Microtubule organization in sperm cells in the pollen tubes ofBrassica oleracea L.

Summary Microtubules tightly cross-linked into bundles are described in the sperm cells ofBrassica oleracea pollen tubes. The sperm cells are lobed and tailed and the microtubule bundles are often located in these parts of the cells. In the present paper we suggest that the cross-linked microtubule organization could determine an intertubular sliding, probably generating a motility system that propels the sperm cells through the tube.Abbreviations GC generative cell - Mfs microfilaments - Mts microtubules - SC sperm cell - VC vegetative cell - VN vegetative nucleus     

Ploidy chimeras in plants regenerated from the tissue cultures ofBrassica oleracea L

Two plants which were sectorial chimeras in the two tested characters,i.e. in the length of stomata and their frequency, were found among the 17 individuals regenerated from the stem pith of the same marrow stem kale plant. The chimeral character was also expressed in the size and variability of pollen grains and in the number of colpae in their exine. The different ploidy of sectors (2n, 4n) was confirmed cytologically.     

Size of stomata and palisade parenchyma on cotyledon adaxial side in someBrassica oleracea L. varieties

Cotyledons of 15 day-old seedlings of fiveBrassica oleracea L. varieties were surveyed to identify salient anatomical features. Both palisade parenchyma cells present in the first subepidermal layer and stomata were found to differ in size.     

The relationships between quantitative characteristics of stomata and epidermal cells of leaf epidermis

Negative linear correlations were established inMagnolia soulangeana Soul. —Bod. andLigustrum vulgare L. leaves between the frequency and the size (length) of the stomata and between the frequency of the stomata and the area of epidermal cells. Most correlations were statistically significant at theP = 0.01 level. Positive linear correlations were established between the area and the thickness of epidermal cells. These correlations were near to theP = 0.05 level of statistical significance. A high variation coefficient “v%” of the total number of stomata per leaf was found in both plant species.     

Tissue distribution of phenylpropanoid metabolism in cotyledons of Raphanus sativus L.

The tissue distributions of sinapic acid esters (1-sinapoylglucose, sinapolyl-l-malate, 6,3-disinapoylsucrose), kaempferol glycosides, free malic acid and of the enzyme involved in the synthesis of sinapoyl-l-malate, 1-sinapoylglucose: l-malate sinapoyltransferase (SMT), have been investigated in cotyledons of Raphanus sativus L. seedlings. The kaempferol glycosides were mainly localized in the upper epidermis. The sinapoyl esters were found in all tissues, but differed markedly in their concentrations. While disinapoylsucrose was localized predominantly in the mesophyll, most sinapoylmalate was found in the epidermal layers, as was most SMT activity. Ultraviolet microscopy and microfluorospectrophotometry of isolated epidermal peels indicated that the epidermal sinapoyl esters were restricted to guard cells, guard mother cells and adjacent epidermal cells. Upon excitation by UV light (365 nm) these exhibited strong blue fluorescence with an emission maximum at about 480 nm. Our results indicate a highly tissue-and cell-specific secondary metabolism in Raphanus cotyledons and indicate that the biosynthesis of sinapoylmalate is intimately related to the malic-acid metabolism of the guard cells.Abbreviations HPLC high-performance liquid chromatography - SMT 1-sinapoylglucose: l-malate sinapoyltransferase     

Structure, distribution and taxonomic importance of foliar stomata in some Indian Amaranthaceae

The structure, distribution and taxonomic importance of foliar stomata in 45 taxa belonging to 19 genera have been studied. In all, six stomatal types have been recognized viz., anomocytic, anisocytic, diacytic, paracytic, hemiparacytic and brachyparacytic. The majority of the taxa are amphistomatic whereas hypostomatic leaves are confined to only three taxa. Stomatal diversity is common but most of the taxa show either dominance or codominance. Stomatal distribution is helpful in distinguishing the three tribes of the Amaranthaceae. The tribe Celosieae shows exclusive presence of anomocytic and anisocytic stomata whereas Amarantheae and Gomphreneae show other stomatal types viz., paracytic and diacytic in addition to anomocytic and anisocytic stomata. Further, the latter two tribes are each distinguishable into two subtribes on the basis of stomata.     

Genetic variation within and among different cultivars and landraces of Brassica campestris L. and B. oleracea L. based on isozymes

Genetic variation based on isozymes was studied in 43 landraces and cultivars of Brassica campestris from China, 4 cultivars of B. campestris from Sweden and 1 from India, and 5 cultivars of B. oleracea from Sweden and 1 from China (B. alboglabra). A total of 17 isozyme loci was studied, 10 of these were polymorphic in B. campestris and 6 were polymorphic in B. oleracea. The level of heterozygosity seemed to be reduced in the Swedish cultivars compared to the Chinese landraces and cultivars of B. campestris. The level of heterozygosity in B. oleracea was even lower than that in the Swedish cultivars of B. campestris. A phylogeny of the cultivars and landraces of B. campestris showed that the B. campestris var yellow sarson cultivar, originating from India, deviated significantly from the other cultivars of B. campestris. A phylogeny of the cultivars of B. oleracea confirmed the expectations that the cultivar B. alboglabra was not closely related to the cultivated forms of B. oleracea.     

Nuclear and nucleolar inclusions in root tip ofBrassica napus L.

Summary Vacuole-like structures were found in the nuclei of root tip cells ofBrassica napus. The cells containing the unusual nuclear inclusions were found to be adjacent to zones of degenerating cells. Such groups of cells occurred irregularly in the meristematic regions of the young root tips. The possibility that they represent changes which have occurred in old seeds is discussed.The vacuole-like structures seen in the cells adjacent to the degenerating zones were bounded by a membranous layer 12 nm thick. This is thicker than most cellular membranes. The vacuoles frequently contained inclusions and showed similarities to protein bodies reported elsewhere. The structures are thought to represent rearrangements of cell products which may have accumulated through an imbalance of metabolism in consequence of the imminent cell degeneration.     

Anatomical distribution of sterols in some filter feeding invertebrates

The sterol composition of separate organs of the filter-feeding invertebrates Anodonta cygnea, Mytilus galloprovincialis and Ascidia sp. is described.The distribution of the individual free sterols and sterol esters is compared in eight different organs of A. cygnea and in five organs of M. galloprovincialis and Ascidia sp.Hypotheses about the metabolism and the physiological functions of sterols in these organisms are suggested.     

Chloroplast DNA study in wild populations and some cultivars of Prunus avium L.

The PCR-RFLP technique was used to detect chloroplast DNA diversity in wild populations of Prunus avium from five European deciduous forests and some cultivars. A study of 10.8% of the total chloroplast genome detected eight insertion-deletion (indel) mutations, distributed over 12 haplotypes. Six haplotypes (H1, H2, H3, H4, H5 and H6) were found in wild populations and eight (H2, H6, H7, H8, H9, H10, H11 and H12) in the cultivars. Only two haplotypes (H2 and H6) are shared by the wild populations and the cultivars. The most-abundant and frequent haplotype in wild populations is H2 (frequency=78%). The wider geographical distribution along with the high frequency reflects its ancient origin. Of the five populations, three are polymorphic. Populations GA (Scotland) and KE (Germany) have unique haplotypes. The total cpDNA diversity in wild populations is h_T=0.40, and a major portion of it is within populations (h_S=0.37). The genetic differentiation among populations was low (G_STC=0.08) and no genetic structure among wild populations was observed. A minimum-length spanning tree, demonstrating relationships among the haplotypes in wild populations, indicated two possible chloroplast lineages. The ten identified cultivars were represented by seven haplotypes; this result proposes the possible utilisation of the PCR-RFLP technique for the characterisation of sweet cherry cultivars. The cpDNA diversity in P. avium should be considered carefully for phylogenetic studies involving this species. Received: 10 July 2000 / Accepted: 19 October 2000     

An efficient Agrobacterium tumefaciens-mediated transformation and regeneration system for cotyledons of spinach (Spinacia oleracea L.)

An efficient transformation and regeneration system was established for the production of transgenic spinach (Spinacia oleracea L.) plants. Cotyledon explants were infected with Agrobacterium tumefaciens strain LBA4404 carrying the selectable marker gene, neomycin phosphotransferase II (nptII), and the reporter gene smgfp, encoding soluble-modified green-fluorescent protein, driven by the cauliflower mosaic virus 35S promoter. The infected explants were cultured on Murashige and Skoog medium, containing 1 mg/l benzyladenine and 0.4 mg/l naphthaleneacetic acid. Shoots were regenerated on selection medium containing 50 mg/l kanamycin. Regenerated kanamycin-resistant shoots were rooted on medium containing 1 mg/l indolebutyric acid and subsequently grown in soil in the greenhouse. Southern blot analysis indicated that the smgfp gene had been integrated into the spinach genome. Northern and Western blots showed that the smgfp gene was expressed in progeny plants. Received: 31 March 1998 / Revision received: 27 September 1998 / Accepted: 10 Ocotber 1998     

The genus Eugenia L. (Myrtaceae) in southern Africa: the structure and taxonomic value of stomata

The mature stomatal morphology of 11 southern African species of Eugenia , and also of E. uniflora L. (naturalized) and E. incerta Diimmer (a garden plant of unknown origin) has been studied by light and scanning electron microscopy.
Leaves of all the species are hypostomatic and water-stomata are occasionally present. Two different stomatal types, X and Y, differing mainly in their cuticular ornamentation, were found in the southern African species. The grouping of species based on stomatal characters supports a previous grouping of species on the basis of periderm and seed characters.
Conspicuous lipid bodies, usually present in the subsidiary cells, are limited to the southern African species. Although the subsidiary cells do not differ in shape and size from adjacent epidermal cells, their contents often have a higher tannin content than ordinary epidermal cells. The variable patterns of arrangement of the three to five subsidiary cells makes it difficult to identify the stomata with existing classifications based on mature topography. Thus, a new term 'anomostaurocytic' is proposed for the stomatal type found in the southern African species.
Stomata of E. uniflora and E. incerta are paracytic and anomocytic respectively, and the cuticular ornamentation of their stomata differs from those of the southern African species. The view that E. incerta is not closely related to the southern African species is supported by differences in its cuticular ornamentation, lack of lipid bodies in the subsidiary cells, anomocytic stomata and prominent T-pieces at the guard cell poles.     

Spatial distribution characteristics of stomata at the areole level in Michelia cavaleriei var. platypetala (Magnoliaceae)

Background and AimsIn hierarchically reticulate venation patterns, smaller orders of veins form areoles in which stomata are located. This study aimed to quantify the spatial relationship among stomata at the areole level.MethodsFor each of 12 leaves of M. cavaleriei var. platypetala, we assumed that stomatal characteristics were symmetrical on either side of the midrib, and divided the leaf surface on one side of the midrib into six layers equidistantly spaced along the apical–basal axis. We then further divided each layer into three positions equidistantly spaced from midrib to leaf margin, resulting in a total of 18 sampling locations. In addition, for 60 leaves, we sampled three positions from midrib to margin within only the widest layer of the leaf. Stomatal density and mean nearest neighbour distance (MNND) were calculated for each section. A replicated spatial point pattern approach quantified stomatal spatial relationships at different distances (0–300 μm).Key ResultsA tendency towards regular arrangement (inhibition as opposed to attraction or clustering) was observed between stomatal centres at distances <100 μm. Leaf layer (leaf length dimension) had no significant effect on local stomatal density, MNND or the spatial distribution characteristics of stomatal centres. In addition, we did not find greater inhibition at the centre of areoles, and in positions farther from the midrib.ConclusionsSpatial inhibition might be caused by the one-cell-spacing rule, resulting in more regular arrangement of stomata, and it was found to exist at distances up to ~100 μm. This work implies that leaf hydraulic architecture, consisting of both vascular and mesophyll properties, is sufficient to prevent important spatial variability in water supply at the areole level.     

Structure, distribution and taxonomic importance of stomata in some Indian Tephrosia Pers.(Fabaceae)

SUBBA RAO, J.V.& SHANMUKHA RAO, S. R.(1994).Structure, distribution and taxonomic importance of stomata in some Indian Tephrosia Pers.(Fabaceae).Structure, distribution and taxonomic importance of stomata in all the vegetative parts of 18 taxa of Indian Tephrosia including five species endemic to south India are described. The stomata are anisocytic, anomocytic or paracytic. In addition, brachyparacytic stomata have been recorded for the first time in this taxon. This is the first attempt to assess subgeneric treatment in the light of stomatal characteristics and it suggests certain realignments at the infrageneric level in Indian Tephrosia.     

Control of soil physical properties and response ofBrassica rapa L. seedling roots

A system was designed, constructed, tested, and used to growBrassica rapa L. seedling roots which were exposed to O₂ concentrations from 0 to 0.21 mol mol⁻¹, water potentials from 0 to −80 kPa, temperatures from 10 to 34°C, and mechanical impedance from 0 to 20.8 kPa. The experimental design was a central composite rotatable design with seven replications of the center point. Measurements were taken of taproot length, taproot diameter at the point of initiation of root hairs (diameter 1), and one cm above the first measurement (diameter 2), and total length and number of first-order laterals. Temperature had the greatest effect on seedling root growth, with linear and quadratic temperature effects significant for all root measurements except taproot diameter 2 which just had a significant linear effect. Water potential had a significant linear effect on lateral length and number of laterals and a significant quadratic effect on taproot diameter 1. Mechanical impedance had a significant effect only on taproot diameter 2. Oxygen was not significant for any root measurement. The mechanical impedance by water potential interaction was significant for taproot length and taproot diameter 1. A temperature optimum was found for taproot length, taproot diameter 1, lateral length, and lateral number, at 26.0, 42.5, 26.5, and 26.4°C, respectively. Taproot diameter 1 had a water potential optimum at −36.5 kPa, whereas taproot diameter 2 had a mechanical impedance optimum at 12.5 kPa. A growth cell designed for this study allows independent control of soil strength, water potential, oxygen concentration, and temperature. Thus, the cell provides the capability which was demonstrated forBrassica rapa L. to grow seedling roots under complete control of the soil physical properties.     

不同产地何首乌叶表皮结构的解剖学特征与气候因子的关系

在光学显微镜下观察了不同产地何首乌叶表皮结构特征,应用多元回归方法对不同产地何首乌的叶表皮特征与气候因子的关系进行了分析。观察的叶表皮特征指标有气孔密度、气孔指数、气孔器长、气孔器宽、气孔极区角质加厚、气孔器类型、表皮细胞垂周壁性状及叶表面角质条纹。观察结果:上表皮有少量气孔器分布;在下表皮,气孔器类型为非典型不等细胞型和不规则型,有少量腺鳞分布,气孔器密度每1mm2为241.7(64～573)个,气孔指数为17.1(7.5～26.5)%,气孔器长31.1(20～44)μm,气孔器宽23.1(16～38)μm。随着产地的不同,何首乌叶下表皮结构有明显差异。分析结果显示气孔器、气孔器宽度以及气孔密度均与纬度关系密切,随纬度的升高,气孔器长、气孔器宽呈减小的趋势,气孔密度呈增加的趋势,R2值分别为0.619、0.729、0.772。