ABSTRACT
Actin dynamics in guard cells play a critical role in stomatal movement. Remodeling of actin arrays is triggered by different biotic and abiotic stimuli, which requires precise control. However, the molecular mechanism underlying this process is not well understood. Here we investigated whether and how the capping protein (CP) regulates actin filaments during fusicoccin (FC) -induced stomatal opening. We found that both stomatal opening and F-actin rearrangement are sensitive in the Capping Protein β-subunit (CPB) cpb-3 mutants, which resulted in its hypersensitivity to drought stress. The leaves detached from cpb-3 had a higher water loss rate (63. 45%) than from the wild type (48. 99%), and the stomatal aperture of cpb-3 was about 20% greater than in the wild type. After 1 h of FC treatment, the proportion of cpb-3 guard cells with radial actin arrays increased to 65. 5% dramatically, while only approximately 47. 2% guard cells in WT exhibited transversely oriented actin filaments. Moreover, the record of transmembrane Ca