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21.
Belay?T.?Ayele Jocelyn?A.?OzgaEmail author Aruna?D.?Wickramarathna Dennis?M.?Reinecke 《Journal of Plant Growth Regulation》2012,31(2):235-252
The role of gibberellins (GAs) during germination and early seedling growth is examined by following the metabolism and transport
of radiolabeled GAs in cotyledon, shoot, and root tissues of pea (Pisum sativum L.) using an aseptic culture system. Mature pea seeds have significant endogenous GA20 levels that fall during germination and early seedling growth, a period when the seedling develops the capacity to transport
GA20 from the cotyledon to the shoot and root of the seedling. Even though cotyledons at 0–2 days after imbibition have appreciable
amounts of GA20, the cotyledons retain the ability to metabolize labeled GA19 to GA20 and express significant levels of PsGA20ox2 message (which encodes a GA biosynthesis enzyme, GA 20-oxidase). The large pool of cotyledonary GA20 likely provides substrate for GA1 synthesis in the cotyledons during germination, as well as for shoots and roots during early seedling growth. The shoots
and roots express GA metabolism genes (PsGA3ox genes which encode GA 3-oxidases for synthesis of bioactive GA1, and PsGA2ox genes which encode GA 2-oxidases for deactivation of GAs to GA29 and GA8), and they develop the capacity to metabolize GAs as necessary for seedling establishment. Auxins also show an interesting
pattern during early seedling growth, with higher levels of 4-chloro-indole-3-acetic acid (4-Cl-IAA) in mature seeds and higher
levels of indole-3-acetic acid (IAA) in young root and shoot tissues. This suggests a changing role for auxins during early
seedling development. 相似文献
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Introduction
Below ground orientation in insects relies mainly on olfaction and taste. The economic impact of plant root feeding scarab beetle larvae gave rise to numerous phylogenetic and ecological studies. Detailed knowledge of the sensory capacities of these larvae is nevertheless lacking. Here, we present an atlas of the sensory organs on larval head appendages of Melolontha melolontha. Our ultrastructural and electrophysiological investigations allow annotation of functions to various sensory structures.Results
Three out of 17 ascertained sensillum types have olfactory, and 7 gustatory function. These sensillum types are unevenly distributed between antennae and palps. The most prominent chemosensory organs are antennal pore plates that in total are innervated by approximately one thousand olfactory sensory neurons grouped into functional units of three-to-four. In contrast, only two olfactory sensory neurons innervate one sensillum basiconicum on each of the palps. Gustatory sensilla chaetica dominate the apices of all head appendages, while only the palps bear thermo-/hygroreceptors. Electrophysiological responses to CO2, an attractant for many root feeders, are exclusively observed in the antennae. Out of 54 relevant volatile compounds, various alcohols, acids, amines, esters, aldehydes, ketones and monoterpenes elicit responses in antennae and palps. All head appendages are characterized by distinct olfactory response profiles that are even enantiomer specific for some compounds.Conclusions
Chemosensory capacities in M. melolontha larvae are as highly developed as in many adult insects. We interpret the functional sensory units underneath the antennal pore plates as cryptic sensilla placodea and suggest that these perceive a broad range of secondary plant metabolites together with CO2. Responses to olfactory stimulation of the labial and maxillary palps indicate that typical contact chemo-sensilla have a dual gustatory and olfactory function. 相似文献24.
Disrupting two Arabidopsis thaliana xylosyltransferase genes results in plants deficient in xyloglucan, a major primary cell wall component 总被引:1,自引:0,他引:1
Cavalier DM Lerouxel O Neumetzler L Yamauchi K Reinecke A Freshour G Zabotina OA Hahn MG Burgert I Pauly M Raikhel NV Keegstra K 《The Plant cell》2008,20(6):1519-1537
Xyloglucans are the main hemicellulosic polysaccharides found in the primary cell walls of dicots and nongraminaceous monocots, where they are thought to interact with cellulose to form a three-dimensional network that functions as the principal load-bearing structure of the primary cell wall. To determine whether two Arabidopsis thaliana genes that encode xylosyltransferases, XXT1 and XXT2, are involved in xyloglucan biosynthesis in vivo and to determine how the plant cell wall is affected by the lack of expression of XXT1, XXT2, or both, we isolated and characterized xxt1 and xxt2 single and xxt1 xxt2 double T-DNA insertion mutants. Although the xxt1 and xxt2 mutants did not have a gross morphological phenotype, they did have a slight decrease in xyloglucan content and showed slightly altered distribution patterns for xyloglucan epitopes. More interestingly, the xxt1 xxt2 double mutant had aberrant root hairs and lacked detectable xyloglucan. The reduction of xyloglucan in the xxt2 mutant and the lack of detectable xyloglucan in the xxt1 xxt2 double mutant resulted in significant changes in the mechanical properties of these plants. We conclude that XXT1 and XXT2 encode xylosyltransferases that are required for xyloglucan biosynthesis. Moreover, the lack of detectable xyloglucan in the xxt1 xxt2 double mutant challenges conventional models of the plant primary cell wall. 相似文献
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Manfred Fobker Reinhard Voss Holger Reinecke Christina Crone Gerd Assmann Michael Walter 《FEBS letters》2001,500(3):595-162
Tangier disease (TD) is an inherited disorder of lipid metabolism characterized by very low high density lipoprotein (HDL) plasma levels, cellular cholesteryl ester accumulation and reduced cholesterol excretion in response to HDL apolipoproteins. Molecular defects in the ATP binding cassette transporter 1 (ABCA1) have recently been identified as the cause of TD. ABCA1 plays a key role in the translocation of cholesterol across the plasma membrane, and defective ABCA1 causes cholesterol storage in TD cells. Not only cholesterol efflux, but also phospholipid efflux was shown to be impaired in TD cells. By use of thin layer chromatography, high performance liquid chromatography and time-of-flight secondary ion mass spectrometry, we characterized the cellular phospholipid content in fibroblasts from three homozygous TD patients. The cellular content of the major phospholipids was not found to be significantly altered in TD fibroblasts. However, the two phospholipids cardiolipin and lysocardiolipin, which make up minute amounts in normal cells, were at least 3–5-fold enriched in fibroblasts from TD subjects. A structurally closely related phospholipid (lysobisphosphatidic acid) has recently been shown to be enriched in Niemann–Pick type C, another lipid storage disorder. Altogether these data may indicate that the role of these phospholipids is a regulatory one rather than that of a bulk mediator of cholesterol solubilization in sterol trafficking and efflux. 相似文献
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1 The two most abundant cockchafer species in Europe, the forest cockchafer Melolontha hippocastani Fabr. and the European cockchafer Melolontha melolontha L., tend to form calamitous mass breedings with casual reports on sympatric and simultaneous occurrence. 2 Both species are known to use feeding‐induced green leaf volatiles (GLV) as primary attractants (sexual kairomones) for mate finding. The attractiveness of GLV is enhanced by the sex pheromones 1,4‐benzoquinone in M. hippocastani and toluquinone in M. melolontha. Phenol attracts males from both species. All three compounds are present in females of both species. 3 In the present study, it is confirmed that only male M. melolontha perform the typical swarming flight at dusk, as has already been shown for M. hippocastani. Furthermore, whether swarming Melolontha males were cross‐attracted to heterospecific females, and whether males could discriminate olfactorily between conspecific and heterospecific females, was tested in the field. 4 Males of both species preferred females when given the choice between females and males of the other species. However, they preferred conspecific females when females from both species were offered simultaneously. 5 The results suggest that species‐specific pheromone blends contribute to precopulatory reproductive isolation in sympatric populations of M. melolontha and M. hippocastani, but are not mutually exclusive or indispensable prerequisites for mate finding as in other insects. 相似文献
29.
Optimized trap lure for male Melolontha cockchafers 总被引:1,自引:0,他引:1
Abstract: Melolontha cockchafer males search for mates using green leaf volatiles (GLV), released by host plants after female feeding. Thus, the feeding-induced plant volatiles act as sexual kairomones. Males of both Melontha hippocastani and Melontha melolontha are strongly attracted by the GLV ( Z )-3-hexen-1-ol ( Z -3-ol). Sex pheromones enhance the attractiveness of Z -3-ol and have been identified as toluquinone (TQ) in M. melolontha , and 1,4-benzoquinone (BQ) in M. hippocastani . Additionally, phenol acts as a male attractant in both species. From the perspective of potential application, we investigated by field experiments with volatile-baited traps the ways of enhancing the number of captured males by the use of specific binary or ternary blends of Z -3-ol with phenol, and TQ or BQ respectively. The data show that in both species binary lures containing Z -3-ol combined with TQ or BQ at a ratio of 10 : 1 are the most potent male attractants. 相似文献
30.