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. 2004 Sep 21;101(39):13974–13975. doi: 10.1073/pnas.0405903101

Fig. 1.

Fig. 1.

Response of morning glories (Ipomea purpurea) to being sprayed by RoundUp. (A) Morning glories in a RoundUp Ready field of soybeans. The soybeans were genetically engineered to withstand application of the herbicide RoundUp, which has been sprayed on the field. The morning glory weeds are flowering despite being sprayed by the herbicide because they have evolved tolerance. The vegetation on the soybeans is brown because they are nearly ready to harvest; earlier in the year they were green. (B) A tolerant morning glory showing that tolerant plants are not resistant to herbicide damage. After contacting RoundUp, the leaves exhibit chlorosis and die. Tolerant plants later regrow (as in C) but remain stunted. (C) Stunted leaves on a glyphosate-tolerant morning glory. Both resistance and tolerance can improve the ability of individuals to survive and reproduce under assault by herbicides. Resistance does so by reducing damage, whereas tolerance does so by reducing the fitness loss despite damage. Photographs courtesy of Regina Baucom (A and C) and R. Scott Cornman (B).