Table 5.

Transformation results from screening of six different inducible promoters driving Cre expression for controlled gene excision.

Promoter	Control					37°C, 1 day					42°C, 2 h/day for 3 days
	Embryos	T0 plants	Single copy event (number)	QE	Excision frequency	Embryos	T0 plants	Single copy event (number)	QE	Excision frequency (%)	Embryos	T0 plants	Single copy event (number)	QE	Excision frequency (%)
					(%)
Hsp17.7	455	59	18	5	27.8	50	6	3	2	66.7	50	20	4	4	100
Hsp26	450	98	0	0	0	50	5	0	0	0	50	21	7	3	43
Rab17	455	127	29	1	3.4	50	10	0	0	0	50	18	0	0	0
Rab21	455	101	22	8	36.4	50	13	1	1	100	50	20	0	0	0
Drp12	450	79	18	2	11.1	50	16	0	0	0	50	22	3	2	66.7
Drp1	438	90	29	8	27.6	50	8	0	0	0	50	27	11	5	45.5
Control (no Cre)	450	182	0	0

Data from two independent transformers was used to determine T0 transformation frequency. The quality events (QE) were identified as single copy, backbone-free, and morphogenic gene-free (excised). The excision frequency was determined as the ratio of the number of excised single-copy events relative to the total single-copy events.

For this study, three different conditions were evaluated: two heat shock treatments (37°C for 1 day and 42°C, 2 h/day for 3 consecutive days) and no heat (control). Data presents the qPCR detection of the number of excised events and excision frequency across the different promoters, and a control construct without the Cre gene, in maize inbred HC69.