Résumé
Water is essential for plants’ growth and development, but water in soils tends to be heterogeneously distributed. To acquire water, maize roots continuously explore the soil by building a highly complex, branched architecture; at the same time, they adjust their water transport capacity. However, the molecular underpinnings and coordinating the response to heterogeneous water distribution, especially the temporal response, are largely unknown. We developed a split-root hydroponic system and found that when subjectedto local water deficit, maize lateral root growth is enhanced in the water-sufficient part and inhibited in the water-deficit part compared to their corresponding controls. To characterize the transcriptional mechanism underlying this response to heterogeneous water availability, we assayed how maize’s roots temporal transcriptome responds to local water deficit during the seedling stage. We treated hybrid maize B73h (B73-UH007) seedlings with Polyethylene glycol 8000 (PEG8000) at 150 g/L in the split-root hydroponic system (0/0PEG, 0/150 PEG, 150/150 PEG) over 10 time points (0, 0.5, 1, 2, 4, 8, 12, 24, 48 and 96h). The lateral roots (LR) and axial root tips (Tips) were collected to conduct RNA-seq. DEGs were identified via fitting a spline to each gene, and comparing the expression with CK/PEG. kmeans clustering was used to identify identical temporal gene clusters. The result clearly identified an early and late molecular response to heterogeneous wateravailability for both LR and Tips. Compared to Tips, LR showed more massive and rapid response especially in the early time. This approach identified a LR specific gene cluster locally and systemically regulated within 30 min pointing out a transient signaling mechanism that will be further described.