change of the transition potential waveshape at the beginning and end of the 16‐hr light period during the healing process. Rewounding results in a potential recovery waveshape similar to the original healing response but of shorter duration. The data are interpreted in terms of the redox status of the wound site.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06052.x

出版商:Wiley    

年代:1978

数据来源: WILEY

摘要:

The development of zonation in the shoot apical meristems of 28 species of cacti was examined. At germination the embryonic apex may have one of three types of organization: 1) tunica/corpus; 2) tunica/central mother cells/corpus; 3) tunica/central mother cells/peripheral zone/pith‐rib meristem. Apices of the third type have complete zonation and undergo little or no further structural development. Both of the other types develop the missing zones. First, the apices become mitotically active, and peripheral zone characters develop in the outer corpus. Simultaneously, or slightly later, the central mother cells differentiate if they are not yet present. The final step is the formation of the pith‐rib meristem. The sequence of appearance of the zones was constant throughout all species examined, but the time of appearance of only one zone could be correlated with any other morphogenetic process: the development of peripheral zone characteristics in the outer corpus occurs with or before the beginning of leaf production. The development of zonation appears to be independent of apical size, shape, or age, either real age or plastochron age. This has been interpreted to indicate that the metabolic mechanism controlling the development of zonation in shoot apical meristems is largely autonomous and independent of other aspects of morphogenesis occurring in the seedling. Also, the fact that leaf initiation and shoot axis production can both occur before the development of either the central mother cells or the pith‐rib meristem indicates that neither of these zones is essential for these two apical morphogenetic activities.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06053.x

出版商:Wiley    

年代:1978

数据来源: WILEY

摘要:

The genusGlycineWilld. is divided into three subgenera,GlycineWilld.,Soja(Moench) F. J. Herm., andBracteataVerdc. Six species are currently recognized in the subgenusGlycine: G. canescensF. J. Herm.,G. clandestinaWilld.,G. falcataBenth.,G. latrobeana(Meissn.) Benth.,G. tabacina(Labill.) Benth., andG. tomentellaHayata. Distribution of the subgenus extends from south China to Tasmania and includes several Pacific islands. A collection of these species was examined cytologically and morphologically in an attempt to evaluate existing variability between and within taxa. Chromosome counts confirmedG. canescens, G. clandestinaandG. falcatato be diploid with 2n= 40. Both tetraploids (2n= 80) and diploids were found inG. tabacina, the latter restricted to Australia.Glycine tomentellaaccessions were primarily tetraploid, but several collections from New South Wales, Australia, were found to be aneuploid with 78 chromosomes. One collection was aneuploid at the diploid level with 38 chromosomes. Meiosis appeared normal in the aneuploids with regular bivalent formation. Several accessions previously identified asG. tomentellawere diploid. Seed ofG. latrobeanawas not available for analysis. Numerical techniques in the form of cluster analysis and principal components analysis were applied to morphological data on vegetative and inflorescence characters obtained from each collection. Numerical analysis grouped the accessions essentially according to current species delimitations with some exceptions.Glycine tabacinaspecimens from Taiwan approachedG. clandestinain several characteristics. The diploidG. tomentellaspecimens formed a separate cluster and appeared morphologically distinct from the remaining taxa.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06054.x

出版商:Wiley    

年代:1978

数据来源: WILEY

摘要:

InNigella damascena, where “doubleness” behaves as a single gene character, recessive to the normal wild “single” form, we detected a number of differential responses of cultured floral apices of the two forms to plant growth regulators. “Single” buds initiated all organ types on a defined medium lacking any plant growth regulators. “Double” buds, however, required either kinetin or GA3for the development of a normal organ complement. Kinetin enhanced the growth and development of buds of both genotypes, whereas GA3, at all concentrations, specifically inhibited the initiation and growth of stamens and nectaries in “single” buds. No combination of IAA or kinetin overcame this inhibition of “single” buds by GA3. In the presence of both IAA and GA3, “single” buds, following the initiation of normal carpels, initiated a few abnormal carpelloid structures from regions which had failed to produce stamens and nectaries. These observations, coupled with other studies including those on the endogenous levels of gibberellin in the two genotypes, suggest that “doubleness” correlates strongly with a modification of gibberellin metabolism. The causal connection between the two phenomena is as yet to be discovered.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06055.x

出版商:Wiley    

年代:1978

数据来源: WILEY

摘要:

Five populations ofPinus rigidagrowing in contrasting ecological situations ranging from North Carolina (35°53'N latitude) to Quebec (45°06'N latitude) showed no significant variation in amounts of nuclear DNA with respect to germinating seedlings. Nuclear volume of dormant nuclei also showed no significant variation between and within populations, a finding that is consistent with the concept that the basic 2C DNA value ofPinus rigidais uniform under all habitats. This finding is in contrast to numerous reports for other coniferous species.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06056.x

出版商:Wiley    

年代:1978

数据来源: WILEY

摘要:

Developmental evidence shows that the acervulus, a distinctive flower cluster found only in the chamaedoreoid group of palms, is a form of cincinnus. InHyophorbe indicaGaertner, the unit consists of a row of sessile flowers, the upper 3–4, staminate and the basal flower, pistillate. During initiation, each new flower originates from divisions in the T2and underlying layers of the lower right or left flank of the apex of the preceding flower. A bract subtending the first flower is evident in early stages, is displaced basipetally as the flowers are formed, but is obscured when flowers are mature. No other bracts are associated with the unit. One to two outer bundles of the vascular cylinder of the rachilla develop first to the uppermost flower. Subsequently, bundles to other flowers arise as lower branches of the first bundle and from other, often small outer bundles of the rachilla that become floral traces or produce one or more branches to a flower. Many of the bundles supplying the flowers bend sharply downward in the cortex of the rachilla, apparently reflecting the basipetal sequence of floral inception.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06057.x

出版商:Wiley    

年代:1978

数据来源: WILEY

摘要:

The changes in distribution of several important mineral nutrients (N, K, Ca, Mg, Mn, and Fe) were studied in relation to monocarpic senescence (measured as leaf yellowing) and fruit development in hydroponically‐grown (and to a lesser extent field‐grown) Anoka soybeans with particular emphasis on the leaves and seeds. Only N shows a clear redistribution from the leaves to the seeds as the seeds grow, and this transfer starts before visible leaf yellowing. K, Ca, Mn and Fe do not seem to redistribute, but Mg may undergo limited redistribution. Depodding prevents the drop in the amounts of minerals in attached leaves by blocking leaf shedding and/or redistribution and also creates some quantitative changes in mineral distribution. On a g fresh weight basis, only the N content of leaf blades decreases during yellowing; the K, Mg, Ca, Mn and Fe contents do not decrease. Therefore, depletion of the latter minerals from the leaves cannot be responsible for their yellowing. Although N deficiency alone could cause foliar chlorosis, the monocarpic yellowing pattern is distinctly different from that induced by N deprivation.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1978.tb06058.x

出版商:Wiley    

年代:1978

数据来源: WILEY