CONTROLLING THE RELEASE OF GMPOLLEN WITH MAIZE PLUSHYBRIDS

1
CONTROLLING THE RELEASE OF GM-POLLEN WITH MAIZE
PLUS-HYBRIDS
B. Feil1, U. Weingartner2, and P. Stamp2
1Agro-Projektmanagement, Langhagweg 5, CH-8600
Dübendorf, Switzerland 2Institute of Plant
Sciences, ETH Zurich, Universitätstr. 2, CH-8092
Zurich, Switzerland
Mixtures of 80 male sterile Bt-maize and 20
male fertile non-GM maize may help avoid the
formation of Bt-resistant insect
populations. Higher grain yields through CMS and
xenia In maize, both CMS 3, 5 and xenia
(non-isogenic pollination) 5 can bring about
considerable increases in grain yield (see
example in Fig. 2). This benefit would facilitate
the introduction of the proposed system. The
production of CMS seeds is reliable and cheap.
Introduction Genetically modified (GM) crop
varieties have raised great public concern in
many countries. The dispersal of GM pollen is of
major ecological and agronomic interest for
several reasons 1 genetic contamination of
non-GM crop plants vertical gene transfer to
related weed species possible adverse effects
on non-target organisms
Here we show that the problems linked to the
release of GM pollen can be prevented or at least
reduced with existing technology.
21.4
15.8
8.2
Method and Discussion Prevention of GM pollen
dispersal The release of GM pollen can be
prevented by growing male sterile GM plants in a
mixture with male fertile non-GM plants which act
as pollen donors (Fig. 1).
fertile sterile
Plus-Hybrids Best combination
Fig. 2 Effect of CMS and combined effects of
xenia and CMS (Plus-Hybrid effect) on the grain
yield of the maize hybrid SILPRO (from 5)
Conclusions GM maize varieties should be grown in
male sterile versions to prevent or reduce the
release of viable GM pollen. Our concept can be
applied to crop species that produce a sufficient
surplus of pollen.
Fig. 1 Male fertile plant of the maize hybrid
Delprim on the left-hand side, on the right-hand
side the male sterile version of the same
cultivar. Photo M. Long
Literature 1 Feil B., Schmid J.E., 2002 Pollen
dispersal from maize, wheat, and rye. A
contribution to determining the necessary
isolation distances for the cultivation of
transgenic crops. Shaker Verlag, Aachen, Germany.
ISBN 3-8265-9750-8. 2 Renard M., Delourme R.,
Valée P., 1998 Hybrid rapeseed breeding and
production. In Grégoire T., Monteiro A.A. (Eds.)
Proc. Int. Symp. on Brassicas, Acta Hort. 459,
291-298. 3 Stamp P., Chowchong S., Menzi M.,
Weingartner U., Kaeser O., 2000 Increase in the
yield of cytoplasmic male sterile maize
revisited. Crop Sci. 40, 1586-1587. 4 Thomison
P.R., Geyer A.B., 1999 Evaluation of TC Blends
() used in high oil maize production. Plant
Variet. Seeds 12, 99-111. 5 Weingartner U.,
Kaeser O., Long M., Stamp P. Combining
cytoplasmic male sterility and xenia increases
grain yield of maize hybrids. Crop Sci. 42,1848-
1856. International patent filed PCT/CH01/00440
Male sterile varieties of rapeseed 2 and maize
4 are already being successfully cultivated in
mixtures containing 20 or less male fertile
pollinator plants. Thus, our method can be
adopted immediately. Reduction of GM pollen
dispersal In cases like transgenic
herbicide-resistance, male fertile GM plants
replace the non-GM pollen donors in the mixture,
reducing the release of viable GM pollen from GM
crop stands by about 80.