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141.
The chloroplast ATP synthase synthesizes ATP from ADP and free phosphate coupled by the electrochemical potential across the thylakoid membrane in the light. The light-dependent regulation of ATP synthase activity is carried out in part through redox modulation of a cysteine disulfide bridge in CF1 gamma-subunit. In order to investigate the function of the redox regulatory domain and the physiological significance of redox modulation for higher plants, we designed four mutations in the redox regulatory domain of the gamma-subunit to create functional mimics of the permanently reduced form of the gamma-subunit. While the inability to reduce the regulatory disulfide results in lower photosynthesis and growth, unexpectedly, the results reported here show that inability to reoxidize the dithiol may not be of any direct detriment to plant photosynthetic performance or growth. 相似文献
142.
Black CC 《Photosynthesis research》2008,95(1):1-10
The very personal touch of Professor Martin Gibbs as a worldwide advocate for photosynthesis and plant physiology was lost
with his death in July 2006. Widely known for his engaging humorous personality and his humanitarian lifestyle, Martin Gibbs
excelled as a strong international science diplomat; like a personal science family patriarch encouraging science and plant
scientists around the world. Immediately after World War II he was a pioneer at the Brookhaven National Laboratory in the
use of 14C to elucidate carbon flow in metabolism and particularly carbon pathways in photosynthesis. His leadership on carbon metabolism
and photosynthesis extended for four decades of working in collaboration with a host of students and colleagues. In 1962,
he was selected as the Editor-in-Chief of Plant Physiology. That appointment initiated 3 decades of strong directional influences by Gibbs on plant research and photosynthesis. Plant Physiology became and remains a premier source of new knowledge about the vital and primary roles of plants in earth’s environmental
history and the energetics of our green-blue planet. His leadership and charismatic humanitarian character became the quintessence
of excellence worldwide. Martin Gibbs was in every sense the personification of a model mentor not only for scientists but
also shown in devotion to family. Here we pay tribute and honor to an exemplary humanistic mentor, Martin Gibbs. 相似文献
143.
144.
Isoprenoid biosynthesis in plants occurs by two independent pathways: the cytosolic mevalonate (MVA) pathway and the plastidic
methylerythritol phosphate (MEP) pathway. In this study, we investigated the cellular effects of depletion of IspE, a protein
involved in the MEP pathway, using virus-induced gene silencing (VIGS). The IspE gene is preferentially expressed in young tissues, and induced by light and methyl jasmonate. The GFP fusion protein of IspE
was targeted to chloroplasts. Reduction of IspE expression by VIGS resulted in a severe leaf yellowing phenotype. At the cellular level, depletion of IspE severely affected
chloroplast development, dramatically reducing both the number and size of chloroplasts. Interestingly, mitochondrial development
was also impaired, suggesting a possibility that the plastidic MEP pathway contributes to mitochondrial isoprenoid biosynthesis
in leaves. A deficiency in IspE activity decreased cellular levels of the metabolites produced by the MEP pathway, such as
chlorophylls and carotenoids, and stimulated expression of some of the downstream MEP pathway genes, particularly IspF and IspG. Interestingly, the IspE VIGS lines had significantly increased numbers of cells of reduced size in all leaf layers, compared
with TRV control and other VIGS lines for the MEP pathway genes. The increased cell division in the IspE VIGS lines was particularly
pronounced in the abaxial epidermal layer, in which the over-proliferated cells bulged out of the plane, making the surface
uneven. In addition, trichome numbers dramatically increased and the stomata size varied in the affected tissues. Our results
show that IspE deficiency causes novel developmental phenotypes distinct from the phenotypes of other MEP pathway mutants,
indicating that IspE may have an additional role in plant development besides its role in isoprenoid biosynthesis.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Genbank accession number for IspE: ABO87658. 相似文献
145.
146.
M. M. Ribeiro C. Plomion R. Petit G. G. Vendramin A. E. Szmidt 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(1):97-103
Genetic variation in 12 Pinus pinaster (maritime pine) populations spanning most of the distribution range of the species in Portugal was evaluated using six polymorphic
chloroplast microsatellite (cpSSR) loci. Thirty-two haplotypes were found. There were indications of very weak differentiation
among populations (Weir’s θcoefficient, 0.023), and the R
ST value, derived from the stepwise mutation model (SMM), was not significantly different from zero. The pattern, in which similarities
in allele size, in base pairs, do not contribute to the genetic structure, may be due to the recent mixing of genetic material
from different stands through plantations. Overall, a high level of haplotypic variation within populations was detected.
Using the SMM estimator (mean genetic distance of individuals within populations, D
2
sh
–––) we divided the populations into two groups, with above and below average values. The first group contained 5 populations,
mainly from the central part of the country, which possess, in general, high levels of haplotypic diversity. Among them, 2
populations were divergent from the others based on the pair-wise Nei’s distance. The results indicate that there is no discernible
geographic genetic pattern for the Portuguese populations of P. pinaster investigated. The history of expansion of the species range in Portugal during the twentieth century (mainly due to human
activity) and extensive gene flow among populations associated with the expansion could explain this finding.
Received: 15 February 2000 / Accepted: 14 April 2000 相似文献
147.
Sodium—A Functional Plant Nutrient 总被引:3,自引:0,他引:3
Plant scientists usually classify plant mineral nutrients based on the concept of “essentiality” defined by Arnon and Stout as those elements necessary to complete the life cycle of a plant. Certain other elements such as Na have a ubiquitous presence in soils and waters and are widely taken up and utilized by plants, but are not considered as plant nutrients because they do not meet the strict definition of “essentiality.” Sodium has a very specific function in the concentration of carbon dioxide in a limited number of C4 plants and thus is essential to these plants, but this in itself is insufficient to generalize that Na is essential for higher plants. The unique set of roles that Na can play in plant metabolism suggests that the basic concept of what comprises a plant nutrient should be reexamined. We contend that the class of plant mineral nutrients should be comprised not only of those elements necessary for completing the life cycle, but also those elements which promote maximal biomass yield and/or which reduce the requirement (critical level) of an essential element. We suggest that nutrients functioning in this latter manner should be termed “functional nutrients.” Thus plant mineral nutrients would be comprised of two major groups, “essential nutrients” and “functional nutrients.” We present an array of evidence and arguments to support the classification of Na as a “functional nutrient,” including its requirement for maximal biomass growth for many plants and its demonstrated ability to replace K in a number of ways, such as being an osmoticium for cell enlargement and as an accompanying cation for long-distance transport. Although in this paper we have only attempted to make the case for Na being a “functional nutrient,” other elements such as Si and Se may also confirm to the proposed category of “functional nutrients.” 相似文献
148.
Chlamydomonas is an unicellular green alga that contains one cup-shaped chloroplast with about 60 copies of cpDNA. Chloroplasts (cp) multiply
in the cytoplasm of the plant cell by binary division, with multiple copies of cpDNA transmitted and maintained in successive
generations. The effect of cpDNA copy number on cell proliferation and aging was investigated using a C. reinhardtii moc mutant, which has an undispersed cp-nucleoid and unequal segregation of cpDNA during cell division. When the mother cell
divided into four daughters, one moc daughter cell chloroplast contained about 60 copies of cpDNA, and the chloroplasts in the three other daughter cells contained
the 4–7 copies of cpDNA. In liquid medium, the number of moc cells at the period of stationary phase was about one-third that of the wild type. To observe the process of proliferation
and aging in the mother cell, we used solid medium. Three out of four moc cell spores were preferentially degenerated 60 days after cell transfer. To confirm this, wild-type and moc mother cells containing four daughter cells were treated with novobiocin to inhibit cpDNA replication. Cell degeneration
increased only in the moc strain following novobiocin introduction. In total, our results suggest that cells possessing smaller amounts of cpDNA degenerate
and age more rapidly.
Received 7 September 2000/ Accepted in revised form 14 February 2001 相似文献
149.
150.
Intact plants and isolated leaves of Zostera capricornii Martens ex Aschers were transferred from daylight to darkness. Substantial amounts of chloropyll a and b continued to accumulate in immature and mature tissue in the same ratio as in the light and were incorporated into chlorophyll-protein complexes in the thylakoids. A small amount of protochlorophyllide also accumulated in immature tissue in the dark. Proplastids and immature chloroplasts continued to develop into mature chloroplasts in the dark in the normal manner but prolamellar bodies, which are a conspicuous feature of immature chloroplasts, took longer to disperse than in the light. Protochlorophyllide accumulation and prolamellar-body formation were not correlated. The results indicate that Zostera has a genetic capacity for dark chlorophyll synthesis which is expressed in immature and mature leaf tissue and enables this plant to continue synthesising chlorophyll and assembling chloroplasts at night.Abbreviations Chl
chlorophyll
-
T
o
time of transfer to darkness 相似文献