RESUMO
Aerial organs of plants, being highly prone to local injuries, require tissue restoration to ensure their survival. However, knowledge of the underlying mechanism is sparse. In this study, we mimicked natural injuries in growing leaves and stems to study the reunion between mechanically disconnected tissues. We show that PLETHORA (PLT) and AINTEGUMENTA (ANT) genes, which encode stem cell-promoting factors, are activated and contribute to vascular regeneration in response to these injuries. PLT proteins bind to and activate the CUC2 promoter. PLT proteins and CUC2 regulate the transcription of the local auxin biosynthesis gene YUC4 in a coherent feed-forward loop, and this process is necessary to drive vascular regeneration. In the absence of this PLT-mediated regeneration response, leaf ground tissue cells can neither acquire the early vascular identity marker ATHB8, nor properly polarise auxin transporters to specify new venation paths. The PLT-CUC2 module is required for vascular regeneration, but is dispensable for midvein formation in leaves. We reveal the mechanisms of vascular regeneration in plants and distinguish between the wound-repair ability of the tissue and its formation during normal development.
Assuntos
Arabidopsis , Redes Reguladoras de Genes/fisiologia , Folhas de Planta/fisiologia , Caules de Planta/fisiologia , Feixe Vascular de Plantas/fisiologia , Regeneração/genética , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Desenvolvimento Vegetal/fisiologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Caules de Planta/genética , Caules de Planta/crescimento & desenvolvimento , Feixe Vascular de Plantas/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas , Transdução de Sinais/genética , Fatores de Transcrição/fisiologia , Cicatrização/genéticaRESUMO
The voltage-dependent anion channel (VDAC) and mitochondrially located hexokinase have been implicated both in pathways leading to cell death on the one hand, and immortalization in tumor formation on the other. While both proteins have also been implicated in death processes in plants, their interaction has not been explored. We have examined cell death following heterologous expression of a rice VDAC in the tobacco cell line BY2 and in leaves of tobacco plants and show that it is ameliorated by co-expression of hexokinase. Hexokinase also abrogates death induced by H2O2. We conclude that the ratio of expression of the two proteins and their interaction play a major role in modulating death pathways in plants.