Enzymes of pollen

Abstract

Pollen enzymes must be very important in rendering stored food available when pollen germinates, in facilitating the passage of the pollen-tube through the pistil, and in stimulating the development of the embryo and maturing of the ovary.

Moreover pollen anaphylaxis is now regarded as the cause of socalled hay-fever and other forms of pollen poisoning. Pollen enzymes may be concerned in these reactions, and the proteolytic enzymes may affect the stability of the pollen-protein solutions used in pollen vaccination.

Yet in spite of the significance of these enzymes few experiments in regard to their nature have been reported, and none recently. Erlenmeyer (1874) found amylase in pine pollen. Van Tieghem (1886) reported invertase in hyacinth, narcissus, wallflower, and violet. Rittinghaus (1886) made observations which indicate the presence of the cytase. J. R. Green cites amylase in pollen tubes. Strasburger (1905) mentions diastase and invertin in grains prior to germination. Kammann (1912) found proteases, diastases, catalases, and lipases in rye pollen.

Although it has been assumed that pollen tubes digest their way through the style there seems to be no experimental evidence as to the exact nature of this enzyme action. Histological examination shows that pollen tubes make their tortuous way between the walls of adjacent cells rather than traversing or penetrating the cell. We should expect, therefore, to find not a cytase or cellose-digesting enzyme, but rather a pectinase, capable of digesting the pectin of the inner lamella. This has been proved in the writer's experiments to be the case.

Twelve kinds of pollen have already been tested, namely, Easter lily, Lilium rubrum, red maple, Norway maple, Siberian crab apple, Austrian pine, magnolia, dandelion, goldenrod, ragweed, and corn. Rye, daisy, dock and timothy are now being examined.