Figure 6.

Gel-PCR analysis of the expression of 33 expansin genes along the base of the maize leaf and in different tissues. Mature leaf tissues were collected from the emerged, nongrowing part of a growing leaf. Root tissues were collected from growing root tips. All tissues were collected from well-watered plants of the F2 line. The number of PCR cycles differed among genes, but was fixed among tissues. 18S rRNA and pAW109 RNA were used as controls. Genes were clustered according to spatial pattern of expression. Group 1 refers to genes most expressed in the first 20 or 40 mm at the leaf base; group 2 refers to genes most expressed in the 20- to 60-mm region. Group 3 refers to genes most expressed beyond the elongation zone (i.e. beyond 60 mm). Group 4 refers to genes most expressed in growing coleoptiles or root tips. Group 5 refers to genes most expressed in pollen grains.