Six species, belonging to two genera of Lemaneaceae in China are described. They are Lemanea Bory (including L. sinica Jao, L. crassa S. L. Xie et Z. X. Shi, L. ramosa S. L. Xie et Z. X. Shi and L. simplex Jao) and Paralemanea (Silva) Vis et Sheath (including P. catenata (Kützing) Vis et Sheath and P. parvula (Sirodot) S. L. Xie et Z. X. Shi). Among them L. crassa S. L. Xie et Z. X. Shi and L. ramosa S. L. Xie et Z. X. Shi are new species. Moreover, Paralemanea (Silva) Vis et Sheath and P. catenata (Kützing) Vis et Sheath, P. parvula (Sirodot) S. L. Xie et Z. X. Shi are newly recorded in China.
We analyzed the effects of plant sizes on nitrogen (N) uptake and use in a dense monospecific stand of an annual herb, Helianthus annuus L. (sunflower) and evaluated the consequences of intraspecific competition. Larger individuals obtained more N disproportionately to their sizes, suggesting that the competition for soil N was asymmetric (one-sided) among individual plants in the stand. Nitrogen loss of individuals also increased with plant size. N influx was greater in larger individuals, while N efflux was lower in small individuals. Therefore, the relative rate of N increment was greater in larger individuals, while it was around zero in the smallest individuals. N use efficiency (NUE) was separated into the N productivity (NP) and the mean residence time of N (MRT). Both NP and MRT were positively related to plant size. Larger individuals showed a higher NP and a longer MRT, while smaller ones displayed the reverse pattern. Consequently, NUE (i.e. the product of NP and MRT), was higher for larger individuals. No trade-off between NP and MRT was found among individuals. N resorption efficiency (NRE) was closely related to plant size. The higher NUE at individual-level was partly a result of greater N resorption during senescence. Asymmetric competition among individuals in this stand resulted mainly from lower efficiency in both N uptake and N use by smaller individuals. This study shows that the concept of NUE defined by Berendse and Aerts offers a powerful tool in studying plant strategies within species as well as among species.
Diaspore traits and germination of four non-viviparous mangrove species in Hong Kong, Lumnitzera racemosa (Jack.) Voigt., Heritiera littoralis (Drgand.) Ait., Excoecaria agallocha L. and Acanthus ilicifolius L., were investigated. L. racemosa fruits planted immediately after collection failed to germinate but those stored in wet condition for 35 or 50 d were successfully germinated. This suggested that L. racemosa had endogenous and morphological seed dormancy, with embryos continued to develop during the dormant period. Germination rates of L. racemosa decreased with increasing salinity and no germination was found at salinities over 25 ppt (ppt, parts per thausand). H. littoralis seeds were easily germinated if the fruit coat was artificially removed. Fruit dissection significantly shortened time for root initiation and leaf expansion. E. agallocha and A. ilicifolius seeds were also easy to germinate, initiating roots within 2 and 3 d, respectively. In terms of germination, A. ilicifolius had more tolerance to high salinity than L. racemosa. The four species exhibited three types of adaptation to unstable environments: (1) prolonged diaspore longevity as shown in L. racemosa and H. littoralis ; (2) shortened rooting time as in E. agallocha and A. ilicifolius ; and (3) produced sinking diaspores in L. racemosa. Diaspore buoyancy was one of the most important factors in determining inter-tidal zonation of non-viviparous mangrove species. Among the four species, L. racemosa was distributed in the most seaward zones because its diaspores were sinkers while diaspores of H. littoralis, E. agallocha and A. ilicifolius, more abundant at backshore locations, were floaters. Root initiation was also important in influencing the inter-tidal zonation of the three species whose diaspores were floaters. H. littoralis with the longest rooting time, as compared to E. agallocha and A. ilicifolius, was distributed in the most backshore zone. None of other factors including salinity of seawater, animal predation, diaspore size and seedling dimension could account for inter-tidal zonation of these species.
In Three Gorges reservoir region, a great many of trees are needed for vegetation restoration and land greening following the massive constructions (e.g. construction of roads, highways, buildings) associated with the great dam project at Three Gorges of Yangtze River. Ficus microcarpa L. and F. virens Ait. var. sublanceolata (Miq.) Cornor (Moraceae) are chosen and widely planted in this region as ornamental trees and/or shade trees due to their shapely crowns and ability of growing on soils with low fertility. Vegetative multiplication, which uses branch cuttings to cultivate saplings, is the main way for tree propagation of the two species in Three Gorges reservoir region. Obtaining branch cuttings causes the damage of tree crown and probably affects the growth of trees. In this study, the shoot production pattern of two Ficus tree species following crown damage, which is crucial to the regrowth of trees, was investigated. Data from a crown damage experiment with two damage seasons and a series of damage intensities were analyzed. It was shown that crown damage, regardless of damage intensity and damage season, had no effect on the shoot production of lateral branches of both species. However, the shoot production on the main stem was position-dependent in both F. microcarpa and F. virens trees. Crown damage, conducted either in spring or in autumn, did not affect the number and density of new shoots on the newly grown upper stem parts and the branched stem parts within the residual crown, but facilitated the shoot production on the bare stem parts beneath the residual crown in terms of both shoot number and density. Shoot production on the bare stem parts increased with damage intensity. In addition, it was found that damage in autumn led to a stronger emergence of shoots from the bare stem parts than spring damage. Some mechanisms which could be involved in these results are discussed. Based on the experimental results, it is suggested that among all investigated variables, only the enhanced shoot production on the bare stem parts may increase the biomass partitioning to leaves and benefit the regrowth of damaged trees.
The main chlorophyll a/b light-harvesting complex (LHCⅡ) has been isolated directly from thylakoid membranes of marine green alga (Bryopsis corticulans Setch.) by two consecutive runs of anion exchange and gel-filtration chromatography. LHCⅡ proteins in the membrane extracts treated with 3% n-Octyl-b-D-glucopyranoside (OG) obtained specific binding ability on Q Sepharose column, and thus were isolated from the thylakoid membranes in a highly selective fraction. The monomeric, trimeric and oligomeric subcomplexes of LHCⅡ have been obtained by fractionation of the LHCⅡ mixes with sucrose density gradient ultracentrifugation. The SDS-PAGE analysis of peptide composition and absorption spectrum showed that LHCⅡ monomers, trimers and oligomers prepared through this work were intact and in high purity. Our report is the first to show that it is possible to purify LHCⅡ directly from thylakoid membranes without extensively biochemical purification.
Effects of NaCl-stress on ammonia assimilation enzymes and the related parameters were determined in the roots of three rice (Oryza sativa L.) cultivars differing in salt tolerance. The results showed that the activities of glutamine synthetase (GS) and NADH-dependent glutamate synthase (NADH-GOGAT), as well as the levels of soluble protein decreased under high concentration salt. The influence extent was in accordance with Zao-hua 2 (salt-sensitive), Jin-zhu 1 (normal cultivar) and Jin-dao 779 (salt-resistant), which was consistent with their salt-tolerance. Nevertheless, under the stress of high salt concentration, NADH-dependent glutamate dehydrogenase (NADH-GDH) activity of Zao-hua 2 and Jin-zhu 1 was induced significantly, but that of Jin-dao 779 did not increase remarkably. The salt stress led to the accumulation of total soluble sugar (TSS) in the root of Jin-zhu 1 and Jin-dao 779 in different degree. The level of TSS in Zao-hua 2 changed with different NaCl concentrations. Among the cultivars observed, content of proline increased in different degree, but under high salt concentrations, it had a more marked rise in the roots of salt-sensitive cultivars.
Jujube (Ziziphus jujuba Mill. cv Dongzao) fruit was stored under controlled atmospheres (CA) of 5% O2 plus 0% CO2, 10% O2 plus 0% CO2, or dynamic CA (70% O2 +0% CO2 for 7 d, followed by transferring to 5% O2) at -1 °C, or in air at 25 °C and -1 °C, respectively, and then determined disease incidence, contents of pigment, total soluble solids, titratable acidity, ethanol and ethyl acetate in storage periods. The results indicated that the contents of ethanol, ethyl acetate and the degradation of anthocyanin, and chlorophyll were significantly lower in the fruit stored in CA at -1 °C than those in air at -1 °C. Short term high O2 (70%) treatment was the most effective in maintaining peel color, anthocyanin and chlorophyll contents and preventing peel browning compared to other treatments. Ethanol content was significantly low in the fruits stored in CA with 10% O2 plus 0% CO2 while storage of CA (5% O2 plus 0% CO2) concentration was effective in reducing ethyl acetate content throughout the storage period. CA conditions effectively controlled disease development of jujube fruit. Soluble solid content (SSC) and titratable acidity were however not significantly affected by CA treatments.
Catharanthus roseus (L.) G. Don cell suspension cultures were used to transform 3b-hydroxyandrost-5-en-17-one, the products were isolated by chromatographic methods. Their structures were established by means of NMR and MS spectral analyses. Nine metabolites were respectively elucidated as: androst-4-ene-3,17-dione (Ⅰ), 6a-hydroxyandrost-4-ene-3,17-dione (Ⅱ), 6a,17b-dihydroxyandrost-4-en-3-one (Ⅲ), 6b-hydroxyandrost-4-ene-3,17-dione (Ⅳ), 17b-hydroxyandrost-4-en-3-one (Ⅴ), 15a,17b-dihydroxyandrost-4-en-3-one (Ⅵ), 15b,17b-dihydroxyandrost-4-en-3-one (Ⅶ), 14a-hydroxyandrost-4-ene-3,17-dione (Ⅷ), 17b-hydroxyandrost-4-ene-3,16-dione (Ⅸ). It is the first time to obtain the above compounds by biotransformation with Catharanthus roseus cell cultures.
Ran is an evolutionarily conserved eukaryotic GTPase that directly participates in cell cycle and whose loss affects many biological processes. We have identified cDNA of TaRAN1, a novel Ran GTPase homologous gene in wheat (Triticum aestivum L. cv. Jingdong No. 1). The cytoplasmic microtubules play an important role in cytoplasmic organization, cell division, and the correct transmission of genetic information in fission yeast cell. Using the fission yeast system in vivo experiments, overexpression of TaRAN1 produced defective spindle microtubules, probably resulting in chromosome missegregation we reported previously. The microtubules of antisense TaRAN1 yeast cells were physically disrupted. This suggested that TaRAN1 plays a role in mitotic spindle assembly and microtubule integrity and stability. Ultrastructural analysis under transmission electron microscope (TEM) showed abnormal nuclear membranes in the overexpression TaRAN1 yeast cells, abnormal vacuole structures and disorganized membranes in the antisense TaRAN1 yeast cells. These results suggested that TaRAN1 was essential for all nucleocytoplasmic transport events.
Matrix attachment regions (MARs) were used to increase resveratrol production in stilbene synthase (STS) gene-transformed tobacco (Nicotiana tabacum L.) in this study. MARs are DNA sequences that bind to the cell's pertinacious nuclear matrix to form DNA loop domains. A range of effects of MARs sequence on mean expression level and variation in expression of transgenes has been reported usually using b-glucuronidase (GUS) gene as reporter gene. The present study investigated the effects of MARs sequence from yeast on transgene expression of STS for the first time. The results of in vitro binding assay showed that the MARs sequence could specifically bind to the matrix of tobacco prepared by lihium diiodosalicylate (LIS) procedure. The stilbene synthase is the key enzyme in metabolic pathway of resveratrol biosynthesis and a cDNA for STS was cloned from Parthenocissus henryana (Hemsl.) Diels et Gilg by RT-PCR method with primers designed according to the conserved sequence of STS gene in grapevine. The cloned sequence showed high nucleotide identity (93.8%) with the STS gene of Vitis vinifera cv. Optima, and the predicted protein sequence also had Cys164 activity core and IPNSAGAIAGN motifs which were specific for stilbene synthases. With or without flanking MARs from yeast, the STS gene under control of CaMV35S promoter with Ω enhancer has been transferred into tobacco. Northern blot and HPLC analysis of the leaf extracts of transgenic tobacco showed the resveratrol had been produced in STS gene-transformed plants, while there was no resveratrol found in the untransformed tobacco. In stably trans-formed strains, the content of resveratrol in the plants with STS gene flanking by MARs averaged about 2-fold higher than those lacking MARs. The results proved that flanking STS by MARs was one of the effective way to increase resveratrol production in transgenic plants, and this work could also play basic roles on the STS gene transformed vegetables or fruits with strong resistance to disease and benefits to human health.
WRKY genes encode plant specific transcription factors that have been extensively studied in dicotyledonous plant species. To investigate the function of these genes in monocots, we isolated a full length cDNA clone of the rice WRKY gene which we tentatively named as OsiWRKY. The open reading frame of OsiWRKY cDNA encoded a polypeptide of 482 amino acid residues. The deduced primary structure of OsiWRKY contained a single WRKY domain of a typical C2-H2 zinc finger motif. A putative nuclear localization signal was also predicted in OsiWRKY. Potential targeting of OsiWRKY to the nucleus was confirmed by transient expression of an OsiWRKY::GFP fusion protein in rice cells. The recombinant OsiWRKY protein bound specifically to the W-box element in electrophoretic mobility shift assay. In inoculation experiments with Xanthomonas oryzae pv. oryzae, OsiWRKY transcription was increased more dramatically in the resistant variety IR-26 than in the susceptible variety Jingang 30. Interestingly, an increase in OsiWRKY transcription was also observed in the mock-inoculated control plants of both IR-26 and Jingang 30. However, the induction of OsiWRKY transcription occurred much earlier and more substantial in pathogen-infected plants than in mock-inoculated controls. These results suggest that OsiWRKY encodes a potential WRKY transcription factor that may function in responses of rice plants to both pathogen attack and mechanical wounding. But the mechanisms underlying the function of OsiWRKY in the two processes may be different.
A new long-culm mutant “D111” was discovered in breeding materials of rice (Oryza sativa L.). Polymorphic analysis of microsatellite markers demonstrated that D111 derived from a gene mutation in the crossing progenies of two semidwarf varieties 6442S-7 and Shuhui 881. Plant height and culm length of D111 increased by 63.0% and 87.0%, respectively, compared with those of its parent Shuhui 881. Genetic analysis suggested that the long-culm trait of D111 was controlled by a pair of dominant genes, and the long-culm gene of D111 was tightly linked or allelic to that of long-culm control variety Nanjing 6. Molecular marker analysis showed that the mutant gene of D111 located on the long arm of rice chromosome 1, 27.7 cM, 25.5 cM and 6.0 cM from microsatellite markers RM212, RM302 and RM472, respectively. This long-culm mutant gene was designated tentatively as LC (t). It was considered that D111 was the first rice example of dominant long-culm mutant derived from spontaneous mutation of semidwarf varieties and that LC(t) was the first mapped long-culm mutant gene of rice. In addition, the possible relationship between LC(t) gene and rice “green revolution gene” sd1 was discussed.
This study describes an innovative approach for detecting mRNA, called in situ reverse transcription (ISRT), which marries in situ hybridization (ISH) with reverse transcription. Specific primers were designed for mRNA-specific reverse transcription. The parameters and key steps of ISRT were optimized. Based on our experience, with proper controls ISRT, can detect mRNA signals with high sensitivity and high specificity. ISRT was used to detect the mRNA of a rice MADS-box gene, M79, which belongs to the AGL2 subgroup. As seen with conventional ISH, M79 is expressed at all stages of rice development, in both vegetative and reproductive processes. ISRT is relatively fast and easy-to-perform, suggesting that this method will become a reliable, fundamental technique that can be used to localize mRNA in situ.
Pathogesis-related gene 1 (PR1) is a valid marker gene for systemic acquired resistance in Arabidopsis thaliana L. Using PCR amplification, we cloned the upstream regulatory region of PR1 gene from Arabidopsis Col-0. The fragment was then fused to the reporter gene encoding b-glucuronidase (GUS) and introduced into Arabidopsis plant by Agrobacterium-mediated gene transfer. PCR analysis and Southern blot hybridization of total DNA extracted from transgenic plants verified that the fusion gene had been integrated into the Arabidopsis genome. GUS activity can be induced by chemical treatment in transgenic Arabidopsis. The response was monitored by histochemical staining of GUS activity in situ, and fluorimetric assay in tissue extracts. Transgenic plants containing PR1-GUS or other defense gene promoter-reporter gene fusions may therefore provide specific assay systems for screening potential activators of systemic acquired resistance.
Cytoplasmic bridge, as a broader cellular connection structure, exists in plants from Volvox to higher plants, but has been subjected to less investigation as compared to plasmodesmata. It has been speculated that the structure may be related to the synchronization of cell division and development during the microsporegenesis and spermatogenesis. During spermatogenesis in bryophytes, the spermatogenous cells are divided into several domains within an antheridium, and their divisions are synchronous. However, their cellular connection system has not been investigated systematically. In this study, we undertook an ultrastructural examination of the structure and dynamics of the intercellular connection system during the spermatogenesis in Funaria hygrometrica Hedw. The result revealed that within each individual domain, synchronously dividing spermatogenous cells were connected with each other by numerous cytoplasmic bridges, which were absent in the walls between different domains. The plasmodesmata connected spermatogenous cells with the cells of jacket layer, and also existed between the jacket layer cells, but absent in the walls between the developing spermatogenous cells. At the late stage of the antheridial development, as the cell wall began to degrade, all of the spermatid cells within an antheridium seem connected with each other by the expanded cytoplasmic bridges. The cytoplasmic bridges retained to the late stage of spermatid’s differentiation, and finally, the spermatids synchronously differentiated into spermatozoids. The different internal structures, biogenesis mechanisms and distribution between the plasmodesmata and cytoplasmic bridges suggest that they may play distinct roles during the development of antheridia.
A novel polysaccharide was isolateded from Chrysanthemum morifolium Ramat. flowers by successive hot water extraction, anion-exchange chromatography and gel permeation chromatography. Sugar and methylation analysis, periodate oxidation, partial acid hydrolysis and NMR spectral analysis revealed that polysaccharide is composed of repeating units with the following structure: Araf-(1→5)-Araf-(1→4)-Glcp-(1→4)-Glcp 1 ↓ 6 ［→4-Galp-(1→4)-Galp-(1→4)- Galp-(1→4)- Galp-(1→6)- Galp-(1］→n
Two new terpenoids, namely taiwaniatriol (1) and senecrassidiol-9-O-b-D-glucopyranoside (8), along with fifteen known compounds including five triterpenoids (2-6), one diterpene (7) and nine phenols (9-17), were isolated from the root bark of Taiwania flousiana Gaussen. Taiwaniatriol was elucidated as (24S)-3b-methoxy-5a-lanost-9(11)-ene-7b, 24, 25-triol. Their structures were established mainly by spectral methods.
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