Signal coordination before, during and after stomatal closure in response to drought stress

Abstract

Summary Signal coordination in response to changes in water availability remains unclear, as does the role of embolism events in signaling drought stress. Sunflowers were exposed to two drought treatments of varying intensity while simultaneously monitoring changes in stomatal conductance, acoustic emissions (AE), turgor pressure, surface‐level electrical potential, organ‐level water potential and leaf abscisic acid (ABA) concentration. Leaf, stem and root xylem vulnerability to embolism were measured with the single vessel injection technique. In both drought treatments, it was found that AE events and turgor changes preceded the onset of stomatal closure, whereas electrical surface potentials shifted concurrently with stomatal closure. Leaf‐level ABA concentration did not change until after stomata were closed. Roots and petioles were equally vulnerable to drought stress based on the single vessel injection technique. However, anatomical analysis of the xylem indicated that the increased AE events were not a result of xylem embolism formation. Additionally, roots and stems never reached a xylem pressure threshold that would initiate runaway embolism throughout the entire experiment. It is concluded that stomatal closure was not embolism‐driven, but, rather, that onset of stomatal closure was most closely correlated with the hydraulic signal from changes in leaf turgor.

Differential response of photosystem II and I photochemistry in leaves of two Crambe abyssinica Hochst lineages submitted to water deficit

“…The lower g s values verified in plants of crambe under WD suggest that there was the closure of the stomatal pore. Plants close stomata to limit water loss, and this is a response to hydraulic signals from changes in leaf turgor (Huber et al 2019). Stomatal closure generally restricts stomatal diffusion of CO2 and is coupled with a decrease in the mesophyll conductance of CO2 (internal CO2 diffusion) (Guha et al 2013).…”

Weighted gene coexpression network analysis-based identification of key modules and hub genes associated with drought sensitivity in rice

“…However, as sessile organisms, higher plant usually adopt the 'overcome' strategy upon encountering any extreme environmental stresses; this strategy, in contrast to that of animals, is preferentially to opt for the tolerance or avoidance of unfavorable circumstances. In general, various tolerance/avoidance mechanisms [1], such as regulation of endogenous hormone signals [2], increases in wax deposition in the cuticle [3], and stomatal regulation [4], are employed in response to abiotic stresses.…”

Weighted gene coexpression network analysis-based identification of key modules and hub genes associated with drought sensitivity in rice 

“…S9D; Table S5-4). However, with the exception of iron-sulfur cluster binding (GO:0051536), no GO term was signi cantly overrepresented in our analysis (Table S5- 4). It is worth noting that only 1 hub gene, OS04G0685300, which encodes a protein with harpin-induced 1 domain, showed signi cant differential expression with a greater upregulation magnitude at two points of PY6 (2.03/2.67) compared with those in PR403 (Table S3- were strongly correlated with MDA under drought treatment; there were 303, 304, and 13 hub genes identi ed in these modules, respectively (Table S3-5~-7).…”