| Abstrak/Abstract |
Leaves serve as essential plant organs that facilitate photosynthesis and consist of several
layers, such as the mesophyll and epidermis, each of which possesses unique metabolite
compositions. These metabolites play a role in the plant’s defensive system against
insects. For instance, the leaves of Ocimum basilicum L. (basil) possess biocidal properties
against a variety of insects. Although the insecticidal properties of these leaves have
been well documented, the distribution studies on the leaf metabolites are inadequate.
Thus, this study examined the metabolite profiles of the two leaf layers, epidermis and
mesophylls. The separation of epidermis and mesophyll extracts was accomplished using
whetstone powder, followed by gas chromatography-mass spectrometry to analyze the
obtained metabolite profiles. The leaf trichomes were examined by scanning electron
microscopy. Certain chemicals were only detectable within the epidermal or mesophyll
tissues. For example, tricosane (16.37%) and geraniol (7.88%) were exclusively detected
in the epidermis, whereas limonene oxide (1.26%) and α-humulene (1.04%) were only
detected in the mesophyll. Furthermore, certain components were found in higher
quantities in the epidermis and mesophyll layers, whereas others were more prevalent in
the opposite layer. Our findings relevant to
the trichome types, specifically glandular
and non-glandular trichomes, indicated
that both play a role in the initial defenses
against herbivorous insects. This study
offers significant insights into the chemicals
that serve as plant defenses in basil leaf
tissue and trichomes. Future studies on
the distribution of chemical compounds in
different leaf tissues can provide further insights into the mechanisms of plant-insect
interaction and facilitate the development of
strategies for identifying compounds that
play a role in defense. |
