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My current interests involve:
(1) The influence of light in the conditional ecological responses of Nicotiana attenuata to herbivory attack. Recent data has shown that UV-B up-regulates plant defenses against herbivory. On the other hand, shade (low red:far-red ratio), a light signature used by plants to detect neighbor’s proximity, conveys the opposite scenario, presumably redirecting plant essential resources into elongated growth to overcome competitors. To understand how these light signals induce opposite trade-offs in plant defense and growth, I make use of stably silenced phytochrome B plants and also different light treatments and investigate their effects on JA -dependent responses.

(2) Ecological relevance of the ethylene-induced triple response. Although ethylene biosynthesis and perception are molecularly well characterized, the function of the triple response (shortened and thickened hypocotyl and apical hook) under natural conditions remains unknown. For this, I make use of different transgenic lines silenced or over-expressing ethylene-related genes (irACO and sETR) and evaluate their emergence capability and ethylene emissions.

(3) Shoot-to-root and root-to-shoot signals underlying defense responses in N. attenuata. After 1 h of mimicked herbivore attack, a local peak of JA and JA-Ile is observed in leaves. This, in turn, induces a set of systemic defense responses such as PI activity in leaves and nicotine production in roots. To unravel the mechanisms underlying plant coordinated above- and below-ground responses to wounding and mimicked herbivore attack, I make use of micrografted plants that display impaired JA-synthesis or perception only at their roots and evaluate the whole-plant performance in response to herbivory.

(4) As a parallel project, I’m also interested in the role of phytochromeB in the belowground parts of the plants. Surprisingly, many photoreceptors are expressed in roots of N. attenuata, organs thought to develop in total darkness of the soil. Using micrografted plants with sighted shoots and blind roots, I investigate how and till which extend light signals in the belowground are required to plant growth and development.

List of Publications

Fragoso, V; Goddard, H; Baldwin, IT; Kim, S-G. A simple and efficient micrografting method for stably transformed Nicotiana attenuata plants to examine shoot-root signaling. BMC Plant Methods (7) 34.

Paranhos, JT; Fragoso, V; da Silveira, VC; et al. Organ-specific and environmental control of accumulation of psychollatine, a major indole alkaloid glucoside from Psychotria umbellata. Biochemical Systematics and Ecology (37) 707-715.

Fragoso, V*; do Nascimento, NC*; Moura, DJ; et al. Antioxidant and antimutagenic properties of the monoterpene indole alkaloid psychollatine and the crude foliar extract of Psychotria umbellata Vell. Toxicology in vitro (22) 559-566.
* These authors contributed equally to this work

do Nascimento, NC*; Fragoso, V*; Moura, DJ; et al. Antioxidant and antimutagenic effects of the crude foliar extract and the alkaloid brachycerine of Psychotria brachyceras. Environmental and Molecular Mutagenesis (48) 728-734.
* These authors contributed equally to this work

Paranhos, JT; Fragoso, V; Henriques, AT; et al. Regeneration of Psychotria umbellata and production of the analgesic indole alkaloid umbellatine. Tree Physiology (25) 251-255.
last updated on 2013-04-05