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981.
Soybean homologs of MPK4 negatively regulate defense responses and positively regulate growth and development 总被引:1,自引:0,他引:1
Liu JZ Horstman HD Braun E Graham MA Zhang C Navarre D Qiu WL Lee Y Nettleton D Hill JH Whitham SA 《Plant physiology》2011,157(3):1363-1378
Mitogen-activated protein kinase (MAPK) cascades play important roles in disease resistance in model plant species such as Arabidopsis (Arabidopsis thaliana) and tobacco (Nicotiana tabacum). However, the importance of MAPK signaling pathways in the disease resistance of crops is still largely uninvestigated. To better understand the role of MAPK signaling pathways in disease resistance in soybean (Glycine max), 13, nine, and 10 genes encoding distinct MAPKs, MAPKKs, and MAPKKKs, respectively, were silenced using virus-induced gene silencing mediated by Bean pod mottle virus. Among the plants silenced for various MAPKs, MAPKKs, and MAPKKKs, those in which GmMAPK4 homologs (GmMPK4s) were silenced displayed strong phenotypes including stunted stature and spontaneous cell death on the leaves and stems, the characteristic hallmarks of activated defense responses. Microarray analysis showed that genes involved in defense responses, such as those in salicylic acid (SA) signaling pathways, were significantly up-regulated in GmMPK4-silenced plants, whereas genes involved in growth and development, such as those in auxin signaling pathways and in cell cycle and proliferation, were significantly down-regulated. As expected, SA and hydrogen peroxide accumulation was significantly increased in GmMPK4-silenced plants. Accordingly, GmMPK4-silenced plants were more resistant to downy mildew and Soybean mosaic virus compared with vector control plants. Using bimolecular fluorescence complementation analysis and in vitro kinase assays, we determined that GmMKK1 and GmMKK2 might function upstream of GmMPK4. Taken together, our results indicate that GmMPK4s negatively regulate SA accumulation and defense response but positively regulate plant growth and development, and their functions are conserved across plant species. 相似文献
982.
? With growing concerns over serious ecological problems, a particular challenge is to reveal the complex mechanisms underlying rapid expansion of invasive species. Ageratina adenophora is of particular interest in addressing this question. ? We used geographic information systems and logistic regression to identify the geographic and environmental factors contributing to the presence of A. adenophora. Join-count spatial statistics with reproduction mode examination were employed to elucidate the spatiotemporal dispersal mechanisms. ? Multiple factors have significantly contributed to the rapid expansion of A. adenophora. Its biological traits, favoring dispersal by water and wind coupled with local spatiotemporally heterogeneous geography and ecology, promote invasion downstream and upstream along river valleys, while other factors associated with human activities facilitate its invasion over high mountains and across river valleys, providing new scope for progressive invasions. We further identified an unusual invasion event of A. adenophora subsequent to a great flood that amplified its dispersal ability from vegetative propagules and seeds. ? These findings suggest that dynamic interactions of multiple factors in heterogeneous ecogeographical environments - a 'combinatorial' invasion mechanism - would generate an unexpected invasion rate of an alien species or a seemingly stochastic invasion event. 相似文献
983.
984.
Identification of a Nosema bombycis (Microsporidia) spore wall protein corresponding to spore phagocytosis 总被引:1,自引:0,他引:1
Life-cycle stages of the microsporidia Nosema bombycis, the pathogen causing silkworm pebrine, were separated and purified by an improved method of Percoll-gradient centrifugation. Soluble protein fractions of late sporoblasts (spore precursor cells) and mature spores were analysed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Protein spots were recovered from gels and analysed by mass spectrometry. The most abundant differential protein spot was identified by database search to be a hypothetical spore wall protein. Using immunoelectron microscopy, we demonstrated that HSWP5 is localized to the exospore of mature spores and renamed it as spore wall protein 5 (NbSWP5). Further spore phagocytosis assays indicated that NbSWP5 can protect spores from phagocytic uptake by cultured insect cells. This spore wall protein may function both for structural integrity and in modulating host cell invasion. 相似文献
985.
Guirong Qiao Renying Zhuo Mingying Liu Jing Jiang Haiying Li Wenmin Qiu Luanyin Pan Sheng lin Xiaoguo Zhang Zongxiu Sun 《Acta Physiologiae Plantarum》2011,33(3):691-696
Soil salinity is a serious problem worldwide. It is necessary to improve the salt tolerance of plants to avoid the progressive
deterioration of saline soil. We showed that the over-expression of AtNHX1 improves salt tolerance in a transgenic poplar (Populus deltoides CL × P. euramericana CL “NL895”) under mannose selection. Four transgenic poplar plants were obtained. Southern blot analysis showed that the
pmi gene had integrated into the genome of the poplar. RT-PCR confirmed that AtNHX1 could be expressed normally in the transgenic plants. When tested for salt tolerance by NaCl stress, we measured a 100%
increase in Na+ content in the three transgenic lines (T18, T50, T98) significantly higher than the 33% increase seen in wild-type plants.
The chlorophyll content of the transgenic plants was not altered significantly, while the chlorophyll content in the control
plants showed a small decrease. MDA content was decreased in the transgenic plants. These results show that the AtNHX1 gene may enhance salt tolerance due to increased vacuolar compartmentalization of sodium ions. 相似文献
986.
Gao C Xu X Zhang X Che B Ma C Qiu J Tao F Xu P 《Applied and environmental microbiology》2011,77(19):7080-7083
Chemoenzymatic synthesis of N-acetyl-d-neuraminic acid from N-acetyl-d-glucosamine using the spore surface-displayed N-acetyl-d-neuraminic acid aldolase at a high concentration (53.9 g liter(-1)) was achieved in this study. Thus, displaying a target enzyme on the surface of spores might be an alternative for integration of biocatalytic conversion into chemical synthesis. 相似文献
987.
GeoChip-based analysis of the functional gene diversity and metabolic potential of microbial communities in acid mine drainage 总被引:3,自引:0,他引:3
Xie J He Z Liu X Liu X Van Nostrand JD Deng Y Wu L Zhou J Qiu G 《Applied and environmental microbiology》2011,77(3):991-999
Acid mine drainage (AMD) is an extreme environment, usually with low pH and high concentrations of metals. Although the phylogenetic diversity of AMD microbial communities has been examined extensively, little is known about their functional gene diversity and metabolic potential. In this study, a comprehensive functional gene array (GeoChip 2.0) was used to analyze the functional diversity, composition, structure, and metabolic potential of AMD microbial communities from three copper mines in China. GeoChip data indicated that these microbial communities were functionally diverse as measured by the number of genes detected, gene overlapping, unique genes, and various diversity indices. Almost all key functional gene categories targeted by GeoChip 2.0 were detected in the AMD microbial communities, including carbon fixation, carbon degradation, methane generation, nitrogen fixation, nitrification, denitrification, ammonification, nitrogen reduction, sulfur metabolism, metal resistance, and organic contaminant degradation, which suggested that the functional gene diversity was higher than was previously thought. Mantel test results indicated that AMD microbial communities are shaped largely by surrounding environmental factors (e.g., S, Mg, and Cu). Functional genes (e.g., narG and norB) and several key functional processes (e.g., methane generation, ammonification, denitrification, sulfite reduction, and organic contaminant degradation) were significantly (P < 0.10) correlated with environmental variables. This study presents an overview of functional gene diversity and the structure of AMD microbial communities and also provides insights into our understanding of metabolic potential in AMD ecosystems. 相似文献
988.
989.
A total of 287 agricultural soil samples collected from 26 provinces or autonomous regions of China were tested on their ability
to suppress the conidial germination of nine biocontrol fungal agents. These soil samples showed great differences in the
degree to inhibit the germination of conidia (22.8% < mean inhibition rate < 97.5%), but all exhibited fungistatic activities
above the moderate levels (mean inhibition rate > 50%) to most of tested fungi. Ten soil samples that have stronger fungistatic
intensity (germination inhibition rate > 68.3%) to the target fungi, Trichoderma viride and Paecilomyces lilacinus, were selected to evaluate their soil actinobacteria involved fungistasis in soil. Of the 1,000 isolates from those soil
samples, 345 actinobacteria exhibited fungistatic activity to conidial germination of T. viride and P. lilacinus with germination inhibition rates higher than 10%. Sequences encoding 16S rRNA gene of the 345 actinobacteria were analyzed
by ARDRA and resulted 44 different ARDRA types. Fifty-six isolates, at least one from each unique ARDRA type, were selected
for 16S rDNA sequencing and phylogenetic analysis. Results indicated that the actinobacteria involved in the soil fungistasis
had close phylogenetic relationship with the members of Sterptomycetaceae, Microbacteriaceae, Micrococcaceae, and Nocardiacea. 相似文献
990.