Vol. 51—1997 - NorthEastern Weed Science Society

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greenhouse for pollination and seed production to determine the inheritance of herbicide resistance.
Transgenic plants remaining in the field were destroyed, before flowering, with another herbicide.
Progeny of transgenic mother plants showed germination rates ranging from 57 to 99%, compared
with control seeds fIjom 47 to 93%. Tests for herbicide resistance are incomplete but indicate that
sev.eral of the mothr· plants behave as heterozygotes with approximately 50 percent of progeny
resistant,
The implications Ior herbicide
resistant turfgrass
The excelleJt playing surfaces desired by golf course managers require intensive turfgrass
cultural practices for their maintenance. These include the use of fertilizers, and pesticides,
including some herbicides that may be highly toxic to nontarget organisms or may have the
potential to pollute ground water. The production of turfgrasses that can be treated with less toxic
herbicides and that fequire fewer fungicide and insecticide treatments, through biotechnology by
transformation, should help by reducing dependence on chemicals with adverse environmental
impacts. Our reports of successful transformation of creeping bentgrass have attracted
considerable interest among commercial and other breeders of this important turfgrass species.
Because of this widespread interest it is important to ensure that commercial introduction occurs in
a way that imposes minimal destructive environmental impacts and maximizes the benefits that
biotechnology offe~s over the long term.
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The introdultion of transgenic turfgrasses poses two potential environmental risks: the
transgenic forms themselves may become important weeds or, through horizontal now of the
trans genes, produce forms of related weed grasses that are more difficult to control. Transgenic
forms of turfgrass ~at are herbicide resistant may also threaten the viability of programs to
introduce the same iherbicide resistance genes carried by the turfgrasses into such widely grown
crops as soybean and com. There is presently considerable commercial activity in testing and
releasing new cultivarswith resistance to such broad spectrum herbicides as Round-up'Dt
(glyphosate), Purs~itTM (imizethapyr), and Finale lM (glufosinate or bialaphos).
The commercial owners of the major herbicide resistance genes presently available are
reluctant to allow their use in turfgrass because they fear that release of herbicide resistant grass
varieties may compromise their use of the same genes, with correspondingly larger scale
applications of the~r herbicides, in major agronomic crops like corn, soybean and cotton. They
reason that the transgenic turfgrass itself may become a weed and/or that the transgene may spread
to other grasses that are already weeds and, through introgression, produce weedy forms that can
no longer be contrflled by the herbicide in question.
The herbicfde resistant creeping bentgrass (Agrostis palustris Huds.) clones in our
laboratory provide' a means of assessing these risks through laboratory and field studies using the
trait herbicide resistance to monitor the occurrence and frequency of gene How under conditions
designed to maximize the opportunities for cross pollination. We plan to study the horizontal
transfer of a trans gene (bar) for resistance to the herbicide Finale between creeping bentgrass
clones and other grasses within the genus Agrostis, and in the related genus Eragrostis, in
greenhouse and field studies of out-crossing. Some of these species are recognized as weeds. The
viability and fertilfty of resultant hybrids between A. palustris. and the other species, detected by
their carrying the gene for bialaphos resistance (bar), will also be assessed in the greenhouse and
field. ]
Agrostis p~lustris,
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or creeping bentgrass, is not recorded as a weed of field crops although
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