Three-dimensional surface topography of the needle stomatal complexes of Pinus rigida and its hybrid species by complementary microscopy

Three-dimensional surface topography of needle stomatal complexes was investigated in Pinus rigida, Pinus taeda, and their interspecific hybrid Pinus rigitaeda. The stomatal complexes of P. rigida appeared to be sunken and ca. 15 μm deep by white light scanning interferometry. Stomatal grooves were evident in P. taeda along the stomata and amounted to ca. 5 μm deep. The centers of stomata maintained the similar height to the stomatal apertures. Meanwhile, the stomatal complexes of P. rigitaeda (ca. 15 μm deep) were characterized by distinct stomatal grooves and sunken stomatal chambers. In addition, field emission scanning electron microscopy revealed the stomatal complexes of P. rigida partially filled with epicuticular waxes. It was common to observe distinct stomatal grooves and chamber-filled stomata on P. taeda needles. The stomatal complexes of P. rigitaeda had the distinct stomatal grooves and were partially filled with wax tubules and rodlets. Surface roughness measurements of stomatal complexes showed higher levels of roughness from P. rigida and P. rigitaeda than that from P. taeda. These results indicate that the hybrid species P. rigitaeda showed intermediacy in surface characteristics between the parent species, suggesting the genetic control of needle stomatal complexes in the hybrid species.