harnessing endophytic and epiphytic relationships

Joel Brooks Gruver (jgruv@wam.umd.edu)
Wed, 13 Oct 1999 12:06:20 -0400 (EDT)

Hello to all...

While pondering the ecological implications of crops with resistance
to herbivory through plant expression of microbial endotoxins (e.g. BT), I
wondered about the potential for increased utilization of endophytic and
epiphytic microbe/plant relationships to manage phytophagous insects.

My understanding is that some turf grasses (e.g. tall fescue) have few
insect pest problems as a result of their hosting of endophytic microbes
which live within the plant and produce compounds that are toxic to plant
feeders... yet this same relationship causes serious problems for
livestock that graze upon endohyte infected forages.

I wondering about the potential for utilizing endophytes to protect grain
species from insect herbivory. Would the endophyte's endotoxins be
expressed in the grain causing problems for grain consumers ? My vague
understanding of the tall fescue endophyte lifecycle is that the endophyte
is carried by the seed.

A major focus in the Ecology of Agriculture class that I am teaching is
positive interactions between species and the potential for much greater
utilization of these interactions in agriculture.

What would be the benefits of having an endotoxin synthesized by an
endophytic organism rather than by the plant itself ?

My understanding is the BT is not an effective epiphytic organism
otherwise live cultures could be sprayed on crop foliage that would
persist and multiply. Are there adapted epiphytic microbes that can be
used to reduce insect feeding ?

What would be the benefits of having an endotoxin synthesized by an
adapted epiphytic microbe rather than the host plant ?

What is the potential for utilizing endophytic and epiphytic/plant
relationships in agricultural systems ?

Joel Gruver
Center for Agriculture, Food and Environment
Tufts University

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