The Nicotiana attenuata NaHD20 is a positive regulator of leaf ABA accumulation during water stress, of benzylacetone emission from flowers and of the timing of bolting and flower transitions

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

JOURNAL OF EXPERIMENTAL BOTANY

OXFORD UNIV PRESS

Año: 2011 vol. 62 p. 155 - 166

0022-0957

Homeodomain-leucine zipper type I (HD-Zip I) proteins are plant specific transcription factors associated to the regulation of growth and development in response to changes in the environment. Nicotiana attenuata NaHD20 was identified as an HD-Zip I whose expression was induced by multiple stress-associated stimuli including drought and wounding. To study the role of NaHD20 in the integration of stress responses with changes in growth and development, its expression was silenced by virus induced gene silencing (VIGS) and control and silenced plants were metabolically and developmentally characterized. Phytohormone profiling showed that NaHD20 is a positive regulator of ABA accumulation in leaves during water stress and of the expression of some dehydration-responsive genes including ABA biosynthetic genes. Moreover, consistent with the high levels of NaHD20 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 specific developmental 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 in NaHD20-silenced plants. In summary, NaHD20 plays multiple roles in N. attenuata and among these are the coordination of responses to dehydration and its integration with changes in flower transitions.