Fang CX, He HB, Wang QS, Qiu L, Wang HB, Zhuang YE, Xiong J, Lin WX Genomic analysis of allelopathic response to low nitrogen and barnyardgrass competition in rice (Oryza sativa L.). Plant Growth Regul

Agroecological Institute/School of Life Sciences, Fujian Agriculture and Forestry University (FAFU), 350002 Fuzhou, People’s Republic of China
Plant Growth Regulation (Impact Factor: 1.67). 07/2010; 61(3):277-286. DOI: 10.1007/s10725-010-9475-8


To explore the molecular mechanism of allelopathic rice in response to low nitrogen (N) supply or accompanying weed stress,
allelopathic rice PI 312777 and its counterpart Lemont were grown under low N supply or co-cultured with barnyardgrass [Echinochloa crus-galli (L.) Beauv.] in hydroponics. The suppression subtractive hybridization (SSH) technique was employed to isolate the up-regulated
genes in the treated rice accession. The results indicated that the expression of the genes associated with N utilization
was significantly up-regulated in allelopathic rice PI 312777, and the higher efficiency of N uptake and its utilization were
also detected in PI 312777 than that in Lemont when the two rice accessions were exposed to low N supply. This result suggested
that the allelopathic rice had higher ability to adapt to low N stress than its non-allelopathic counterpart. However, a different
response was observed when the allelopathic rice was exposed to accompanying weed (barnyardgrass) co-cultured in full Hoagland
solution (normal N supply). It showed that the expression of the genes associated with allelochemical synthesis and its detoxification
were all up-regulated in the allelopathic rice when co-cultured with the target weed under normal N supply. The results suggested
that the allelopathic rice should be a better competitor in the rice-weed co-culture system, which could be attributed to
increasing de novo biosynthesis and detoxification of allelochemicals in rice, consequently resulting in enhanced allelopathic
effect on the target and preventing the autotoxicity in this process. These findings suggested that the accompanying weed,
barnyardgrass is not only the stressful factor, but also one of the triggers in activating allelopathy in rice. This implies
that the allelopathic rice is sensible of the existing target in chemical communication.

KeywordsAllelopathy-Barnyardgrass-Gene expression-Low nitrogen-Plant defense-Rice

1 Follower
30 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Proline is one of the most important osmoregulatory solutes subjected to osmotic stresses. In this study, low nitrogen supply suppressed the dry biomass, leaf area, and proline biosynthesis of the seedlings of the energy plant Jatropha curcas, which could grow in poor, dry soil. Low-nitrogen stress induced JcP5CS mRNA expression and decreased the activity of P5CS enzyme and the content of free proline in leaves of J. curcas seedlings. When the seedlings grown in low-nitrogen conditions were suddenly exposed to PEG-6000 (−1.6MPa) stress, the expression of JcP5CS gene was highly induced, and both the activity of P5CS and the content of free proline increased and maintained at high levels to mitigate the impact of drought stresses. This may be one of the reasons why J. curcas could adapt to poor and drought conditions. KeywordsLow nitrogen supply–Proline–Drought stress–P5CS– Jatropha curcas
    No preview · Article · Sep 2011 · Acta Physiologiae Plantarum
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Alllelopathic potential of chicory was investigated by evaluating its effect on seed germination, soluble sugar, malondialdehyde (MDA) and the chlorophyll content of three target plants species (Festuca arundinacea, Trifolium repens and Medicago sativa). The secretion of allelochemicals was regulated by keeping the donor plant (chicory) separate from the three target plant species and using different pH and nitrogen levels. Leachates from donor pots with different pH levels and nitrogen concentrations continuously irrigated the target pots containing the seedlings. The allelopathic effects of the chicory at equivalent coupling of nitrogen supply and pH level on the three target plants species were explored via models analyses. The results suggested a positive effect of nitrogen supply and pH level on allelochemical secretion from chicory plants. The nitrogen supply and pH level were located at a rectangular area defined by 149 to 168 mg/l nitrogen supply combining 4.95 to 7.0 pH value and point located at nitrogen supply 177 mg/l, pH 6.33 when they were in equivalent coupling effects; whereas the inhibitory effects of equivalent coupling nitrogen supply and pH level were located at rectangular area defined by 125 to 131 mg/l nitrogen supply combining 6.71 to 6.88 pH value and two points respectively located at nitrogen supply 180 mg/l with pH 6.38 and nitrogen supply 166 mg/l with pH 7.59. Aqueous extracts of chicory fleshy roots and leaves accompanied by treatment at different sand pH values and nitrogen concentrations influenced germination, seedling growth, soluble sugar, MDA and chlorophyll of F. arundinacea, T. repens and M. sativa. Additionally, we determined the phenolics contents of root and leaf aqueous extracts, which were 0.104% and 0.044% on average, respectively.
    Preview · Article · Feb 2012 · PLoS ONE
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Plant-plant interference is the combined effect of allelopathy, resource competition, and many other factors. Separating allelopathy from resource competition is almost impossible in natural systems but it is important to evaluate the relative contribution of each of the two mechanisms on plant interference. Research on allelopathy in natural and cultivated plant communities has been hindered in the absence of a reliable method that can separate allelopathic effect from resource competition. In this paper, the interactions between allelopathic rice accession PI312777, non-allelopathic rice accession Lemont and barnyardgrass were explored respectively by using a target (rice)-neighbor (barnyardgrass) mixed-culture in hydroponic system. The relative competitive intensity (RCI), the relative neighbor effect (RNE) and the competitive ratio (CR) were used to quantify the intensity of competition between each of the two different potentially allelopathic rice accessions and barnyardgrass. Use of hydroponic culture system enabled us to exclude any uncontrolled factors that might operate in the soil and we were able to separate allelopathy from resource competition between each rice accession and barnyardgrass. The RCI and RNE values showed that the plant-plant interaction was positive (facilitation) for PI312777 but that was negative (competition) for Lemont and barnyardgrass in rice/barnyardgrass mixed-cultures. The CR values showed that one PI312777 plant was more competitive than 2 barnyardgrass plants. The allelopathic effects of PI312777 were much more intense than the resource competition in rice/barnyardgrass mixed cultures. The reverse was true for Lemont. These results demonstrate that the allelopathic effect of PI312777 was predominant in rice/barnyardgrass mixed-cultures. The most significant result of our study is the discovery of an experimental design, target-neighbor mixed-culture in combination with competition indices, can successfully separate allelopathic effects from competition.
    Full-text · Article · May 2012 · PLoS ONE
Show more