Biomedical subjects

Jianjun Tang

Publications and source records attributed to Jianjun Tang.

7 recordsLinked to original sources

PubMed2005

Arbuscular mycorrhizae enhance metal lead uptake and growth of host plants under a sand culture experiment.

A sand culture experiment was conducted to investigate whether mycorrhizal colonization and mycorrhizal fungal vesicular numbers were influenced by metal lead, and whether mycorrhizae enhance host plants tolerance to metal lead. Metal lead was applied as Pb(NO3)2 in solution at three levels (0, 300 and 600 mg kg(-1) sand). Five mycorrhizal host plant species, Kummerowia striata (Thunb.) Schindl, Ixeris denticulate L., Lolium perenne L., Trifolium repens L. and Echinochloa crusgalli var. mitis were used to examine Pb-mycorrhizal interactions. The arbuscular mycorrhizal inoculum consisted of mixed spores of mycorrhizal fungal species directly isolated from orchard soil. Compared to the untreated control, both Pb concentrations reduced mycorrhizal colonization by 3.8-70.4%. Numbers of AM fungal vesicles increased by 13.2-51.5% in 300 mg Pb kg(-1) sand but decreased by 9.4-50.9% in 600 mg Pb kg(-1) sand. Mycorrhizae significantly enhanced Pb accumulation both in shoot by 10.2-85.5% and in root by 9.3-118.4%. Mycorrhizae also enhanced shoot biomass and shoot P concentration under both Pb concentrations. Root/shoot ratios of Pb concentration were higher in highly mycorrhizal plant species (K.striata, I. denticulate, and E. crusgalli var. mitis) than that in poorly mycorrhizal ones (L. perenne and T. repens,). Mycorrhizal inoculation increased the root/shoot ratio of Pb concentration of highly mycorrhizal plant species by 7.6-57.2% but did not affect the poorly mycorrhizal ones. In the treatments with 300 Pb mg kg(-1) sand, plant species with higher vesicular numbers tended to show higher root/shoot ratios of the Pb concentration. We suggest that under an elevated Pb condition, mycorrhizae could promote plant growth by increasing P uptake and mitigate Pb toxicity by sequestrating more Pb in roots.

Lead↗

PubMed2005

QTL analysis and QTL-based prediction of flowering phenology in recombinant inbred lines of barley.

Combining ecophysiological modelling and genetic mapping has increasingly received attention from researchers who wish to predict complex plant or crop traits under diverse environmental conditions. The potential for using this combined approach to predict flowering time of individual genotypes in a recombinant inbred line (RIL) population of spring barley (Hordeum vulgare L.) was examined. An ecophysiological phenology model predicts preflowering duration as affected by temperature and photoperiod, based on the following four input traits: f(o) (the minimum number of days to flowering at the optimum temperature and photoperiod), theta1 and theta2 (the development stages for the start and the end of the photoperiod-sensitive phase, respectively), and delta (the photoperiod sensitivity). The model-input trait values were obtained from a photoperiod-controlled greenhouse experiment. Assuming additivity of QTL effects, a multiple QTL model was fitted for the model-input traits using composite interval mapping. Four to seven QTL were identified for each trait. Each trait had at least one QTL specific to that trait alone. Other QTL were shared by two or all traits. Values of the model-input traits predicted for the RILs from the QTL model were fed back into the ecophysiological model. This QTL-based ecophysiological model was subsequently used to predict preflowering duration (d) for eight field trial environments. The model accounted for 72% of the observed variation among 94 RILs and 94% of the variation among the two parents across the eight environments, when observations in different environments were pooled. However, due to the low percentage (34-41%) of phenotypic variation accounted for by the identified QTL for three model-input traits (theta1, theta2 and delta), the QTL-based model accounted for somewhat less variation among the RILs than the model using original phenotypic input trait values. Nevertheless, days to flowering as predicted from the QTL-based ecophysiological model were highly correlated with days to flowering as predicted from QTL-models per environment for days to flowering per se. The ecophysiological phenology model was thus capable of extrapolating (QTL) information from one environment to another.

Chromosome Mapping↗

PubMed2005

Model analysis of flowering phenology in recombinant inbred lines of barley.

A generic model for flowering phenology as a function of daily temperature and photoperiod was applied to predict differences of flowering times among 96 individuals (including the two parents) of a recombinant inbred line population in barley (Hordeum vulgare L.). Because of the large number of individuals to study, there is a need for simple ways to derive model parameters for each genotype. Therefore the number of genotype-specific parameters was reduced to four, namely f(o) (the minimum number of days to flowering at the optimum temperature and photoperiod), (1) and (2) (the development stages for the start and the end of the photoperiod-sensitive phase, respectively), and delta (the photoperiod sensitivity). Values of these parameters were estimated using a newly described methodological framework based on data from a photoperiod-controlled experiment where plants were mutually transferred between long-day and short-day environments at regular intervals. This modelling approach was tested in eight independent field environments of different sowing dates in two growing seasons. The four-parameter model predicted 37-67% of observed phenotypic variation in an environment, 76% of variation in across-environment mean days to flowering among the genotypes, and 96% of variation in across-genotype mean among the eight environments. When all the observations of the 96 genotypes across the eight environments were pooled, the model explained 81% of the total variation. Sensitivity analysis showed that all four model parameters were important for predicting differences in flowering time among the genotypes; but their relative importance differed and the ranking was in the order of f(o), delta, theta1, and theta2. This study highlighted the potential of using ecophysiological models to assist the genetic analysis of quantitative crop traits whose phenotype is often environment-dependent.

Flowers↗

PubMed2005

[Relationships between climate change and rice development and its yield formation: a simulation study].

With the application of mechanistic model (RICAM 1.3, RIce growth Calendar Model), this paper simulated the rice development and its yield formation under different climatic conditions at multi-locations of Asia. A three-stage Beta model (3s-Beta) was developed to predict the flowering stage of rice and to describe its three successive phases of photo-thermal response, i.e., basic vegetative phase, photoperiod-sensitive phase, and post photoperiod-sensitive phase. The 1980-1989 multi-location data of Morioka (Japan, 39 degrees 43'N), Nanchang (China, 28 degrees 36'N) and Los Banos (Philippines, 14 degrees 11'N) were used to verify the suitability of the model in studying ecosystem change. Comparisons of simulated results with observed data showed that this model could generally predict the eco-physiological processes of rice, and performed very well over a wide range of environments.

Biomass↗

PubMed2005

[Effects of simulated nitrogen deposition on weeds growth and nitrogen uptake].

In this paper, a greenhouse experiment was conducted to study the responses of different functional groups weeds to simulated nitrogen deposition (4.0 g N.m(-2).yr(-1)). Native weed species Poa annua, Lolium perenne, Avena fatua, Medicago lupulina, Trifolium repens, Plantago virginica, Veronica didyma, Echinochloa crusgalli var. mitis, Eleusine indica and Amaranthus spinosus in orchard ecosystem were used test materials, and their above-and underground biomass and nitrogen uptake were measured. The results showed that under simulated N deposition, the total biomass, shoot biomass and root biomass of all weed species tended increase, while the total biomass was differed for different functional groups of weeds. The biomass of C4 grass, legumes and C3 grass was significantly increased under N deposition, while that of C3 and C4 forbs was not significantly impacted. The root/shoot biomass ratio of Avena fatua and Plantago virginica was enhanced by N deposition, but that of Poa annu, Lolium perenne, Medicago lupulina, Trifolium repens and Amarathus spinosus was not impacted significantly. N deposition had no significant effect on plant N concentration, but significantly enhanced the N uptake of all test weed species except Amarathus spinosus, Poa annua and Veronica didyma. was suggested that the further increase of N deposition might speed up the changes of the community structure weed species due to their different responses to N deposition.

Avena↗

PubMed2005

[Allelopathic effects of invasive weed Solidago canadensis on native plants].

With growth chamber method, this paper studied the allelopathic potential of invasive weed Solidago canadensis on native plant species. Different concentration S. canadensis root and rhizome extracts were examined, and the test plants were Trifolium repens, Trifolium pretense, Medicago lupulina, Lolium perenne, Suaeda glauca, Plantago virginica, Kummerowia stipulacea, Festuca arundinacea, Ageratum conyzoides, Portulaca oleracea, and Amaranthus spinosus. The results showed that the allelopathic inhibitory effect of the extracts from both S. canadensis root and rhizome was enhanced with increasing concentration, and rhizome extracts had a higher effect than root extracts. At the lowest concentration (1:60), root extract had little effect on the seed germination and seedling growth of T. repens, but rhizome extract could inhibit the germination of all test plants though the inhibitory effect varied with different species. The inhibition was the greatest for grass, followed by forb and legume. 1:60 (m:m) rhizome extract had similar effects on seed germination and radicel growth, but for outgrowth, the extract could inhibit Kummerowia stipulacea, Amaranthus spinosus and Festuca arundinacea, had no significant impact on Lolium perenne, Plantago virginica, Ageratum conyzoides, Portulaca oleracea and Amaranthus spinosus, and stimulated Trifolium repens, Trifolium pretense and Medicago lupulina.

Pheromones↗

PubMed2004

[Influence of elevated atmospheric CO2 on rhizosphere microbes and arbuscular mycorrhizae].

The changes of microbial communities in rhizosphere and the formation of mycorrhizae play an important role in affecting the dynamics of plant communities and terrestrial ecosystems. This paper summarized and discussed the effects of elevated atmospheric CO2 on them. Under elevated atmospheric CO2, the carbohydrates accumulated in root systems increased, and the rhizospheric environment and its microbial communities as well as the formation of mycorrhizae changed. It is suggested that the researches in the future should be focused on the effects of rhizosphere microbes and arbuscular mycorrhizae on regulating the carbon dynamics of plant communities and terrestrial ecosystems under elevated atmospheric CO2.

Atmosphere↗