The clonal origin of the lateral meristem generating the ear shoot of maize

Abstract

Abstract. The ear shoot of maize (Zea mays L.) consists of the peduncle and reproductive tissues (ear). Genetic mosaics induced by the unstable allele of the chl locus were used for cell lineage analysis of the ear shoot. The unstable chl-ml allele, caused by the insertion of a transposable element, gives rise to yellow-green seedlings with many small revertant green stripes. Rare plants with large reverrant sectors comprising 30-50% of the plant were selected. Nineteen plants showing large sectors on the main stem were subjected to sector boundary analysis. Sectoring was recorded for the main stem, leaf subtending the ear shoot, peduncle, prophyll and ear. The reproductive part of the ear shoot, the ear, was scored after removal of the husks and subsequent exposure to light. In 18 cases the ear was non-sectored yellow-green or green. In an additional four cases, peduncle cell lineages entered the ear, but only in the proximal part, while the tip of the ear was non-sectored. Two additional ears showed longitudinal sectors which reached the tip of the ear. These observations indicate that in the lateral meristem of the ear shoot two types of cellular clone exist. One will generate the peduncle, the other will found the ear. Sector boundary analysis indicates that for the vegetative part of the ear shoot the number of meristem founder cells is high, whereas only a few initials are recruited for the formation of the ear. The presence of ear sectors not starting in the peduncle and reaching the ear tip, and the finding that the ear is frequently non-sectored, suggest that this organ derives from an apical type of growth.

Cloning and Characterization of GLOSSY1, a Maize Gene Involved in Cuticle Membrane and Wax Production

“…These results demonstrate that the GL1 protein, like the products of other GLOSSY genes, is not merely involved in the cuticle formation of the green part of the maize seedling. Together, these findings indicate that factors conditioning tissue juvenility may be reactivated after the formation of the lateral meristem (Uhrig et al, 1997). Alternatively, a different control mechanism affecting wax biosynthetic genes should exist in adult plant tissues.…”

On the potential for evolutionary change in meristematic cell lineages through intraorganismal selection

“…Since empirical observations suggest that each component meristem holds between two and four initial cells ( Steeves & Sussex, 1989; Uhrig et al , 1997 ) we will here limit our analysis to α=2, α=3, and only briefly mention the trends for α>3.…”

Axillary Meristem Formation in Rice Requires the WUSCHEL Ortholog TILLERS ABSENT1

“…In grasses, the prophyll is formed as a two-keeled organ, which is also distinct from a foliage leaf (Arber, 1923;Sharman, 1945;Bossinger et al, 1992). Concerning the ear shoot of maize, developmental and clonal analyses suggest that a two-keeled prophyll is formed via congenital fusion of two leaf primordia and that prophyll formation is closely associated with axillary meristem development (Uhrig et al, 1997;Johnston et al, 2010). In rice, the vegetative axillary bud is composed of the axillary meristem, the primordia of foliage leaves, and the prophyll that encloses them (Hoshikawa, 1989).…”