Xenia - Part II

Kiesselback, T.A. 1980. The Structure and Reproduction of Corn. University of Nebraska Free Press. Lincoln, Nebraska. (pg 85-86).

Xenia - Kiesselback stated that:

"all effects of foreign pollen which appeared in fruit, seed, or vegetative structure of the female parent. Any change in the tissue of the mother plant, such as a change in weight or size of pericarp, is now called metaxenia. Change in embryo tissue, as in the color or composition of the cotyledons of peas, is not generally regarded as xenia, so that use of the term is now usually limited to any changes in endosperm resulting as an immediate effect of foreign pollen.

Xenia is common in corn, especially by way of aleurone - and endosperm - color responses and changes in the composition, texture, and weight of the endosperm. For example, the kernels of white sweet corn become yellow, starchy, and heavier when outcrossed by plants with yellow starchy kernels.

Xenia is very convenient in the demonstration of segregation, as the kernels can be counted, where as most sporophytic responses are not apparent until the seed is planted and the character becomes visible in the progeny plants."

Xenia - the direct effect of pollen genotype on the endosperm, which includes the aleurone layer.

Example:

In maize, due to double fertilization of embryo and endosperm tissue, the alleles carried by the pollen parent may be manifested on the endosperm tissue.

(Rr of the male) x (rr of the female) results in:

1/2 Rrr (purple aleurone)
1/2 rrr (yellow aleurone)

(rr of the male) x (rr of the female) results in - rrr, all yellow aleurone.

The effect of the pollen genotype is immediately evident.