Boron deficiency affects cell morphology and structure of young leaves of radish

Boron (B) is an essential microelement for the growth and development of plants. B-deficient radish plants grew slowly compared to B-sufficient controls. Soluble B and cell wall-bound B decreased in young leaves on removal of B from culture medium. In old leaves, B deficiency reduced soluble B content but there was no significant effect on cell wall-bound B content compared to controls. The mesophyll cells in the middle of leaves were enlarged abnormally and had greater cell wall thickness under B-deficient conditions. B deficiency reduced the stomata frequency, inhibited the stomata aperture, and guard cells had thickened cell walls. B-starved leaves showed decreased photosynthesis and stomatal conductance. These indicate that B deficiency could interfere with cell wall development, especially irregular guard cell walls as a result of B deficiency severely affected the rhythmic stomatal closing and opening, preventing the normal functioning of stomata. Correspondingly, photosynthesis was indirectly affected, and plant growth decreased.