Guard cells on the adaxial and abaxial leaf surfaces use different compositions of potassium ion channels to drive light-induced stomatal opening.

In the leaves of most herbaceous plants, stomata exist in both the adaxial (upper) and abaxial (lower) surfaces. Many previous studies have reported that stomata on the abaxial surface are more responsive to light than those on the adaxial surface. However, the underlying molecular mechanism is still unclear. Here, by examining the model plants Arabidopsis and tobacco, we confirmed that the distinct feature occurred at the guard cell level. Next, with both single-cell RNA sequencing and transcriptome sequencing, we compared gene expression patterns of adaxial and abaxial guard cells and highlighted the possibility of different utilization of potassium ion (K) channels. Via in silico OnGuard simulation and genetic modifications, we found that adaxial and abaxial guard cells rely on different K channels, which control K influx for stomatal opening. The present study provides insights into understanding the distinct stomatal light response of different leaf surfaces.