10 research outputs found
Some aspects of underground organs of spotleaf orchis growth and phenolic compounds accumulation at the generative stage of ontogenesis
Effect of light quality and tissue origin on phenolic compound accumulation and antioxidant activity in Camellia japonica calli
Molecular and Physiological Adaptations of Tea Plant in Response to Low Light and UV Stress
The sensory quality, economic value, and health functions of tea liquor
depend on several metabolites in leaves of tea (Camellia sinensis L.), such as polyphenols
(the most representative quality- and function-related compounds, especially
catechins), caffeine, amino acids, aroma compounds, vitamins, and
carbohydrates. The biosynthesis of these molecules is significantly affected by both
management practices in the field and environmental factors, such as shading and
ultraviolet (UV) stress. In this chapter, therefore, we review existing literature reporting
the effects of shade and UV irradiances on tea plants with the aim to reappraise
morphological, biochemical, physiological, and molecular responses found in this
species. Cultivation of tea plants under shade can (i) induce anatomical and ultrastructural
adaptations; (ii) influence leaf color, providing characteristic vivid greenness
due to incremented chlorophyll content; (iii) decrease the risk of photoinhibition;
and finally (iv) improve the quality of tea beverages by causing the reduction of the
concentration of phenylpropanoids and caffeine (which contribute to astringency)
while increasing the level of amino acids (the compounds that contribute to sweetness).
However, the shade practice in tea is still subjected to controversy, and the
correct managing of the shade practice is essential. Elevated UV irradiances, especially
UV-B, can alter the plant morphology and affect several biochemical and
physiological processes; most plant species respond to UV in a dose dependent manner.
Protracted exposition to low UV-B doses (similar to UV peaks actually perceive
by plants in the ambient) leads to an enhancement of phenylpropanoid metabolism
and in particular stimulates the biosynthesis of UV-protecting flavonoids (mainly
catechins). Conversely, UV-B doses much higher than those usually experienced in
natural environment lead to the downregulation of the phenylpropanoid metabolism
likely due to irreversible (to some extent) UV-triggered damages. The understandings
of the reactions of tea plants to different light conditions, including situations of
low light and high UV, are of pivotal importance to enhance both plant yield and tea
quality by “driving” the accumulation of desired compounds in tea leaves