Nicotiana attenuata NaHD20 plays a role in leaf ABA accumulation during water stress, benzylacetone emission from flowers, and the timing of bolting and flower transitions

RE DA; DEZAR CA; CHAN RL; BALDWIN IT; BONAVENTURE G

JOURNAL OF EXPERIMENTAL BOTANY

OXFORD UNIV PRESS

Lugar: Lancaster; Año: 2011 vol. 62 p. 155 - 166

0022-0957

Homeodomain-leucine zipper type I (HD-Zip I) proteins are plant-specific transcription factors associated with theregulation of growth and development in response to changes in the environment. Nicotiana attenuata NaHD20 wasidentified as an HD-Zip I-coding gene whose expression was induced by multiple stress-associated stimuli includingdrought and wounding. To study the role of NaHD20 in the integration of stress responses with changes in growthand development, its expression was silenced by virus-induced gene silencing (VIGS), and control and silencedplants were metabolically and developmentally characterized. Phytohormone profiling showed that NaHD20 playsa positive role in abscisic acid (ABA) accumulation in leaves during water stress and in the expression of somedehydration-responsive genes including ABA biosynthetic genes. Moreover, consistent with the high levels ofNaHD20 expression in corollas, the emission of benzylacetone from flowers was reduced in NaHD20-silenced plants.Additionally, bolting time and the opening of the inflorescence buds was decelerated in these plants in a specificdevelopmental stage without affecting the total number of flowers produced. Water stress potentiated these effects;however, after plants recovered from this condition, the opening of the inflorescence buds was accelerated inNaHD20-silenced plants. In summary, NaHD20 plays multiple roles in N. attenuata and among these are thecoordination of responses to dehydration and its integration with changes in flower transitions.