Characterization of Terpene Synthase from Tea Green Leafhopper Being Involved in Formation of Geraniol in Tea (Camellia sinensis) Leaves and Potential Effect of Geraniol on Insect-Derived Endobacteria

Abstract

When insects attack plants, insect-derived elicitors and mechanical damage induce the formation and emission of plant volatiles that have important ecological functions and flavor properties. These events have mainly been studied in model plants, rather than crop plants. Our study showed that tea green leafhopper (Empoasca (Matsumurasca) onukii Matsuda), a major pest infesting tea attack significantly induced the emission of geraniol from tea leaves, but did not affect the crude enzyme activity of geraniol synthase in tea leaves. An enzyme extract of E. (M.) onukii specifically produced geraniol from geraniol diphosphate. Furthermore, a terpene synthase (EoTPS) was isolated from E. (M.) onukii. This terpene synthase was able to convert geraniol diphosphate to geraniol in vitro. In addition, geraniol had in vitro ability to inhibit the growth of Acinetobacter johnsonii that is endobacterial isolated from E. (M.) onukii. This information illustrates that elicitors from piercing-sucking insects can induce the formation of volatiles from crop plants and advances our understanding of the roles of plant volatiles in the interaction among crops-insects-microorganisms.Biomolecules 2019, 9, 808 2 of 17 and shown to induce the formation and emission of plant volatiles. These elicitors have mainly been identified in chewing insects, and rarely in piercing-sucking insects. This may be because the amount of elicitors produced by small piercing-sucking insects is insufficient for analysis and difficult to obtain [2]. In addition, the first events in the interaction between insects and plants have mainly been studied in model plants, rather than horticultural crop plants.Tea (Camellia sinensis) is an important horticultural crop in almost 30 countries, including China, Japan, India, and Kenya. Abundant volatiles compounds such as fatty acid-derivatives including (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate, (E)-2-hexenal, and (E)-2-hexenoic acid; volatile phenylpropanoids/benzenoids including benzyl nitrile, benzaldehyde, and indole; and volatile terpenes including geraniol, farnesene, ocimenes, linalool, and nerolidol were found in tea [5,[11][12][13]. These volatile compounds are important quality components of teas and contribute to tea flavor [14]. Among these volatiles, terpenes are major floral and honey flavor-related volatiles [14]. During tea plant growth, many pest insects such as tea green leafhoppers, tea geometrid, tea aphids, smaller tea tortrix, and Kanzawa spider mites attack tea leaves and affect the yield and quality of the crop [13]. In response to these insect attacks, tea plants emit numerous compounds. Insect-induced volatiles may play important roles in defense [11,12]. On the other hand, insect-induced volatiles may change the flavor the tea and increase the tea quality. As a classical example, a famous oolong tea (oriental beauty), which is manufactured from tea leaves infected with tea green leafhoppers, contains characteristic volatile monoterpenes and has a unique ripe fruit and honey aroma [5,15].In our ...

Roles of specialized metabolites in biological function and environmental adaptability of tea plant (Camellia sinensis) as a metabolite studying model

“…Furthermore, HIPVs might influence insect feeding physiology by regulating microbes [130] , [131] . Tea green leafhopper has also been found to induce geraniol release, but has no effect on the activity of geraniol synthase (GS) in tea leaves [132] . However, GS from tea green leafhopper can induce geraniol formation in tea plants, suggesting that the protein from this insect might be the main factor.…”

“…Furthermore, geraniol inhibited the endobacteria isolated from tea green leafhoppers in vitro . Therefore, during attack, tea green leafhoppers are speculated to use their own GS to enhance geraniol formation in tea plants, with the produced geraniol then being able to affect the insect physiological activity by mediating the growth of its endobacteria [132] .…”

Natural Products for the Prevention and Control of the COVID-19 Pandemic: Sustainable Bioresources

“…Even geraniol has been reported in numerous medicinal plants, for instance, Pelargonium graveolens L'Hér. ( Gupta et al, 2001 ), Camellia sinensis (L.) Kuntze ( Zhou et al, 2019 ), Rosa × damascena Herrm. ( Sadraei et al, 2013 ), Cymbopogon flexuosus (Nees ex Steud.)…”

Cytosolic Nudix Hydrolase 1 Is Involved in Geranyl β-Primeveroside Production in Tea

“…However, no geraniol synthase ( GES ) genes have been identified in tea plants, while many GES genes have been found in other plant species ( Degenhardt et al, 2009 ). Interestingly, it was once suggested that a leafhopper geraniol synthase was likely contributing to tea geraniol production and the characteristic aroma of “Oriental Beauty” tea ( Zhou et al, 2019 ).…”