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REGISTRATIONS OF PARENTAL LINES

Registration of Tx807

^a Soil and Crop Sciences Dep., Texas A&M Univ., College Station, TX 77843-2474
^b Texas A&M Agriculture Research & Extension Center, Hwy. 44 West, Route 2, Box 589, Corpus Christi, TX

^* Corresponding author (javier-betran{at}tamu.edu)

Tx807 (Reg. no. PL-309, PI 619430) was developed as a maize (Zea mays L.) parental line to be used in the production of high-yielding, white-grained maize hybrids with high grain lysine content and aflatoxin resistance. Tx807 was released by the Texas Agricultural Experiment Station at College Station, TX, on May 2001.

Tx807 was developed by pedigree breeding from Pob63 and has a pedigree of Pob63-17-1-1-1-1-1-#-#-B-B. Pob63 [Blanco Dentado-1 quality protein maize (QPM)] is a white dent QPM population from CIMMYT with intermediate to late maturity and hard endosperm. Pob63 is derived from QPM versions of Tuxpeño and La Posta populations and has a tropical/subtropical adaptation. Selections in the S₁ through S₆ selfing generations were made at College Station, TX, based on maturity, grain color, endosperm texture, lodging, and plant characteristics. After S₆, the line has been increased either by sib mating or by bulk selfing.

Tx807 is adapted to southern U.S. areas. It has an intermediate maturity of 2 d later than B73 in the College Station, TX, conditions. It flowers earlier than tropical and subtropical QPM inbreds. Tx807 ears are thin and short with 10-12 kernel rows. Cobs are white (p-ww, p-ww) and thin. Kernels are flint with bright white color (yyy). Plants are short and ear placement is low. Tx807 is an intermediate pollen shedder and has low per se grain yield.

Tx807 carries the opaque-2 mutation and is classified as QPM (Vasal, 2000). It has lysine contents of 4.8 g kg^-1 of grain equivalent to 60% higher lysine content than standard non-QPM inbreds such as B104 (3.0 g kg^-1 of grain). The crude protein content is 123.6 g kg^-1 of grain. The proportion of lysine to total protein is 38.8 g lysine kg^-1 of protein, which is 35% greater than in regular field corn. SDS-PAGE gel of zeins showed reduced -zein and a moderate increase in -zein for Tx807 (Yau, 1995). Tx807 as inbred line per se appears to have resistant factors to Aspergillus flavus infection and aflatoxin production. Preliminary results from laboratory kernel screening assay (Brown et al., 1993) to assess the degree of infection on individual kernels indicate that Tx807 was the most resistant inbred. The line has not been evaluated for reaction to any insect pests.

Tx807 has been evaluated in several hybrid combinations in >25 environments in Texas and Mexico. Tx807 hybrids have desirable agronomic traits including shorter plants, lower ear placement, earlier maturity, lower moisture content at harvest, less root and stalk lodging, easier pericarp removal, greater test weights, and greater hardness relative to other white experimental QPM hybrids. However, Tx807 hybrids have lower 1000-kernel weight, and greater susceptibility to common smut [caused by Usitlago zeae (Beckm.) Unger = U. maydis (DC.) Corda]. Tx807 combines well with high-lysine inbreds Tx811, Bo46w (Bockholt and Rooney, 1992; Gevers and Lake, 1992), and CIMMYT lines CML176 and CML181.

Lysine content is 40% greater in hybrid combinations between Tx811 and other QPM inbreds than in standard corn. In hybrid evaluations for aflatoxin resistance conducted under artificial inoculation with Aspergillus flavus, the hybrid Tx807 x Tx811 had the lowest levels of aflatoxin among 40 commercial and public corn hybrids (Odvody et al., 1996). Since Tx811 is susceptible to aflatoxin, it is likely that Tx807 contributed resistance to Tx807 x Tx811, resulting in reduced aflatoxin levels.

Seed of Tx811 will be maintained and distributed by the Department of Soil & Crop Sciences, Texas A&M University, College Station, TX 77843-2474.

ACKNOWLEDGMENTS

This research was supported in part by the Texas Corn Producers Board. We acknowledge the support of the TAMU Corn Breeding Program, Crop Testing Program, Cereal Quality Lab, and Research Stations staff involved in testing this line. CIMMYT provided the original parental QPM source for this line.

NOTES

Registration by CSSA.

Accepted for publication January 31, 2003.

REFERENCES

• Bockholt, A.J., and L.W. Rooney. 1992. QPM hybrids for the United States. p. 111–121. In E.T. Mertz (ed.) Quality protein maize. American Association of Cereal Chemists, St. Paul, MN.
• Brown, R.L., P.J. Cotty, T.E. Cleveland, N.W. Widstrom. 1993. Living maize embryo influences accumulation of aflatoxin in maize kernels. J. Food Prot. 56:967–971.
• Gevers, H.O., and J.K. Lake. 1992. Development of modified Opaque-2 Maize in South Africa. p. 49–78. In E.T. Mertz (ed.) Quality protein maize. American Association of Cereal Chemists, St. Paul, MN.
• Odvody, G.N., S.D. Livingston, T.J. Gerik, and C.G. Coffman. 1996. Field screening commercial corn hybrids for vulnerability to aflatoxin in south and central Texas. Rep. to the Texas Corn Producers Board. Texas Corn Producers Board, Corpus Christi, TX.
• Vasal, S. 2000. High quality protein maize. p. 85–129. In A.R. Hallauer (ed.) Specialty corns. CRC Press, Boca Raton, FL.
• Yau, J. 1995. Characterization of endosperm proteins in quality protein maize. Ph.D. diss. Texas A&M Univ., College Station, TX.

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