Table 1.

The phenotypic characterization of maize–Tripsacum intergeneric hybrids

Genotype	Gsf1/Ts2	Gsf1/ts2	gsf1/Ts2	gsf1/ts2
Plants flowered, n	6	2	5	4
Branches per inflorescence	6–12	4–6	6–12	6–10
Paired spikelets on the main branch (X2)	21–32	27	25–40	30–39
Solitary spikelets on main axis	0–4	0	0–5	0–2
Pistillate spikelets on the main axis	0–4	0	0–3	(27–34) × 2

Intergeneric hybrid plants were genotyped by PCR analysis; Ts2 and ts2 alleles were identified by a microsatellite repeat located 3 kb downstream of the Ts2 gene in maize (19). Gsf1 and gsf1 alleles were distinguished using primers P1 and P2 (shown in Fig. 5B) amplifying a 300-bp fragment from gsf1 mutant DNA and a 1.6-kb product from wild-type DNA. Thirteen plants (genotyped as Gsf1/Ts2, Gsf1/ts2, or gsf1/Ts2) produced normal inflorescences (Fig. 7A). Four plants (genotyped as gsf1/ts2) formed feminized inflorescences (Fig. 7B).