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991.
Chuan-yu Guo Guang-heng Wu Jin Xing Wen-qi Li Ding-zhong Tang Bai-ming Cui 《Plant cell reports》2013,32(5):687-702
Key message
A gene encoding a coproporphyrinogen III oxidase mediates disease resistance in plants by the salicylic acid pathway.Abstract
A number of genes that regulate powdery mildew resistance have been identified in Arabidopsis, such as ENHANCED DISEASE RESISTANCE 1 to 3 (EDR1 to 3). To further study the molecular interactions between the powdery mildew pathogen and Arabidopsis, we isolated and characterized a mutant that exhibited enhanced resistance to powdery mildew. The mutant also showed dramatic powdery mildew-induced cell death as well as growth defects and early senescence in the absence of pathogens. We identified the affected gene by map-based cloning and found that the gene encodes a coproporphyrinogen III oxidase, a key enzyme in the tetrapyrrole biosynthesis pathway, previously known as LESION INITIATION 2 (LIN2). Therefore, we designated the mutant lin2-2. Further studies revealed that the lin2-2 mutant also displayed enhanced resistance to Hyaloperonospora arabidopsidis (H.a.) Noco2. Genetic analysis showed that the lin2-2-mediated disease resistance and spontaneous cell death were dependent on PHYTOALEXIN DEFICIENT 4 (PAD4), SALICYLIC ACID INDUCTION-DEFICIENT 2 (SID2), and NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1), which are all involved in salicylic acid signaling. Furthermore, the relative expression levels of defense-related genes were induced after powdery mildew infection in the lin2-2 mutant. These data indicated that LIN2 plays an important role in cell death control and defense responses in plants. 相似文献992.
993.
994.
Estrogen receptor α (ERα) may play important roles in many estrogen physiological effects, but little is known about the fluctuation of ERα during the estrous cycle. In this study, the dynamic expression of ERα mRNA and protein in periodontal tissue during the estrous cycle were examined. Forty 12‐week‐old female rats were divided into four groups, based on the estrous cycle stage, and sacrificed. Immunohistochemistry and in situ hybridization were used to detect dynamic changes in ERα protein and mRNA in periodontal tissue during the estrous cycle, and data were analyzed by one‐way ANOVA and cosinor analysis for temporal patterns. Significant differences (p<0.05) were found in the expression of ERα protein and mRNA among the four groups. The expression of ERα protein and mRNA exhibited an infradian rhythm with a period of about 120 h (five days). The phase and amplitude differences between ERα protein and mRNA were not significant (p>0.05). The results suggest the expression of ERα is dynamic during the estrous cycle and that in the future chronobiologic methods should be used to study the mechanism of estrogen effect on periodontal tissue. 相似文献
995.
996.
Chanjuan Guo Judy Simon Rainer Gasche Pascale Sarah Naumann Carolin Bimüller Rodica Pena Andrea Polle Ingrid Kögel-Knabner Bernd Zeller Heinz Rennenberg Michael Dannenmann 《Plant and Soil》2013,369(1-2):657-668
Aims
Our aims were to characterize the fate of leaf-litter-derived nitrogen in the plant-soil-microbe system of a temperate beech forest of Southern Germany and to identify its importance for N nutrition of beech seedlings.Methods
15N-labelled leaf litter was traced in situ into abiotic and biotic N pools in mineral soil as well as into beech seedlings and mycorrhizal root tips over three growing seasons.Results
There was a rapid transfer of 15N into the mineral soil already 21 days after tracer application with soil microbial biomass initially representing the dominant litter-N sink. However, 15N recovery in non-extractable soil N pools strongly increased over time and subsequently became the dominant 15N sink. Recovery in plant biomass accounted for only 0.025 % of 15N excess after 876 days. After three growing seasons, 15N excess recovery was characterized by the following sequence: non-extractable soil N?>>?extractable soil N including microbial biomass?>>?plant biomass?>?ectomycorrhizal root tips.Conclusions
After quick vertical dislocation and cycling through microbial N pools, there was a rapid stabilization of leaf-litter-derived N in non-extractable N pools of the mineral soil. Very low 15N recovery in beech seedlings suggests a high importance of other N sources such as root litter for N nutrition of beech understorey. 相似文献997.
Yifu Yuan Weihua Guo Wenjuan Ding Ning Du Yujie Luo Jian Liu Fei Xu Renqing Wang 《Plant and Soil》2013,366(1-2):389-400
Background and aims
Anthropogenic nitrogen (N) and phosphorus (P) input has changed the relative importance of nutrient elements. This study aimed to examine the effects of different nutrient conditions on the interaction between exotic and native plants.Methods
We conducted a greenhouse experiment with a native species Quercus acutissima Carr. and an exotic species Rhus typhina L. grown in monocultures or mixtures, under three N:P ratios (5, 15 and 45 corresponding to N-limited, basic N and P supply and P-limited conditions, respectively). After 12 weeks of treatment, traits related to biomass allocation, leaf physiology and nutrient absorption were determined.Results
R. typhina was dominant under competition, with a high capacity for carbon assimilation and nutrient absorption, and the dominance was unaffected by increasing N:P ratios. R. typhina invested more photosynthate in leaves and more nutrients in the photosynthetic apparatus, enabling high biomass production. Q. acutissima invested more photosynthate in roots and more nutrients in leaf persistence at the expense of reduced carbon assimilation capacity.Conclusions
Different trade-offs in biomass and nutrient allocation of the two species is an important reason for their distinct performances under competition and helps R. typhina to maintain dominance under different nutrient conditions. 相似文献998.
Chanjuan Guo Michael Dannenmann Rainer Gasche Bernd Zeller Hans Papen Andrea Polle Heinz Rennenberg Judy Simon 《Plant and Soil》2013,368(1-2):519-534
Background and aims
Litter decomposition is regulated by e.g. substrate quality and environmental factors, particularly water availability. The partitioning of nutrients released from litter between vegetation and soil microorganisms may, therefore, be affected by changing climate. This study aimed to elucidate the impact of litter type and drought on the fate of litter-derived N in beech seedlings and soil microbes.Methods
We quantified 15N recovery rates in plant and soil N pools by adding 15N-labelled leaf and/or root litter under controlled conditions.Results
Root litter was favoured over leaf litter for N acquisition by beech seedlings and soil microorganisms. Drought reduced 15N recovery from litter in seedlings thereby affecting root N nutrition. 15N accumulated in seedlings in different sinks depending on litter type.Conclusions
Root turnover appears to influence (a) N availability in the soil for plants and soil microbes and (b) N acquisition and retention despite a presumably extremely dynamic turnover of microbial biomass. Compared to soil microorganisms, beech seedlings represent a very minor short-term N sink, despite a potentially high N residence time. Furthermore, soil microbes constitute a significant N pool that can be released in the long term and, thus, may become available for N nutrition of plants. 相似文献999.
1000.
Chengjin Guo Xiaolei Zhao Xiaoman Liu Lijun Zhang Juntao Gu Xiaojuan Li Wenjing Lu Kai Xiao 《Planta》2013,237(4):1163-1178
Several phosphate transporters (PTs) that belong to the Pht2 family have been released in bioinformatics databases, but only a few members of this family have been functionally characterized. In this study, we found that wheat TaPHT2;1 shared high identity with a subset of Pht2 in diverse plants. Expression analysis revealed that TaPHT2;1 was strongly expressed in the leaves, was up-regulated by low Pi stress, and exhibited a circadian rhythmic expression pattern. TaPHT2;1–green fluorescent protein fusions in the leaves of tobacco and wheat were specifically detected in the chloroplast envelop. TaPHT2;1 complemented the Pi transporter activities in a yeast mutant with a defect in Pi uptake. Knockdown expression of TaPHT2;1 significantly reduced Pi concentration in the chloroplast under sufficient (2 mM Pi) and deficient Pi (100 μM Pi) conditions, suggesting that TaPHT2;1 is crucial in the mediation of Pi translocation from the cytosol to the chloroplast. The down-regulated expression of TaPHT2;1 resulted in reduced photosynthetic capacities, total P contents, and accumulated P amounts in plants under sufficient and deficient Pi conditions, eventually leading to worse plant growth phenotypes. The TaPHT2;1 knockdown plants exhibited pronounced decrease in accumulated phosphorus in sufficient and deficient Pi conditions, suggesting that TaPHT2;1 is an important factor to associate with a distinct P signaling that up-regulates other PT members to control Pi acquisition and translocation within plants. Therefore, TaPHT2;1 is a key member of the Pht2 family involved in Pi translocation, and that it can function in the improvement of phosphorus usage efficiency in wheat. 相似文献