7 days old	16 days old

The purple color found in plants of the standard or purple stem, hairy stocks is the pigment anthocyanin. Non-purple stem plants are identified by the lack of expression of this pigment in any part and are a bright true green color. Plants of this stock have few to no hairs known as trichomes. The seed coat is yellow to muddy-yellow due to a lack of anthocyanin, rather than red brown to dark purple as in the standard stock.

Tips for the Grower
Basic experience with growing Fast Plants is recommended prior to using this stock.

Notes on Genetics
The single recessive gene for non-purple stem "blocks" the expression of the purple pigment anthocyanin in all plant parts. The genotype for this stock is anl/anl.

Dihybrid - Use the non-purple stem stock in a cross with yellow-green leaf plants. What do the offspring look like? If these offspring are crossed, do students find the predicted 9:3:3:1 segregation ratio in the F2 generation?

Monohybrid - Cross non-purple stem plants with purple stem plants. What do the offspring look like? Are there any plants in the F1 generation that do not express the purple pigment?

Plant reproduction - The non-purple stem allele can be used as a marker for identifying selfs and sibs in the female parent line in crosses where the male parent has the wildtype purple allele (as in the standard stock). If F1 plants from the non-purple stem "mother" plant are green with no purple anthocyanin expression, they are a product of self-pollination.

Ecology - Explore the positive and/or negative adaptive attributes associated with this genotype. Does the lack of anthocyanin makes the plants more vulnerable to UV irradiation? Does it have any impact on the plant's defense against herbivory?

C. O. Chichester, The Chemistry of Plant Pigments, Academic Press (New York), 1972.

T. W. Goodwin, ed., Chemistry and Biochemistry of Plant Pigments, Academic Press (New York), 1976.

G. Mazza, Anthocyanins in Fruits Vegetables and Grains, CRC Press (Boca Raton).