Figure 9.

Unfertilized Ovules Failed to Form Seed Coat Transfer Cells.

(A) Cross-section of a wild-type seed at 12 DAA showing the presence of transfer cells at the innermost layer of the inner seed coat.

(B) Unfertilized ovules had a disorganized mass of numerous small cells rather than transfer cells (arrows) by 12 DAA. Also note the residual nucellus and the absence of endosperm tissue.

(C) Cross-section of a wild-type seed at 12 DAA viewed by dark-field microscopy showing the wall ingrowth (arrowheads) of the transfer cells toward the cellularized endosperm.

(D) Cross-section of an unfertilized ovule viewed by dark-field microscopy showing numerous small cells at the innermost layer of the inner seed coat, which lacked the wall ingrowths characteristic of the transfer cells shown in (C). Also note the presence of the residual nucellus tissue and the absence of endosperm.

en, endosperm; isc, inner seed coat; n, nucellus; tc, transfer cell. Bar = 60 μm in (A). The scale in (B) to (D) is the same as that in (A).