The Biology of Zea mays L. ssp. Mays

A detailed review of the biology of Z. mays is presented in Appendix 1: The Biology of Zea mays and its Cultivation in Southeast Asia.

MON 810 Case Study

Genetic and Phenotypic Variability
The behavior and characteristics of maize line MON 810 have been studied in a range of field environments in the United States and in Europe since 1992. The assessment of the interaction of MON 810 with the environment has included studies on: susceptibility to insects and diseases; survival capacity (volunteers); seed multiplication capacity (yields); Cry1Ab protein expression in leaves and grain; seed composition analysis; safety for birds; and safety for mammals. No significant differences have been observed between this line and other maize varieties apart from protection from certain lepidopteran insects.

Modes and/or rate of reproduction
Extensive observations recorded by field co-operators in 1993, 1994, and 1995 field trials demonstrate that the mode and rate of reproduction of MON 810 are typical of other maize varieties. This maize line continues to exhibit the same separate staminate (tassel) and pistillate (silk) features. Pollen was produced entirely in the staminate inflorescence with anthesis (pollen shed) synchronous with silk emergence. No differences in seed or plant maturity have been observed. In some trials, non-insect protected plants matured more rapidly due to premature senescence caused by stalk boring insect damage.

Expression Levels of the Cry1Ab, CP4 EPSPS, GOX, and NPTII Proteins
Protein expression in young leaf, grain, whole plant, and pollen tissues harvested from six field locations in 1994 was determined by enzyme linked immunosorbent assay (ELISA) (Harlow & Lane 1988) and Western blot (Matsudaira 1987). The results are presented in Table 1.

Yield Characteristics
Yield comparisons for MON 810 and representative controls were assessed in up to nine locations in the U.S.. A comparison of a non-transgenic hybrid with the same hybrid in which one parent was a backcross derived MON 810 line showed no significant difference between these hybrids in yield (Table 2).

Disease and Pest Susceptibilities
MON 810 was tested in the U.S. in over sixty plantings in at least ten states in addition to Puerto Rico. Detailed monitoring for the disease and insect susceptibility of this line versus non-transgenic control plants was performed in 1993 and 1994. Plant examination was not restricted to obviously diseased plants; healthy plants were examined for abnormal growth and the development of sub-chronic disease symptomology. No differences in agronomic quality, disease, or insect susceptibility other than European corn borer control were detected between MON 810 and non-transgenic plants. Diseases observed included northern leaf blight (Exserohilum turcicum), southern leaf blight (Bipolaris maydis), bacterial leaf blight (Erwinia stewartii), common corn smut (Ustilago maydis), maize stripe virus and common maize rust (Puccinia sorghi).

Insect-protected maize hybrids will be managed by the grower the same as they presently manage the growth and production of maize hybrids with the exception that each grower is expected to be required to implement an insect resistance management plan (see Insect Resistance Management). The purpose of the insect management plan is to delay or prevent the target insects from building resistance to the Cry1Ab protein.