Poplar PtabZIP1 positively regulates lateral root formation and flavonoid synthesis and enhance biomass growth under drought.
Madhumita Dash,Yordan S. Yordanov,Tatyana Georgieva,Timothy J. Tschaplinski,Elena Yordanova,Victor Busov
2016 November 04 The Plant Journal; DOI: 10.111/tpj.13413
Developing drought-resistance varieties is a major goal for bioenergy crops, such as poplar (Populus),
which will be grown on marginal lands with little or no water input.
Root architecture can affect drought-resistance, but few genes that
affect root architecture in relation to water availability have been
identified. Here, using activation tagging in the prime bioenergy crop
poplar, we have identified a mutant that overcomes the block of lateral
root (LR) formation under osmotic stress. Positioning of the tag,
validation of the activation and recapitulation showed that the
phenotype is caused by the poplar PtabZIP1-like (PtabZIP1L) gene with highest homology to bZIP1 fromArabidopsis. PtabZIP1L
is predominantly expressed in roots, particularly in zones where
lateral root primordia (LRP) initiate and LR differentiate and emerge.
Transgenics overexpressing PtabZIP1L showed precocious LRP and LR development, while PtabZIP1L suppression significantly delayed both LRP and LR formation. Transgenic overexpression and suppression of PtabZIP1L
also resulted in modulation of key metabolites like proline,
asparagine, valine and several flavonoids. Consistently, expression of
both of the poplar Proline Dehydrogenase orthologs and two of the Flavonol Synthases
genes was also increased and decreased in overexpressed and suppressed
transgenics, respectively. These findings suggest that PtabZIP1L
mediates LR development and drought resistance through modulation of
multiple metabolic pathways.
Dash, M., Yordanov, Y. S., Georgieva, T., Tschaplinski, T. J., Yordanova, E. and Busov, V. (2016), Poplar PtabZIP1-like enhances lateral root formation and biomass growth under drought stress. Plant J. Accepted Author Manuscript. doi:10.1111/tpj.13413