Division zone activity determines the potential of drought-stressed
maize leaves to resume growth after rehydration
Abstract
Drought is one of the most devastating causes of yield losses in crops
like maize and the anticipated increases in severity and duration of
drought spells due to climate change pose an imminent threat to
agricultural productivity. To understand the drought response,
phenotypic and molecular studies are typically performed at a given time
point after drought onset, representing a steady-state adaptation
response. Because growth is a dynamic process, we monitored the drought
response with high temporal resolution and examined cellular and
transcriptomic changes after rehydration at 4 and 6 days after leaf four
appearance. These data showed that the division zone activity is a
determinant for full organ growth recovery upon rehydration. Moreover, a
prolonged maintenance of cell division by the ectopic expression of
PLASTOCHRON1 extends the ability to resume growth after
rehydration. The transcriptome analysis also indicated that
GROWTH-REGULATING FACTORS (GRFs) affected leaf growth by impacting cell
division duration, which was confirmed by a prolonged recovery potential
of the GRF1-overexpression line after rehydration. Finally, we
used a multiplex genome editing approach to evaluate the most promising
differentially expressed genes from the transcriptome study and as such
narrowed down the gene space from forty to seven genes for future
functional characterization.