6-Methoxy-benzoxazolin-2(3H)-one (MBOA) is a degradation product derived from 2,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA), one of the bioactive compounds found e.g., in maize. Here we present hitherto unknown 6-methoxy-4-nitro-benzoxazolin-2(3H)-one (NMBOA) produced in Czapek medium by Pantoea ananatis (Enterobacteriaceae). P. ananatis is a member of a microbial consortium dominated by the zygomycete Actinomucor elegans, which was isolated from roots of Abutilon theophrasti. NMBOA was identified by NMR spectra and HR-ESI-MS analyses, revealing an unusual position of the nitro group at C-4. Nitration of MBOA initiates the degradation of the compound that is almost completed within three days by the entire consortium and isolated P. ananatis. The yeast Papiliotrema baii, another member of the consortium, is unable to degrade NMBOA but stored it at the surface of its polysacchararide capsule. NMBOA has negative effects on microbial growth in liquid medium whereas seedlings of Brassica oleracea var. gongylodes L. (kohlrabi) or Lepidium sativum (cress) are not impaired up to 500 µM. Degradation via nitration may be important to understand the behavior of microbial species and effects of microbiomes when exposed to MBOA.

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Some sweet tasting plant secondary metabolites are non-caloric or low nutritive compounds that have traditional use in food formulations. This mini-review focuses on conventional and advanced cultivation regimes of plants that accumulate sweet tasting or sweet taste modulating secondary metabolites of potential economic importance, in particular mogrosides (Siraitia grosvenorii), phyllodulcin (Hydrangea macrophylla), glycyrrhizin (Glycyrrhiza glabra), steviol glycosides (Stevia grosvenorii), and rubusoside (Rubus suavissimus). Consequential obstacles during the cultivation of Hydrangea macrophylla cultivars outside their natural habitat in a protected cultivation environment are addressed. Culturing at non-habitat locations facilitates short transportation routes of plant material for processing, which can be a key to an economically and environmentally compatible usage. The biosynthetic pathways, as far as known, are shortly mentioned. The proved or hypothetical degradation pathways of the compounds to minimalize environmental contamination are another focal point.

Peppermint (Mentha x piperita) is a species with inhibitory allelopathic properties due to its high amounts of terpenes. Recent studies have disclosed dosage dependent growth promotion or defense reactions in plants when facing appropriate amounts of Mentha bouquet terpenes. These positive effects could be of interest for agricultural applications. To obtain more insights into leaf growth modulations, the expression of Arabidopsis and Brassica rapa TCP transcription factors were studied after fumigation with M. x piperita bouquets (Arabidopsis), with M. x piperita essential oil or with limonene (Arabidopsis and Chinese cabbage). According to qPCR studies, expression of TCP3, TCP24, and TCP20 were downregulated by all treatments in Arabidopsis, leading to altered leaf growth. Expressions of B. rapa TCPs after fumigation with the essential oil or limonene were less affected. Extensive greenhouse and polytunnel trials with white cabbage and Mentha plants showed that the developmental stage of the leaves, the dosage, and the fumigation time are of crucial importance for changed fresh and dry weights. Although further research is needed, the study may contribute to a more intensive utilization of ecologically friendly and species diversity conservation and positive allelopathic interactions in future agricultural systems.