jasmonic-acid and 2-4-dihydroxy-7-methoxy-1-4-benzoxazin-3-one

Plants may chemically affect the performance of neighbouring plants through allelopathy, allelobiosis or both. In spite of increasing knowledge about allelobiosis, defined as the signalling interactions mediated by non-toxic chemicals involved in plant-plant interactions, the phenomenon has received relatively little attention in the scientific literature. This study examined the role of allelobiosis in the interference of allelopathic wheat with weeds.. Allelopathic wheat inhibited the growth of five weed species tested, and the allelochemical (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) production of wheat was elicited in the presence of these weeds, even with root segregation. The inhibition and allelochemical levels varied greatly with the mixed species density. Increased inhibition and allelochemical levels occurred at low and medium densities but declined at high densities. All the root exudates and their components of jasmonic acid and salicylic acid from five weeds stimulated allelochemical production. Furthermore, jasmonic acid and salicylic acid were found in plants, root exudates and rhizosphere soils, regardless of weed species, indicating their participation in the signalling interactions defined as allelobiosis.. Through root-secreted chemical signals, allelopathic wheat can detect competing weeds and respond by increased allelochemical levels to inhibit them, providing an advantage for its own growth. Allelopathy and allelobiosis are two probably inseparable processes that occur together in wheat-weed chemical interactions. © 2016 Society of Chemical Industry.

Topics: Allelopathy; Benzoxazines; Cyclopentanes; Oxylipins; Plant Growth Regulators; Plant Roots; Plant Weeds; Rhizosphere; Salicylic Acid; Signal Transduction; Triticum

Biochemical and gene expression analysis methods were adopted to investigate the defensive substances and the defense-related genes expression in the roots and leaves of maize (Zea mays L. ) cultivar Gaoyou 115 after underground treatment with 10, 50, 100 and 200 micromol x L(-1) of jasmonic acid (JA) for 3-48 h, aimed to explore the timing- and concentration effect of belowground treatment with JA on the chemical defense response of maize. The chemical defense response of both treated roots and non-treated leaves of Gaoyou 115 was related to the time span of JA treatment and the concentration of JA. After treated with JA for 3-12 h, the gene expression of Bx9, PAL, PR-2a, MPI and FPS in treated roots was directly induced, resulting in an increase of DIMBOA content and a decrease of total phenol content, with the strongest induction effect detected at 100 micromol x L(-1) of JA, followed by at 50 micromol x L(-1), and at 10 micromol x L(-1). The induction effect weakened with time. Underground treatment with JA indirectly affected the chemical defense response of non-treated leaves. After underground treatment with 50 micromol x L(-1) of JA for 3 h, the gene expression of Bx9 and FPS in non-treated leaves was induced, which caused a consequent increase of leaf DIMBOA content. Within 6-24 h of JA treatment, the gene expression of Bx9, PAL, PR-1, MPI and TPS in leaves was enhanced, while the leaf DIMBOA and total phenol contents were declined. For most of the parameters measured, the direct induction effect on roots was much more significant and started earlier than the indirect induction effect on leaves, and an increasing trend was observed in the induction effect with increasing JA concentration.

Topics: Benzoxazines; Cyclopentanes; Dose-Response Relationship, Drug; Oxylipins; Phenol; Plant Roots; Seedlings; Time Factors; Zea mays