Fig. 1.

a–e The promoter of ZmMRP-1 shows transfer cell specificity in maize. GUS staining pattern of ZmMRP-1prom-GUS transgenic kernels at 10 (a), 14 (b) 20 (c) and 30 (d) days after pollination (DAP). e Basal area of the endosperm from c at a higher magnification. An indigo precipitate, indicating GUS activity, is observed in the transfer cell layer (TCL), which extends at the base of the endosperm, in front of the phloem terminals at the pedicel. En endosperm, Em embryo, Pd pedicel. Bars  1 mm