Figure 1.

Maize tassel and anther development. Fertile maize anthers contain four locules. At ~0.1 mm there are about 50 cells in each locule. The line drawing of a transverse section (a) shows that the L2-derived (L2-d) cells are distinguishable from the L1-derived epidermis (ep) within a locule. At 0.3 mm (b) the L2-d has developed into endothecium (en), secondary parietal (2p) and archesporial cell types (ar). At 1.0 mm (c) middle layer (ml) and tapetum (tp) are apparent after a periclinal division of the 2p layer cells. Apart from the general morphology of no anther exertion, the mature tassel on the male-sterile am1-praI plant (e) is highly similar to a fertile sibling tassel (d) with the same number of tassel branches. In contrast, the am1-489 tassels (g) have fewer side branches (5-6) than fertile siblings (f). The individual reproductive units on the tassel are spikelets (sp). There are two florets in each spikelet, and each floret contains 3 anthers (h). The adaxial, upper florets used in the array experiment are developmentally 1 day ahead of the abaxial, lower florets. Anthers on a male sterile am1-praI plant (i) can reach 4-5 mm in length before they shrivel and degenerate; am1-489 anthers show growth arrest at 2-2.5 mm (data not shown). Based on cytological evidence and published results, anther sizes and the developmental timeline showing days after locular primordium initiation are diagrammed (j).

Nan et al. BMC Plant Biology 2011 11:120   doi:10.1186/1471-2229-11-120
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