Figure 1.

blk1-R Mutants Exhibit Progressive Defects in Shoot Meristem Maintenance.

(A) and (B) 21-DAG SAMs in B73 background; red lines indicate reference points for measurement for height and width. Bars = 50 μm.

(A) Wild-type (wt) SAM.

(B) blk1-R SAM is reduced in height.

(C) blk1-R meristems (black bars) are shorter than wild-type SAMs (gray bars) in the B73, W22, and W23 inbred backgrounds at 21 DAG. Note that SAM height is essentially unaffected at 7 DAG. Error bars indicate ±se; n = 15.

(D) to (G) Mature maize inflorescences.

(D) Wild-type tassel.

(E) blk1-R mutant tassel has barren branched devoid of florets.

(F) Wild-type ear.

(G) blk1-R ear is greatly reduced in size and has few florets.

(H) to (K) Scanning electron microscopy of immature maize inflorescences, SPMs, and tassel branch meristems (bm). Bars = 500 μm.

(H) Wild-type tassel primordium.

(I) blk1-R tassel primordium has aberrant branches and fewer SPMs.

(J) Wild-type ear primordium.

(K) blk1-R ear primordium is truncated and has fewer SPMs.