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1.
Charlette Said 《Sexual plant reproduction》1989,2(2):77-84
Summary The mature pollen of Larix leptolepis Gord. (Conifer) contains five different cell types, and the plasma membrane of the vegetative cell is continuous and organized. The pollen wall is composed of two morphologically and cytochemically distinct domains: the exine and the intine. In the multilayered exine, the ektexine appears granular and the endexine, lamellar. The intine is thick and bilayered with a microfibrillar structure occupying its inner portion. Cytochemical reactions of the exine and the intine are similar to those found in angiosperms. Pollen wall involvement in the male female recognition system is discussed with respecl to the angiosperms. 相似文献
2.
Fushi Wen Ho Hyung Woo Elizabeth A. Pierson Toril D. Eldhuset C. G. Fossdal N. E. Nagy Martha C. Hawes 《Plant Molecular Biology Reporter》2009,27(1):58-68
Root cap development in cereals and legumes is self-regulated by a repressor that accumulates in the extracellular environment,
and immersing the root tip into water results in renewed cap development. By exploiting this phenomenon, root cap mitosis
and differentiation can be synchronously induced among populations. In Pisum sativum L., messenger RNA (mRNA) differential display revealed changes in expression of approximately 1% of the sample mRNA population
within minutes of induced cap turnover. This profile changes sequentially over a period of 30 min, then stabilizes. Microarray
analysis of Medicago truncatula root caps confirmed changes in expression of approximately 1% of the target population, within minutes. A cell specific marker
for cap turnover exhibited the same temporal and spatial expression profile in the gymnosperm species Norway spruce (Picea abies) as in pea. Induced cap development provides a means to profile cell-specific gene expression among phylogenetically diverse
species from the early moments of mitosis and cellular differentiation. 相似文献
3.
John M. Manners 《Plant Molecular Biology Reporter》2009,27(3):237-242
The founder of the MiAMP1 protein family was originally isolated from Macadamia integrifolia and had antimicrobial activity in vitro. MiAMP1 was the first plant protein with a structure containing a βγ-crystallin precursor
fold, a structural superfamily associated with antimicrobial proteins in other kingdoms. In recent times, expanding plant
genomics information has revealed that genes encoding homologues of MiAMP1 are conserved across the plant kingdom from lycophytes,
gymnosperms to early angiosperms (e.g. Amborella, Papaver) and some monocots (e.g. Zantedeschia, Zea, Sorghum). Many studies of plant–pathogen interactions in gymnosperms have demonstrated a potential role for MiAMP1 family members
in defence against fungal pathogens. This commentary describes the discovery and diversity of this protein family and considers
current evidence supporting, and future opportunities for substantiating, a role in defence in primitive plants, and why this
role may have diminished in higher plants. 相似文献
4.
Growth and development of conifer pollen tubes 总被引:1,自引:0,他引:1
Conifer pollen tubes are an important but underused experimental system in plant biology. They represent a major evolutionary
step in male gametophyte development as an intermediate form between the haustorial pollen tubes of cycads and Ginkgo and the structurally reduced and faster growing pollen tubes of flowering plants. Conifer pollen grains are available in
large quantities, most can be stored for several years, and they grow very well in culture. The study of pollen tube growth
and development furthers our understanding of conifer reproduction and contributes towards our ability to improve on their
productivity. This review covers taxonomy and morphology to cell, developmental, and molecular biology. It explores recent
advances in research on conifer pollen and pollen tubes in vivo, focusing on pollen wall structure, male gametophyte development
within the pollen wall, pollination mechanisms, pollen tube growth and development, and programmed cell death. It also explores
recent research in vitro, including the cellular mechanisms underlying pollen tube elongation, in vitro fertilization, genetic
transformation and gene expression, and pine pollen tube proteomics. With the ongoing sequencing of the Pinus taeda genome in several labs, we expect the use of conifer pollen tubes as an experimental system to increase in the next decade. 相似文献
5.
The top, the lateral and the underside of basal branch segments of two gymnosperm species, spruce (Picea abies [L.] Karst.) and yew (Taxus baccata L.), were studied with respect to possible adaptation in structural and mechanical properties. Microtensile tests were performed on thin wet foils, which were removed from the periphery of the branches. Structural parameters such as density and the microfibril angle in the S2-layer were examined to investigate the structure-function relationships of the branch wood. The top, the lateral and the underside of both branches showed significant differences in their structural and mechanical properties. However, no significant variations were observed as a function of age and size development. The findings were discussed in view of adaptive growth strategies of trees, including biomechanical constraints of a horizontally growing branch. 相似文献
6.
A fossil coleopteran larva was found in a permineralized female fructification of a new extinct gymnosperm from the Late Cretaceous
of Japan. The fossil provides the firstin situ evidence that the insects used some gymnosperm fructification as foods as well as pupation sites before they started using
angiosperm fruits. 相似文献
7.
M. D. Lazzaro 《Protoplasma》1996,194(3-4):186-194
Summary Actin microfilaments form a dense network within pollen tubes of the gymnosperm Norway spruce (Picea abies). Microfilaments emanate from within the pollen grain and form long, branching arrays passing through the aperture and down the length of the pollen tube to the tip. Pollen tubes are densely packed with large amyloplasts, which are surrounded by branching microfilament bundles. The vegetative nucleus is suspended within the elongating pollen tube within a complex array of microfilaments oriented both parallel to and perpendicular with the growing axis. Microfilament bundles branch out along the nuclear surface, and some filaments terminate on or emanate from the surface. Microfilaments in the pollen tube tip form a 6 m thick, dense, uniform layer beneath the plasma membrane. This layer ensheathes an actin depleted core which contains cytoplasm and organelles, including small amyloplasts, and extends back 36 m from the tip. Behind the core region, the distinct actin layer is absent as microfilaments are present throughout the pollen tube. Organelle zonation is not always maintained in these conifer pollen tubes. Large amyloplasts will fill the pollen tube up to the growing tip, while the distinct layer of microfilaments and cytoplasm beneath the plasma membrane is maintained. The distinctive microfilament arrangement in the pollen tube tips of this conifer is similar to that seen in tip growth in fungi, ferns and mosses, but has not been reported previously in seed plants. 相似文献
8.
S. Gerber F. Rodolphe 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,88(3-4):289-292
The genome length, in units of Morgans or centimorgans, is a fundamental feature of a species. It can be calculated from a complete linkage map. However, the genome size can be estimated with partial linkage data. Using linkage data obtained by the analysis of a two-dimensional electrophoresis of the proteins contained in an haploid organ, the megagametophyte, we suggest an estimation and a confidence interval of the genome length of a gymnosperm, the maritime pine (Pinus pinaster Ait.). The results indicate an important gap between the physical and the genetic maps. 相似文献
9.
Polyamines are ubiquitous polycationic compounds that mediate fundamental aspects of cell growth, differentiation, and cell
death in eukaryotic and prokaryotic organisms. In plants, polyamines are implicated in a variety of growth and developmental
processes, in addition to abiotic and biotic stress responses. In the last decade, mutant studies conducted predominantly
in Arabidopsis thaliana revealed an obligatory requirement for polyamines in zygotic and somatic embryogenesis. Moreover, our appreciation for the
intricate spatial and temporal regulation of intracellular polyamine levels has advanced considerably. The exact molecular
mechanism(s) through which polyamines exert their physiological response remains somewhat enigmatic and likely serves as a
major area for future research efforts. In the following review, we discuss recent advances in the plant polyamine field,
which range from metabolism and mutant characterization to molecular genetics and potential mode(s) of polyamine action during
growth and development in vitro and in vivo. This review will also focus on the specific role of polyamines during embryogenesis and organogenesis. 相似文献
10.
广西大瑶山裸子植物区系分析及其在林业中的意义 总被引:4,自引:0,他引:4
大瑶山是广西中部偏东最大的山脉,是广西植物最丰富且在植物学上也是著名的地区。本地区有野生裸子植物6科,11属,17种,4变种,占广西野生裸子植物属的61.11%,种的41.18%。本文通过对属种地理成分的分析,探讨了大瑶山裸子植物区系的性质,是一兼有热带和温带成分的亚热带区系。本文还讨论了大瑶山裸子植物主要种类的分布,以及在植被中的地位及其生产意义。 相似文献