X-ray microanalysis of papillar cells and pollen grains in the pollination process in Brassica using a variable-pressure scanning electron microscope

Using an energy dispersive X-ray microanalysis (EDX) system fitted with variable-pressure scanning electron microscopy (VP-SEM), we examined the changes of elemental distribution in papillar cells and pollen grains in the process of cross- and self-pollination in a self-incompatible species of Brassica. The emission of P-K alpha, S-K alpha, K-K alpha and Ca-K alpha was usually detected both in papillar cells and pollen grains. In cross-pollination, the intensity of Ca-K alpha emission in the papillar cell increased once at 30 min and again at 3 h after pollination. In the pollen, Cl-K alpha emission was detected after 3 h with an increase in emission of S-K alpha and K-K alpha. These elemental redistributions will be correlated with the structural change of the cell wall during the penetration of the pollen tube. In self-pollination, the intensity of Ca-K alpha emission in the papillar cell was larger at 30 min and again at 3 h after pollination than chat before pollination. The increase may be related to callose formation.