Alternaria alternata is a critical plant pathogen, and the black spot caused by this fungus is the main cause of crop loss. In this study, four monoterpenes commonly found in plant essential oils, β -lonone, citral, γ -terpinene and myrcene, were found to possess a two-way interaction relationship with A. alternata . Four monoterpenes exhibited moderate inhibitory activities against A. alternata with MIC values of 128, 256, 512 and 256 μg/mL, respectively. However, when the concentration of monoterpenes in the culture medium was reduced to 1/4 MIC, A. alternata could facilitate the biotransformation of the aforementioned four monoterpenes by hydroxylation, dihydroxylation or carboxylation. These biotransformations were verified to be promoted by the P450 enzyme. Considering that none of the converted products showed inhibitory activity against A. alternata , these transformations were hypothesized to be self-protective mechanism of A. alternata . Expectedly, the combined use of P450 enzyme inhibitors and monoterpenes exhibited stronger antifungal activities, and could significantly inhibited black spot development in tomatoes. This work provides a reference for the development of effective antifungal agents.
Herbivore-induced plant volatiles (HIPVs) play an important role in insect resistance. As a common HIPV in tea plants (Camellia sinensis), β-ocimene has shown anti-insect function in other plants. However, whether β-ocimene in tea plants also provides insect resistance, and its mechanism of synthesis and emission are unknown. In this study, β-ocimene was confirmed to interfere with tea geometrid growth via signaling. Light was identified as the key factor controlling regular emission of β-ocimene induced by the wounding from tea geometrids. β-Ocimene synthase (CsBOS1) was located in plastids and catalyzed β-ocimene formation in overexpressed tobacco. CsBOS1 expression in tea leaves attacked by tea geometrids showed a day-low and night-high variation pattern, while CsABCG expression involved in volatile emission showed the opposite pattern. These two genes might regulate the regular β-ocimene emission from tea plants induced by tea geometrid attack. This study advances the understanding on HIPV emission and signaling in tea plants.
Sunlight withering (SWT) enhanced the floral aroma of white tea, whereas withering–tank withering (WWT) enriched its grassy aroma. This study investigated the impact of diverse withering methods on white tea aroma, examining aroma formation mechanisms by analyzing changes in essential compounds, their precursors, and enzyme activities during these treatments. Findings revealed that tea at 50% moisture concentration decreased the concentration of isopentenyl pyrophosphate and dimethylallyl pyrophosphate, leading to increased levels of linalool, geraniol, and β -myrcene. Sunlight spurred non-enzymatic reactions, elevating β -ionone concentration. The breakdown of linoleic and linolenic acids increased the hexanal and ( Z )-3-hexenol levels. Enzyme activity analysis indicated that the prominent floral aroma in SWT was linked to heightened geranyl pyrophosphate synthase and alcohol dehydrogenase activity, enriching terpene–catalyzed products and benzeneacetaldehyde concentration, respectively. Elevated levels of lipoxygenase and arogenate dehydratase promoted grassy compounds in WWT. This study underscores how withering methods shape white tea aromas and offers operational insights.
危险品化学品经营许可证（带存储）