The Role of Microtubules in Stomatal Opening

In contrast to most plant cells, the cortical microtubules of guard cells remain well organized even after microfibril deposition and cellular differentiation is complete. This has led some researchers to speculate that microtubules might play an important role in the regulation of stomatal function. However, recent pharmacological studies concerning the effects of microtubule inhibitors on stomatal opening have yielded seemingly contradictory findings. To gain insight into the role of microtubules in guard cell function, Marcus et al. (pp. 387–395) employ a microtubule reporter gene construct consisting of the microtubule-binding domain of the mammalian MAP4 protein fused to green fluorescent protein (GFP::MBD). Biolistically-transformed guard cells expressing GFP::MBD display the distinctive microtubule arrays that characterize guard cells (Fig. 1), but no longer retain